package internal

import (
	"fmt"
	"strings"

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

// --- HISTORY 三栏渲染 ---

func (m *Model) renderHistory() string {
	if !m.history.Loaded && !m.history.Scanning {
		return style.ScanningStyle.Render("  press Tab to load sessions...")
	}
	if len(m.history.Projects) == 0 && m.history.Scanning {
		return style.ScanningStyle.Render("  scanning sessions...")
	}
	if len(m.history.Projects) == 0 {
		return style.SubtitleStyle.Render("  no sessions found")
	}

	avail := m.width - 8
	dirW := max(18, avail*20/100)
	sessW := max(28, avail*40/100)
	detailW := avail - dirW - sessW
	listH := max(3, m.height-7)

	dirCw := dirW - 2
	sessCw := sessW - 2
	detailCw := detailW - 2

	dirLines := m.dirColumnLines(dirCw, listH-1)
	sessLines := m.sessColumnLines(sessCw, listH-1)
	detailLines := m.detailColumnLines(detailCw, listH-1)

	maxRows := min(listH-1, max(max(len(dirLines), len(sessLines)), len(detailLines)))

	panelSty := lipgloss.NewStyle().
		Border(lipgloss.RoundedBorder()).
		BorderForeground(style.BgPanel)

	dirBox := panelSty.Width(dirW).Render(
		style.DetailTitle.Render("dirs") + "\n" + padLinesTo(dirLines, dirCw, maxRows))
	sessBox := panelSty.Width(sessW).Render(
		style.DetailTitle.Render("sessions") + "\n" + padLinesTo(sessLines, sessCw, maxRows))
	detailBox := panelSty.Width(detailW).Render(
		style.DetailTitle.Render("detail") + "\n" + padLinesTo(detailLines, detailCw, maxRows))

	return lipgloss.JoinHorizontal(lipgloss.Top, dirBox, " ", sessBox, " ", detailBox)
}

func (m *Model) dirColumnLines(w, listH int) []string {
	var lines []string
	total := len(m.history.Projects) + 3
	start, end := viewport(m.history.DirCursor, total, listH)

	prefixW := 3

	buildDirLine := func(cur, name, cnt string, selected bool) string {
		cntW := stringWidth(cnt)
		nameW := max(2, w-prefixW-cntW)
		name = truncateByWidth(name, nameW)
		line := " " + cur + " " + padRightByWidth(name, nameW) + cnt
		sty := style.NormStyle
		if selected {
			sty = style.SelStyle
		}
		return sty.Render(padRightByWidth(truncateByWidth(line, w), w))
	}

	// 0: 全部
	if start == 0 {
		totalSess := 0
		for _, pd := range m.history.Projects {
			totalSess += len(pd.Sessions)
		}
		cur := " "
		if m.history.DirCursor == 0 {
			cur = "▸"
		}
		lines = append(lines, buildDirLine(cur, "全部", fmt.Sprintf("(%d)", totalSess),
			m.history.DirCursor == 0 && m.history.FocusPanel == 0))
	}

	// 1: 收藏
	if start <= 1 && end > 1 {
		favCnt := countFavorites(m.history.Projects, m.history.Favorites)
		cur := " "
		if m.history.DirCursor == 1 {
			cur = "▸"
		}
		lines = append(lines, buildDirLine(cur, "★ 收藏", fmt.Sprintf("(%d)", favCnt),
			m.history.DirCursor == 1 && m.history.FocusPanel == 0))
	}

	// 2..N+1: 项目目录
	for i := 0; i < len(m.history.Projects); i++ {
		idx := i + 2
		if idx < start || idx >= end {
			continue
		}
		pd := m.history.Projects[i]
		cur := " "
		if m.history.DirCursor == idx {
			cur = "▸"
		}
		lines = append(lines, buildDirLine(cur, pd.DirShort, fmt.Sprintf("(%d)", len(pd.Sessions)),
			m.history.DirCursor == idx && m.history.FocusPanel == 0))
	}

	// N+2: 回到工作空间入口
	backIdx := len(m.history.Projects) + 2
	if end > backIdx {
		renderNavEntry(&lines, w, "工作空间", "#7aa2f7", m.history.DirCursor == backIdx, m.history.FocusPanel == 0)
	}
	return lines
}

func (m *Model) sessColumnLines(w, listH int) []string {
	sessions := m.currentSessions()
	if len(sessions) == 0 {
		return []string{style.SubtitleStyle.Render(fitWidth("  no sessions", w))}
	}

	prefixW := 16
	textW := max(8, w-prefixW)

	type sessBlock struct {
		lines []string
	}
	var blocks []sessBlock
	totalLines := 0
	curLineOffset := 0

	for i, s := range sessions {
		cur := "  "
		if i == m.history.SessCursor {
			cur = "▸ "
		}
		timeStr := s.StartTime.Local().Format("01-02 15:04")
		favMark := " "
		if m.history.Favorites[s.ID] {
			favMark = "★"
		}
		title := s.DisplayTitle()

		wrapped := wrapByWidth(title, textW)
		if len(wrapped) == 0 {
			wrapped = []string{""}
		}

		sty := style.NormStyle
		if i == m.history.SessCursor && m.history.FocusPanel == 1 {
			sty = style.SelStyle
		}

		var blockLines []string
		for li, part := range wrapped {
			var line string
			if li == 0 {
				line = fmt.Sprintf(" %s%s%s %s", cur, timeStr, favMark, part)
			} else {
				line = strings.Repeat(" ", prefixW+1) + part
			}
			blockLines = append(blockLines, sty.Render(padRightByWidth(truncateByWidth(line, w), w)))
		}

		if i == m.history.SessCursor {
			curLineOffset = totalLines
		}
		totalLines += len(blockLines)
		blocks = append(blocks, sessBlock{lines: blockLines})
	}

	startLine, endLine := viewport(curLineOffset, totalLines, listH)

	var allLines []string
	for _, b := range blocks {
		allLines = append(allLines, b.lines...)
	}
	if endLine > len(allLines) {
		endLine = len(allLines)
	}
	return allLines[startLine:endLine]
}

func (m *Model) detailColumnLines(w, listH int) []string {
	s := m.currentSession()
	if s == nil {
		return []string{lipgloss.NewStyle().Foreground(style.Dim).Render(fitWidth(" ← select to view", w))}
	}

	sepSty := lipgloss.NewStyle().Foreground(style.BgPanel)
	var lines []string

	favPrefix := " "
	if m.history.Favorites[s.ID] {
		favPrefix = "★ "
	}
	lines = append(lines, style.DetailTitle.Render(fitWidth(favPrefix+s.DisplayTitle(), w)))
	lines = append(lines, sepSty.Render(fitWidth(strings.Repeat("─", w), w)))

	fav := "-"
	if m.history.Favorites[s.ID] {
		fav = "★"
	}
	kvRows := []struct{ k, v string }{
		{"dir", s.Cwd},
		{"time", fmt.Sprintf("%s ~ %s", s.StartTime.Local().Format("01-02 15:04"), s.EndTime.Local().Format("15:04"))},
		{"msgs", fmt.Sprintf("%d", s.MsgCount)},
		{"fav", fav},
	}
	for _, r := range kvRows {
		line := fmt.Sprintf("  %-4s %s", r.k, r.v)
		lines = append(lines, style.NormStyle.Render(fitWidth(line, w)))
	}

	if summary := s.DisplaySummary(); summary != "" {
		lines = append(lines, sepSty.Render(fitWidth(strings.Repeat("─", w), w)))
		lines = append(lines, style.SessionSummaryStyle.Render(fitWidth("  "+summary, w)))
	}

	if len(s.Completed) > 0 {
		lines = append(lines, sepSty.Render(fitWidth(strings.Repeat("─", w), w)))
		lines = append(lines, lipgloss.NewStyle().Foreground(style.Success).Bold(true).Render(fitWidth(" ✓ 已完成", w)))
		for _, item := range s.Completed {
			lines = append(lines, style.NormStyle.Render(fitWidth("   · "+cleanText(item), w)))
		}
	}

	if len(s.Pending) > 0 {
		lines = append(lines, sepSty.Render(fitWidth(strings.Repeat("─", w), w)))
		lines = append(lines, lipgloss.NewStyle().Foreground(style.Warning).Bold(true).Render(fitWidth(" ○ 待办", w)))
		for _, item := range s.Pending {
			lines = append(lines, style.NormStyle.Render(fitWidth("   · "+cleanText(item), w)))
		}
	}

	lines = append(lines, lipgloss.NewStyle().Foreground(style.Dim).Render(fitWidth("  [Enter]resume", w)))

	if s.ForkFrom != "" {
		forkID := s.ForkFrom
		if len(forkID) > 8 {
			forkID = forkID[:8]
		}
		lines = append(lines, lipgloss.NewStyle().Foreground(style.Cyan).Render(fitWidth(fmt.Sprintf("  ⎇ fork from %s", forkID), w)))
	}

	if len(lines) > listH {
		lines = lines[:listH]
	}
	return lines
}