package bonfire

// Live views ported from SSU's terminal UI (internal/cli/tui spinner.go,
// process.go and progress.go) to bubbletea v2, without SSU's git and
// engine types. Each runs as a bubbletea program with input off (stdin
// stays in cooked mode, so Ctrl+C reaches the command's own signal
// handling), without bubbletea's signal handler and with the command's
// context. While a view runs, runLive relays SIGINT and SIGTERM only to
// restore the terminal before the signal takes its usual effect.

import (
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"os/signal"
	"strings"
	"sync"
	"syscall"

	"charm.land/bubbles/v2/progress"
	"charm.land/bubbles/v2/spinner"
	tea "charm.land/bubbletea/v2"
	"charm.land/lipgloss/v2"
)

// Progress bar colors: the cyan to green gradient of the earlier bonfire
// bar (256-color 37 and 34).
var (
	barFrom = lipgloss.Color("#00afaf")
	barTo   = lipgloss.Color("#00af00")
)

const barWidth = 40

// Messages sent to the live models from the command's goroutine.
type (
	// itemMsg reports progress: done of total, the current item, and a
	// failure of the current item when err is set.
	itemMsg struct {
		done, total int
		item        string
		err         error
	}
	// stepMsg reports one item of the process view changing state.
	stepMsg struct {
		item  string
		state itemState
		err   error
		done  int
	}
	// finishMsg ends a live view; err is the result of the work.
	finishMsg struct{ err error }
)

// printLine is the message that prints s, one or more lines, above the
// running view. It is bubbletea's own Println message, sent straight to
// the program's queue: the event loop prints it itself, in the order the
// messages arrive. Returning tea.Println as a command instead would run
// it on a goroutine of its own, so lines would race each other and a line
// still in flight when the view quits would be lost.
func printLine(s string) tea.Msg {
	return tea.Println(s)()
}

// itemState is the display state of one item in the process view.
type itemState int

const (
	itemWaiting itemState = iota
	itemRunning
	itemDone
	itemFailed
)

const symWaiting = "○"

// newSpinner is SSU's MiniDot spinner in the current (cyan) style.
func newSpinner(p Palette) spinner.Model {
	return spinner.New(spinner.WithSpinner(spinner.MiniDot), spinner.WithStyle(p.Current))
}

// newBar is the gradient progress bar without its own percentage.
func newBar() progress.Model {
	bar := progress.New(progress.WithColors(barFrom, barTo), progress.WithoutPercentage())
	bar.SetWidth(barWidth)
	return bar
}

// spinnerModel shows a spinner, the label and, once known, a done/total
// counter with the current item; it ends with ✓ or ✗ and the label.
type spinnerModel struct {
	palette  Palette
	spin     spinner.Model
	label    string
	done     int
	total    int
	current  string
	failed   int
	finished bool
	err      error
}

func newSpinnerModel(p Palette, label string) spinnerModel {
	return spinnerModel{palette: p, spin: newSpinner(p), label: label}
}

func (m spinnerModel) Init() tea.Cmd { return m.spin.Tick }

func (m spinnerModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case itemMsg:
		m.done, m.total, m.current = msg.done, msg.total, msg.item
		if msg.err != nil {
			m.failed++
		}
		return m, nil
	case finishMsg:
		m.finished, m.err = true, msg.err
		return m, tea.Quit
	case spinner.TickMsg:
		var cmd tea.Cmd
		m.spin, cmd = m.spin.Update(msg)
		return m, cmd
	}
	return m, nil
}

func (m spinnerModel) View() tea.View {
	p := m.palette
	if m.finished {
		if m.err != nil {
			return tea.NewView(p.Error.Render(symCross) + " " + m.label + "\n")
		}
		return tea.NewView(p.Success.Render(symCheck) + " " + m.label + "\n")
	}
	line := m.spin.View() + " " + m.label
	if m.total > 0 {
		line += fmt.Sprintf(" %d/%d", m.done, m.total)
	}
	if m.current != "" {
		line += " " + p.Muted.Render(Sanitize(m.current)+"…")
	}
	if m.failed > 0 {
		line += "  " + p.ErrorBold.Render(fmt.Sprintf("! %d failed", m.failed))
	}
	return tea.NewView(line)
}

// progressModel shows the gradient bar, done/total and the current item.
type progressModel struct {
	palette  Palette
	bar      progress.Model
	done     int
	total    int
	current  string
	failed   int
	finished bool
}

func newProgressModel(p Palette, total int) progressModel {
	return progressModel{palette: p, bar: newBar(), total: total}
}

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

func (m progressModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.bar.SetWidth(min(max(msg.Width-30, 10), barWidth))
		return m, nil
	case itemMsg:
		m.done, m.total = msg.done, msg.total
		if msg.item != "" {
			m.current = msg.item
		}
		if msg.err != nil {
			m.failed++
		}
		return m, nil
	case finishMsg:
		m.finished = true
		return m, tea.Quit
	}
	return m, nil
}

func (m progressModel) View() tea.View {
	pct := 0.0
	if m.total > 0 {
		pct = float64(m.done) / float64(m.total)
	}
	line := " " + m.bar.ViewAs(pct) + m.palette.Muted.Render(fmt.Sprintf(" %d/%d", m.done, m.total))
	if m.current != "" && !m.finished {
		line += " " + m.palette.Muted.Render(Sanitize(m.current))
	}
	if m.failed > 0 {
		line += "  " + m.palette.ErrorBold.Render(fmt.Sprintf("! %d failed", m.failed))
	}
	if m.finished {
		line += "\n"
	}
	return tea.NewView(line)
}

// processItem is one row of the process view.
type processItem struct {
	name  string
	state itemState
	err   error
}

// processModel is SSU's multi-row view: one row per item (waiting, running
// with a spinner, done or failed with its error) and the bar below.
type processModel struct {
	palette   Palette
	items     []processItem
	spin      spinner.Model
	bar       progress.Model
	operation string
	done      int
	height    int
	finished  bool
}

func newProcessModel(p Palette, operation string, items []string) processModel {
	rows := make([]processItem, len(items))
	for i, name := range items {
		rows[i] = processItem{name: name}
	}
	return processModel{palette: p, items: rows, spin: newSpinner(p), bar: newBar(), operation: operation}
}

func (m processModel) Init() tea.Cmd { return m.spin.Tick }

func (m processModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.WindowSizeMsg:
		m.height = msg.Height
		return m, nil
	case stepMsg:
		m.done = msg.done
		for i := range m.items {
			if m.items[i].name == msg.item && m.items[i].state < msg.state {
				m.items[i].state, m.items[i].err = msg.state, msg.err
				break
			}
		}
		return m, nil
	case finishMsg:
		m.finished = true
		return m, tea.Quit
	case spinner.TickMsg:
		var cmd tea.Cmd
		m.spin, cmd = m.spin.Update(msg)
		return m, cmd
	}
	return m, nil
}

// window is the range of rows that fits the terminal: around the running
// item, or the last finished ones.
func (m processModel) window() (int, int) {
	visible := len(m.items)
	if m.height > 0 && visible > m.height-3 {
		visible = max(m.height-3, 3)
	}
	start := 0
	if visible < len(m.items) {
		active := -1
		for i, it := range m.items {
			if it.state == itemRunning {
				active = i
				break
			}
		}
		if active >= 0 {
			start = min(max(active-visible/2, 0), len(m.items)-visible)
		} else {
			start = max(m.done-visible, 0)
		}
	}
	return start, min(start+visible, len(m.items))
}

func (m processModel) View() tea.View {
	p := m.palette
	var b strings.Builder
	start, end := m.window()
	for _, it := range m.items[start:end] {
		name := Sanitize(it.name)
		switch it.state {
		case itemWaiting:
			b.WriteString(p.Muted.Render("  "+symWaiting) + "  " + p.Muted.Render(name))
		case itemRunning:
			b.WriteString("  " + m.spin.View() + "  " + name)
		case itemDone:
			b.WriteString(p.Success.Render("  "+symCheck) + "  " + name)
		case itemFailed:
			b.WriteString(p.Error.Render("  "+symCross) + "  " + name)
			if it.err != nil {
				b.WriteString("  " + p.Error.Render(Sanitize(it.err.Error())))
			}
		}
		b.WriteString("\n")
	}
	total := len(m.items)
	pct := 0.0
	if total > 0 {
		pct = float64(m.done) / float64(total)
	}
	op := m.operation
	if op == "" {
		op = "Processing"
	}
	b.WriteString(fmt.Sprintf("\n  %s %d/%d %s %s", op, m.done, total, m.bar.ViewAs(pct), p.Muted.Render(fmt.Sprintf("%d%%", int(pct*100)))))
	if m.finished {
		b.WriteString("\n")
	}
	return tea.NewView(b.String())
}

// liveView is the running live program and the console that started it.
type liveView struct {
	owner *console
	prog  *tea.Program
}

// The running live view, for PrintAbove and the owning console's output.
// Only one live view runs at a time; a widget that cannot claim the slot
// (a nested widget, or a second console at the same moment) prints plain
// lines.
var (
	liveMu     sync.Mutex
	activeView *liveView
)

// errLivePanic is the result the final frame shows when work panicked.
var errLivePanic = errors.New("bonfire: live view work panicked")

// runLive runs model as a bubbletea program on out while work runs on the
// calling goroutine, with c as the owner of the view. It first claims the
// single live slot under liveMu; when another view holds it, runLive
// returns started false without running work, and the caller prints plain
// lines instead. work gets a send function for progress messages. When
// work returns or panics, the view is unregistered (so PrintAbove stops
// sending to it), told to finish and waited for, all under liveMu; it
// never receives lines after that, and a panic goes on after the cleanup.
func runLive(ctx context.Context, out io.Writer, c *console, model tea.Model, work func(send func(tea.Msg)) error) (started bool, err error) {
	if ctx == nil {
		ctx = context.Background()
	}
	prog := tea.NewProgram(model,
		tea.WithInput(nil),
		tea.WithOutput(out),
		tea.WithoutSignalHandler(),
		tea.WithContext(ctx),
		tea.WithColorProfile(c.profile()),
	)
	view := &liveView{owner: c, prog: prog}
	liveMu.Lock()
	if activeView != nil {
		liveMu.Unlock()
		return false, nil
	}
	activeView = view
	liveMu.Unlock()

	finished := make(chan struct{})
	go func() {
		defer close(finished)
		_, _ = prog.Run()
	}()
	stopSignals := watchSignals(view, finished)

	completed := false
	defer func() {
		result := err
		if !completed {
			result = errLivePanic
		}
		// Unregister, finish and wait as one step: a printer that arrives
		// meanwhile waits for the lock and then writes after the final
		// frame, so no line reaches a stopped program or races the last
		// frame.
		liveMu.Lock()
		if activeView == view {
			activeView = nil
		}
		prog.Send(finishMsg{err: result})
		<-finished
		liveMu.Unlock()
		stopSignals()
	}()
	err = work(prog.Send)
	completed = true
	return true, err
}

// watchSignals relays SIGINT and SIGTERM (those not ignored) while view
// runs. The views run without bubbletea's own signal handling, so without
// this a Ctrl+C would end the process with the cursor still hidden. On a
// signal the program is killed (bubbletea then restores the cursor and the
// terminal), the view is unregistered and the signal is raised again on
// the process with the relay stopped, so its default action, or the
// command's own handler, still applies. The returned function stops the
// relay when the view ends normally; a signal that arrived meanwhile is
// raised again too.
func watchSignals(view *liveView, finished <-chan struct{}) (stop func()) {
	var relay []os.Signal
	for _, sig := range []os.Signal{os.Interrupt, syscall.SIGTERM} {
		if !signal.Ignored(sig) {
			relay = append(relay, sig)
		}
	}
	if len(relay) == 0 {
		return func() {}
	}
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, relay...)
	quit := make(chan struct{})
	done := make(chan struct{})
	go func() {
		defer close(done)
		select {
		case sig := <-sigs:
			view.prog.Kill()
			<-finished
			liveMu.Lock()
			if activeView == view {
				activeView = nil
			}
			liveMu.Unlock()
			signal.Stop(sigs)
			raise(sig)
		case <-quit:
		}
	}()
	return func() {
		close(quit)
		<-done
		signal.Stop(sigs)
		select {
		case sig := <-sigs:
			raise(sig)
		default:
		}
	}
}

// raise sends sig to the own process; when that fails, it exits with 128
// plus the signal number, as a shell reports a death by that signal.
func raise(sig os.Signal) {
	p, err := os.FindProcess(os.Getpid())
	if err == nil {
		err = p.Signal(sig)
	}
	if err != nil {
		code := 1
		if s, ok := sig.(syscall.Signal); ok {
			code = 128 + int(s)
		}
		os.Exit(code)
	}
}

// printAboveLines prints s, one or more lines, above the running live view,
// whichever console started it (bonfire.PrintAbove). It reports false when
// no view runs.
func printAboveLines(s string) bool {
	return printAbove(nil, s)
}

// printAbove prints s above the running live view when owner is nil or is
// the console that started the view, and reports whether it did.
func printAbove(owner *console, s string) bool {
	liveMu.Lock()
	defer liveMu.Unlock()
	if activeView == nil || (owner != nil && activeView.owner != owner) {
		return false
	}
	// One message for the whole block, sent while holding liveMu: blocks
	// from different goroutines keep the order of their calls.
	activeView.prog.Send(printLine(strings.TrimSuffix(s, "\n")))
	return true
}