package internal

import (
	"fmt"
	"strings"

	"charm.land/bubbletea/v2"
	"charm.land/lipgloss/v2"
	"u-tabs/internal/style"
)

// --- View 入口 ---

func (m *Model) View() tea.View {
	v := tea.NewView(m.render())
	v.AltScreen = true
	v.MouseMode = tea.MouseModeCellMotion
	v.WindowTitle = "U-TABS"
	return v
}

func (m *Model) render() string {
	if m.width == 0 {
		return "loading..."
	}

	var b strings.Builder

	b.WriteString(m.renderTabBar())
	b.WriteString("\n")
	b.WriteString(lipgloss.NewStyle().Foreground(style.BgPanel).Render(strings.Repeat("─", m.width)))
	b.WriteString("\n")

	if m.IsHistoryTab() {
		b.WriteString(m.renderHistory())
	} else {
		b.WriteString(m.renderWorkspace())
	}

	// footer
	b.WriteString("\n")
	if m.inputBuf != "" {
		b.WriteString(style.InputStyle.Render(fmt.Sprintf(" ▶ num:%s [Enter]go [Esc]cancel", m.inputBuf)))
	}
	if m.forkMode {
		b.WriteString(style.InputStyle.Render(fmt.Sprintf(" ⎇ fork:%s [Enter]confirm [Esc]cancel", m.forkBuf)))
	}
	if m.launched != "" {
		b.WriteString(lipgloss.NewStyle().Foreground(style.Accent).Render(fmt.Sprintf(" ✓ %s", m.launched)))
		m.launched = ""
	}
	if m.update.Done {
		b.WriteString(lipgloss.NewStyle().Foreground(style.Success).Bold(true).
			Render(fmt.Sprintf(" updated to v%s, restart to apply", m.update.NewVersion)))
	} else if m.update.Error != nil {
		b.WriteString(lipgloss.NewStyle().Foreground(style.Red).
			Render(fmt.Sprintf(" update failed: %v", m.update.Error)))
	} else if m.update.Updating {
		b.WriteString(lipgloss.NewStyle().Foreground(style.Warning).
			Render(" updating..."))
	} else if m.update.Available {
		b.WriteString(lipgloss.NewStyle().Foreground(style.Warning).Bold(true).
			Render(fmt.Sprintf(" v%s available [u]update", m.update.NewVersion)))
	}
	b.WriteString("\n")

	helpParts := m.renderHelp()
	helpStr := " " + strings.Join(helpParts, "  ")
	verStr := lipgloss.NewStyle().Foreground(style.Dim).Render("绝尘 v" + Version)
	padW := m.width - lipgloss.Width(helpStr) - lipgloss.Width(verStr)
	if padW > 0 {
		b.WriteString(helpStr + strings.Repeat(" ", padW) + verStr)
	} else {
		b.WriteString(helpStr + "  " + verStr)
	}

	if hint := ConfigHint(); hint != "" {
		b.WriteString("\n" + hint)
	}
	return b.String()
}

// renderTabBar 顶部两个主 tab
func (m *Model) renderTabBar() string {
	var b strings.Builder
	b.WriteString(style.TitleStyle.Render(" U-TABS "))
	sep := style.TabSep.Render(" │ ")

	wsLabel := " 1 工作空间 "
	if !m.IsHistoryTab() {
		b.WriteString(lipgloss.NewStyle().
			Bold(true).Background(style.BgPanel).Foreground(style.Accent).
			Render(wsLabel))
	} else {
		b.WriteString(style.TabInactiveStyle.Render(wsLabel))
	}

	b.WriteString(sep)
	histLabel := " 2 历史对话 "
	if m.IsHistoryTab() {
		b.WriteString(lipgloss.NewStyle().
			Bold(true).Background(style.BgPanel).Foreground(style.Cyan).
			Render(histLabel))
	} else {
		b.WriteString(style.TabInactiveStyle.Render(histLabel))
	}

	return b.String()
}

func (m *Model) renderHelp() []string {
	if m.IsHistoryTab() {
		return []string{
			m.fmtHelp("↑↓", "sel"),
			m.fmtHelp("←→", "panel"),
			m.fmtHelp("Enter", "resume"),
			m.fmtHelp("f", "star"),
			m.fmtHelp("n", "new"),
			m.fmtHelp("c", "fork"),
			m.fmtHelp("1", "workspace"),
			m.fmtHelp("r/F5", "refresh"),
			m.fmtHelp("q", "quit"),
		}
	}
	return []string{
		m.fmtHelp("←→", "col"),
		m.fmtHelp("↑↓", "sel"),
		m.fmtHelp("Enter", "run"),
		m.fmtHelp("2", "history"),
		m.fmtHelp("q", "quit"),
	}
}

func (m *Model) fmtHelp(key, desc string) string {
	return lipgloss.NewStyle().Foreground(style.Accent).Render(key) +
		lipgloss.NewStyle().Foreground(style.Dim).Render(":" + desc)
}

func renderNavEntry(lines *[]string, w int, label string, activeFg string, isCur, focused bool) {
	sep := lipgloss.NewStyle().Foreground(style.BgPanel).Render(fitWidth(" ─────────", w))
	*lines = append(*lines, sep)
	if isCur {
		curLabel := " → " + label
		line := padRightByWidth(truncateByWidth(curLabel, w), w)
		if focused {
			*lines = append(*lines, style.SelStyle.Render(line))
		} else {
			*lines = append(*lines, lipgloss.NewStyle().Foreground(lipgloss.Color(activeFg)).Bold(true).Render(line))
		}
	} else {
		inactiveLabel := "   " + label
		line := padRightByWidth(truncateByWidth(inactiveLabel, w), w)
		*lines = append(*lines, lipgloss.NewStyle().Foreground(style.Dim).Render(line))
	}
}