package internal

import (
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"log"
	"math/big"
	"os/exec"
	"strconv"
	"strings"
	"unicode/utf16"
	"unicode/utf8"

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

// Model 主模型
type Model struct {
	activeGroup int
	cursor      int
	selected    map[int]bool
	inputBuf    string
	width       int
	height      int
	launched    string
}

func NewModel() *Model {
	return &Model{
		activeGroup: 0,
		selected:    make(map[int]bool),
	}
}

func (m *Model) Init() tea.Cmd {
	return nil
}

func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyPressMsg:
		s := msg.String()
		switch s {
		case "q", "ctrl+c":
			return m, tea.Quit
		case "tab", "right", "l":
			m.activeGroup = (m.activeGroup + 1) % len(Groups)
			m.cursor = 0
			m.inputBuf = ""
		case "shift+tab", "left", "h":
			m.activeGroup = (m.activeGroup - 1 + len(Groups)) % len(Groups)
			m.cursor = 0
			m.inputBuf = ""
		case "1", "2", "3", "4":
			idx, _ := strconv.Atoi(s)
			if idx <= len(Groups) {
				m.activeGroup = idx - 1
				m.cursor = 0
				m.inputBuf = ""
			}
		case "up", "k":
			m.moveCursor(-1)
		case "down", "j":
			m.moveCursor(1)
		case " ":
			m.toggleMultiSelect()
		case "enter":
			if m.inputBuf != "" {
				return m.launchByInput()
			}
			return m.launchSelected()
		default:
			if len(s) == 1 && s[0] >= '0' && s[0] <= '9' {
				m.inputBuf += s
			}
		}
	case tea.WindowSizeMsg:
		m.width = msg.Width
		m.height = msg.Height
	}
	return m, nil
}

func (m *Model) moveCursor(dir int) {
	svcs := WorkspacesByGroup(Groups[m.activeGroup].Label)
	if len(svcs) == 0 {
		return
	}
	m.cursor += dir
	if m.cursor < 0 {
		m.cursor = len(svcs) - 1
	}
	if m.cursor >= len(svcs) {
		m.cursor = 0
	}
}

func (m *Model) toggleMultiSelect() {
	svcs := WorkspacesByGroup(Groups[m.activeGroup].Label)
	if m.cursor < len(svcs) {
		idx := svcs[m.cursor].Index
		if m.selected[idx] {
			delete(m.selected, idx)
		} else {
			m.selected[idx] = true
		}
	}
}

func (m *Model) launchSelected() (*Model, tea.Cmd) {
	if len(m.selected) > 0 {
		var launched []string
		for idx := range m.selected {
			ws := &AllWorkspaces[idx]
			go launchWorkspace(*ws)
			launched = append(launched, ws.Title)
		}
		m.launched = strings.Join(launched, ", ")
		m.selected = make(map[int]bool)
		return m, nil
	}
	svcs := WorkspacesByGroup(Groups[m.activeGroup].Label)
	if m.cursor < len(svcs) {
		ws := svcs[m.cursor]
		go launchWorkspace(ws)
		m.launched = ws.Title
	}
	return m, nil
}

func (m *Model) launchByInput() (*Model, tea.Cmd) {
	num, err := strconv.Atoi(m.inputBuf)
	if err != nil {
		m.inputBuf = ""
		return m, nil
	}
	ws := FindByNumber(num)
	if ws != nil {
		go launchWorkspace(*ws)
		m.launched = ws.Title
	}
	m.inputBuf = ""
	return m, nil
}


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

	// layout widths
	listW := max(42, min(65, m.width*55/100))
	detailW := max(30, m.width-listW-3)

	// ── header: title + tabs ──
	b.WriteString(style.TitleStyle.Render(" u-tabs "))
	sep := style.TabSep.Render(" | ")
	for i, g := range Groups {
		if i > 0 {
			b.WriteString(sep)
		}
		label := fmt.Sprintf(" %s %s ", g.Label, g.Desc)
		if i == m.activeGroup {
			gs, ok := style.GroupStyles[g.Label]
			if ok {
				b.WriteString(lipgloss.NewStyle().
					Bold(true).Background(style.BgPanel).Foreground(gs.GetForeground()).
					Padding(0, 1).Render(label))
			} else {
				b.WriteString(style.TabActiveStyle.Render(label))
			}
		} else {
			b.WriteString(style.TabInactiveStyle.Render(label))
		}
	}
	b.WriteString("\n")
	b.WriteString(lipgloss.NewStyle().Foreground(style.BgPanel).Render(strings.Repeat("─", m.width)))
	b.WriteString("\n")

	g := Groups[m.activeGroup]
	gs, _ := style.GroupStyles[g.Label]
	svcs := WorkspacesByGroup(g.Label)
	if len(svcs) == 0 {
		b.WriteString(style.SubtitleStyle.Render("  empty"))
		return b.String()
	}

	// ═══ left: list ═══
	var left strings.Builder
	innerW := listW - 4
	for i, ws := range svcs {
		cur := " "
		if i == m.cursor {
			cur = "▸"
		}
		mark := " "
		if m.selected[ws.Index] {
			mark = style.MarkStyle.Render("✓")
		}
		num := style.NumStyle.Render(fmt.Sprintf("%02d", ws.N))

		prefix := cur + " " + mark + " " + num + " "
		remainW := max(10, innerW-lipgloss.Width(prefix))
		text := truncateByWidth(ws.Title+"  "+ws.Prompt, remainW)

		line := prefix + text
		if i == m.cursor {
			left.WriteString(style.SelStyle.Width(innerW).Render(line))
		} else {
			left.WriteString(style.NormStyle.Render(line))
		}
		left.WriteString("\n")
	}

	groupHeader := gs.Render(fmt.Sprintf(" %s · %d ", g.Label, len(svcs)))
	listBox := lipgloss.NewStyle().
		Border(lipgloss.NormalBorder()).
		BorderForeground(style.BgPanel).
		Width(listW).
		Padding(0, 1).
		Render(groupHeader + "\n" + left.String())

	// ═══ right: detail ═══
	var right strings.Builder
	if m.cursor < len(svcs) {
		ws := svcs[m.cursor]

		right.WriteString(style.DetailTitle.Render(" detail "))
		right.WriteString(lipgloss.NewStyle().Foreground(style.BgPanel).Render(strings.Repeat("─", detailW-10)))
		right.WriteString("\n\n")

		rows := []struct {
			key string
			val string
			sty lipgloss.Style
		}{
			{"dir", ws.Dir, style.ValStyle},
			{"no", fmt.Sprintf("%02d · %s", ws.N, ws.Group), style.NumStyle},
			{"desc", ws.Prompt, style.ValStyle},
			{"tech", ws.Tech, style.TechStyle},
			{"deploy", ws.Deploy, style.DeployStyle},
		}
		for _, r := range rows {
			right.WriteString("  ")
			right.WriteString(style.KeyStyle.Render(r.key))
			right.WriteString("  ")
			right.WriteString(r.sty.Render(r.val))
			right.WriteString("\n")
		}

		right.WriteString("\n")
		right.WriteString(lipgloss.NewStyle().Foreground(style.BgPanel).Render("  " + strings.Repeat("─", detailW-6)))
		right.WriteString("\n")
		right.WriteString(lipgloss.NewStyle().Foreground(style.Accent).Italic(true).Render("  $ wt → CC @" + ws.Title))
		right.WriteString("\n")
		right.WriteString(lipgloss.NewStyle().Foreground(style.Dim).Render("  [Enter]start  [Space]multi"))
	} else {
		right.WriteString(lipgloss.NewStyle().Foreground(style.Dim).Render(" ← select to view"))
	}

	detailBox := lipgloss.NewStyle().
		Border(lipgloss.NormalBorder()).
		BorderForeground(style.BgPanel).
		Width(detailW).
		Padding(0, 1).
		Render(right.String())

	b.WriteString(lipgloss.JoinHorizontal(lipgloss.Left, listBox, " ", detailBox))

	// ── footer ──
	b.WriteString("\n")
	if m.inputBuf != "" {
		b.WriteString(style.InputStyle.Render(fmt.Sprintf(" ▶ num:%s [Enter]go [Esc]cancel", m.inputBuf)))
	}
	if m.launched != "" {
		b.WriteString(lipgloss.NewStyle().Foreground(style.Accent).Render(fmt.Sprintf(" ✓ %s", m.launched)))
		m.launched = ""
	}
	b.WriteString("\n")

	helpParts := []string{
		m.fmtHelp("j/k", "sel"),
		m.fmtHelp("Enter", "run"),
		m.fmtHelp("Space", "multi"),
		m.fmtHelp("Tab", "group"),
		m.fmtHelp("q", "quit"),
	}
	b.WriteString(" " + strings.Join(helpParts, "  "))

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

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

// truncateByWidth 按显示宽度截断字符串，不切断多字节字符
func truncateByWidth(s string, maxW int) string {
	w := 0
	for i := 0; i < len(s); {
		_, size := utf8.DecodeRuneInString(s[i:])
		r := rune(s[i])
		rw := runeWidth(r)
		if w+rw > maxW {
			return s[:i]
		}
		w += rw
		i += size
	}
	return s
}

// runeWidth 返回单个 rune 的终端显示宽度 (CJK=2, 其他=1)
func runeWidth(r rune) int {
	if r >= 0x1100 &&
		(r <= 0x115F || r == 0x2329 || r == 0x232A ||
			(r >= 0x2E80 && r <= 0xA4CF && r != 0x303F) ||
			(r >= 0xAC00 && r <= 0xD7A3) ||
			(r >= 0xF900 && r <= 0xFAFF) ||
			(r >= 0xFE10 && r <= 0xFE19) ||
			(r >= 0xFE30 && r <= 0xFE6F) ||
			(r >= 0xFF01 && r <= 0xFF60) ||
			(r >= 0xFFE0 && r <= 0xFFE6) ||
			(r >= 0x20000 && r <= 0x2FFFD) ||
			(r >= 0x30000 && r <= 0x3FFFD)) {
		return 2
	}
	return 1
}

// --- launch ---

func launchWorkspace(ws Workspace) {
	script := buildLaunchScript(ws)
	encoded := encodePSCommand(script)
	color := fmt.Sprintf("#%02X%02X%02X", randRange(80, 255), randRange(80, 255), randRange(80, 255))
	cmd := exec.Command("wt.exe", "-w", "0",
		"-d", ws.Dir,
		"--tabColor", color,
		"pwsh", "-NoExit", "-EncodedCommand", encoded,
	)
	if err := cmd.Start(); err != nil {
		log.Printf("[u-tabs] launch fail %s(%d): %v", ws.Title, ws.N, err)
	}
}

func buildLaunchScript(ws Workspace) string {
	return fmt.Sprintf(`$Host.UI.RawUI.WindowTitle = "%s"
Write-Host "=== %s ===" -ForegroundColor Cyan
Write-Host "Prompt: %s" -ForegroundColor Yellow
cd "%s"
claude --name "%s" --permission-mode bypassPermissions`,
		ws.Title, ws.Title, ws.Prompt, ws.Dir, ws.Title)
}

func encodePSCommand(script string) string {
	u16 := utf16.Encode([]rune(script))
	b := make([]byte, len(u16)*2)
	for i, r := range u16 {
		b[i*2] = byte(r)
		b[i*2+1] = byte(r >> 8)
	}
	return base64.StdEncoding.EncodeToString(b)
}

func randRange(min, max int) int {
	n, _ := rand.Int(rand.Reader, big.NewInt(int64(max-min)))
	return min + int(n.Int64())
}