// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package app

import (
	"log/slog"
	"strings"
	"time"

	"git.stormux.org/storm/cthulhu/internal/atspi"
	"git.stormux.org/storm/cthulhu/internal/input"
	"git.stormux.org/storm/cthulhu/internal/platform/xorg"
	"git.stormux.org/storm/cthulhu/internal/wine"
)

type windowTitleSource interface {
	ForegroundTitle() atspi.ForegroundTitle
	TitleChanges() <-chan struct{}
}

type pendingWindowTitle struct {
	text          string
	previousText  string
	window        atspi.ObjectID
	epoch         uint64
	native        xorg.WindowTitle
	changed       bool
	application   string
	observedAt    time.Time
	inputSequence uint64
}

type windowTitleRepeatKey struct {
	window                    atspi.ObjectID
	nativeWindow, titleWindow uint64
	text                      string
}

// windowTitleController is owned by the accessibility event loop. Discovery
// stays in the native adapter; this controller owns coalescing, preferences,
// and duplicate suppression across AT-SPI and X11.
type windowTitleController struct {
	state       *eventLoopState
	live        *liveSettings
	gate        *focusGate
	speech      speechEnqueuer
	logger      *slog.Logger
	source      windowTitleSource
	foreground  foregroundMonitor
	inputSource any
	lastNative  atspi.ForegroundTitle
	lastTitle   string
	recent      map[windowTitleRepeatKey]time.Time
	application string
	pending     *pendingWindowTitle
	timer       *time.Timer
	due         <-chan time.Time
}

const (
	windowTitleChangeDelay       = 25 * time.Millisecond
	windowTitleIntroductionDelay = 250 * time.Millisecond
	// Animated titles (terminal TUI spinners) cycle through the same set
	// of frames about once a second. A title already announced within
	// this window is another cycle, not a new title.
	windowTitleRepeatWindow = 3 * time.Second
)

func (titles *windowTitleController) clearPending() {
	if titles.timer != nil {
		titles.timer.Stop()
	}
	titles.timer, titles.due, titles.pending = nil, nil, nil
}

// The animated-title repeat history (titles.recent) deliberately
// survives reset and activation: it expires by time on its own, and a
// workspace round-trip away from a window with an animated title must
// not restart its announcement cycle on return.
func (titles *windowTitleController) reset() {
	titles.clearPending()
	titles.lastTitle, titles.application = "", ""
	titles.lastNative = atspi.ForegroundTitle{}
}

func (titles *windowTitleController) activated(event atspi.Event) {
	titles.lastTitle = titles.state.owner.title
	// XTerm activation is consumed by the Fenrir handoff before presentation.
	// Its native title still needs an introduction, even if AT-SPI named it.
	if isXTermSnapshot(event.Source) {
		titles.lastTitle = ""
	}
	titles.application = titles.applicationForEvent(event)
	if titles.pending != nil && titles.pending.native.Window == 0 {
		titles.clearPending()
	}
}

func (titles *windowTitleController) applicationForEvent(event atspi.Event) string {
	if titles.source != nil {
		native := titles.source.ForegroundTitle()
		if native.Epoch == event.Foreground.Epoch && native.Title.Window != 0 &&
			native.Title.TitleWindow != native.Title.Window && native.Title.Application != "" {
			return native.Title.Application
		}
	}
	if event.Source.ApplicationName != "" {
		return event.Source.ApplicationName
	}
	return event.Source.ApplicationProcess
}

func (titles *windowTitleController) queue(pending pendingWindowTitle) {
	if pending.observedAt.IsZero() {
		pending.observedAt = time.Now()
		pending.inputSequence = recentInput(titles.inputSource).TitleInterruptionSequence
	}
	if titles.pending != nil {
		// Coalescing must not revive a burst interrupted since its first sample.
		pending.inputSequence = titles.pending.inputSequence
		// Compare the whole burst so an intervening status change cannot
		// disappear behind a later title which mirrors an edit.
		pending.previousText = titles.pending.previousText
	}
	if previous := titles.pending; previous != nil && !previous.changed && previous.epoch == pending.epoch &&
		previous.window == pending.window && previous.native.Window == pending.native.Window &&
		previous.native.TitleWindow == pending.native.TitleWindow {
		pending.changed = false
	}
	titles.pending = &pending
	// Keep the first deadline: continuous progress must not postpone speech
	// forever. Each burst speaks its latest value rather than every update.
	if titles.timer == nil {
		delay := windowTitleIntroductionDelay
		if pending.changed {
			delay = windowTitleChangeDelay
		}
		titles.timer = time.NewTimer(delay)
		titles.due = titles.timer.C
	}
}

func isWindowTitleEvent(event atspi.Event) bool {
	return event.Type == atspi.AccessibleNameEvent &&
		(event.Source.Role == "frame" || event.Source.Role == "window" || event.Source.Role == "dialog")
}

func (titles *windowTitleController) accessible(event atspi.Event) bool {
	if !isWindowTitleEvent(event) {
		return false
	}
	if event.Source.ID() == titles.state.owner.window && strings.TrimSpace(event.Source.Name) == "" {
		titles.state.owner.changeTitle(event)
		titles.clearPending()
		titles.lastTitle = ""
		// Keep the repeat history: animated title cycles include a
		// blank frame every cycle (observed from terminal TUIs), and
		// clearing here would restart the cycle announcement each
		// second. A title restored after a genuine removal announces
		// again once the repeat window expires.
		return true
	}
	previousTitle := titles.state.owner.title
	if !titles.state.owner.changeTitle(event) {
		return true
	}
	titles.queue(pendingWindowTitle{text: strings.TrimSpace(event.Source.Name),
		previousText: previousTitle,
		window:       titles.state.owner.window, epoch: titles.state.foregroundState.Epoch,
		changed: true, application: titles.application})
	return true
}

func (titles *windowTitleController) nativeChanged() {
	latest := titles.source.ForegroundTitle()
	if latest == titles.lastNative {
		return
	}
	previous := titles.lastNative
	titles.lastNative = latest
	if latest.Title.Window == 0 {
		titles.reset()
		return
	}
	switched := latest.Epoch != previous.Epoch || latest.Title.Window != previous.Title.Window ||
		latest.Title.TitleWindow != previous.Title.TitleWindow
	// Wine review establishes navigation ownership without speaking an
	// activation. Its stored title is metadata, not an announced title.
	accessibleActivation := titles.state.owner.activated && !wine.IsReviewID(titles.state.owner.window)
	if switched {
		titles.clearPending()
		// Keep the repeat history: a native sampler can re-report the
		// same client as a switch (new epoch or title-window id) on
		// every title sample, and clearing here would defeat animated
		// title suppression. History is scoped to the window identity,
		// so another window can still announce the same title.
		if titles.logger != nil {
			titles.logger.Debug("native window title switch",
				"epoch", latest.Epoch, "window", latest.Title.Window,
				"title_window", latest.Title.TitleWindow)
		}
		// An AT-SPI activation may already have introduced this client.
		titles.lastTitle = titles.state.owner.title
		if wine.IsReviewID(titles.state.owner.window) {
			titles.lastTitle = ""
		}
		if strings.EqualFold(latest.Title.Application, "xterm") {
			titles.lastTitle = ""
		}
	}
	if latest.Title.Title == "" {
		titles.clearPending()
		titles.lastTitle = ""
		return
	}
	changed := !switched
	// AT-SPI can introduce a window before its first X11 title sample. A
	// later differing sample is still a title change, not a new activation.
	if switched && accessibleActivation && titles.state.owner.title != "" &&
		latest.Title.TitleWindow == latest.Title.Window && !strings.EqualFold(latest.Title.Application, "xterm") {
		changed = true
	}
	previousTitle := previous.Title.Title
	if switched {
		previousTitle = ""
	}
	titles.queue(pendingWindowTitle{text: latest.Title.Title, previousText: previousTitle, epoch: latest.Epoch,
		native: latest.Title, changed: changed})
}

// animatedWindowTitleKey reduces a title to the part that carries meaning
// across animation frames. Only recognized, single-character spinner frames
// are removed; symbols such as a check or cross can carry meaningful status.
// Announcement suppression uses this only to detect cycles; the spoken text
// remains the original title.
func animatedWindowTitleKey(title string) string {
	fields := strings.Fields(strings.ToLower(title))
	if len(fields) > 1 {
		frame := []rune(fields[0])
		if len(frame) == 1 && (frame[0] >= 0x2800 && frame[0] <= 0x28ff || strings.ContainsRune("|/-\\", frame[0])) {
			fields = fields[1:]
		}
	}
	return strings.Join(fields, " ")
}

// repeatedWithinWindow reports whether this title was already announced in
// the repeat window. A suppressed sighting refreshes its entry, so a
// running animation stays suppressed instead of breaking through once per
// window; it expires shortly after the animation stops.
func (titles *windowTitleController) repeatedWithinWindow(pending pendingWindowTitle, at time.Time) bool {
	key := windowTitleRepeatKey{window: pending.window, text: animatedWindowTitleKey(pending.text)}
	if key.text == "" {
		return false
	}
	// Correlate AT-SPI and native samples through the same native client
	// when available. Do not include its epoch: returning to that client
	// should retain its animation history.
	native := pending.native
	if native.Window == 0 && titles.source != nil {
		latest := titles.source.ForegroundTitle()
		if latest.Epoch == pending.epoch {
			native = latest.Title
		}
	}
	if native.Window != 0 {
		key.window = atspi.ObjectID{}
		key.nativeWindow, key.titleWindow = native.Window, native.TitleWindow
	} else if !key.window.Valid() {
		return false
	}
	if at.IsZero() {
		at = time.Now()
	}
	for seen, when := range titles.recent {
		if at.Sub(when) > windowTitleRepeatWindow {
			delete(titles.recent, seen)
		}
	}
	if titles.recent == nil {
		titles.recent = make(map[windowTitleRepeatKey]time.Time)
	}
	_, repeated := titles.recent[key]
	titles.recent[key] = at
	return repeated
}

func equivalentWindowTitles(first, second string) bool {
	normalize := func(value string) string { return strings.Join(strings.Fields(strings.ToLower(value)), " ") }
	first, second = normalize(first), normalize(second)
	if first == "" || second == "" {
		return false
	}
	// Compare full titles: a changed status suffix is meaningful information.
	return first == second
}

func (titles *windowTitleController) enabled() bool {
	return titles.live == nil || titles.live.Load().Reading.AutomaticallyReadTitleChanges
}

// Explicit requests bypass automatic-title preferences and duplicate suppression.
// Read copied foreground metadata only; never block the event loop on native I/O
// or move either the browser cursor or object focus.
func (titles *windowTitleController) present() {
	if titles.gate.Locked() || titles.gate.Suspended() {
		return
	}
	foreground := titles.state.foregroundState
	if titles.foreground != nil && titles.foreground.Foreground().Epoch != foreground.Epoch {
		return
	}
	titles.clearPending()
	window := titles.state.owner.window
	text := ""
	if titles.source != nil {
		latest := titles.source.ForegroundTitle()
		if latest.Epoch == foreground.Epoch && latest.Title.Window != 0 && latest.Title.Window == foreground.Client.Window {
			text = strings.TrimSpace(latest.Title.Title)
		}
	}
	if text == "" && window.Valid() {
		text = strings.TrimSpace(titles.state.owner.title)
	}
	if text == "" {
		text = "Could not find current window title."
	} else {
		titles.lastTitle = text
	}
	titles.speech.Enqueue(speechRequest{Text: text, Role: "system", Cause: "present-window-title",
		Window: window, ExcludeFromHistory: titles.state.historyWindow.Valid() && window == titles.state.historyWindow})
}

// repeats_focused_edit recognizes titles whose only changed portion mirrors
// the owned entry. Use copied focus and input evidence, never application names
// or field labels. Window introductions and unrelated status changes still speak.
func (titles *windowTitleController) repeats_focused_edit(previousTitle, title string) bool {
	current := titles.state.current
	if previousTitle == "" || !current.Editable || current.ReadOnly || !current.Focused ||
		!titles.state.focusedID.Valid() || current.ID() != titles.state.focusedID ||
		titles.state.owner.focus != current.ID() || current.BusName != titles.state.owner.window.BusName {
		return false
	}
	activity := recentInput(titles.inputSource)
	if activity.Intent != input.TypingIntent && activity.Intent != input.DeleteIntent &&
		activity.Clipboard != input.CutAction && activity.Clipboard != input.PasteAction {
		return false
	}
	text := strings.TrimSpace(current.Text)
	if text == "" || strings.Count(title, text) != 1 {
		return false
	}
	start := strings.Index(title, text)
	prefix, suffix := title[:start], title[start+len(text):]
	return len(previousTitle) >= len(prefix)+len(suffix) &&
		strings.HasPrefix(previousTitle, prefix) && strings.HasSuffix(previousTitle, suffix)
}

func (titles *windowTitleController) flush() {
	pending := titles.pending
	titles.clearPending()
	if pending == nil || titles.gate.Locked() {
		return
	}
	// Only a native foreground introduction may cross the terminal handoff.
	// Content and subsequent title changes remain Fenrir's responsibility.
	xtermIntroduction := !pending.changed && pending.native.Window != 0 &&
		strings.EqualFold(pending.native.Application, "xterm")
	if titles.gate.Suspended() && !xtermIntroduction {
		return
	}
	if titles.foreground != nil && pending.epoch != titles.foreground.Foreground().Epoch {
		return
	}
	if pending.native.Window != 0 {
		latest := titles.source.ForegroundTitle()
		if latest.Epoch != pending.epoch || latest.Title != pending.native {
			return
		}
		pending.window = titles.state.owner.window
		pending.application = titles.application
		if !pending.window.Valid() || wine.IsReviewID(pending.window) || pending.native.TitleWindow != pending.native.Window {
			pending.application = pending.native.Application
		}
	} else if pending.window != titles.state.owner.window {
		return
	}
	if strings.HasPrefix(strings.ToLower(pending.application), "cthulhu") {
		pending.application = ""
	}
	if pending.application != "" && titles.live != nil && titles.live.onApplication != nil {
		titles.live.onApplication(pending.application)
		// Application switching is asynchronous. Wait for its committed
		// settings before reading a title, including Wine without AT-SPI.
		applied := titles.live.application.Load()
		if applied == nil || *applied != pending.application {
			titles.queue(*pending)
			return
		}
	}
	if pending.changed && !titles.enabled() {
		titles.lastTitle = pending.text
		return
	}
	if equivalentWindowTitles(titles.lastTitle, pending.text) {
		return
	}
	titles.lastTitle = pending.text
	if pending.changed && titles.repeats_focused_edit(pending.previousText, pending.text) {
		return
	}
	if pending.inputSequence != recentInput(titles.inputSource).TitleInterruptionSequence {
		return
	}
	if pending.changed && titles.repeatedWithinWindow(*pending, time.Now()) {
		if titles.logger != nil {
			titles.logger.Debug("suppressed repeated window title",
				"key", animatedWindowTitleKey(pending.text), "recent", len(titles.recent))
		}
		return
	}
	if titles.logger != nil {
		titles.logger.Debug("queued automatic window title", "title_changed", pending.changed,
			"observed_to_queue_ms", time.Since(pending.observedAt).Milliseconds())
	}
	titles.speech.Enqueue(speechRequest{Text: pending.text, Role: "system", Cause: "window-title",
		Window: pending.window, Append: true, BypassFocusGate: xtermIntroduction,
		ExcludeFromHistory: titles.state.historyWindow.Valid() && pending.window == titles.state.historyWindow})
}