package gust

import (
	"fmt"
	"strconv"
	"strings"
	"time"
	"unicode/utf8"

	"github.com/charmbracelet/lipgloss"
	"github.com/muesli/reflow/wordwrap"
)

func (m Model) View() string {
	var b strings.Builder

	b.WriteString(m.viewStatus())

	m.viewport.SetContent(m.viewBody())
	b.WriteString(m.viewport.View())

	b.WriteString("\n")

	b.WriteString(m.viewHelp())

	return b.String()
}

func (m Model) viewBody() string {
	style := m.config.Styles
	sign := m.config.Signs

	var b strings.Builder
	if m.config.Mode == "build" || m.end != nil && m.process.cmd.ProcessState.ExitCode() != 0 {
		b.WriteString(m.viewBuild())
	} else {
		b.WriteString(m.viewRun())
	}

	for _, o := range m.extra {
		b.WriteString(style.Error.Render(sign.System))
		b.WriteString(" ")
		b.WriteString(o)
		b.WriteString("\n")
	}

	for _, e := range m.systemErrors {
		b.WriteString(style.Error.Render(sign.System))
		b.WriteString(" ")
		b.WriteString(e.Error())
		b.WriteString("\n")
	}

	b.WriteString("\n")
	return b.String()
}

func (m Model) viewBuild() string {
	var b strings.Builder
	maxLineLen := 1
	maxColLen := 1
	style := m.config.Styles
	sign := m.config.Signs

	for _, msg := range m.messages {
		lineLen := len(msg.Location.Line)
		colLen := len(msg.Location.Column)

		if lineLen > maxLineLen {
			maxLineLen = lineLen
		}
		if colLen > maxColLen {
			maxColLen = colLen
		}
	}

	for _, msg := range m.messages {
		var mb strings.Builder
		if msg.Type == "error" {
			mb.WriteString(style.Error.Render(sign.Error))
			mb.WriteString(" ")
		} else {
			mb.WriteString(style.Warning.Render(sign.Warning))
			mb.WriteString(" ")
		}

		if msg.Location.Line != "" {
			mb.WriteString(style.Line.Align(lipgloss.Right).Width(maxLineLen).Render(msg.Location.Line))

			if msg.Location.Column != "" {
				mb.WriteString(":")
				mb.WriteString(style.Line.Align(lipgloss.Left).Width(maxColLen).Render(msg.Location.Column))
			}
		}
		if msg.Location.File != "" {
			mb.WriteString(" ")
			mb.WriteString(style.File.Render(msg.Location.File))
			mb.WriteString(" ")
		}

		mb.WriteString(msg.Message)

		b.WriteString(wordwrap.String(mb.String(), m.width))

		// display context
		if !m.config.Summarized {
			b.WriteString("\n")
			start := msg.Context.Start()
			style := style.Context
			for offset, line := range msg.Context.Ordered() {
				nr := fmt.Sprintf("%d", start+offset)
				nrStyle := style.PassiveLineNr
				lineStyle := style.PassiveLine
				indent := sign.PassiveIndent
				active := false
				if msg.Location.Line == nr {
					active = true
					nrStyle = style.ActiveLineNr
					lineStyle = style.ActiveLine
					indent = sign.ActiveIndent
				}
				b.WriteString(nrStyle.Render(indent))
				b.WriteString(nrStyle.Align(lipgloss.Right).Render(nr))
				b.WriteString(" ")

				simplifiedLine := strings.ReplaceAll(line, "\t", "    ")
				b.WriteString(lineStyle.Render(simplifiedLine)) // makes this easier to reason about
				if active && msg.Location.Column != "" {
					col, _ := strconv.Atoi(msg.Location.Column)
					// special logic to handle tab characters in the target line
					tabCount := strings.Count(line[:col-1], "\t")

					b.WriteString("\n")
					b.WriteString(style.PassiveLineNr.Render(sign.PassiveIndent))

					leftPadding := col + // current column to place the pointer at
						3*tabCount + // if the line has tabs, we convert to spaces and offset
						len(msg.Location.Line) + // we always print line-numbers, so offset by that too
						1 // there is a single space between line-number and line content
					b.WriteString(style.ActiveLineNr.Width(leftPadding).Align(lipgloss.Right).Render("^"))
				}
				b.WriteString("\n")
			}
		}

		b.WriteString("\n")
	}

	return b.String()
}

func (m Model) viewRun() string {
	var b strings.Builder

	if m.config.Stream == "stderr" {
		b.WriteString(m.stderr())
	} else {
		b.WriteString(m.stdout())
	}

	return b.String()
}

func (m Model) viewStatus() string {
	var b strings.Builder

	errorCount := 0
	warningCount := 0
	for _, msg := range m.messages {
		if msg.Type == "error" {
			errorCount++
		} else if msg.Type == "warning" {
			warningCount++
		}
	}

	style := m.config.Styles
	sign := m.config.Signs

	// write mode
	b.WriteString(style.Mode.Render(m.config.Mode))

	// write status
	statusStyle := style.Success
	switch m.status.Kind {
	case Running, Initializing:
		statusStyle = style.Running
	case Error:
		statusStyle = style.Error
	}
	if len(m.messages) == 0 {
		b.WriteString(style.Separator.Render(sign.Separator))
		b.WriteString(statusStyle.Render(m.status.View()))
	}

	plural := func(s string, n int) string {
		if n == 1 {
			return s
		} else {
			return fmt.Sprintf("%ss", s)
		}
	}

	// write message summary
	if errorCount != 0 {
		b.WriteString(style.Separator.Render(sign.Separator))
		b.WriteString(style.Error.Render(fmt.Sprintf("%d %s", errorCount, plural("error", errorCount))))
	}
	if warningCount != 0 {
		b.WriteString(style.Separator.Render(sign.Separator))
		b.WriteString(style.Warning.Render(fmt.Sprintf("%d %s", warningCount, plural("warning", warningCount))))
	}

	b.WriteString(style.Separator.Render(sign.Separator))

	if m.start != nil && m.end != nil {
		b.WriteString(style.Duration.Render(m.end.Sub(*m.start).String()))
	} else if m.start != nil && m.end == nil {
		b.WriteString(style.Duration.Render(time.Now().Sub(*m.start).String()))
	}

	b.WriteString(" ")
	line := strings.Repeat(sign.HorizontalBar, max(0, (m.viewport.Width-lipgloss.Width(b.String()))/utf8.RuneCountInString(sign.HorizontalBar)))
	b.WriteString(style.Separator.Render(line))

	b.WriteString("\n")

	return b.String()
}

func (m Model) viewHelp() string {
	if !m.config.Help {
		return ""
	}

	var b strings.Builder
	style := m.config.Styles
	sign := m.config.Signs

	b.WriteString("s ")
	if m.config.Summarized {
		b.WriteString(style.Separator.Render("show context"))
	} else {
		b.WriteString(style.Separator.Render("hide context"))
	}
	b.WriteString(style.Separator.Render(sign.Separator))

	if m.config.Mode != "build" {
		b.WriteString("b ")
		b.WriteString(style.Separator.Render("build"))
		b.WriteString(style.Separator.Render(sign.Separator))

		b.WriteString("o ")
		if m.config.Stream != "stdout" {
			b.WriteString(style.Separator.Render("stdout"))
			b.WriteString(style.Separator.Render(sign.Separator))
		}
		if m.config.Stream != "stderr" {
			b.WriteString(style.Separator.Render("stderr"))
			b.WriteString(style.Separator.Render(sign.Separator))
		}
	}

	if m.config.Mode != "run" {
		b.WriteString("r ")
		b.WriteString(style.Separator.Render("run"))
		b.WriteString(style.Separator.Render(sign.Separator))
	}

	b.WriteString("q ")
	b.WriteString(style.Separator.Render("quit"))
	b.WriteString(style.Separator.Render(sign.Separator))

	b.WriteString("h/? ")
	b.WriteString(style.Separator.Render("hide help"))
	b.WriteString(" ")

	var rightStatus strings.Builder
	rightStatus.WriteString(" ")
	if m.config.Mode == "run" {
		if m.config.Stream == "stderr" {
			rightStatus.WriteString(style.Stderr.Render("stderr"))
		} else {
			rightStatus.WriteString(style.Stdout.Render("stdout"))
		}
		rightStatus.WriteString(style.Separator.Render(sign.Separator))
	}
	rightStatus.WriteString(fmt.Sprintf("%3.f%%", m.viewport.ScrollPercent()*100))

	right := rightStatus.String()
	line := strings.Repeat(sign.HorizontalBar, max(0, (m.viewport.Width-lipgloss.Width(b.String())-lipgloss.Width(right))/utf8.RuneCountInString(sign.HorizontalBar)))
	b.WriteString(style.Separator.Render(line))
	b.WriteString(style.Duration.Render(right))

	return lipgloss.NewStyle().Render(b.String())
}