import { createRequire } from 'node:module';
import { existsSync } from 'node:fs';
import { dirname, join } from 'node:path';
import type { LanguageAdapter } from './types';
import { javascriptAdapter } from './languages/javascript';
import { typescriptAdapter, tsxAdapter } from './languages/typescript';
import { pythonAdapter } from './languages/python';
import { goAdapter } from './languages/go';
import { rustAdapter } from './languages/rust';
import { svelteAdapter } from './languages/svelte';

const require = createRequire(import.meta.url);
const adapters = [typescriptAdapter, tsxAdapter, javascriptAdapter, pythonAdapter, goAdapter, rustAdapter, svelteAdapter];
const registry = new Map<string, LanguageAdapter>();
for (const adapter of adapters) for (const extension of adapter.extensions) registry.set(extension, adapter);

export function adapterFor(path: string): LanguageAdapter | undefined {
  const dot = path.lastIndexOf('.');
  return dot < 0 ? undefined : registry.get(path.slice(dot).toLowerCase());
}

export function supportedExtensions(): string[] { return [...registry.keys()].sort(); }

/**
 * Directory holding the Tree-sitter WASM assets shipped beside a `bun --compile`
 * native binary. `SHARD_TREE_SITTER_DIR` lets a deployment point elsewhere;
 * otherwise it is `<dir-of-executable>/tree-sitter`. `process.argv[0]` is the
 * resolved executable path even for a `--compile` binary (its `argv[1]` is the
 * `/$bunfs/root/<bin>` virtual entry, which is NOT a directory to resolve against).
 */
export function bundledTreeSitterDir(): string {
  return process.env.SHARD_TREE_SITTER_DIR ?? join(dirname(process.argv[0] ?? process.cwd()), 'tree-sitter');
}

export function grammarPath(name: string): string {
  // Prefer a grammar shipped beside the native binary; keep package resolution
  // as the development fallback (node_modules/tree-sitter-wasms/out/...).
  const candidate = join(bundledTreeSitterDir(), `tree-sitter-${name}.wasm`);
  if (existsSync(candidate)) return candidate;
  return require.resolve(`tree-sitter-wasms/out/tree-sitter-${name}.wasm`);
}

/**
 * Resolve the `web-tree-sitter` *runtime* wasm (`tree-sitter.wasm` — the
 * emscripten glue, distinct from the `tree-sitter-<lang>.wasm` grammars). The
 * emscripten loader's default `locateFile` uses the bundled module's `__dirname`,
 * which a `bun --compile` binary bakes in as the BUILD-TIME path
 * (`…/node_modules/web-tree-sitter/`); on a deployed host that path does not exist
 * and every `Parser.init()` aborts with
 * `ENOENT: …/node_modules/web-tree-sitter/tree-sitter.wasm`. Prefer the wasm
 * shipped beside the binary (see {@link bundledTreeSitterDir}); fall back to the
 * package's own file in development.
 */
export function runtimeWasmPath(): string {
  const candidate = join(bundledTreeSitterDir(), 'tree-sitter.wasm');
  if (existsSync(candidate)) return candidate;
  return require.resolve('web-tree-sitter/tree-sitter.wasm');
}