package main

import (
	"fmt"
	"io"
	"sort"
	"strings"
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/charmbracelet/lipgloss"
)

var (
	amber      = lipgloss.Color("214")
	green      = lipgloss.Color("42")
	red        = lipgloss.Color("196")
	muted      = lipgloss.Color("241")
	panel      = lipgloss.NewStyle().Border(lipgloss.RoundedBorder()).BorderForeground(lipgloss.Color("238")).Padding(0, 1)
	titleStyle = lipgloss.NewStyle().Bold(true).Foreground(amber)
	readyStyle = lipgloss.NewStyle().Foreground(green)
	blockStyle = lipgloss.NewStyle().Foreground(red)
	mutedStyle = lipgloss.NewStyle().Foreground(muted)
)

type tuiMode int

const (
	modeReady tuiMode = iota
	modeConfirm
	modeSyncing
)

type tickMsg time.Time
type scanDoneMsg struct {
	repos []repo
	err   error
}
type syncDoneMsg struct {
	results []syncResult
	repos   []repo
	err     error
}
type syncStartedMsg struct{ path string }
type syncFinishedMsg struct{ result syncResult }

type tuiModel struct {
	root        string
	repos       []repo
	selected    map[string]bool
	opts        options
	cursor      int
	offset      int
	width       int
	height      int
	mode        tuiMode
	frame       int
	status      string
	lastResult  []syncResult
	syncEvents  <-chan tea.Msg
	syncTotal   int
	syncDone    int
	syncOK      int
	syncFailed  int
	syncSkipped int
	syncActive  map[string]bool
	syncRecent  []syncResult
	syncStarted time.Time
}

func runTUI(root string, repos []repo, opts options) error {
	m := newTUIModel(root, repos, opts)
	program := tea.NewProgram(m, tea.WithAltScreen())
	_, err := program.Run()
	return err
}

func newTUIModel(root string, repos []repo, opts options) tuiModel {
	selected := make(map[string]bool)
	for _, r := range repos {
		selected[r.Path] = r.Eligible
	}
	return tuiModel{root: root, repos: repos, selected: selected, opts: opts, mode: modeReady}
}

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

func (m tuiModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.width, m.height = msg.Width, msg.Height
		m.clampViewport()
		return m, nil
	case tickMsg:
		if m.mode == modeSyncing {
			m.frame++
			return m, tickCmd()
		}
		return m, nil
	case scanDoneMsg:
		if msg.err != nil {
			m.status = "Refresh failed: " + msg.err.Error()
			return m, nil
		}
		m.repos = msg.repos
		m.reconcileSelection()
		m.status = "Workspace refreshed"
		m.clampViewport()
		return m, nil
	case syncStartedMsg:
		m.syncActive[msg.path] = true
		return m, waitSyncEventCmd(m.syncEvents)
	case syncFinishedMsg:
		delete(m.syncActive, msg.result.Path)
		m.syncDone++
		switch {
		case msg.result.Success:
			m.syncOK++
		case msg.result.Skipped:
			m.syncSkipped++
		default:
			m.syncFailed++
		}
		m.syncRecent = append(m.syncRecent, msg.result)
		if len(m.syncRecent) > 4 {
			m.syncRecent = m.syncRecent[len(m.syncRecent)-4:]
		}
		return m, waitSyncEventCmd(m.syncEvents)
	case syncDoneMsg:
		m.mode = modeReady
		m.syncEvents = nil
		m.lastResult = msg.results
		if msg.err != nil {
			m.status = "Sync failed: " + msg.err.Error()
			return m, nil
		}
		m.repos = msg.repos
		m.reconcileSelection()
		var ok, failed, skipped int
		for _, result := range msg.results {
			switch {
			case result.Success:
				ok++
			case result.Skipped:
				skipped++
			default:
				failed++
			}
		}
		m.status = fmt.Sprintf("Finished: %d synced, %d failed, %d safety-skipped", ok, failed, skipped)
		if path := firstAttentionPath(msg.results); path != "" {
			m.focusPath(path)
			m.status += "; focused first issue"
		}
		return m, nil
	case tea.KeyMsg:
		return m.handleKey(msg)
	}
	return m, nil
}

func (m tuiModel) handleKey(key tea.KeyMsg) (tea.Model, tea.Cmd) {
	value := key.String()
	if m.mode == modeSyncing {
		if value == "q" || value == "ctrl+c" {
			m.status = "Sync is running; wait for it to finish before quitting"
		}
		return m, nil
	}
	if m.mode == modeConfirm {
		switch value {
		case "y", "Y":
			selected := m.selectedRepos()
			m.mode = modeSyncing
			m.status = ""
			m.lastResult = nil
			m.syncTotal = len(selected)
			m.syncDone, m.syncOK, m.syncFailed, m.syncSkipped = 0, 0, 0, 0
			m.syncActive = make(map[string]bool)
			m.syncRecent = nil
			m.syncStarted = time.Now()
			events := make(chan tea.Msg, max(4, len(selected)*2+1))
			m.syncEvents = events
			return m, tea.Batch(m.startSyncCmd(selected, events), tickCmd())
		case "n", "N", "esc", "q":
			m.mode = modeReady
			m.status = "Sync cancelled; nothing changed"
		}
		return m, nil
	}

	switch value {
	case "q", "ctrl+c":
		return m, tea.Quit
	case "up", "k":
		if m.cursor > 0 {
			m.cursor--
		}
	case "down", "j":
		if m.cursor+1 < len(m.repos) {
			m.cursor++
		}
	case " ":
		if len(m.repos) > 0 && m.repos[m.cursor].Eligible {
			path := m.repos[m.cursor].Path
			m.selected[path] = !m.selected[path]
		}
	case "a":
		for _, r := range m.repos {
			if r.Eligible {
				m.selected[r.Path] = true
			}
		}
		m.status = "Selected every eligible repository"
	case "n":
		for path := range m.selected {
			m.selected[path] = false
		}
		m.status = "Selection cleared"
	case "r":
		m.status = "Refreshing workspace…"
		return m, m.scanCmd()
	case "f":
		if !m.focusNextAttention() {
			m.status = "The last run has no failures, skips, warnings, or protected branches"
		}
	case "s", "enter":
		count := len(m.selectedRepos())
		if count == 0 {
			m.status = "Select at least one eligible repository"
		} else {
			m.mode = modeConfirm
		}
	}
	m.clampViewport()
	return m, nil
}

func (m tuiModel) View() string {
	width := m.width
	if width <= 0 {
		width = 100
	}
	contentWidth := max(40, width-6)
	ready, blocked, selected := eligibleCount(m.repos), blockedCount(m.repos), len(m.selectedRepos())

	var b strings.Builder
	b.WriteString(titleStyle.Render("STACK SYNC"))
	b.WriteString(mutedStyle.Render("  workspace control deck"))
	b.WriteString("\n")
	b.WriteString(mutedStyle.Render(truncateMiddle(m.root, contentWidth)))
	b.WriteString("\n\n")
	b.WriteString(readyStyle.Render(fmt.Sprintf("● %d ready", ready)))
	b.WriteString("   ")
	b.WriteString(blockStyle.Render(fmt.Sprintf("● %d blocked", blocked)))
	b.WriteString("   ")
	b.WriteString(titleStyle.Render(fmt.Sprintf("◆ %d selected", selected)))
	b.WriteString("\n\n")

	visible := m.visibleRows()
	nameWidth := max(12, min(42, contentWidth-38))
	b.WriteString(mutedStyle.Render(fmt.Sprintf("   %-3s %-*s %-16s %s", "", nameWidth, "REPOSITORY", "BRANCH", "STATE")))
	b.WriteString("\n")
	for i := visible.start; i < visible.end; i++ {
		r := m.repos[i]
		pointer := " "
		if i == m.cursor {
			pointer = "›"
		}
		check := "[ ]"
		if !r.Eligible {
			check = "[–]"
		} else if m.selected[r.Path] {
			check = "[×]"
		}
		state := readyStyle.Render("ready")
		if !r.Eligible {
			state = blockStyle.Render("blocked")
		} else if len(r.Dirty) > 0 {
			state = titleStyle.Render("ready (dirty)")
		}
		line := fmt.Sprintf("%s  %-3s %-*s %-16s %s", pointer, check, nameWidth, truncateMiddle(r.RelativePath, nameWidth), truncateMiddle(r.Branch, 16), state)
		if i == m.cursor {
			line = lipgloss.NewStyle().Bold(true).Foreground(amber).Render(line)
		}
		b.WriteString(line)
		b.WriteString("\n")
	}
	if visible.start > 0 || visible.end < len(m.repos) {
		b.WriteString(mutedStyle.Render(fmt.Sprintf("   showing %d–%d of %d", visible.start+1, visible.end, len(m.repos))))
		b.WriteString("\n")
	}

	b.WriteString("\n")
	b.WriteString(m.detailView(contentWidth))
	b.WriteString("\n")

	switch m.mode {
	case modeConfirm:
		b.WriteString(blockStyle.Bold(true).Render(fmt.Sprintf("Synchronize branches in %d selected repositories?", selected)))
		b.WriteString("\n")
		b.WriteString(mutedStyle.Render("Dirty checked-out branches are protected; merged branches with deleted upstreams may be removed.  y confirm • n/esc cancel"))
	case modeSyncing:
		b.WriteString(m.syncProgressView(contentWidth))
	default:
		if m.status != "" {
			b.WriteString(m.status)
			b.WriteString("\n")
		}
		if len(m.lastResult) > 0 {
			b.WriteString(m.lastRunView(contentWidth))
			b.WriteString("\n")
		}
		b.WriteString(mutedStyle.Render("↑/k ↓/j move  •  space toggle  •  a all  •  n none  •  s/enter sync  •  r refresh  •  f next issue  •  q quit"))
	}
	return panel.Width(contentWidth).Render(b.String())
}

type rowRange struct{ start, end int }

func (m tuiModel) visibleRows() rowRange {
	reserved := 15
	if m.mode == modeSyncing {
		reserved = 20
	} else if len(m.lastResult) > 0 {
		reserved = 20
	}
	available := m.height - reserved
	if available < 4 {
		available = 4
	}
	end := min(len(m.repos), m.offset+available)
	return rowRange{start: min(m.offset, end), end: end}
}

func (m *tuiModel) clampViewport() {
	if len(m.repos) == 0 {
		m.cursor, m.offset = 0, 0
		return
	}
	m.cursor = max(0, min(m.cursor, len(m.repos)-1))
	reserved := 15
	if m.mode == modeSyncing || len(m.lastResult) > 0 {
		reserved = 20
	}
	available := max(4, m.height-reserved)
	if m.cursor < m.offset {
		m.offset = m.cursor
	}
	if m.cursor >= m.offset+available {
		m.offset = m.cursor - available + 1
	}
}

func (m tuiModel) detailView(width int) string {
	if len(m.repos) == 0 {
		return mutedStyle.Render("No repositories found")
	}
	r := m.repos[m.cursor]
	var lines []string
	if r.Eligible {
		state := readyStyle.Render("READY")
		if len(r.Dirty) > 0 {
			state = titleStyle.Render("READY · CHECKED-OUT BRANCH PROTECTED")
		}
		lines = append(lines, state+"  "+r.RelativePath+"  "+mutedStyle.Render(r.Branch))
	} else {
		lines = append(lines, blockStyle.Render("BLOCKED")+"  "+r.RelativePath+"  "+r.BlockReason)
	}
	for i, item := range r.Dirty {
		if i == 3 {
			lines = append(lines, mutedStyle.Render(fmt.Sprintf("… and %d more changes", len(r.Dirty)-3)))
			break
		}
		lines = append(lines, "  "+truncateMiddle(item, width-4))
	}
	if len(r.NestedRepoEntries) > 0 {
		lines = append(lines, mutedStyle.Render(fmt.Sprintf("%d nested repository path(s) safely excluded from parent dirtiness", len(r.NestedRepoEntries))))
	}
	for _, result := range m.lastResult {
		if result.Path != r.RelativePath || result.Message == "" {
			continue
		}
		state := readyStyle.Render("LAST SYNC")
		if !result.Success {
			state = blockStyle.Render("LAST SYNC FAILED")
		}
		lines = append(lines, state+mutedStyle.Render("  "+result.Duration))
		output := strings.Split(strings.ReplaceAll(result.Message, "\r", "\n"), "\n")
		shown := 0
		for _, outputLine := range output {
			if strings.TrimSpace(outputLine) == "" {
				continue
			}
			if shown == 3 {
				lines = append(lines, mutedStyle.Render("  … more output available in the CLI/JSON interface"))
				break
			}
			lines = append(lines, "  "+truncateMiddle(strings.TrimSpace(outputLine), width-4))
			shown++
		}
		break
	}
	return strings.Join(lines, "\n")
}

func (m tuiModel) selectedRepos() []repo {
	selected := make([]repo, 0)
	for _, r := range m.repos {
		if r.Eligible && m.selected[r.Path] {
			selected = append(selected, r)
		}
	}
	return selected
}

func (m *tuiModel) reconcileSelection() {
	next := make(map[string]bool)
	for _, r := range m.repos {
		next[r.Path] = r.Eligible && m.selected[r.Path]
	}
	m.selected = next
}

func (m tuiModel) scanCmd() tea.Cmd {
	return func() tea.Msg {
		paths, err := discover(m.root, m.opts.exclusions)
		if err != nil {
			return scanDoneMsg{err: err}
		}
		return scanDoneMsg{repos: inspectAll(m.root, paths, m.opts.jobs)}
	}
}

func (m tuiModel) startSyncCmd(selected []repo, events chan tea.Msg) tea.Cmd {
	return func() tea.Msg {
		go func() {
			results := syncSelectedWithProgress(m.root, selected, m.repos, m.opts.jobs, m.opts.timeout, io.Discard, true, false, func(event syncProgressEvent) {
				if event.Started {
					events <- syncStartedMsg{path: event.Path}
				} else {
					events <- syncFinishedMsg{result: event.Result}
				}
			})
			paths, err := discover(m.root, m.opts.exclusions)
			if err != nil {
				events <- syncDoneMsg{results: results, err: err}
				return
			}
			events <- syncDoneMsg{results: results, repos: inspectAll(m.root, paths, m.opts.jobs)}
		}()
		return <-events
	}
}

func waitSyncEventCmd(events <-chan tea.Msg) tea.Cmd {
	if events == nil {
		return nil
	}
	return func() tea.Msg { return <-events }
}

func (m tuiModel) syncProgressView(width int) string {
	spinner := []string{"◐", "◓", "◑", "◒"}[m.frame%4]
	phase := "Synchronizing repositories"
	if m.syncDone == m.syncTotal && m.syncTotal > 0 {
		phase = "Refreshing workspace"
	}
	elapsed := time.Since(m.syncStarted).Round(time.Second)
	if elapsed < 0 {
		elapsed = 0
	}
	barWidth := max(12, min(32, width-30))
	filled := 0
	if m.syncTotal > 0 {
		filled = barWidth * m.syncDone / m.syncTotal
	}
	bar := strings.Repeat("█", filled) + strings.Repeat("░", barWidth-filled)

	var lines []string
	lines = append(lines, titleStyle.Render(fmt.Sprintf("%s %s", spinner, phase))+mutedStyle.Render("  "+elapsed.String()))
	lines = append(lines, readyStyle.Render(bar)+fmt.Sprintf("  %d/%d", m.syncDone, m.syncTotal))
	lines = append(lines, fmt.Sprintf("%s  %s  %s", readyStyle.Render(fmt.Sprintf("%d synced", m.syncOK)), blockStyle.Render(fmt.Sprintf("%d failed", m.syncFailed)), mutedStyle.Render(fmt.Sprintf("%d skipped", m.syncSkipped))))
	if len(m.syncActive) > 0 {
		active := make([]string, 0, len(m.syncActive))
		for path := range m.syncActive {
			active = append(active, path)
		}
		sort.Strings(active)
		lines = append(lines, mutedStyle.Render("Active: ")+truncateMiddle(strings.Join(active, ", "), max(10, width-8)))
	}
	if len(m.syncRecent) > 0 {
		recent := m.syncRecent[len(m.syncRecent)-1]
		label := readyStyle.Render("Latest ✓")
		if recent.Skipped {
			label = titleStyle.Render("Latest ↷")
		} else if !recent.Success {
			label = blockStyle.Render("Latest ✗")
		}
		lines = append(lines, label+"  "+truncateMiddle(recent.Path+resultHeadline(recent), max(10, width-12)))
	}
	return strings.Join(lines, "\n")
}

func (m tuiModel) lastRunView(width int) string {
	var ok, failed, skipped, protected, warnings int
	var critical, caution []string
	for _, result := range m.lastResult {
		switch {
		case result.Success:
			ok++
		case result.Skipped:
			skipped++
			critical = append(critical, "↷ "+result.Path+": "+firstLine(result.Message))
		default:
			failed++
			critical = append(critical, "✗ "+result.Path+": "+firstLine(result.Message))
		}
		for _, branch := range result.Branches {
			switch branch.Action {
			case "protected":
				protected++
				caution = append(caution, "◆ "+result.Path+" / "+branch.Branch+": "+branch.Message)
			case "warning":
				warnings++
				caution = append(caution, "! "+result.Path+" / "+branch.Branch+": "+branch.Message)
			}
		}
	}
	details := append(critical, caution...)

	header := titleStyle.Render("LAST RUN") + fmt.Sprintf("  %s  %s  %s", readyStyle.Render(fmt.Sprintf("%d synced", ok)), blockStyle.Render(fmt.Sprintf("%d failed", failed)), mutedStyle.Render(fmt.Sprintf("%d skipped", skipped)))
	if protected+warnings > 0 {
		header += titleStyle.Render(fmt.Sprintf("  %d protected · %d warnings", protected, warnings))
	}
	lines := []string{header}
	shown := min(3, len(details))
	for _, detail := range details[:shown] {
		lines = append(lines, "  "+truncateMiddle(detail, max(10, width-2)))
	}
	if len(details) > shown {
		lines = append(lines, mutedStyle.Render(fmt.Sprintf("  … %d more; press f to cycle through issues", len(details)-shown)))
	}
	return strings.Join(lines, "\n")
}

func resultHeadline(result syncResult) string {
	if result.Success && len(result.Branches) == 0 {
		return " · up to date"
	}
	if result.Message == "" {
		return ""
	}
	return " · " + firstLine(result.Message)
}

func resultNeedsAttention(result syncResult) bool {
	if !result.Success || result.Skipped {
		return true
	}
	for _, branch := range result.Branches {
		if branch.Action == "warning" || branch.Action == "protected" {
			return true
		}
	}
	return false
}

func firstAttentionPath(results []syncResult) string {
	for _, result := range results {
		if !result.Success && !result.Skipped {
			return result.Path
		}
	}
	for _, result := range results {
		if result.Skipped {
			return result.Path
		}
	}
	for _, result := range results {
		for _, branch := range result.Branches {
			if branch.Action == "warning" || branch.Action == "protected" {
				return result.Path
			}
		}
	}
	return ""
}

func (m *tuiModel) focusPath(path string) bool {
	for i, repo := range m.repos {
		if repo.RelativePath == path {
			m.cursor = i
			m.clampViewport()
			return true
		}
	}
	return false
}

func (m *tuiModel) focusNextAttention() bool {
	var paths []string
	for _, result := range m.lastResult {
		if resultNeedsAttention(result) {
			paths = append(paths, result.Path)
		}
	}
	if len(paths) == 0 {
		return false
	}
	current := ""
	if len(m.repos) > 0 {
		current = m.repos[m.cursor].RelativePath
	}
	next := paths[0]
	for i, path := range paths {
		if path == current {
			next = paths[(i+1)%len(paths)]
			break
		}
	}
	m.focusPath(next)
	m.status = "Focused issue in " + next
	return true
}

func tickCmd() tea.Cmd {
	return tea.Tick(100*time.Millisecond, func(t time.Time) tea.Msg { return tickMsg(t) })
}

func truncateMiddle(value string, width int) string {
	if width < 2 || len(value) <= width {
		return value
	}
	left := (width - 1) / 2
	right := width - left - 1
	return value[:left] + "…" + value[len(value)-right:]
}