package app

import (
	"sort"
	"strings"

	"github.com/charmbracelet/lipgloss"
)

// center composites a modal over a scrim-filled screen. Immediate-mode: the modal
// is recomputed from state every frame, so there is no separate show/restore path
// to desync (the "diff won't come back" bug class can't occur here).
func (m Model) center(modal string) string {
	return lipgloss.Place(m.width, m.height, lipgloss.Center, lipgloss.Center, modal,
		lipgloss.WithWhitespaceBackground(m.theme.P.BgDeep),
		lipgloss.WithWhitespaceForeground(m.theme.P.BgDeep))
}

func (m Model) modalWidth() int {
	w := m.width * 70 / 100
	if w > 92 {
		w = 92
	}
	if w < 24 {
		w = 24
	}
	return w
}

func (m Model) renderOverlay(base string) string {
	switch m.overlay {
	case OverlayPalette:
		return m.center(m.paletteModal())
	case OverlayEventInspector:
		return m.center(m.eventInspectorModal())
	case OverlayDiff:
		return m.center(m.diffModal())
	case OverlayToolPalette:
		return m.center(m.toolPaletteModal())
	}
	return base
}

func (m Model) titleLine(text string) string {
	t := m.theme
	return lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Bold(true).Render(text)
}

func mbg(t Theme, s string, fg lipgloss.Color) string {
	return lipgloss.NewStyle().Foreground(fg).Background(t.P.BgPanel).Render(s)
}

func (m Model) renderApproval(base string) string {
	t := m.theme
	s := m.session(m.selectedID)
	if s == nil || s.Pending == nil {
		return base
	}
	a := s.Pending
	w := m.modalWidth()
	textW := w - 6

	riskColor := t.P.Warn
	switch strings.ToUpper(a.Risk) {
	case "HIGH", "CRITICAL":
		riskColor = t.P.Bad
	case "LOW":
		riskColor = t.P.OK
	}

	var b strings.Builder
	b.WriteString(m.titleLine("approval required") + "\n\n")
	b.WriteString(mbg(t, "tool   ", t.P.Faint) + mbg(t, a.ToolName, t.P.FgStrong) + "\n")
	b.WriteString(mbg(t, "tier   ", t.P.Faint) + mbg(t, a.Tier, t.P.Accent2) + "\n")
	b.WriteString(mbg(t, "risk   ", t.P.Faint) + lipgloss.NewStyle().Foreground(riskColor).Background(t.P.BgPanel).Bold(true).Render(strings.ToUpper(a.Risk)) + "\n")
	if a.Preview != "" {
		b.WriteString("\n" + mbg(t, "preview", t.P.Faint) + "\n")
		for _, ln := range limitLines(a.Preview, 6) {
			b.WriteString(mbg(t, "  "+truncate(ln, textW), t.P.Dim) + "\n")
		}
	}
	b.WriteString("\n" + mbg(t, "steer  ", t.P.Faint))
	if m.steerBuffer == "" {
		b.WriteString(mbg(t, "(optional note)", t.P.Faint))
	} else {
		b.WriteString(mbg(t, m.steerBuffer, t.P.FgStrong))
	}
	b.WriteString(lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▏") + "\n\n")
	b.WriteString(modalHints(t, [][2]string{{"^a", "approve"}, {"^r", "reject"}, {"enter", "approve"}, {"^x", "diff"}, {"esc", "later"}}))

	modal := t.Overlay.Width(w).Render(b.String())
	return m.center(modal)
}

func (m Model) diffModal() string {
	t := m.theme
	w := m.modalWidth()
	h := m.height * 70 / 100
	if h < 8 {
		h = 8
	}
	bodyH := h - 6
	diff := m.currentDiff()
	lines := strings.Split(strings.TrimRight(diff, "\n"), "\n")

	off := m.diffScrollOffset
	if off > len(lines)-1 {
		off = len(lines) - 1
	}
	if off < 0 {
		off = 0
	}
	end := off + bodyH
	if end > len(lines) {
		end = len(lines)
	}

	var b strings.Builder
	b.WriteString(m.titleLine("diff") + mbg(t, "   ("+itoa(len(lines))+" lines)", t.P.Faint) + "\n\n")
	for _, ln := range lines[off:end] {
		fg := t.P.Dim
		switch {
		case strings.HasPrefix(ln, "+"):
			fg = t.P.OK
		case strings.HasPrefix(ln, "-"):
			fg = t.P.Bad
		case strings.HasPrefix(ln, "@@"):
			fg = t.P.Accent2
		}
		b.WriteString(mbg(t, truncate(ln, w-6), fg) + "\n")
	}
	b.WriteString("\n" + modalHints(t, [][2]string{{"↑↓", "scroll"}, {"^x/esc", "close"}}))

	modal := t.Overlay.Width(w).Render(b.String())
	return m.center(modal)
}

func (m Model) eventInspectorModal() string {
	t := m.theme
	w := m.modalWidth()
	evs := m.currentEvents()

	var b strings.Builder
	b.WriteString(m.titleLine("event inspector") + "\n\n")
	if len(evs) == 0 {
		b.WriteString(mbg(t, "no events", t.P.Faint))
	}
	// Budget the plain detail so the styled row never needs ANSI-aware truncation
	// (truncating a styled string would cut through escape codes and corrupt it).
	detailBudget := (w - 6) - (2 + 9 + 11 + 1 + 18 + 1)
	if detailBudget < 4 {
		detailBudget = 4
	}
	for i, e := range evs {
		cat := inferCategory(e.Type)
		marker := mbg(t, "  ", t.P.BgPanel)
		fg := t.P.Fg
		if i == m.overlayEventIdx {
			marker = lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▸ ")
			fg = t.P.FgStrong
		}
		row := marker + mbg(t, padRaw(e.Time, 8)+" ", t.P.Faint) +
			lipgloss.NewStyle().Foreground(t.categoryColor(cat)).Background(t.P.BgPanel).Render(padRaw("["+cat+"]", 11)) + " " +
			lipgloss.NewStyle().Foreground(fg).Background(t.P.BgPanel).Render(padRaw(e.Type, 18)) +
			mbg(t, " "+truncate(e.Detail, detailBudget), t.P.Dim)
		b.WriteString(row + "\n")
	}
	b.WriteString("\n" + modalHints(t, [][2]string{{"↑↓", "select"}, {"esc", "close"}}))

	modal := t.Overlay.Width(w).Render(b.String())
	return m.center(modal)
}

func (m Model) paletteModal() string {
	t := m.theme
	w := m.modalWidth()
	cmds := m.filteredPalette()

	var b strings.Builder
	b.WriteString(m.titleLine("command palette") + "\n\n")

	// filter input line
	filter := m.paletteFilter
	caret := mbg(t, " ", t.P.BgPanel)
	if m.caretVisible() {
		caret = lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▏")
	}
	prompt := lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("› ")
	if filter == "" {
		b.WriteString(prompt + caret + mbg(t, "type to filter…", t.P.Faint) + "\n\n")
	} else {
		b.WriteString(prompt + mbg(t, filter, t.P.FgStrong) + caret + "\n\n")
	}

	if len(cmds) == 0 {
		b.WriteString(mbg(t, "  no matching commands", t.P.Faint) + "\n")
	}
	for i, c := range cmds {
		marker := mbg(t, "  ", t.P.BgPanel)
		titleFg := t.P.Fg
		if i == m.paletteIndex {
			marker = lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("▌ ")
			titleFg = t.P.FgStrong
		}
		b.WriteString(marker +
			lipgloss.NewStyle().Foreground(titleFg).Background(t.P.BgPanel).Render(padRaw(c.title, 18)) +
			mbg(t, "  "+c.hint, t.P.Faint) + "\n")
	}
	b.WriteString("\n" + modalHints(t, [][2]string{{"↑↓", "select"}, {"enter", "run"}, {"esc", "close"}}))
	modal := t.Overlay.Width(w).Render(b.String())
	return m.center(modal)
}

func (m Model) toolPaletteModal() string {
	t := m.theme
	w := m.modalWidth()
	s := m.session(m.selectedID)

	var b strings.Builder
	b.WriteString(m.titleLine("tool palette") + "\n\n")
	if s == nil || len(s.ToolsByStage) == 0 {
		b.WriteString(mbg(t, "no tool manifest for this session", t.P.Faint) + "\n")
	} else {
		stages := make([]string, 0, len(s.ToolsByStage))
		for st := range s.ToolsByStage {
			stages = append(stages, st)
		}
		sort.Strings(stages)
		for _, st := range stages {
			label := mbg(t, st, t.P.Accent2)
			if st == s.CurrentStage {
				label += lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Render("  ◂ current")
			}
			b.WriteString(label + "\n")
			for _, tool := range s.ToolsByStage[st] {
				tier := lipgloss.NewStyle().Foreground(tierColor(t, tool.Tier)).Background(t.P.BgPanel).Render("T" + itoa(tool.Tier))
				b.WriteString(mbg(t, "    "+padRaw(tool.Name, 22), t.P.Fg) + tier + "\n")
			}
		}
	}
	b.WriteString("\n" + modalHints(t, [][2]string{{"t/esc", "close"}}))
	modal := t.Overlay.Width(w).Render(b.String())
	return m.center(modal)
}

func tierColor(t Theme, tier int) lipgloss.Color {
	switch {
	case tier >= 3:
		return t.P.Bad
	case tier == 2:
		return t.P.Warn
	case tier == 1:
		return t.P.Accent2
	default:
		return t.P.OK
	}
}

func modalHints(t Theme, pairs [][2]string) string {
	parts := make([]string, 0, len(pairs))
	for _, p := range pairs {
		parts = append(parts,
			lipgloss.NewStyle().Foreground(t.P.Accent).Background(t.P.BgPanel).Bold(true).Render(p[0])+
				mbg(t, " "+p[1], t.P.Faint))
	}
	return strings.Join(parts, mbg(t, "   ", t.P.Faint))
}

func limitLines(s string, n int) []string {
	lines := strings.Split(strings.TrimRight(s, "\n"), "\n")
	if len(lines) > n {
		lines = lines[:n]
	}
	return lines
}

func truncate(s string, w int) string {
	if len([]rune(s)) <= w {
		return s
	}
	r := []rune(s)
	if w < 1 {
		return ""
	}
	return string(r[:w-1]) + "…"
}