//! Recursive-descent JavaScript parser with Pratt expression parsing.
//!
//! Transforms a token stream from the [`crate::lexer::Lexer`] into an
//! [`crate::ast::Program`] AST.

use crate::ast::*;
use crate::lexer::{LexError, Lexer, SourcePos, Span, Token, TokenKind};
use std::fmt;

// ── Error ───────────────────────────────────────────────────

/// An error produced during parsing.
#[derive(Debug, Clone, PartialEq)]
pub struct ParseError {
    pub message: String,
    pub pos: SourcePos,
}

impl fmt::Display for ParseError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "ParseError at {}:{}: {}",
            self.pos.line, self.pos.col, self.message
        )
    }
}

impl From<LexError> for ParseError {
    fn from(e: LexError) -> Self {
        ParseError {
            message: e.message,
            pos: e.pos,
        }
    }
}

// ── Parser ──────────────────────────────────────────────────

pub struct Parser {
    tokens: Vec<Token>,
    pos: usize,
    /// When false, `in` is not treated as a binary operator (for-init disambiguation).
    allow_in: bool,
}

impl Parser {
    /// Parse source as a script.
    pub fn parse(source: &str) -> Result<Program, ParseError> {
        let tokens = Lexer::tokenize(source)?;
        let mut parser = Parser {
            tokens,
            pos: 0,
            allow_in: true,
        };
        parser.parse_program(SourceType::Script)
    }

    /// Parse source as a module.
    pub fn parse_module(source: &str) -> Result<Program, ParseError> {
        let tokens = Lexer::tokenize(source)?;
        let mut parser = Parser {
            tokens,
            pos: 0,
            allow_in: true,
        };
        parser.parse_program(SourceType::Module)
    }

    // ── Token navigation ────────────────────────────────────

    fn peek(&self) -> &Token {
        &self.tokens[self.pos.min(self.tokens.len() - 1)]
    }

    fn peek_kind(&self) -> &TokenKind {
        &self.peek().kind
    }

    fn peek_ahead(&self, offset: usize) -> &TokenKind {
        let idx = (self.pos + offset).min(self.tokens.len() - 1);
        &self.tokens[idx].kind
    }

    fn at(&self, kind: &TokenKind) -> bool {
        std::mem::discriminant(self.peek_kind()) == std::mem::discriminant(kind)
    }

    fn at_eof(&self) -> bool {
        matches!(self.peek_kind(), TokenKind::Eof)
    }

    fn advance(&mut self) -> Token {
        let tok = self.tokens[self.pos.min(self.tokens.len() - 1)].clone();
        if self.pos < self.tokens.len() - 1 {
            self.pos += 1;
        }
        tok
    }

    fn eat(&mut self, kind: &TokenKind) -> bool {
        if self.at(kind) {
            self.advance();
            true
        } else {
            false
        }
    }

    fn expect(&mut self, kind: &TokenKind) -> Result<Token, ParseError> {
        if self.at(kind) {
            Ok(self.advance())
        } else {
            Err(self.error(format!("expected {:?}, found {:?}", kind, self.peek_kind())))
        }
    }

    fn expect_semicolon(&mut self) -> Result<(), ParseError> {
        if self.eat(&TokenKind::Semicolon) {
            return Ok(());
        }
        // ASI: insert semicolon before `}`, at EOF, or after newline
        if matches!(self.peek_kind(), TokenKind::RBrace | TokenKind::Eof)
            || self.peek().preceded_by_newline
        {
            return Ok(());
        }
        Err(self.error(format!("expected `;`, found {:?}", self.peek_kind())))
    }

    fn expect_identifier(&mut self) -> Result<String, ParseError> {
        match self.peek_kind().clone() {
            TokenKind::Identifier(name) => {
                self.advance();
                Ok(name)
            }
            kind if is_contextual_identifier(&kind) => {
                let name = format!("{kind}");
                self.advance();
                Ok(name)
            }
            _ => Err(self.error(format!("expected identifier, found {:?}", self.peek_kind()))),
        }
    }

    /// Per ES5+, an "identifier name" allows any identifier OR any keyword.
    /// Used for property access after `.` and similar positions where reserved
    /// words are legal property names.
    fn expect_identifier_name(&mut self) -> Result<String, ParseError> {
        match self.peek_kind().clone() {
            TokenKind::Identifier(name) => {
                self.advance();
                Ok(name)
            }
            kind if is_keyword(&kind) => {
                let name = format!("{kind}");
                self.advance();
                Ok(name)
            }
            _ => Err(self.error(format!(
                "expected identifier name, found {:?}",
                self.peek_kind()
            ))),
        }
    }

    fn expect_module_export_name(&mut self) -> Result<(String, bool), ParseError> {
        match self.peek_kind().clone() {
            TokenKind::Identifier(name) => {
                self.advance();
                Ok((name, true))
            }
            TokenKind::String(name) => {
                self.advance();
                Ok((name, false))
            }
            kind if is_keyword(&kind) => {
                let binding_ok = is_contextual_identifier(&kind);
                let name = format!("{kind}");
                self.advance();
                Ok((name, binding_ok))
            }
            _ => Err(self.error(format!(
                "expected module export name, found {:?}",
                self.peek_kind()
            ))),
        }
    }

    fn start_span(&self) -> SourcePos {
        self.peek().span.start
    }

    fn end_span(&self) -> SourcePos {
        if self.pos > 0 {
            self.tokens[self.pos - 1].span.end
        } else {
            self.peek().span.start
        }
    }

    fn span_from(&self, start: SourcePos) -> Span {
        Span {
            start,
            end: self.end_span(),
        }
    }

    fn error(&self, message: String) -> ParseError {
        ParseError {
            message,
            pos: self.peek().span.start,
        }
    }

    // ── Program ─────────────────────────────────────────────

    fn parse_program(&mut self, source_type: SourceType) -> Result<Program, ParseError> {
        let start = self.start_span();
        let mut body = Vec::new();
        while !self.at_eof() {
            body.push(self.parse_statement_list_item()?);
        }
        Ok(Program {
            body,
            source_type,
            span: self.span_from(start),
        })
    }

    fn parse_statement_list_item(&mut self) -> Result<Stmt, ParseError> {
        match self.peek_kind() {
            TokenKind::Function => self.parse_function_declaration(),
            TokenKind::Class => self.parse_class_declaration(),
            TokenKind::Var | TokenKind::Let | TokenKind::Const => {
                self.parse_variable_declaration_stmt()
            }
            TokenKind::Async
                if matches!(self.peek_ahead(1), TokenKind::Function)
                    && !self.tokens[self.pos + 1].preceded_by_newline =>
            {
                self.parse_async_function_declaration()
            }
            TokenKind::Import
                if !matches!(self.peek_ahead(1), TokenKind::LParen | TokenKind::Dot) =>
            {
                self.parse_import_declaration()
            }
            TokenKind::Export => self.parse_export_declaration(),
            _ => self.parse_statement(),
        }
    }

    // ── Statements ──────────────────────────────────────────

    fn parse_statement(&mut self) -> Result<Stmt, ParseError> {
        match self.peek_kind() {
            TokenKind::LBrace => self.parse_block_stmt(),
            TokenKind::Semicolon => {
                let start = self.start_span();
                self.advance();
                Ok(Stmt {
                    kind: StmtKind::Empty,
                    span: self.span_from(start),
                })
            }
            TokenKind::If => self.parse_if(),
            TokenKind::For => self.parse_for(),
            TokenKind::While => self.parse_while(),
            TokenKind::Do => self.parse_do_while(),
            TokenKind::Switch => self.parse_switch(),
            TokenKind::Try => self.parse_try(),
            TokenKind::Return => self.parse_return(),
            TokenKind::Throw => self.parse_throw(),
            TokenKind::Break => self.parse_break(),
            TokenKind::Continue => self.parse_continue(),
            TokenKind::With => self.parse_with(),
            TokenKind::Debugger => {
                let start = self.start_span();
                self.advance();
                self.expect_semicolon()?;
                Ok(Stmt {
                    kind: StmtKind::Debugger,
                    span: self.span_from(start),
                })
            }
            // Labeled statement: `ident: stmt`
            TokenKind::Identifier(_) if matches!(self.peek_ahead(1), TokenKind::Colon) => {
                self.parse_labeled()
            }
            // Variable declarations can also appear as statements
            TokenKind::Var | TokenKind::Let | TokenKind::Const => {
                self.parse_variable_declaration_stmt()
            }
            // Function/class declarations in statement position
            TokenKind::Function => self.parse_function_declaration(),
            TokenKind::Class => self.parse_class_declaration(),
            TokenKind::Async
                if matches!(self.peek_ahead(1), TokenKind::Function)
                    && !self.tokens[self.pos + 1].preceded_by_newline =>
            {
                self.parse_async_function_declaration()
            }
            _ => self.parse_expression_statement(),
        }
    }

    fn parse_block_stmt(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        let body = self.parse_block_body()?;
        Ok(Stmt {
            kind: StmtKind::Block(body),
            span: self.span_from(start),
        })
    }

    fn parse_block_body(&mut self) -> Result<Vec<Stmt>, ParseError> {
        self.expect(&TokenKind::LBrace)?;
        let mut body = Vec::new();
        while !self.at(&TokenKind::RBrace) && !self.at_eof() {
            body.push(self.parse_statement_list_item()?);
        }
        self.expect(&TokenKind::RBrace)?;
        Ok(body)
    }

    fn parse_expression_statement(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        let expr = self.parse_expression()?;
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::Expr(expr),
            span: self.span_from(start),
        })
    }

    fn parse_if(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::If)?;
        self.expect(&TokenKind::LParen)?;
        let test = self.parse_expression()?;
        self.expect(&TokenKind::RParen)?;
        let consequent = Box::new(self.parse_statement()?);
        let alternate = if self.eat(&TokenKind::Else) {
            Some(Box::new(self.parse_statement()?))
        } else {
            None
        };
        Ok(Stmt {
            kind: StmtKind::If {
                test,
                consequent,
                alternate,
            },
            span: self.span_from(start),
        })
    }

    fn parse_while(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::While)?;
        self.expect(&TokenKind::LParen)?;
        let test = self.parse_expression()?;
        self.expect(&TokenKind::RParen)?;
        let body = Box::new(self.parse_statement()?);
        Ok(Stmt {
            kind: StmtKind::While { test, body },
            span: self.span_from(start),
        })
    }

    fn parse_do_while(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Do)?;
        let body = Box::new(self.parse_statement()?);
        self.expect(&TokenKind::While)?;
        self.expect(&TokenKind::LParen)?;
        let test = self.parse_expression()?;
        self.expect(&TokenKind::RParen)?;
        // ASI special case (ECMA-262 12.10.1): the terminating semicolon of a
        // `do-while` statement is inserted automatically whenever it is absent,
        // even without an intervening line terminator. So `do {} while (x) y`
        // and `do {} while (x) return 1` both parse, with `y`/`return` starting
        // a new statement. Consume an explicit `;` if present; otherwise rely on
        // unconditional ASI rather than requiring a newline.
        self.eat(&TokenKind::Semicolon);
        Ok(Stmt {
            kind: StmtKind::DoWhile { body, test },
            span: self.span_from(start),
        })
    }

    fn parse_for(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::For)?;
        let is_await = self.eat(&TokenKind::Await);
        self.expect(&TokenKind::LParen)?;

        // Check for for-in/for-of with var/let/const
        if matches!(
            self.peek_kind(),
            TokenKind::Var | TokenKind::Let | TokenKind::Const
        ) {
            let var_kind = match self.peek_kind() {
                TokenKind::Var => VarKind::Var,
                TokenKind::Let => VarKind::Let,
                TokenKind::Const => VarKind::Const,
                _ => unreachable!(),
            };
            self.advance();
            let pattern = self.parse_binding_pattern()?;

            if self.eat(&TokenKind::In) {
                let right = self.parse_expression()?;
                self.expect(&TokenKind::RParen)?;
                let body = Box::new(self.parse_statement()?);
                return Ok(Stmt {
                    kind: StmtKind::ForIn {
                        left: ForInOfLeft::VarDecl {
                            kind: var_kind,
                            pattern,
                        },
                        right,
                        body,
                    },
                    span: self.span_from(start),
                });
            }
            if self.eat(&TokenKind::Of) {
                let right = self.parse_assignment_expression()?;
                self.expect(&TokenKind::RParen)?;
                let body = Box::new(self.parse_statement()?);
                return Ok(Stmt {
                    kind: StmtKind::ForOf {
                        left: ForInOfLeft::VarDecl {
                            kind: var_kind,
                            pattern,
                        },
                        right,
                        body,
                        is_await,
                    },
                    span: self.span_from(start),
                });
            }

            // Regular for: parse remaining declarators
            let mut declarators = vec![VarDeclarator {
                span: pattern.span,
                init: if self.eat(&TokenKind::Assign) {
                    Some(self.parse_assignment_expression_no_in()?)
                } else {
                    None
                },
                pattern,
            }];
            while self.eat(&TokenKind::Comma) {
                declarators.push(self.parse_var_declarator_no_in()?);
            }
            self.expect(&TokenKind::Semicolon)?;
            let test = if self.at(&TokenKind::Semicolon) {
                None
            } else {
                Some(self.parse_expression()?)
            };
            self.expect(&TokenKind::Semicolon)?;
            let update = if self.at(&TokenKind::RParen) {
                None
            } else {
                Some(self.parse_expression()?)
            };
            self.expect(&TokenKind::RParen)?;
            let body = Box::new(self.parse_statement()?);
            return Ok(Stmt {
                kind: StmtKind::For {
                    init: Some(ForInit::VarDecl {
                        kind: var_kind,
                        declarators,
                    }),
                    test,
                    update,
                    body,
                },
                span: self.span_from(start),
            });
        }

        // No var/let/const
        if self.eat(&TokenKind::Semicolon) {
            // for(; ...)
            let test = if self.at(&TokenKind::Semicolon) {
                None
            } else {
                Some(self.parse_expression()?)
            };
            self.expect(&TokenKind::Semicolon)?;
            let update = if self.at(&TokenKind::RParen) {
                None
            } else {
                Some(self.parse_expression()?)
            };
            self.expect(&TokenKind::RParen)?;
            let body = Box::new(self.parse_statement()?);
            return Ok(Stmt {
                kind: StmtKind::For {
                    init: None,
                    test,
                    update,
                    body,
                },
                span: self.span_from(start),
            });
        }

        // Expression init — might be for-in/for-of
        let old_allow_in = self.allow_in;
        self.allow_in = false;
        let init_expr = self.parse_expression()?;
        self.allow_in = old_allow_in;

        if self.eat(&TokenKind::In) {
            let pattern = self.expr_to_pattern(&init_expr)?;
            let right = self.parse_expression()?;
            self.expect(&TokenKind::RParen)?;
            let body = Box::new(self.parse_statement()?);
            return Ok(Stmt {
                kind: StmtKind::ForIn {
                    left: ForInOfLeft::Pattern(pattern),
                    right,
                    body,
                },
                span: self.span_from(start),
            });
        }
        if self.eat(&TokenKind::Of) {
            let pattern = self.expr_to_pattern(&init_expr)?;
            let right = self.parse_assignment_expression()?;
            self.expect(&TokenKind::RParen)?;
            let body = Box::new(self.parse_statement()?);
            return Ok(Stmt {
                kind: StmtKind::ForOf {
                    left: ForInOfLeft::Pattern(pattern),
                    right,
                    body,
                    is_await,
                },
                span: self.span_from(start),
            });
        }

        self.expect(&TokenKind::Semicolon)?;
        let test = if self.at(&TokenKind::Semicolon) {
            None
        } else {
            Some(self.parse_expression()?)
        };
        self.expect(&TokenKind::Semicolon)?;
        let update = if self.at(&TokenKind::RParen) {
            None
        } else {
            Some(self.parse_expression()?)
        };
        self.expect(&TokenKind::RParen)?;
        let body = Box::new(self.parse_statement()?);
        Ok(Stmt {
            kind: StmtKind::For {
                init: Some(ForInit::Expr(init_expr)),
                test,
                update,
                body,
            },
            span: self.span_from(start),
        })
    }

    fn parse_switch(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Switch)?;
        self.expect(&TokenKind::LParen)?;
        let discriminant = self.parse_expression()?;
        self.expect(&TokenKind::RParen)?;
        self.expect(&TokenKind::LBrace)?;
        let mut cases = Vec::new();
        while !self.at(&TokenKind::RBrace) && !self.at_eof() {
            let case_start = self.start_span();
            let test = if self.eat(&TokenKind::Case) {
                Some(self.parse_expression()?)
            } else {
                self.expect(&TokenKind::Default)?;
                None
            };
            self.expect(&TokenKind::Colon)?;
            let mut consequent = Vec::new();
            while !matches!(
                self.peek_kind(),
                TokenKind::Case | TokenKind::Default | TokenKind::RBrace
            ) && !self.at_eof()
            {
                consequent.push(self.parse_statement_list_item()?);
            }
            cases.push(SwitchCase {
                test,
                consequent,
                span: self.span_from(case_start),
            });
        }
        self.expect(&TokenKind::RBrace)?;
        Ok(Stmt {
            kind: StmtKind::Switch {
                discriminant,
                cases,
            },
            span: self.span_from(start),
        })
    }

    fn parse_try(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Try)?;
        let block = self.parse_block_body()?;

        let handler = if self.eat(&TokenKind::Catch) {
            let catch_start = self.start_span();
            let param = if self.eat(&TokenKind::LParen) {
                let pat = self.parse_binding_pattern()?;
                self.expect(&TokenKind::RParen)?;
                Some(pat)
            } else {
                None
            };
            let body = self.parse_block_body()?;
            Some(CatchClause {
                param,
                body,
                span: self.span_from(catch_start),
            })
        } else {
            None
        };

        let finalizer = if self.eat(&TokenKind::Finally) {
            Some(self.parse_block_body()?)
        } else {
            None
        };

        if handler.is_none() && finalizer.is_none() {
            return Err(self.error("try requires catch or finally".into()));
        }

        Ok(Stmt {
            kind: StmtKind::Try {
                block,
                handler,
                finalizer,
            },
            span: self.span_from(start),
        })
    }

    fn parse_return(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Return)?;
        // Restricted production: newline after return inserts semicolon
        let argument = if matches!(
            self.peek_kind(),
            TokenKind::Semicolon | TokenKind::RBrace | TokenKind::Eof
        ) || self.peek().preceded_by_newline
        {
            None
        } else {
            Some(self.parse_expression()?)
        };
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::Return(argument),
            span: self.span_from(start),
        })
    }

    fn parse_throw(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Throw)?;
        if self.peek().preceded_by_newline {
            return Err(ParseError {
                message: "newline not allowed after throw".into(),
                pos: self.peek().span.start,
            });
        }
        let argument = self.parse_expression()?;
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::Throw(argument),
            span: self.span_from(start),
        })
    }

    fn parse_break(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Break)?;
        let label = if !self.peek().preceded_by_newline {
            if let TokenKind::Identifier(name) = self.peek_kind().clone() {
                self.advance();
                Some(name)
            } else {
                None
            }
        } else {
            None
        };
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::Break(label),
            span: self.span_from(start),
        })
    }

    fn parse_continue(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Continue)?;
        let label = if !self.peek().preceded_by_newline {
            if let TokenKind::Identifier(name) = self.peek_kind().clone() {
                self.advance();
                Some(name)
            } else {
                None
            }
        } else {
            None
        };
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::Continue(label),
            span: self.span_from(start),
        })
    }

    fn parse_labeled(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        let label = self.expect_identifier()?;
        self.expect(&TokenKind::Colon)?;
        let body = Box::new(self.parse_statement()?);
        Ok(Stmt {
            kind: StmtKind::Labeled { label, body },
            span: self.span_from(start),
        })
    }

    fn parse_with(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::With)?;
        self.expect(&TokenKind::LParen)?;
        let object = self.parse_expression()?;
        self.expect(&TokenKind::RParen)?;
        let body = Box::new(self.parse_statement()?);
        Ok(Stmt {
            kind: StmtKind::With { object, body },
            span: self.span_from(start),
        })
    }

    // ── Variable declarations ───────────────────────────────

    fn parse_variable_declaration_stmt(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        let kind = match self.peek_kind() {
            TokenKind::Var => VarKind::Var,
            TokenKind::Let => VarKind::Let,
            TokenKind::Const => VarKind::Const,
            _ => return Err(self.error("expected var, let, or const".into())),
        };
        self.advance();
        let mut declarators = vec![self.parse_var_declarator()?];
        while self.eat(&TokenKind::Comma) {
            declarators.push(self.parse_var_declarator()?);
        }
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::VarDecl { kind, declarators },
            span: self.span_from(start),
        })
    }

    fn parse_var_declarator(&mut self) -> Result<VarDeclarator, ParseError> {
        let start = self.start_span();
        let pattern = self.parse_binding_pattern()?;
        let init = if self.eat(&TokenKind::Assign) {
            Some(self.parse_assignment_expression()?)
        } else {
            None
        };
        Ok(VarDeclarator {
            pattern,
            init,
            span: self.span_from(start),
        })
    }

    fn parse_var_declarator_no_in(&mut self) -> Result<VarDeclarator, ParseError> {
        let start = self.start_span();
        let pattern = self.parse_binding_pattern()?;
        let init = if self.eat(&TokenKind::Assign) {
            Some(self.parse_assignment_expression_no_in()?)
        } else {
            None
        };
        Ok(VarDeclarator {
            pattern,
            init,
            span: self.span_from(start),
        })
    }

    // ── Binding patterns (destructuring) ────────────────────

    fn parse_binding_pattern(&mut self) -> Result<Pattern, ParseError> {
        match self.peek_kind() {
            TokenKind::LBracket => self.parse_array_pattern(),
            TokenKind::LBrace => self.parse_object_pattern(),
            _ => {
                let start = self.start_span();
                let name = self.expect_identifier()?;
                Ok(Pattern {
                    kind: PatternKind::Identifier(name),
                    span: self.span_from(start),
                })
            }
        }
    }

    fn parse_array_pattern(&mut self) -> Result<Pattern, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::LBracket)?;
        let mut elements = Vec::new();
        let mut rest = None;
        while !self.at(&TokenKind::RBracket) && !self.at_eof() {
            if self.eat(&TokenKind::Comma) {
                elements.push(None);
                continue;
            }
            if self.at(&TokenKind::Ellipsis) {
                self.advance();
                rest = Some(Box::new(self.parse_binding_pattern()?));
                self.eat(&TokenKind::Comma); // trailing comma after rest
                break;
            }
            let mut pat = self.parse_binding_pattern()?;
            if self.eat(&TokenKind::Assign) {
                let right = self.parse_assignment_expression()?;
                let span = Span {
                    start: pat.span.start,
                    end: right.span.end,
                };
                pat = Pattern {
                    kind: PatternKind::Assign {
                        left: Box::new(pat),
                        right: Box::new(right),
                    },
                    span,
                };
            }
            elements.push(Some(pat));
            if !self.eat(&TokenKind::Comma) {
                break;
            }
        }
        self.expect(&TokenKind::RBracket)?;
        Ok(Pattern {
            kind: PatternKind::Array { elements, rest },
            span: self.span_from(start),
        })
    }

    fn parse_object_pattern(&mut self) -> Result<Pattern, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::LBrace)?;
        let mut properties = Vec::new();
        let mut rest = None;
        while !self.at(&TokenKind::RBrace) && !self.at_eof() {
            if self.at(&TokenKind::Ellipsis) {
                self.advance();
                rest = Some(Box::new(self.parse_binding_pattern()?));
                self.eat(&TokenKind::Comma);
                break;
            }
            let prop_start = self.start_span();
            let (key, computed) = self.parse_property_name()?;
            if self.eat(&TokenKind::Colon) {
                // { key: pattern }
                let mut value = self.parse_binding_pattern()?;
                if self.eat(&TokenKind::Assign) {
                    let right = self.parse_assignment_expression()?;
                    let span = Span {
                        start: value.span.start,
                        end: right.span.end,
                    };
                    value = Pattern {
                        kind: PatternKind::Assign {
                            left: Box::new(value),
                            right: Box::new(right),
                        },
                        span,
                    };
                }
                properties.push(ObjectPatternProp {
                    key,
                    value,
                    computed,
                    shorthand: false,
                    span: self.span_from(prop_start),
                });
            } else {
                // Shorthand: { name } or { name = default }
                let name = match &key {
                    PropertyKey::Identifier(n) => n.clone(),
                    _ => return Err(self.error("shorthand properties require identifier".into())),
                };
                let ident_span = self.span_from(prop_start);
                let mut value = Pattern {
                    kind: PatternKind::Identifier(name.clone()),
                    span: ident_span,
                };
                if self.eat(&TokenKind::Assign) {
                    let right = self.parse_assignment_expression()?;
                    let span = Span {
                        start: value.span.start,
                        end: right.span.end,
                    };
                    value = Pattern {
                        kind: PatternKind::Assign {
                            left: Box::new(value),
                            right: Box::new(right),
                        },
                        span,
                    };
                }
                properties.push(ObjectPatternProp {
                    key,
                    value,
                    computed,
                    shorthand: true,
                    span: self.span_from(prop_start),
                });
            }
            if !self.eat(&TokenKind::Comma) {
                break;
            }
        }
        self.expect(&TokenKind::RBrace)?;
        Ok(Pattern {
            kind: PatternKind::Object { properties, rest },
            span: self.span_from(start),
        })
    }

    // ── Function declarations ───────────────────────────────

    fn parse_function_declaration(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Function)?;
        let is_generator = self.eat(&TokenKind::Star);
        let id = Some(self.expect_identifier()?);
        let (params, body) = self.parse_function_params_and_body()?;
        Ok(Stmt {
            kind: StmtKind::FunctionDecl(FunctionDef {
                id,
                params,
                body,
                is_async: false,
                is_generator,
            }),
            span: self.span_from(start),
        })
    }

    fn parse_async_function_declaration(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Async)?;
        self.expect(&TokenKind::Function)?;
        let is_generator = self.eat(&TokenKind::Star);
        let id = Some(self.expect_identifier()?);
        let (params, body) = self.parse_function_params_and_body()?;
        Ok(Stmt {
            kind: StmtKind::FunctionDecl(FunctionDef {
                id,
                params,
                body,
                is_async: true,
                is_generator,
            }),
            span: self.span_from(start),
        })
    }

    fn parse_function_params_and_body(&mut self) -> Result<(Vec<Pattern>, Vec<Stmt>), ParseError> {
        // Formal-parameter initializers and the function body are `[+In]`
        // regardless of an enclosing `for`-initializer NoIn context.
        self.with_in(|p| {
            p.expect(&TokenKind::LParen)?;
            let params = p.parse_formal_parameters()?;
            p.expect(&TokenKind::RParen)?;
            let body = p.parse_block_body()?;
            Ok((params, body))
        })
    }

    fn parse_formal_parameters(&mut self) -> Result<Vec<Pattern>, ParseError> {
        // Parameter `Initializer`s are `[+In]`, independent of any enclosing
        // `for`-initializer NoIn context (reached directly via the arrow path).
        let old_allow_in = self.allow_in;
        self.allow_in = true;
        let result = self.parse_formal_parameters_inner();
        self.allow_in = old_allow_in;
        result
    }

    fn parse_formal_parameters_inner(&mut self) -> Result<Vec<Pattern>, ParseError> {
        let mut params = Vec::new();
        while !self.at(&TokenKind::RParen) && !self.at_eof() {
            if self.at(&TokenKind::Ellipsis) {
                let start = self.start_span();
                self.advance();
                let inner = self.parse_binding_pattern()?;
                params.push(Pattern {
                    kind: PatternKind::Rest(Box::new(inner)),
                    span: self.span_from(start),
                });
                self.eat(&TokenKind::Comma);
                break;
            }
            let mut pat = self.parse_binding_pattern()?;
            if self.eat(&TokenKind::Assign) {
                let right = self.parse_assignment_expression()?;
                let span = Span {
                    start: pat.span.start,
                    end: right.span.end,
                };
                pat = Pattern {
                    kind: PatternKind::Assign {
                        left: Box::new(pat),
                        right: Box::new(right),
                    },
                    span,
                };
            }
            params.push(pat);
            if !self.eat(&TokenKind::Comma) {
                break;
            }
        }
        Ok(params)
    }

    // ── Class declarations ──────────────────────────────────

    fn parse_class_declaration(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        let class_def = self.parse_class(true)?;
        Ok(Stmt {
            kind: StmtKind::ClassDecl(class_def),
            span: self.span_from(start),
        })
    }

    fn parse_class(&mut self, require_name: bool) -> Result<ClassDef, ParseError> {
        self.expect(&TokenKind::Class)?;
        let id = if require_name {
            Some(self.expect_identifier()?)
        } else if let TokenKind::Identifier(_) = self.peek_kind() {
            Some(self.expect_identifier()?)
        } else {
            None
        };
        let super_class = if self.eat(&TokenKind::Extends) {
            Some(Box::new(self.parse_left_hand_side_expression()?))
        } else {
            None
        };
        let body = self.parse_class_body()?;
        Ok(ClassDef {
            id,
            super_class,
            body,
        })
    }

    fn parse_class_body(&mut self) -> Result<Vec<ClassMember>, ParseError> {
        self.expect(&TokenKind::LBrace)?;
        let mut members = Vec::new();
        while !self.at(&TokenKind::RBrace) && !self.at_eof() {
            if self.eat(&TokenKind::Semicolon) {
                continue;
            }
            members.push(self.parse_class_member()?);
        }
        self.expect(&TokenKind::RBrace)?;
        Ok(members)
    }

    fn parse_class_member(&mut self) -> Result<ClassMember, ParseError> {
        let start = self.start_span();
        let is_static = self.eat(&TokenKind::Static);

        // Check for getter/setter
        if let TokenKind::Identifier(ref name) = self.peek_kind().clone() {
            if (name == "get" || name == "set")
                && !matches!(
                    self.peek_ahead(1),
                    TokenKind::LParen | TokenKind::Assign | TokenKind::Semicolon
                )
            {
                let kind = if name == "get" {
                    MethodKind::Get
                } else {
                    MethodKind::Set
                };
                self.advance();
                let (key, computed) = self.parse_property_name()?;
                let (params, body) = self.parse_function_params_and_body()?;
                return Ok(ClassMember {
                    kind: ClassMemberKind::Method {
                        key,
                        value: FunctionDef {
                            id: None,
                            params,
                            body,
                            is_async: false,
                            is_generator: false,
                        },
                        kind,
                        is_static,
                        computed,
                    },
                    span: self.span_from(start),
                });
            }
        }

        // Generator method
        let is_generator = self.eat(&TokenKind::Star);

        // Async method
        let is_async = if !is_generator
            && matches!(self.peek_kind(), TokenKind::Async)
            && !matches!(
                self.peek_ahead(1),
                TokenKind::LParen | TokenKind::Assign | TokenKind::Semicolon
            ) {
            self.advance();
            true
        } else {
            false
        };

        let is_generator = is_generator || (is_async && self.eat(&TokenKind::Star));

        let (key, computed) = self.parse_property_name()?;

        // Check for constructor
        let method_kind =
            if !is_static && !computed && key == PropertyKey::Identifier("constructor".into()) {
                MethodKind::Constructor
            } else {
                MethodKind::Method
            };

        if self.at(&TokenKind::LParen) {
            let (params, body) = self.parse_function_params_and_body()?;
            Ok(ClassMember {
                kind: ClassMemberKind::Method {
                    key,
                    value: FunctionDef {
                        id: None,
                        params,
                        body,
                        is_async,
                        is_generator,
                    },
                    kind: method_kind,
                    is_static,
                    computed,
                },
                span: self.span_from(start),
            })
        } else {
            // Class field
            let value = if self.eat(&TokenKind::Assign) {
                Some(self.parse_assignment_expression()?)
            } else {
                None
            };
            self.expect_semicolon()?;
            Ok(ClassMember {
                kind: ClassMemberKind::Property {
                    key,
                    value,
                    is_static,
                    computed,
                },
                span: self.span_from(start),
            })
        }
    }

    // ── Import / Export ─────────────────────────────────────

    fn parse_import_declaration(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Import)?;

        // `import "source"` — side-effect import
        if let TokenKind::String(source) = self.peek_kind().clone() {
            self.advance();
            self.expect_semicolon()?;
            return Ok(Stmt {
                kind: StmtKind::Import {
                    specifiers: vec![],
                    source,
                },
                span: self.span_from(start),
            });
        }

        let mut specifiers = Vec::new();

        // `import * as ns from "source"`
        if self.eat(&TokenKind::Star) {
            self.expect_identifier_matching("as")?;
            let local = self.expect_identifier()?;
            specifiers.push(ImportSpecifier::Namespace(local));
        }
        // `import { a, b as c } from "source"`
        else if self.at(&TokenKind::LBrace) {
            self.advance();
            while !self.at(&TokenKind::RBrace) && !self.at_eof() {
                let (imported, imported_can_bind) = self.expect_module_export_name()?;
                let local = if self.eat_identifier_matching("as") {
                    self.expect_identifier()?
                } else {
                    if !imported_can_bind {
                        return Err(
                            self.error(format!("imported name {imported:?} requires `as` binding"))
                        );
                    }
                    imported.clone()
                };
                specifiers.push(ImportSpecifier::Named { imported, local });
                if !self.eat(&TokenKind::Comma) {
                    break;
                }
            }
            self.expect(&TokenKind::RBrace)?;
        }
        // `import defaultExport from "source"` or `import defaultExport, { ... } from "source"`
        else {
            let default_name = self.expect_identifier()?;
            specifiers.push(ImportSpecifier::Default(default_name));

            if self.eat(&TokenKind::Comma) {
                if self.eat(&TokenKind::Star) {
                    self.expect_identifier_matching("as")?;
                    let local = self.expect_identifier()?;
                    specifiers.push(ImportSpecifier::Namespace(local));
                } else {
                    self.expect(&TokenKind::LBrace)?;
                    while !self.at(&TokenKind::RBrace) && !self.at_eof() {
                        let (imported, imported_can_bind) = self.expect_module_export_name()?;
                        let local = if self.eat_identifier_matching("as") {
                            self.expect_identifier()?
                        } else {
                            if !imported_can_bind {
                                return Err(self.error(format!(
                                    "imported name {imported:?} requires `as` binding"
                                )));
                            }
                            imported.clone()
                        };
                        specifiers.push(ImportSpecifier::Named { imported, local });
                        if !self.eat(&TokenKind::Comma) {
                            break;
                        }
                    }
                    self.expect(&TokenKind::RBrace)?;
                }
            }
        }

        self.expect_identifier_matching("from")?;
        let source = match self.peek_kind().clone() {
            TokenKind::String(s) => {
                self.advance();
                s
            }
            _ => return Err(self.error("expected module source string".into())),
        };
        self.expect_semicolon()?;
        Ok(Stmt {
            kind: StmtKind::Import { specifiers, source },
            span: self.span_from(start),
        })
    }

    fn parse_export_declaration(&mut self) -> Result<Stmt, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Export)?;

        // `export default ...`
        if self.eat(&TokenKind::Default) {
            if matches!(self.peek_kind(), TokenKind::Function) {
                // Named function → declaration, anonymous → default expression
                let has_name = matches!(self.peek_ahead(1), TokenKind::Identifier(_))
                    || (matches!(self.peek_ahead(1), TokenKind::Star)
                        && matches!(self.peek_ahead(2), TokenKind::Identifier(_)));
                if has_name {
                    let decl = self.parse_function_declaration()?;
                    return Ok(Stmt {
                        kind: StmtKind::Export(ExportDecl::Declaration(Box::new(decl))),
                        span: self.span_from(start),
                    });
                }
                let expr = self.parse_function_expression()?;
                return Ok(Stmt {
                    kind: StmtKind::Export(ExportDecl::Default(expr)),
                    span: self.span_from(start),
                });
            }
            if matches!(self.peek_kind(), TokenKind::Class) {
                // Named class → declaration, anonymous → default expression
                if matches!(self.peek_ahead(1), TokenKind::Identifier(_)) {
                    let decl = self.parse_class_declaration()?;
                    return Ok(Stmt {
                        kind: StmtKind::Export(ExportDecl::Declaration(Box::new(decl))),
                        span: self.span_from(start),
                    });
                }
                let expr = self.parse_class_expression()?;
                return Ok(Stmt {
                    kind: StmtKind::Export(ExportDecl::Default(expr)),
                    span: self.span_from(start),
                });
            }
            let expr = self.parse_assignment_expression()?;
            self.expect_semicolon()?;
            return Ok(Stmt {
                kind: StmtKind::Export(ExportDecl::Default(expr)),
                span: self.span_from(start),
            });
        }

        // `export * from "source"`
        if self.eat(&TokenKind::Star) {
            self.expect_identifier_matching("from")?;
            let source = match self.peek_kind().clone() {
                TokenKind::String(s) => {
                    self.advance();
                    s
                }
                _ => return Err(self.error("expected module source string".into())),
            };
            self.expect_semicolon()?;
            return Ok(Stmt {
                kind: StmtKind::Export(ExportDecl::AllFrom(source)),
                span: self.span_from(start),
            });
        }

        // `export { a, b as c } [from "source"]`
        if self.at(&TokenKind::LBrace) {
            self.advance();
            let mut specifiers = Vec::new();
            while !self.at(&TokenKind::RBrace) && !self.at_eof() {
                let (local, _) = self.expect_module_export_name()?;
                let exported = if self.eat_identifier_matching("as") {
                    self.expect_module_export_name()?.0
                } else {
                    local.clone()
                };
                specifiers.push(ExportSpecifier { local, exported });
                if !self.eat(&TokenKind::Comma) {
                    break;
                }
            }
            self.expect(&TokenKind::RBrace)?;
            let source = if self.eat_identifier_matching("from") {
                match self.peek_kind().clone() {
                    TokenKind::String(s) => {
                        self.advance();
                        Some(s)
                    }
                    _ => return Err(self.error("expected module source string".into())),
                }
            } else {
                None
            };
            self.expect_semicolon()?;
            return Ok(Stmt {
                kind: StmtKind::Export(ExportDecl::Named { specifiers, source }),
                span: self.span_from(start),
            });
        }

        // `export var/let/const/function/class ...`
        let decl = self.parse_statement_list_item()?;
        Ok(Stmt {
            kind: StmtKind::Export(ExportDecl::Declaration(Box::new(decl))),
            span: self.span_from(start),
        })
    }

    // ── Helper for contextual keywords ──────────────────────

    fn expect_identifier_matching(&mut self, expected: &str) -> Result<(), ParseError> {
        match self.peek_kind().clone() {
            TokenKind::Identifier(ref name) if name == expected => {
                self.advance();
                Ok(())
            }
            _ => Err(self.error(format!("expected '{}'", expected))),
        }
    }

    fn eat_identifier_matching(&mut self, expected: &str) -> bool {
        if let TokenKind::Identifier(ref name) = self.peek_kind() {
            if name == expected {
                self.advance();
                return true;
            }
        }
        false
    }

    // ── Expressions ─────────────────────────────────────────

    fn parse_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        let expr = self.parse_assignment_expression()?;
        if !self.at(&TokenKind::Comma) {
            return Ok(expr);
        }
        let mut exprs = vec![expr];
        while self.eat(&TokenKind::Comma) {
            exprs.push(self.parse_assignment_expression()?);
        }
        Ok(Expr {
            kind: ExprKind::Sequence(exprs),
            span: self.span_from(start),
        })
    }

    fn parse_assignment_expression(&mut self) -> Result<Expr, ParseError> {
        // Check for `async (...) => ...` before treating `async(...)` as a call.
        if matches!(self.peek_kind(), TokenKind::Async)
            && !self.peek().preceded_by_newline
            && matches!(self.peek_ahead(1), TokenKind::LParen)
            && self.is_parenthesized_arrow_params(1)
        {
            let start = self.start_span();
            self.advance(); // async
            self.expect(&TokenKind::LParen)?;
            let params = self.parse_formal_parameters()?;
            self.expect(&TokenKind::RParen)?;
            self.expect(&TokenKind::Arrow)?;
            return self.parse_arrow_body(start, params, true);
        }

        // Check for `(...) => ...` before parsing the parenthesized expression.
        // This accepts rest parameters after earlier parameters, e.g.
        // `(value, ...rest) => rest`, which expression parsing cannot represent.
        if matches!(self.peek_kind(), TokenKind::LParen) && self.is_parenthesized_arrow_params(0) {
            let start = self.start_span();
            self.expect(&TokenKind::LParen)?;
            let params = self.parse_formal_parameters()?;
            self.expect(&TokenKind::RParen)?;
            self.expect(&TokenKind::Arrow)?;
            return self.parse_arrow_body(start, params, false);
        }

        // Check for arrow function: `x => ...` or `async x => ...`
        if let TokenKind::Identifier(ref name) = self.peek_kind().clone() {
            if matches!(self.peek_ahead(1), TokenKind::Arrow) && !self.peek().preceded_by_newline {
                let param_start = self.start_span();
                let name = name.clone();
                self.advance(); // identifier
                self.advance(); // =>
                let params = vec![Pattern {
                    kind: PatternKind::Identifier(name),
                    span: self.span_from(param_start),
                }];
                return self.parse_arrow_body(param_start, params, false);
            }
        }

        // Check for `async x => ...` or `async (...)` arrow
        if matches!(self.peek_kind(), TokenKind::Async) && !self.peek().preceded_by_newline {
            if let TokenKind::Identifier(_) = self.peek_ahead(1) {
                if matches!(self.peek_ahead(2), TokenKind::Arrow) {
                    let start = self.start_span();
                    self.advance(); // async
                    let param_start = self.start_span();
                    let name = self.expect_identifier()?;
                    self.advance(); // =>
                    let params = vec![Pattern {
                        kind: PatternKind::Identifier(name),
                        span: self.span_from(param_start),
                    }];
                    return self.parse_arrow_body(start, params, true);
                }
            }
        }

        let start = self.start_span();
        let left = self.parse_conditional_expression()?;

        // Check for arrow function after parenthesized expr: `(a, b) => ...`
        if matches!(self.peek_kind(), TokenKind::Arrow) && !self.peek().preceded_by_newline {
            self.advance(); // =>
            let params = self.expr_to_params(&left)?;
            return self.parse_arrow_body(start, params, false);
        }

        // Assignment
        if let Some(op) = self.peek_assign_op() {
            self.advance();
            let right = self.parse_assignment_expression()?;
            return Ok(Expr {
                span: self.span_from(start),
                kind: ExprKind::Assignment {
                    op,
                    left: Box::new(left),
                    right: Box::new(right),
                },
            });
        }

        Ok(left)
    }

    fn is_parenthesized_arrow_params(&self, paren_offset: usize) -> bool {
        let mut depth = 0usize;
        let mut idx = self.pos + paren_offset;
        while idx < self.tokens.len() {
            match &self.tokens[idx].kind {
                TokenKind::LParen | TokenKind::LBracket | TokenKind::LBrace => {
                    depth += 1;
                }
                TokenKind::RParen | TokenKind::RBracket | TokenKind::RBrace => {
                    if depth == 0 {
                        return false;
                    }
                    depth -= 1;
                    if depth == 0 {
                        return matches!(
                            self.tokens.get(idx + 1).map(|t| &t.kind),
                            Some(TokenKind::Arrow)
                        );
                    }
                }
                TokenKind::Eof => return false,
                _ => {}
            }
            idx += 1;
        }
        false
    }

    fn parse_assignment_expression_no_in(&mut self) -> Result<Expr, ParseError> {
        let old = self.allow_in;
        self.allow_in = false;
        let result = self.parse_assignment_expression();
        self.allow_in = old;
        result
    }

    /// Run `f` with the grammar's `[In]` parameter forced on, restoring the
    /// previous value afterwards. The ECMAScript grammar only threads the
    /// NoIn restriction through the `for`-initializer expression spine; every
    /// nested bracketed production (call arguments, array/object literals,
    /// computed member access, template substitutions, function/arrow bodies)
    /// is evaluated with `[+In]`. Use this at those boundaries so that, e.g.,
    /// `for (var x = f("k" in o); ;) {}` parses the `in` operator correctly.
    fn with_in<T>(
        &mut self,
        f: impl FnOnce(&mut Self) -> Result<T, ParseError>,
    ) -> Result<T, ParseError> {
        let old = self.allow_in;
        self.allow_in = true;
        let result = f(self);
        self.allow_in = old;
        result
    }

    fn parse_arrow_body(
        &mut self,
        start: SourcePos,
        params: Vec<Pattern>,
        is_async: bool,
    ) -> Result<Expr, ParseError> {
        // A braced arrow body is `{ FunctionBody }` (`[+In]`); a concise
        // expression body is `ExpressionBody[?In]`, so it inherits the
        // enclosing NoIn context and must not reset `allow_in`.
        let body = if self.at(&TokenKind::LBrace) {
            ArrowBody::Block(self.with_in(|p| p.parse_block_body())?)
        } else {
            ArrowBody::Expr(Box::new(self.parse_assignment_expression()?))
        };
        Ok(Expr {
            kind: ExprKind::Arrow {
                params,
                body,
                is_async,
            },
            span: self.span_from(start),
        })
    }

    fn parse_conditional_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        let expr = self.parse_binary_expression(0)?;
        if !self.eat(&TokenKind::Question) {
            return Ok(expr);
        }
        let consequent = self.parse_assignment_expression()?;
        self.expect(&TokenKind::Colon)?;
        let alternate = self.parse_assignment_expression()?;
        Ok(Expr {
            kind: ExprKind::Conditional {
                test: Box::new(expr),
                consequent: Box::new(consequent),
                alternate: Box::new(alternate),
            },
            span: self.span_from(start),
        })
    }

    // ── Pratt expression parsing ────────────────────────────

    fn parse_binary_expression(&mut self, min_bp: u8) -> Result<Expr, ParseError> {
        let start = self.start_span();
        let mut left = self.parse_unary_expression()?;

        while let Some((op, left_bp, right_bp)) = self.peek_binary_op() {
            if left_bp < min_bp {
                break;
            }
            self.advance();

            let right = self.parse_binary_expression(right_bp)?;
            let span = self.span_from(start);

            left = match op {
                BinOrLogical::Binary(op) => Expr {
                    kind: ExprKind::Binary {
                        op,
                        left: Box::new(left),
                        right: Box::new(right),
                    },
                    span,
                },
                BinOrLogical::Logical(op) => Expr {
                    kind: ExprKind::Logical {
                        op,
                        left: Box::new(left),
                        right: Box::new(right),
                    },
                    span,
                },
            };
        }

        Ok(left)
    }

    fn parse_unary_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        match self.peek_kind() {
            TokenKind::Minus => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::Minus,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Plus => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::Plus,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Not => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::Not,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Tilde => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::BitwiseNot,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Typeof => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::Typeof,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Void => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::Void,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Delete => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Unary {
                        op: UnaryOp::Delete,
                        argument: Box::new(arg),
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::PlusPlus => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Update {
                        op: UpdateOp::Increment,
                        argument: Box::new(arg),
                        prefix: true,
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::MinusMinus => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Update {
                        op: UpdateOp::Decrement,
                        argument: Box::new(arg),
                        prefix: true,
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::Await => {
                self.advance();
                let arg = self.parse_unary_expression()?;
                Ok(Expr {
                    kind: ExprKind::Await(Box::new(arg)),
                    span: self.span_from(start),
                })
            }
            _ => self.parse_postfix_expression(),
        }
    }

    fn parse_postfix_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        let mut expr = self.parse_call_expression()?;

        if !self.peek().preceded_by_newline {
            if matches!(self.peek_kind(), TokenKind::PlusPlus) {
                self.advance();
                expr = Expr {
                    kind: ExprKind::Update {
                        op: UpdateOp::Increment,
                        argument: Box::new(expr),
                        prefix: false,
                    },
                    span: self.span_from(start),
                };
            } else if matches!(self.peek_kind(), TokenKind::MinusMinus) {
                self.advance();
                expr = Expr {
                    kind: ExprKind::Update {
                        op: UpdateOp::Decrement,
                        argument: Box::new(expr),
                        prefix: false,
                    },
                    span: self.span_from(start),
                };
            }
        }

        Ok(expr)
    }

    fn parse_call_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();

        let mut expr = if matches!(self.peek_kind(), TokenKind::New) {
            self.parse_new_expression()?
        } else {
            self.parse_primary_expression()?
        };

        let mut saw_optional = false;
        loop {
            match self.peek_kind() {
                TokenKind::Dot => {
                    self.advance();
                    let prop_start = self.start_span();
                    let property = self.parse_member_property_after_dot(prop_start)?;
                    expr = Expr {
                        kind: ExprKind::Member {
                            object: Box::new(expr),
                            property: Box::new(property),
                            computed: false,
                        },
                        span: self.span_from(start),
                    };
                }
                TokenKind::LBracket => {
                    self.advance();
                    let prop = self.with_in(|p| p.parse_expression())?;
                    self.expect(&TokenKind::RBracket)?;
                    expr = Expr {
                        kind: ExprKind::Member {
                            object: Box::new(expr),
                            property: Box::new(prop),
                            computed: true,
                        },
                        span: self.span_from(start),
                    };
                }
                TokenKind::LParen => {
                    let arguments = self.parse_arguments()?;
                    expr = Expr {
                        kind: ExprKind::Call {
                            callee: Box::new(expr),
                            arguments,
                        },
                        span: self.span_from(start),
                    };
                }
                TokenKind::QuestionDot => {
                    self.advance();
                    saw_optional = true;
                    // ?. can be followed by identifier, [expr], or (args)
                    match self.peek_kind() {
                        TokenKind::LBracket => {
                            self.advance();
                            let prop = self.with_in(|p| p.parse_expression())?;
                            self.expect(&TokenKind::RBracket)?;
                            expr = Expr {
                                kind: ExprKind::Member {
                                    object: Box::new(Expr {
                                        kind: ExprKind::OptionalChain {
                                            base: Box::new(expr.clone()),
                                        },
                                        span: self.span_from(start),
                                    }),
                                    property: Box::new(prop),
                                    computed: true,
                                },
                                span: self.span_from(start),
                            };
                        }
                        TokenKind::LParen => {
                            let arguments = self.parse_arguments()?;
                            expr = Expr {
                                kind: ExprKind::Call {
                                    callee: Box::new(Expr {
                                        kind: ExprKind::OptionalChain {
                                            base: Box::new(expr.clone()),
                                        },
                                        span: self.span_from(start),
                                    }),
                                    arguments,
                                },
                                span: self.span_from(start),
                            };
                        }
                        _ => {
                            let prop_start = self.start_span();
                            let property = self.parse_member_property_after_dot(prop_start)?;
                            expr = Expr {
                                kind: ExprKind::Member {
                                    object: Box::new(Expr {
                                        kind: ExprKind::OptionalChain {
                                            base: Box::new(expr.clone()),
                                        },
                                        span: self.span_from(start),
                                    }),
                                    property: Box::new(property),
                                    computed: false,
                                },
                                span: self.span_from(start),
                            };
                        }
                    }
                }
                TokenKind::TemplateFull(_) | TokenKind::TemplateHead(_) => {
                    let quasi = self.parse_template_literal()?;
                    expr = Expr {
                        kind: ExprKind::TaggedTemplate {
                            tag: Box::new(expr),
                            quasi: Box::new(quasi),
                        },
                        span: self.span_from(start),
                    };
                }
                _ => break,
            }
        }

        if saw_optional {
            expr = Expr {
                kind: ExprKind::OptionalChainExpr {
                    chain: Box::new(expr),
                },
                span: self.span_from(start),
            };
        }

        Ok(expr)
    }

    fn parse_new_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::New)?;

        if self.eat(&TokenKind::Dot) {
            let name = self.expect_identifier_name()?;
            if name != "target" {
                return Err(self.error(format!("expected new.target, found new.{name}")));
            }
            return Ok(Expr {
                kind: ExprKind::NewTarget,
                span: self.span_from(start),
            });
        }

        // new new Foo() → new (new Foo())
        if matches!(self.peek_kind(), TokenKind::New) {
            let callee = self.parse_new_expression()?;
            return Ok(Expr {
                kind: ExprKind::New {
                    callee: Box::new(callee),
                    arguments: vec![],
                },
                span: self.span_from(start),
            });
        }

        let callee = self.parse_primary_expression()?;
        // Allow member access on the callee
        let callee = self.parse_member_chain(start, callee)?;
        let arguments = if self.at(&TokenKind::LParen) {
            self.parse_arguments()?
        } else {
            vec![]
        };
        Ok(Expr {
            kind: ExprKind::New {
                callee: Box::new(callee),
                arguments,
            },
            span: self.span_from(start),
        })
    }

    fn parse_member_chain(&mut self, start: SourcePos, mut expr: Expr) -> Result<Expr, ParseError> {
        loop {
            match self.peek_kind() {
                TokenKind::Dot => {
                    self.advance();
                    let prop_start = self.start_span();
                    let property = self.parse_member_property_after_dot(prop_start)?;
                    expr = Expr {
                        kind: ExprKind::Member {
                            object: Box::new(expr),
                            property: Box::new(property),
                            computed: false,
                        },
                        span: self.span_from(start),
                    };
                }
                TokenKind::LBracket => {
                    self.advance();
                    let prop = self.with_in(|p| p.parse_expression())?;
                    self.expect(&TokenKind::RBracket)?;
                    expr = Expr {
                        kind: ExprKind::Member {
                            object: Box::new(expr),
                            property: Box::new(prop),
                            computed: true,
                        },
                        span: self.span_from(start),
                    };
                }
                _ => break,
            }
        }
        Ok(expr)
    }

    /// Parse the property that follows a `.` (or `?.`) in a member access.
    /// Returns a `PrivateName` expression for `obj.#x`, otherwise an
    /// `Identifier` (keywords are permitted as property names).
    fn parse_member_property_after_dot(
        &mut self,
        prop_start: SourcePos,
    ) -> Result<Expr, ParseError> {
        if let TokenKind::PrivateName(name) = self.peek_kind().clone() {
            self.advance();
            return Ok(Expr {
                kind: ExprKind::PrivateName(name),
                span: self.span_from(prop_start),
            });
        }
        let name = self.expect_identifier_name()?;
        Ok(Expr {
            kind: ExprKind::Identifier(name),
            span: self.span_from(prop_start),
        })
    }

    fn parse_left_hand_side_expression(&mut self) -> Result<Expr, ParseError> {
        self.parse_call_expression()
    }

    fn parse_arguments(&mut self) -> Result<Vec<Expr>, ParseError> {
        // `Arguments` evaluates each `AssignmentExpression` with `[+In]`.
        self.with_in(|p| {
            p.expect(&TokenKind::LParen)?;
            let mut args = Vec::new();
            while !p.at(&TokenKind::RParen) && !p.at_eof() {
                if p.at(&TokenKind::Ellipsis) {
                    let start = p.start_span();
                    p.advance();
                    let arg = p.parse_assignment_expression()?;
                    args.push(Expr {
                        kind: ExprKind::Spread(Box::new(arg)),
                        span: p.span_from(start),
                    });
                } else {
                    args.push(p.parse_assignment_expression()?);
                }
                if !p.eat(&TokenKind::Comma) {
                    break;
                }
            }
            p.expect(&TokenKind::RParen)?;
            Ok(args)
        })
    }

    // ── Primary expressions ─────────────────────────────────

    fn parse_primary_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        match self.peek_kind().clone() {
            TokenKind::Number(n) => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Number(n),
                    span: self.span_from(start),
                })
            }
            TokenKind::String(s) => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::String(s),
                    span: self.span_from(start),
                })
            }
            TokenKind::True => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Bool(true),
                    span: self.span_from(start),
                })
            }
            TokenKind::False => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Bool(false),
                    span: self.span_from(start),
                })
            }
            TokenKind::Null => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Null,
                    span: self.span_from(start),
                })
            }
            TokenKind::This => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::This,
                    span: self.span_from(start),
                })
            }
            TokenKind::Identifier(name) => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Identifier(name),
                    span: self.span_from(start),
                })
            }
            // A leading private name is only legal as the left operand of an
            // `in` expression (`#x in obj`); the binary-expression parser
            // continues from here and the compiler rejects other uses.
            TokenKind::PrivateName(name) => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::PrivateName(name),
                    span: self.span_from(start),
                })
            }
            kind if is_contextual_identifier(&kind) && !matches!(kind, TokenKind::Async) => {
                let name = format!("{kind}");
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Identifier(name),
                    span: self.span_from(start),
                })
            }
            TokenKind::LParen => self.parse_parenthesized_expression(),
            TokenKind::LBracket => self.parse_array_expression(),
            TokenKind::LBrace => self.parse_object_expression(),
            TokenKind::Function => self.parse_function_expression(),
            TokenKind::Class => self.parse_class_expression(),
            TokenKind::Async => {
                // async function expression
                if matches!(self.peek_ahead(1), TokenKind::Function)
                    && !self.tokens[self.pos + 1].preceded_by_newline
                {
                    return self.parse_async_function_expression();
                }
                // Otherwise treat 'async' as an identifier
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Identifier("async".into()),
                    span: self.span_from(start),
                })
            }
            TokenKind::TemplateFull(_) | TokenKind::TemplateHead(_) => {
                self.parse_template_literal()
            }
            TokenKind::RegExp { pattern, flags } => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::RegExp { pattern, flags },
                    span: self.span_from(start),
                })
            }
            TokenKind::Yield => {
                self.advance();
                let delegate = self.eat(&TokenKind::Star);
                let argument = if !self.peek().preceded_by_newline
                    && !matches!(
                        self.peek_kind(),
                        TokenKind::Semicolon
                            | TokenKind::RBrace
                            | TokenKind::RParen
                            | TokenKind::RBracket
                            | TokenKind::Colon
                            | TokenKind::Comma
                            | TokenKind::Eof
                    ) {
                    Some(Box::new(self.parse_assignment_expression()?))
                } else {
                    None
                };
                Ok(Expr {
                    kind: ExprKind::Yield { argument, delegate },
                    span: self.span_from(start),
                })
            }
            TokenKind::Super => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::Super,
                    span: self.span_from(start),
                })
            }
            TokenKind::Import => {
                self.advance();
                if self.at(&TokenKind::Dot) {
                    // `import.meta` — leave as a bare identifier so the member
                    // access evaluates against the (currently absent) global,
                    // yielding `undefined` rather than a dynamic import.
                    Ok(Expr {
                        kind: ExprKind::Identifier("import".into()),
                        span: self.span_from(start),
                    })
                } else {
                    // Dynamic `import(specifier)`. The trailing `(...)` is parsed
                    // by the call-expression suffix logic, producing a call to
                    // the `__we_dynamic_import` runtime helper which returns a
                    // Promise for the imported module namespace.
                    Ok(Expr {
                        kind: ExprKind::Identifier("__we_dynamic_import".into()),
                        span: self.span_from(start),
                    })
                }
            }
            _ => Err(self.error(format!("unexpected token {:?}", self.peek_kind()))),
        }
    }

    fn parse_parenthesized_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::LParen)?;

        // Empty parens: `() => ...`
        if self.at(&TokenKind::RParen) {
            self.advance();
            // Must be arrow
            if !matches!(self.peek_kind(), TokenKind::Arrow) {
                return Err(self.error("unexpected empty parentheses".into()));
            }
            // Arrow will be handled by caller
            return Ok(Expr {
                kind: ExprKind::Sequence(vec![]),
                span: self.span_from(start),
            });
        }

        // `(...rest) => ...`
        if self.at(&TokenKind::Ellipsis) {
            // This must be an arrow parameter list with rest
            let rest_start = self.start_span();
            self.advance();
            let rest_pat = self.parse_binding_pattern()?;
            self.expect(&TokenKind::RParen)?;
            // Must be followed by =>
            if !matches!(self.peek_kind(), TokenKind::Arrow) {
                return Err(self.error("expected '=>'".into()));
            }
            let _ = rest_pat; // Will be handled as pattern
                              // Return a marker that the arrow handler will convert
            return Ok(Expr {
                kind: ExprKind::Spread(Box::new(Expr {
                    kind: match rest_pat.kind {
                        PatternKind::Identifier(name) => ExprKind::Identifier(name),
                        _ => {
                            return Err(ParseError {
                                message: "complex rest pattern in arrow".into(),
                                pos: rest_start,
                            })
                        }
                    },
                    span: rest_pat.span,
                })),
                span: self.span_from(start),
            });
        }

        // `in` is disallowed at the top level of a regular `for` initializer
        // so `for (x in y)` can be parsed as for-in. Parentheses start a nested
        // expression where `in` is valid again, e.g. `for (x = ("k" in obj);;)`.
        let old_allow_in = self.allow_in;
        self.allow_in = true;
        let expr = self.parse_expression();
        self.allow_in = old_allow_in;
        let expr = expr?;
        self.expect(&TokenKind::RParen)?;
        Ok(expr)
    }

    fn parse_array_expression(&mut self) -> Result<Expr, ParseError> {
        // `ArrayLiteral` evaluates each element `AssignmentExpression` with `[+In]`.
        self.with_in(|p| {
            let start = p.start_span();
            p.expect(&TokenKind::LBracket)?;
            let mut elements = Vec::new();
            while !p.at(&TokenKind::RBracket) && !p.at_eof() {
                if p.eat(&TokenKind::Comma) {
                    elements.push(None);
                    continue;
                }
                if p.at(&TokenKind::Ellipsis) {
                    let spread_start = p.start_span();
                    p.advance();
                    let arg = p.parse_assignment_expression()?;
                    elements.push(Some(ArrayElement::Spread(Expr {
                        kind: ExprKind::Spread(Box::new(arg)),
                        span: p.span_from(spread_start),
                    })));
                } else {
                    let elem = p.parse_assignment_expression()?;
                    elements.push(Some(ArrayElement::Expr(elem)));
                }
                if !p.eat(&TokenKind::Comma) {
                    break;
                }
            }
            p.expect(&TokenKind::RBracket)?;
            Ok(Expr {
                kind: ExprKind::Array(elements),
                span: p.span_from(start),
            })
        })
    }

    fn parse_object_expression(&mut self) -> Result<Expr, ParseError> {
        // Object literal computed keys and property values are `[+In]`.
        self.with_in(|p| {
            let start = p.start_span();
            p.expect(&TokenKind::LBrace)?;
            let mut properties = Vec::new();
            while !p.at(&TokenKind::RBrace) && !p.at_eof() {
                let prop = p.parse_object_property()?;
                properties.push(prop);
                if !p.eat(&TokenKind::Comma) {
                    break;
                }
            }
            p.expect(&TokenKind::RBrace)?;
            Ok(Expr {
                kind: ExprKind::Object(properties),
                span: p.span_from(start),
            })
        })
    }

    fn parse_object_property(&mut self) -> Result<Property, ParseError> {
        let prop_start = self.start_span();

        // Spread: `...expr`
        if self.at(&TokenKind::Ellipsis) {
            self.advance();
            let arg = self.parse_assignment_expression()?;
            return Ok(Property {
                key: PropertyKey::Identifier("".into()),
                value: Some(arg),
                kind: PropertyKind::Init,
                computed: false,
                shorthand: false,
                method: false,
                span: self.span_from(prop_start),
            });
        }

        // Getter/setter: `get name() {}` or `set name(v) {}`
        if let TokenKind::Identifier(ref name) = self.peek_kind().clone() {
            if (name == "get" || name == "set")
                && !matches!(
                    self.peek_ahead(1),
                    TokenKind::Colon
                        | TokenKind::Comma
                        | TokenKind::RBrace
                        | TokenKind::LParen
                        | TokenKind::Assign
                )
            {
                let kind = if name == "get" {
                    PropertyKind::Get
                } else {
                    PropertyKind::Set
                };
                self.advance();
                let (key, computed) = self.parse_property_name()?;
                let (params, body) = self.parse_function_params_and_body()?;
                return Ok(Property {
                    key,
                    value: Some(Expr {
                        kind: ExprKind::Function(FunctionDef {
                            id: None,
                            params,
                            body,
                            is_async: false,
                            is_generator: false,
                        }),
                        span: self.span_from(prop_start),
                    }),
                    kind,
                    computed,
                    shorthand: false,
                    method: true,
                    span: self.span_from(prop_start),
                });
            }
        }

        // Generator method: `*name() {}`
        if self.eat(&TokenKind::Star) {
            let (key, computed) = self.parse_property_name()?;
            let (params, body) = self.parse_function_params_and_body()?;
            return Ok(Property {
                key,
                value: Some(Expr {
                    kind: ExprKind::Function(FunctionDef {
                        id: None,
                        params,
                        body,
                        is_async: false,
                        is_generator: true,
                    }),
                    span: self.span_from(prop_start),
                }),
                kind: PropertyKind::Init,
                computed,
                shorthand: false,
                method: true,
                span: self.span_from(prop_start),
            });
        }

        // Async method: `async name() {}`
        let is_async = if matches!(self.peek_kind(), TokenKind::Async)
            && !matches!(
                self.peek_ahead(1),
                TokenKind::Colon | TokenKind::Comma | TokenKind::RBrace | TokenKind::Assign
            )
            && !self
                .tokens
                .get(self.pos + 1)
                .is_none_or(|t| t.preceded_by_newline)
        {
            self.advance();
            true
        } else {
            false
        };

        let is_generator = is_async && self.eat(&TokenKind::Star);

        let (key, computed) = self.parse_property_name()?;

        // Method shorthand: `name() {}` or `name(params) {}`
        if self.at(&TokenKind::LParen) {
            let (params, body) = self.parse_function_params_and_body()?;
            return Ok(Property {
                key,
                value: Some(Expr {
                    kind: ExprKind::Function(FunctionDef {
                        id: None,
                        params,
                        body,
                        is_async,
                        is_generator,
                    }),
                    span: self.span_from(prop_start),
                }),
                kind: PropertyKind::Init,
                computed,
                shorthand: false,
                method: true,
                span: self.span_from(prop_start),
            });
        }

        // Shorthand: `{ name }` or `{ name = default }`
        if !computed
            && matches!(
                self.peek_kind(),
                TokenKind::Comma | TokenKind::RBrace | TokenKind::Assign
            )
        {
            let name = match &key {
                PropertyKey::Identifier(n) => n.clone(),
                _ => return Err(self.error("expected identifier for shorthand property".into())),
            };
            let value = if self.eat(&TokenKind::Assign) {
                let default = self.parse_assignment_expression()?;
                Some(Expr {
                    kind: ExprKind::Assignment {
                        op: AssignOp::Assign,
                        left: Box::new(Expr {
                            kind: ExprKind::Identifier(name.clone()),
                            span: self.span_from(prop_start),
                        }),
                        right: Box::new(default),
                    },
                    span: self.span_from(prop_start),
                })
            } else {
                Some(Expr {
                    kind: ExprKind::Identifier(name),
                    span: self.span_from(prop_start),
                })
            };
            return Ok(Property {
                key,
                value,
                kind: PropertyKind::Init,
                computed,
                shorthand: true,
                method: false,
                span: self.span_from(prop_start),
            });
        }

        // Regular: `key: value`
        self.expect(&TokenKind::Colon)?;
        let value = self.parse_assignment_expression()?;
        Ok(Property {
            key,
            value: Some(value),
            kind: PropertyKind::Init,
            computed,
            shorthand: false,
            method: false,
            span: self.span_from(prop_start),
        })
    }

    fn parse_property_name(&mut self) -> Result<(PropertyKey, bool), ParseError> {
        match self.peek_kind().clone() {
            TokenKind::Identifier(name) => {
                self.advance();
                Ok((PropertyKey::Identifier(name), false))
            }
            TokenKind::PrivateName(name) => {
                self.advance();
                Ok((PropertyKey::PrivateName(name), false))
            }
            TokenKind::String(s) => {
                self.advance();
                Ok((PropertyKey::String(s), false))
            }
            TokenKind::Number(n) => {
                self.advance();
                Ok((PropertyKey::Number(n), false))
            }
            TokenKind::LBracket => {
                self.advance();
                let expr = self.parse_assignment_expression()?;
                self.expect(&TokenKind::RBracket)?;
                Ok((PropertyKey::Computed(expr), true))
            }
            // Keywords can also be property names
            _ if is_keyword(self.peek_kind()) => {
                let name = format!("{}", self.peek_kind());
                self.advance();
                Ok((PropertyKey::Identifier(name), false))
            }
            _ => Err(self.error(format!(
                "expected property name, found {:?}",
                self.peek_kind()
            ))),
        }
    }

    fn parse_function_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Function)?;
        let is_generator = self.eat(&TokenKind::Star);
        let id = if let TokenKind::Identifier(_) = self.peek_kind() {
            Some(self.expect_identifier()?)
        } else {
            None
        };
        let (params, body) = self.parse_function_params_and_body()?;
        Ok(Expr {
            kind: ExprKind::Function(FunctionDef {
                id,
                params,
                body,
                is_async: false,
                is_generator,
            }),
            span: self.span_from(start),
        })
    }

    fn parse_async_function_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        self.expect(&TokenKind::Async)?;
        self.expect(&TokenKind::Function)?;
        let is_generator = self.eat(&TokenKind::Star);
        let id = if let TokenKind::Identifier(_) = self.peek_kind() {
            Some(self.expect_identifier()?)
        } else {
            None
        };
        let (params, body) = self.parse_function_params_and_body()?;
        Ok(Expr {
            kind: ExprKind::Function(FunctionDef {
                id,
                params,
                body,
                is_async: true,
                is_generator,
            }),
            span: self.span_from(start),
        })
    }

    fn parse_class_expression(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        let class_def = self.parse_class(false)?;
        Ok(Expr {
            kind: ExprKind::Class(class_def),
            span: self.span_from(start),
        })
    }

    fn parse_template_literal(&mut self) -> Result<Expr, ParseError> {
        let start = self.start_span();
        match self.peek_kind().clone() {
            TokenKind::TemplateFull(s) => {
                self.advance();
                Ok(Expr {
                    kind: ExprKind::TemplateLiteral {
                        quasis: vec![s],
                        expressions: vec![],
                    },
                    span: self.span_from(start),
                })
            }
            TokenKind::TemplateHead(s) => {
                self.advance();
                let mut quasis = vec![s];
                let mut expressions = Vec::new();
                loop {
                    // Template substitutions are `${ Expression[+In] }`.
                    expressions.push(self.with_in(|p| p.parse_expression())?);
                    match self.peek_kind().clone() {
                        TokenKind::TemplateMiddle(s) => {
                            self.advance();
                            quasis.push(s);
                        }
                        TokenKind::TemplateTail(s) => {
                            self.advance();
                            quasis.push(s);
                            break;
                        }
                        _ => {
                            return Err(self.error("expected template continuation or tail".into()));
                        }
                    }
                }
                Ok(Expr {
                    kind: ExprKind::TemplateLiteral {
                        quasis,
                        expressions,
                    },
                    span: self.span_from(start),
                })
            }
            _ => Err(self.error("expected template literal".into())),
        }
    }

    // ── Operator tables ─────────────────────────────────────

    fn peek_binary_op(&self) -> Option<(BinOrLogical, u8, u8)> {
        let kind = self.peek_kind();
        let (op, left_bp, right_bp) = match kind {
            TokenKind::Or => (BinOrLogical::Logical(LogicalOp::Or), 2, 3),
            TokenKind::And => (BinOrLogical::Logical(LogicalOp::And), 4, 5),
            TokenKind::Nullish => (BinOrLogical::Logical(LogicalOp::Nullish), 6, 7),
            TokenKind::Pipe => (BinOrLogical::Binary(BinaryOp::BitOr), 8, 9),
            TokenKind::Caret => (BinOrLogical::Binary(BinaryOp::BitXor), 10, 11),
            TokenKind::Amp => (BinOrLogical::Binary(BinaryOp::BitAnd), 12, 13),
            TokenKind::Eq => (BinOrLogical::Binary(BinaryOp::Eq), 14, 15),
            TokenKind::Ne => (BinOrLogical::Binary(BinaryOp::Ne), 14, 15),
            TokenKind::StrictEq => (BinOrLogical::Binary(BinaryOp::StrictEq), 14, 15),
            TokenKind::StrictNe => (BinOrLogical::Binary(BinaryOp::StrictNe), 14, 15),
            TokenKind::Lt => (BinOrLogical::Binary(BinaryOp::Lt), 16, 17),
            TokenKind::Gt => (BinOrLogical::Binary(BinaryOp::Gt), 16, 17),
            TokenKind::Le => (BinOrLogical::Binary(BinaryOp::Le), 16, 17),
            TokenKind::Ge => (BinOrLogical::Binary(BinaryOp::Ge), 16, 17),
            TokenKind::Instanceof => (BinOrLogical::Binary(BinaryOp::Instanceof), 16, 17),
            TokenKind::In if self.allow_in => (BinOrLogical::Binary(BinaryOp::In), 16, 17),
            TokenKind::Shl => (BinOrLogical::Binary(BinaryOp::Shl), 18, 19),
            TokenKind::Shr => (BinOrLogical::Binary(BinaryOp::Shr), 18, 19),
            TokenKind::Ushr => (BinOrLogical::Binary(BinaryOp::Ushr), 18, 19),
            TokenKind::Plus => (BinOrLogical::Binary(BinaryOp::Add), 20, 21),
            TokenKind::Minus => (BinOrLogical::Binary(BinaryOp::Sub), 20, 21),
            TokenKind::Star => (BinOrLogical::Binary(BinaryOp::Mul), 22, 23),
            TokenKind::Slash => (BinOrLogical::Binary(BinaryOp::Div), 22, 23),
            TokenKind::Percent => (BinOrLogical::Binary(BinaryOp::Rem), 22, 23),
            TokenKind::Exp => (BinOrLogical::Binary(BinaryOp::Exp), 25, 24), // right-assoc
            _ => return None,
        };
        Some((op, left_bp, right_bp))
    }

    fn peek_assign_op(&self) -> Option<AssignOp> {
        match self.peek_kind() {
            TokenKind::Assign => Some(AssignOp::Assign),
            TokenKind::PlusAssign => Some(AssignOp::AddAssign),
            TokenKind::MinusAssign => Some(AssignOp::SubAssign),
            TokenKind::StarAssign => Some(AssignOp::MulAssign),
            TokenKind::SlashAssign => Some(AssignOp::DivAssign),
            TokenKind::PercentAssign => Some(AssignOp::RemAssign),
            TokenKind::ExpAssign => Some(AssignOp::ExpAssign),
            TokenKind::ShlAssign => Some(AssignOp::ShlAssign),
            TokenKind::ShrAssign => Some(AssignOp::ShrAssign),
            TokenKind::UshrAssign => Some(AssignOp::UshrAssign),
            TokenKind::AmpAssign => Some(AssignOp::BitAndAssign),
            TokenKind::PipeAssign => Some(AssignOp::BitOrAssign),
            TokenKind::CaretAssign => Some(AssignOp::BitXorAssign),
            TokenKind::AndAssign => Some(AssignOp::AndAssign),
            TokenKind::OrAssign => Some(AssignOp::OrAssign),
            TokenKind::NullishAssign => Some(AssignOp::NullishAssign),
            _ => None,
        }
    }

    // ── Expression ↔ Pattern conversion ─────────────────────

    fn expr_to_pattern(&self, expr: &Expr) -> Result<Pattern, ParseError> {
        let span = expr.span;
        match &expr.kind {
            ExprKind::Identifier(name) => Ok(Pattern {
                kind: PatternKind::Identifier(name.clone()),
                span,
            }),
            ExprKind::Array(elements) => {
                let mut pats = Vec::new();
                let mut rest = None;
                for elem in elements {
                    match elem {
                        None => pats.push(None),
                        Some(ArrayElement::Spread(e)) => {
                            if let ExprKind::Spread(inner) = &e.kind {
                                rest = Some(Box::new(self.expr_to_pattern(inner)?));
                            } else {
                                rest = Some(Box::new(self.expr_to_pattern(e)?));
                            }
                        }
                        Some(ArrayElement::Expr(e)) => {
                            pats.push(Some(self.expr_to_pattern(e)?));
                        }
                    }
                }
                Ok(Pattern {
                    kind: PatternKind::Array {
                        elements: pats,
                        rest,
                    },
                    span,
                })
            }
            ExprKind::Object(properties) => {
                let mut pats = Vec::new();
                let mut rest = None;
                for prop in properties {
                    if prop.key == PropertyKey::Identifier("".into()) {
                        if let Some(val) = &prop.value {
                            // Spread property
                            rest = Some(Box::new(self.expr_to_pattern(val)?));
                        }
                        continue;
                    }
                    let value = if let Some(val) = &prop.value {
                        self.expr_to_pattern(val)?
                    } else {
                        continue;
                    };
                    pats.push(ObjectPatternProp {
                        key: prop.key.clone(),
                        value,
                        computed: prop.computed,
                        shorthand: prop.shorthand,
                        span: prop.span,
                    });
                }
                Ok(Pattern {
                    kind: PatternKind::Object {
                        properties: pats,
                        rest,
                    },
                    span,
                })
            }
            ExprKind::Assignment {
                op: AssignOp::Assign,
                left,
                right,
            } => {
                let left_pat = self.expr_to_pattern(left)?;
                Ok(Pattern {
                    kind: PatternKind::Assign {
                        left: Box::new(left_pat),
                        right: right.clone(),
                    },
                    span,
                })
            }
            ExprKind::Spread(inner) => self.expr_to_pattern(inner),
            _ => Err(ParseError {
                message: "invalid destructuring pattern".into(),
                pos: span.start,
            }),
        }
    }

    fn expr_to_params(&self, expr: &Expr) -> Result<Vec<Pattern>, ParseError> {
        match &expr.kind {
            ExprKind::Sequence(exprs) if exprs.is_empty() => Ok(vec![]),
            ExprKind::Sequence(exprs) => {
                let mut params = Vec::new();
                for e in exprs {
                    if let ExprKind::Spread(inner) = &e.kind {
                        let pat = self.expr_to_pattern(inner)?;
                        params.push(Pattern {
                            kind: PatternKind::Rest(Box::new(pat)),
                            span: e.span,
                        });
                    } else {
                        params.push(self.expr_to_pattern(e)?);
                    }
                }
                Ok(params)
            }
            ExprKind::Spread(inner) => {
                let pat = self.expr_to_pattern(inner)?;
                Ok(vec![Pattern {
                    kind: PatternKind::Rest(Box::new(pat)),
                    span: expr.span,
                }])
            }
            _ => {
                // Single expression as single parameter
                Ok(vec![self.expr_to_pattern(expr)?])
            }
        }
    }
}

// ── Helpers ─────────────────────────────────────────────────

/// Distinguishes binary operators from logical operators in Pratt parsing.
enum BinOrLogical {
    Binary(BinaryOp),
    Logical(LogicalOp),
}

/// Returns true if the token kind is a keyword (used for property name parsing).
fn is_keyword(kind: &TokenKind) -> bool {
    matches!(
        kind,
        TokenKind::Await
            | TokenKind::Break
            | TokenKind::Case
            | TokenKind::Catch
            | TokenKind::Class
            | TokenKind::Const
            | TokenKind::Continue
            | TokenKind::Debugger
            | TokenKind::Default
            | TokenKind::Delete
            | TokenKind::Do
            | TokenKind::Else
            | TokenKind::Export
            | TokenKind::Extends
            | TokenKind::Finally
            | TokenKind::For
            | TokenKind::Function
            | TokenKind::If
            | TokenKind::Import
            | TokenKind::In
            | TokenKind::Instanceof
            | TokenKind::Let
            | TokenKind::New
            | TokenKind::Of
            | TokenKind::Return
            | TokenKind::Static
            | TokenKind::Super
            | TokenKind::Switch
            | TokenKind::This
            | TokenKind::Throw
            | TokenKind::Try
            | TokenKind::Typeof
            | TokenKind::Var
            | TokenKind::Void
            | TokenKind::While
            | TokenKind::With
            | TokenKind::Yield
            | TokenKind::Async
            | TokenKind::True
            | TokenKind::False
            | TokenKind::Null
    )
}

fn is_contextual_identifier(kind: &TokenKind) -> bool {
    matches!(kind, TokenKind::Async | TokenKind::Of)
}

// ── Tests ───────────────────────────────────────────────────

#[cfg(test)]
mod tests {
    use super::*;

    fn parse(src: &str) -> Program {
        Parser::parse(src).unwrap()
    }

    fn parse_expr(src: &str) -> Expr {
        let prog = parse(src);
        match &prog.body[0].kind {
            StmtKind::Expr(e) => e.clone(),
            _ => panic!("expected expression statement, got {:?}", prog.body[0].kind),
        }
    }

    fn parse_stmt(src: &str) -> Stmt {
        let prog = parse(src);
        prog.body[0].clone()
    }

    #[test]
    fn test_in_after_string_outside_for_init() {
        // `in` after a string literal at statement level (regression for the
        // tradera.net webpack chunk; isu issue 362).
        for src in [
            "a&&\"dotAll\"in js&&b;",
            "\"dotAll\" in js;",
            "x=(\"dotAll\" in js);",
            "h=t,ps&&\"dotAll\"in js&&(n=1),r=e;",
        ] {
            assert!(Parser::parse(src).is_ok(), "should parse: {src}");
        }
    }

    #[test]
    fn test_no_in_does_not_leak_into_nested_contexts() {
        // The `for`-initializer NoIn restriction must not propagate into the
        // bracketed productions nested inside it, which the grammar always
        // evaluates with `[+In]` (isu issue 362).
        for src in [
            "for(var x=f(\"k\" in o);;){}",                 // call arguments
            "for(var x=[\"k\" in o];;){}",                  // array element
            "for(var x=o[\"k\" in p];;){}",                 // computed member
            "for(var x={a:(\"k\" in o)};;){}",              // object value
            "for(var x={[\"k\" in o]:1};;){}",              // computed key
            "for(var x=`${\"k\" in o}`;;){}",               // template substitution
            "for(var x=function(){return \"k\" in o};;){}", // function body
            "for(var x=(a=\"k\" in o)=>a;;){}",             // arrow param default
            "for(var f=function(a=\"k\" in o){};;){}",      // function param default
            "for(var x=f(\"k\" in o), y=2;;){}",            // multi-declarator
            "for(x=f(\"k\" in o);;){}",                     // no-var expression init
        ] {
            assert!(Parser::parse(src).is_ok(), "should parse: {src}");
        }
    }

    #[test]
    fn test_top_level_for_in_still_parses() {
        // The NoIn restriction at the for-init spine must remain so `for (k in
        // obj)` is still recognised as a for-in statement.
        assert!(matches!(
            parse_stmt("for (k in obj) {}").kind,
            StmtKind::ForIn { .. }
        ));
        assert!(matches!(
            parse_stmt("for (var k in obj) {}").kind,
            StmtKind::ForIn { .. }
        ));
    }

    // ── Literals ────────────────────────────────────────

    #[test]
    fn test_number_literal() {
        let expr = parse_expr("42");
        assert_eq!(expr.kind, ExprKind::Number(42.0));
    }

    #[test]
    fn test_string_literal() {
        let expr = parse_expr("\"hello\"");
        assert_eq!(expr.kind, ExprKind::String("hello".into()));
    }

    #[test]
    fn test_boolean_literals() {
        assert_eq!(parse_expr("true").kind, ExprKind::Bool(true));
        assert_eq!(parse_expr("false").kind, ExprKind::Bool(false));
    }

    #[test]
    fn test_null_literal() {
        assert_eq!(parse_expr("null").kind, ExprKind::Null);
    }

    #[test]
    fn test_this() {
        assert_eq!(parse_expr("this").kind, ExprKind::This);
    }

    #[test]
    fn test_identifier() {
        assert_eq!(parse_expr("foo").kind, ExprKind::Identifier("foo".into()));
    }

    #[test]
    fn test_contextual_identifier_of_expression() {
        let expr = parse_expr("of(e, t)");
        match expr.kind {
            ExprKind::Call {
                callee, arguments, ..
            } => {
                assert_eq!(callee.kind, ExprKind::Identifier("of".into()));
                assert_eq!(arguments.len(), 2);
            }
            _ => panic!("expected call"),
        }
    }

    #[test]
    fn test_regexp() {
        let expr = parse_expr("x = /test/gi");
        match &expr.kind {
            ExprKind::Assignment { right, .. } => {
                assert_eq!(
                    right.kind,
                    ExprKind::RegExp {
                        pattern: "test".into(),
                        flags: "gi".into()
                    }
                );
            }
            _ => panic!("expected assignment"),
        }
    }

    #[test]
    fn test_regexp_after_function_declaration() {
        Parser::parse("function f(){}/iPhone|iPad/.test(navigator.userAgent);").unwrap();
    }

    #[test]
    fn test_regexp_after_control_flow_header() {
        // isu #361: the for-of body is an expression statement beginning with a
        // RegExp literal; `/` after the header `)` must lex as a regex.
        Parser::parse("for(let t of Object.keys(e))/didomi/gi.test(t)||0;").unwrap();
        Parser::parse("if(a)/re/.test(x);").unwrap();
        Parser::parse("while(a)/re/g.exec(x);").unwrap();
    }

    #[test]
    fn test_async_function_expression_object_function_property() {
        Parser::parse(
            "let f = async function(e) {
                return { reference: function(e, t, a) { return 1; } };
            };",
        )
        .unwrap();
    }

    // ── Binary expressions ──────────────────────────────

    #[test]
    fn test_addition() {
        let expr = parse_expr("1 + 2");
        match expr.kind {
            ExprKind::Binary { op, left, right } => {
                assert_eq!(op, BinaryOp::Add);
                assert_eq!(left.kind, ExprKind::Number(1.0));
                assert_eq!(right.kind, ExprKind::Number(2.0));
            }
            _ => panic!("expected binary"),
        }
    }

    #[test]
    fn test_precedence() {
        // 1 + 2 * 3 should be 1 + (2 * 3)
        let expr = parse_expr("1 + 2 * 3");
        match expr.kind {
            ExprKind::Binary {
                op: BinaryOp::Add,
                left,
                right,
            } => {
                assert_eq!(left.kind, ExprKind::Number(1.0));
                match right.kind {
                    ExprKind::Binary {
                        op: BinaryOp::Mul, ..
                    } => {}
                    _ => panic!("expected multiply on right"),
                }
            }
            _ => panic!("expected binary add"),
        }
    }

    #[test]
    fn test_exponentiation_right_assoc() {
        // 2 ** 3 ** 2 should be 2 ** (3 ** 2)
        let expr = parse_expr("2 ** 3 ** 2");
        match expr.kind {
            ExprKind::Binary {
                op: BinaryOp::Exp,
                left,
                right,
            } => {
                assert_eq!(left.kind, ExprKind::Number(2.0));
                match right.kind {
                    ExprKind::Binary {
                        op: BinaryOp::Exp, ..
                    } => {}
                    _ => panic!("expected exp on right"),
                }
            }
            _ => panic!("expected binary exp"),
        }
    }

    #[test]
    fn test_comparison() {
        let expr = parse_expr("a === b");
        match expr.kind {
            ExprKind::Binary {
                op: BinaryOp::StrictEq,
                ..
            } => {}
            _ => panic!("expected strict eq"),
        }
    }

    #[test]
    fn test_logical_operators() {
        let expr = parse_expr("a && b || c");
        // Should be (a && b) || c because && has higher precedence
        match expr.kind {
            ExprKind::Logical {
                op: LogicalOp::Or, ..
            } => {}
            _ => panic!("expected logical or"),
        }
    }

    // ── Unary expressions ───────────────────────────────

    #[test]
    fn test_unary_minus() {
        let expr = parse_expr("-x");
        match expr.kind {
            ExprKind::Unary {
                op: UnaryOp::Minus,
                argument,
            } => {
                assert_eq!(argument.kind, ExprKind::Identifier("x".into()));
            }
            _ => panic!("expected unary minus"),
        }
    }

    #[test]
    fn test_typeof() {
        let expr = parse_expr("typeof x");
        match expr.kind {
            ExprKind::Unary {
                op: UnaryOp::Typeof,
                ..
            } => {}
            _ => panic!("expected typeof"),
        }
    }

    #[test]
    fn test_prefix_increment() {
        let expr = parse_expr("++x");
        match expr.kind {
            ExprKind::Update {
                op: UpdateOp::Increment,
                prefix: true,
                ..
            } => {}
            _ => panic!("expected prefix increment"),
        }
    }

    #[test]
    fn test_postfix_decrement() {
        let expr = parse_expr("x--");
        match expr.kind {
            ExprKind::Update {
                op: UpdateOp::Decrement,
                prefix: false,
                ..
            } => {}
            _ => panic!("expected postfix decrement"),
        }
    }

    // ── Conditional expression ──────────────────────────

    #[test]
    fn test_ternary() {
        let expr = parse_expr("a ? b : c");
        match expr.kind {
            ExprKind::Conditional {
                test,
                consequent,
                alternate,
            } => {
                assert_eq!(test.kind, ExprKind::Identifier("a".into()));
                assert_eq!(consequent.kind, ExprKind::Identifier("b".into()));
                assert_eq!(alternate.kind, ExprKind::Identifier("c".into()));
            }
            _ => panic!("expected conditional"),
        }
    }

    // ── Assignment ──────────────────────────────────────

    #[test]
    fn test_assignment() {
        let expr = parse_expr("x = 42");
        match expr.kind {
            ExprKind::Assignment {
                op: AssignOp::Assign,
                left,
                right,
            } => {
                assert_eq!(left.kind, ExprKind::Identifier("x".into()));
                assert_eq!(right.kind, ExprKind::Number(42.0));
            }
            _ => panic!("expected assignment"),
        }
    }

    #[test]
    fn test_compound_assignment() {
        let expr = parse_expr("x += 1");
        match expr.kind {
            ExprKind::Assignment {
                op: AssignOp::AddAssign,
                ..
            } => {}
            _ => panic!("expected add-assign"),
        }
    }

    // ── Member expressions ──────────────────────────────

    #[test]
    fn test_dot_access() {
        let expr = parse_expr("a.b");
        match expr.kind {
            ExprKind::Member {
                computed: false, ..
            } => {}
            _ => panic!("expected member access"),
        }
    }

    #[test]
    fn test_bracket_access() {
        let expr = parse_expr("a[0]");
        match expr.kind {
            ExprKind::Member { computed: true, .. } => {}
            _ => panic!("expected computed member"),
        }
    }

    // ── Call expressions ────────────────────────────────

    #[test]
    fn test_function_call() {
        let expr = parse_expr("foo(1, 2)");
        match expr.kind {
            ExprKind::Call {
                callee, arguments, ..
            } => {
                assert_eq!(callee.kind, ExprKind::Identifier("foo".into()));
                assert_eq!(arguments.len(), 2);
            }
            _ => panic!("expected call"),
        }
    }

    #[test]
    fn test_method_call() {
        let expr = parse_expr("obj.method()");
        match expr.kind {
            ExprKind::Call { callee, .. } => match callee.kind {
                ExprKind::Member { .. } => {}
                _ => panic!("expected member callee"),
            },
            _ => panic!("expected call"),
        }
    }

    #[test]
    fn test_new_expression() {
        let expr = parse_expr("new Foo(1)");
        match expr.kind {
            ExprKind::New {
                callee, arguments, ..
            } => {
                assert_eq!(callee.kind, ExprKind::Identifier("Foo".into()));
                assert_eq!(arguments.len(), 1);
            }
            _ => panic!("expected new"),
        }
    }

    #[test]
    fn test_new_expression_member_chain() {
        // new MemberExpression Arguments is itself a MemberExpression, so
        // `.forEach` after it must parse as a member access on the new'd object.
        // Regression: Reddit's bot-check inline script uses
        // `new URLSearchParams(document.location.search).forEach(...)`.
        let expr = parse_expr("new URLSearchParams(s).forEach(cb)");
        match expr.kind {
            ExprKind::Call {
                callee, arguments, ..
            } => {
                assert_eq!(arguments.len(), 1);
                match callee.kind {
                    ExprKind::Member {
                        object,
                        property,
                        computed,
                    } => {
                        assert!(!computed);
                        assert_eq!(property.kind, ExprKind::Identifier("forEach".into()));
                        match object.kind {
                            ExprKind::New {
                                callee: new_callee,
                                arguments: new_args,
                            } => {
                                assert_eq!(
                                    new_callee.kind,
                                    ExprKind::Identifier("URLSearchParams".into())
                                );
                                assert_eq!(new_args.len(), 1);
                            }
                            _ => panic!("expected new inside member"),
                        }
                    }
                    _ => panic!("expected member callee"),
                }
            }
            _ => panic!("expected call expression"),
        }
    }

    #[test]
    fn test_new_expression_computed_member() {
        let expr = parse_expr("new Foo()[0]");
        match expr.kind {
            ExprKind::Member {
                object, computed, ..
            } => {
                assert!(computed);
                assert!(matches!(object.kind, ExprKind::New { .. }));
            }
            _ => panic!("expected member"),
        }
    }

    #[test]
    fn test_new_expression_call_chain() {
        // new X(a)(b) → call the constructed object
        let expr = parse_expr("new Foo()()");
        match expr.kind {
            ExprKind::Call { callee, .. } => {
                assert!(matches!(callee.kind, ExprKind::New { .. }));
            }
            _ => panic!("expected call"),
        }
    }

    #[test]
    fn test_new_target() {
        let expr = parse_expr("new.target");
        assert!(matches!(expr.kind, ExprKind::NewTarget));
    }

    // ── Array and object literals ───────────────────────

    #[test]
    fn test_array_literal() {
        let expr = parse_expr("[1, 2, 3]");
        match expr.kind {
            ExprKind::Array(elements) => {
                assert_eq!(elements.len(), 3);
            }
            _ => panic!("expected array"),
        }
    }

    #[test]
    fn test_object_literal() {
        let expr = parse_expr("({a: 1, b: 2})");
        match expr.kind {
            ExprKind::Object(props) => {
                assert_eq!(props.len(), 2);
                assert_eq!(props[0].key, PropertyKey::Identifier("a".into()));
            }
            _ => panic!("expected object"),
        }
    }

    #[test]
    fn test_shorthand_property() {
        let expr = parse_expr("({x, y})");
        match expr.kind {
            ExprKind::Object(props) => {
                assert!(props[0].shorthand);
                assert!(props[1].shorthand);
            }
            _ => panic!("expected object"),
        }
    }

    #[test]
    fn test_computed_property() {
        let expr = parse_expr("({[key]: value})");
        match expr.kind {
            ExprKind::Object(props) => {
                assert!(props[0].computed);
            }
            _ => panic!("expected object"),
        }
    }

    // ── Arrow functions ─────────────────────────────────

    #[test]
    fn test_arrow_single_param() {
        let expr = parse_expr("x => x + 1");
        match expr.kind {
            ExprKind::Arrow {
                params,
                body: ArrowBody::Expr(_),
                is_async: false,
            } => {
                assert_eq!(params.len(), 1);
            }
            _ => panic!("expected arrow"),
        }
    }

    #[test]
    fn test_arrow_multi_param() {
        let expr = parse_expr("(a, b) => a + b");
        match expr.kind {
            ExprKind::Arrow { params, .. } => {
                assert_eq!(params.len(), 2);
            }
            _ => panic!("expected arrow"),
        }
    }

    #[test]
    fn test_arrow_rest_after_param() {
        let expr = parse_expr("(value, ...rest) => rest");
        match expr.kind {
            ExprKind::Arrow { params, .. } => {
                assert_eq!(params.len(), 2);
                assert!(matches!(
                    &params[1].kind,
                    PatternKind::Rest(inner)
                        if matches!(&inner.kind, PatternKind::Identifier(n) if n == "rest")
                ));
            }
            _ => panic!("expected arrow"),
        }
    }

    #[test]
    fn test_async_parenthesized_arrow() {
        let expr = parse_expr("async (value) => value");
        match expr.kind {
            ExprKind::Arrow {
                params, is_async, ..
            } => {
                assert!(is_async);
                assert_eq!(params.len(), 1);
            }
            _ => panic!("expected async arrow"),
        }
    }

    #[test]
    fn test_async_empty_parenthesized_arrow_without_space() {
        let expr = parse_expr("async()=>value");
        match expr.kind {
            ExprKind::Arrow {
                params, is_async, ..
            } => {
                assert!(is_async);
                assert!(params.is_empty());
            }
            _ => panic!("expected async arrow"),
        }
    }

    #[test]
    fn test_async_parenthesized_arrow_without_space() {
        let expr = parse_expr("async(value)=>value");
        match expr.kind {
            ExprKind::Arrow {
                params, is_async, ..
            } => {
                assert!(is_async);
                assert_eq!(params.len(), 1);
            }
            _ => panic!("expected async arrow"),
        }
    }

    #[test]
    fn test_arrow_body_block() {
        let expr = parse_expr("() => { return 1; }");
        match expr.kind {
            ExprKind::Arrow {
                body: ArrowBody::Block(stmts),
                ..
            } => {
                assert_eq!(stmts.len(), 1);
            }
            _ => panic!("expected arrow with block body"),
        }
    }

    // ── Template literals ───────────────────────────────

    #[test]
    fn test_template_no_subst() {
        let expr = parse_expr("`hello`");
        match expr.kind {
            ExprKind::TemplateLiteral {
                quasis,
                expressions,
            } => {
                assert_eq!(quasis, vec!["hello"]);
                assert!(expressions.is_empty());
            }
            _ => panic!("expected template literal"),
        }
    }

    #[test]
    fn test_template_with_subst() {
        let expr = parse_expr("`hello ${name}!`");
        match expr.kind {
            ExprKind::TemplateLiteral {
                quasis,
                expressions,
            } => {
                assert_eq!(quasis, vec!["hello ", "!"]);
                assert_eq!(expressions.len(), 1);
            }
            _ => panic!("expected template literal"),
        }
    }

    // ── Spread ──────────────────────────────────────────

    #[test]
    fn test_spread_in_call() {
        let expr = parse_expr("foo(...args)");
        match expr.kind {
            ExprKind::Call { arguments, .. } => {
                assert_eq!(arguments.len(), 1);
                assert!(matches!(arguments[0].kind, ExprKind::Spread(_)));
            }
            _ => panic!("expected call"),
        }
    }

    // ── Variable declarations ───────────────────────────

    #[test]
    fn test_var_decl() {
        let stmt = parse_stmt("var x = 42;");
        match stmt.kind {
            StmtKind::VarDecl { kind, declarators } => {
                assert_eq!(kind, VarKind::Var);
                assert_eq!(declarators.len(), 1);
                assert!(matches!(
                    declarators[0].pattern.kind,
                    PatternKind::Identifier(ref n) if n == "x"
                ));
                assert!(declarators[0].init.is_some());
            }
            _ => panic!("expected var decl"),
        }
    }

    #[test]
    fn test_const_decl() {
        let stmt = parse_stmt("const [a, b] = arr;");
        match stmt.kind {
            StmtKind::VarDecl {
                kind: VarKind::Const,
                declarators,
            } => {
                assert!(matches!(
                    declarators[0].pattern.kind,
                    PatternKind::Array { .. }
                ));
            }
            _ => panic!("expected const decl"),
        }
    }

    #[test]
    fn test_destructuring_object() {
        let stmt = parse_stmt("let { a, b: c } = obj;");
        match stmt.kind {
            StmtKind::VarDecl { declarators, .. } => match &declarators[0].pattern.kind {
                PatternKind::Object { properties, .. } => {
                    assert_eq!(properties.len(), 2);
                    assert!(properties[0].shorthand);
                    assert!(!properties[1].shorthand);
                }
                _ => panic!("expected object pattern"),
            },
            _ => panic!("expected var decl"),
        }
    }

    // ── Function declaration ────────────────────────────

    #[test]
    fn test_function_decl() {
        let stmt = parse_stmt("function add(a, b) { return a + b; }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert_eq!(def.id, Some("add".into()));
                assert_eq!(def.params.len(), 2);
                assert!(!def.is_async);
                assert!(!def.is_generator);
                assert_eq!(def.body.len(), 1);
            }
            _ => panic!("expected function decl"),
        }
    }

    #[test]
    fn test_function_decl_contextual_name_of() {
        let stmt = parse_stmt("function of(value) { return value; }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert_eq!(def.id, Some("of".into()));
                assert_eq!(def.params.len(), 1);
            }
            _ => panic!("expected function decl"),
        }
    }

    #[test]
    fn test_generator_function() {
        let stmt = parse_stmt("function* gen() { yield 1; }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert!(def.is_generator);
            }
            _ => panic!("expected function decl"),
        }
    }

    #[test]
    fn test_async_function() {
        let stmt = parse_stmt("async function fetch() { await get(); }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert!(def.is_async);
            }
            _ => panic!("expected function decl"),
        }
    }

    #[test]
    fn test_default_params() {
        let stmt = parse_stmt("function f(a, b = 10) {}");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert_eq!(def.params.len(), 2);
                assert!(matches!(def.params[1].kind, PatternKind::Assign { .. }));
            }
            _ => panic!("expected function decl"),
        }
    }

    #[test]
    fn test_rest_params() {
        let stmt = parse_stmt("function f(...args) {}");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert_eq!(def.params.len(), 1);
                assert!(matches!(
                    &def.params[0].kind,
                    PatternKind::Rest(inner)
                        if matches!(&inner.kind, PatternKind::Identifier(n) if n == "args")
                ));
            }
            _ => panic!("expected function decl"),
        }
    }

    // ── Class declaration ───────────────────────────────

    #[test]
    fn test_class_decl() {
        let stmt = parse_stmt("class Foo { constructor() {} method() {} }");
        match stmt.kind {
            StmtKind::ClassDecl(def) => {
                assert_eq!(def.id, Some("Foo".into()));
                assert_eq!(def.body.len(), 2);
            }
            _ => panic!("expected class decl"),
        }
    }

    #[test]
    fn test_class_extends() {
        let stmt = parse_stmt("class Bar extends Foo {}");
        match stmt.kind {
            StmtKind::ClassDecl(def) => {
                assert!(def.super_class.is_some());
            }
            _ => panic!("expected class decl"),
        }
    }

    #[test]
    fn test_class_getter_setter() {
        let stmt = parse_stmt("class C { get x() { return 1; } set x(v) {} }");
        match stmt.kind {
            StmtKind::ClassDecl(def) => {
                assert_eq!(def.body.len(), 2);
                match &def.body[0].kind {
                    ClassMemberKind::Method { kind, .. } => {
                        assert_eq!(*kind, MethodKind::Get);
                    }
                    _ => panic!("expected getter"),
                }
            }
            _ => panic!("expected class decl"),
        }
    }

    // ── Control flow statements ─────────────────────────

    #[test]
    fn test_if_else() {
        let stmt = parse_stmt("if (x) { a(); } else { b(); }");
        match stmt.kind {
            StmtKind::If { alternate, .. } => {
                assert!(alternate.is_some());
            }
            _ => panic!("expected if"),
        }
    }

    #[test]
    fn test_for_loop() {
        let stmt = parse_stmt("for (let i = 0; i < 10; i++) {}");
        match stmt.kind {
            StmtKind::For {
                init, test, update, ..
            } => {
                assert!(init.is_some());
                assert!(test.is_some());
                assert!(update.is_some());
            }
            _ => panic!("expected for"),
        }
    }

    #[test]
    fn test_for_in() {
        let stmt = parse_stmt("for (const key in obj) {}");
        assert!(matches!(stmt.kind, StmtKind::ForIn { .. }));
    }

    #[test]
    fn test_for_initializer_allows_parenthesized_in_expression() {
        let stmt = parse_stmt("for (s = (t in f) ? f[t] : null, h = 0; h < c; h++) {}");
        assert!(matches!(stmt.kind, StmtKind::For { .. }));
    }

    #[test]
    fn test_for_initializer_allows_parenthesized_in_expression_minified() {
        // Minified equivalent of test_for_initializer_allows_parenthesized_in_expression
        // (no whitespace, expression-statement body). Mirrors a pattern found in
        // production code (e.g., bing.com's minified bundles).
        let stmt = parse_stmt("for(s=(t in f)?f[t]:null,h=0;h<c;h++)r=u[h];");
        assert!(matches!(stmt.kind, StmtKind::For { .. }));
    }

    #[test]
    fn test_for_of() {
        let stmt = parse_stmt("for (const item of arr) {}");
        assert!(matches!(stmt.kind, StmtKind::ForOf { .. }));
    }

    #[test]
    fn test_while_loop() {
        let stmt = parse_stmt("while (true) {}");
        assert!(matches!(stmt.kind, StmtKind::While { .. }));
    }

    #[test]
    fn test_do_while() {
        let stmt = parse_stmt("do {} while (true);");
        assert!(matches!(stmt.kind, StmtKind::DoWhile { .. }));
    }

    #[test]
    fn test_do_while_asi_no_semicolon_no_newline() {
        // ECMA-262 12.10.1: the terminating semicolon of a do-while is inserted
        // automatically even with no intervening line terminator, so the token
        // following `)` begins a new statement. Minifiers (e.g. Next.js chunks)
        // emit `do{...}while(cond)return x` on a single line. Regression for
        // isu issue 344 (tradera.com static chunk parse error).
        let prog = parse("function f(){do{}while(x)return 1}");
        match &prog.body[0].kind {
            StmtKind::FunctionDecl(func) => {
                let body = &func.body;
                assert!(matches!(body[0].kind, StmtKind::DoWhile { .. }));
                assert!(matches!(body[1].kind, StmtKind::Return(_)));
            }
            other => panic!("expected function, got {other:?}"),
        }
    }

    #[test]
    fn test_do_while_asi_followed_by_expr_statement() {
        let prog = parse("do {} while (x) y");
        assert_eq!(prog.body.len(), 2);
        assert!(matches!(prog.body[0].kind, StmtKind::DoWhile { .. }));
        assert!(matches!(prog.body[1].kind, StmtKind::Expr(_)));
    }

    #[test]
    fn test_switch() {
        let stmt = parse_stmt("switch (x) { case 1: break; default: break; }");
        match stmt.kind {
            StmtKind::Switch { cases, .. } => {
                assert_eq!(cases.len(), 2);
                assert!(cases[0].test.is_some());
                assert!(cases[1].test.is_none()); // default
            }
            _ => panic!("expected switch"),
        }
    }

    #[test]
    fn test_try_catch() {
        let stmt = parse_stmt("try { f(); } catch (e) { g(); }");
        match stmt.kind {
            StmtKind::Try {
                handler, finalizer, ..
            } => {
                assert!(handler.is_some());
                assert!(finalizer.is_none());
            }
            _ => panic!("expected try"),
        }
    }

    #[test]
    fn test_try_catch_finally() {
        let stmt = parse_stmt("try {} catch (e) {} finally {}");
        match stmt.kind {
            StmtKind::Try {
                handler, finalizer, ..
            } => {
                assert!(handler.is_some());
                assert!(finalizer.is_some());
            }
            _ => panic!("expected try"),
        }
    }

    #[test]
    fn test_return() {
        let stmt = parse_stmt("function f() { return 42; }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => match &def.body[0].kind {
                StmtKind::Return(Some(expr)) => {
                    assert_eq!(expr.kind, ExprKind::Number(42.0));
                }
                _ => panic!("expected return"),
            },
            _ => panic!("expected function"),
        }
    }

    #[test]
    fn test_throw() {
        let stmt = parse_stmt("function f() { throw new Error(); }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert!(matches!(def.body[0].kind, StmtKind::Throw(_)));
            }
            _ => panic!("expected function"),
        }
    }

    #[test]
    fn test_break_continue() {
        let prog = parse("while (true) { break; continue; }");
        let while_stmt = &prog.body[0];
        match &while_stmt.kind {
            StmtKind::While { body, .. } => match &body.kind {
                StmtKind::Block(stmts) => {
                    assert!(matches!(stmts[0].kind, StmtKind::Break(None)));
                    assert!(matches!(stmts[1].kind, StmtKind::Continue(None)));
                }
                _ => panic!("expected block"),
            },
            _ => panic!("expected while"),
        }
    }

    #[test]
    fn test_labeled_statement() {
        let stmt = parse_stmt("outer: for (;;) {}");
        match stmt.kind {
            StmtKind::Labeled { label, .. } => {
                assert_eq!(label, "outer");
            }
            _ => panic!("expected labeled"),
        }
    }

    // ── Import / Export ─────────────────────────────────

    #[test]
    fn test_import_default() {
        let stmt = parse_stmt("import foo from \"mod\";");
        match stmt.kind {
            StmtKind::Import { specifiers, source } => {
                assert_eq!(source, "mod");
                assert_eq!(specifiers.len(), 1);
                assert!(matches!(&specifiers[0], ImportSpecifier::Default(n) if n == "foo"));
            }
            _ => panic!("expected import"),
        }
    }

    #[test]
    fn test_import_named() {
        let prog = Parser::parse_module("import { a, b as c } from \"mod\";").unwrap();
        match &prog.body[0].kind {
            StmtKind::Import { specifiers, .. } => {
                assert_eq!(specifiers.len(), 2);
            }
            _ => panic!("expected import"),
        }
    }

    #[test]
    fn test_import_default_as_named_export() {
        let prog = Parser::parse_module("import { default as React } from \"react\";").unwrap();
        match &prog.body[0].kind {
            StmtKind::Import { specifiers, .. } => {
                assert!(
                    matches!(&specifiers[0], ImportSpecifier::Named { imported, local } if imported == "default" && local == "React")
                );
            }
            _ => panic!("expected import"),
        }
    }

    #[test]
    fn test_import_namespace() {
        let prog = Parser::parse_module("import * as ns from \"mod\";").unwrap();
        match &prog.body[0].kind {
            StmtKind::Import { specifiers, .. } => {
                assert!(matches!(&specifiers[0], ImportSpecifier::Namespace(n) if n == "ns"));
            }
            _ => panic!("expected import"),
        }
    }

    #[test]
    fn test_export_default() {
        let prog = Parser::parse_module("export default 42;").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Default(expr)) => {
                assert_eq!(expr.kind, ExprKind::Number(42.0));
            }
            _ => panic!("expected export default"),
        }
    }

    #[test]
    fn test_export_named() {
        let prog = Parser::parse_module("export { a, b as c };").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Named { specifiers, .. }) => {
                assert_eq!(specifiers.len(), 2);
            }
            _ => panic!("expected export named"),
        }
    }

    #[test]
    fn test_export_named_as_default() {
        let prog = Parser::parse_module("export { value as default };").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Named { specifiers, .. }) => {
                assert_eq!(specifiers.len(), 1);
                assert_eq!(specifiers[0].local, "value");
                assert_eq!(specifiers[0].exported, "default");
            }
            _ => panic!("expected export named"),
        }
    }

    #[test]
    fn test_export_declaration() {
        let prog = Parser::parse_module("export const x = 1;").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Declaration(_)) => {}
            _ => panic!("expected export declaration"),
        }
    }

    #[test]
    fn test_export_default_anonymous_function() {
        let prog = Parser::parse_module("export default function() {}").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Default(expr)) => {
                assert!(matches!(expr.kind, ExprKind::Function(ref def) if def.id.is_none()));
            }
            _ => panic!("expected export default anonymous function"),
        }
    }

    #[test]
    fn test_export_default_anonymous_class() {
        let prog = Parser::parse_module("export default class {}").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Default(expr)) => {
                assert!(matches!(expr.kind, ExprKind::Class(ref def) if def.id.is_none()));
            }
            _ => panic!("expected export default anonymous class"),
        }
    }

    #[test]
    fn test_export_default_anonymous_generator() {
        let prog = Parser::parse_module("export default function*() {}").unwrap();
        match &prog.body[0].kind {
            StmtKind::Export(ExportDecl::Default(expr)) => {
                assert!(matches!(
                    expr.kind,
                    ExprKind::Function(ref def) if def.id.is_none() && def.is_generator
                ));
            }
            _ => panic!("expected export default anonymous generator"),
        }
    }

    // ── ASI (Automatic Semicolon Insertion) ─────────────

    #[test]
    fn test_asi_newline() {
        let prog = parse("let x = 1\nlet y = 2");
        assert_eq!(prog.body.len(), 2);
    }

    #[test]
    fn test_asi_before_rbrace() {
        let stmt = parse_stmt("function f() { return 1 }");
        match stmt.kind {
            StmtKind::FunctionDecl(def) => {
                assert_eq!(def.body.len(), 1);
            }
            _ => panic!("expected function"),
        }
    }

    // ── Complex programs ────────────────────────────────

    #[test]
    fn test_fibonacci() {
        let src = r#"
            function fib(n) {
                if (n <= 1) return n;
                return fib(n - 1) + fib(n - 2);
            }
        "#;
        let prog = parse(src);
        assert_eq!(prog.body.len(), 1);
        assert!(matches!(prog.body[0].kind, StmtKind::FunctionDecl(_)));
    }

    #[test]
    fn test_class_with_methods() {
        let src = r#"
            class Animal {
                constructor(name) {
                    this.name = name;
                }
                speak() {
                    return this.name;
                }
                static create(name) {
                    return new Animal(name);
                }
            }
        "#;
        let prog = parse(src);
        assert_eq!(prog.body.len(), 1);
        match &prog.body[0].kind {
            StmtKind::ClassDecl(def) => {
                assert_eq!(def.body.len(), 3);
            }
            _ => panic!("expected class"),
        }
    }

    #[test]
    fn test_for_of_destructuring() {
        let stmt = parse_stmt("for (const [k, v] of map) {}");
        match stmt.kind {
            StmtKind::ForOf { left, .. } => match left {
                ForInOfLeft::VarDecl { pattern, .. } => {
                    assert!(matches!(pattern.kind, PatternKind::Array { .. }));
                }
                _ => panic!("expected var decl"),
            },
            _ => panic!("expected for-of"),
        }
    }

    #[test]
    fn test_multiple_statements() {
        let src = "let x = 1; let y = 2; x + y;";
        let prog = parse(src);
        assert_eq!(prog.body.len(), 3);
    }

    // ── Error cases ─────────────────────────────────────

    #[test]
    fn test_error_unexpected_token() {
        assert!(Parser::parse(")").is_err());
    }

    #[test]
    fn test_error_unterminated_block() {
        assert!(Parser::parse("{ let x = 1;").is_err());
    }

    #[test]
    fn test_error_missing_paren() {
        assert!(Parser::parse("if x {}").is_err());
    }
}