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

package app

import (
	"context"
	"fmt"
	"log/slog"
	"os"
	"strings"
	"sync"
	"syscall"
	"time"

	"git.stormux.org/storm/fenrir/internal/datetime"
	"git.stormux.org/storm/fenrir/internal/diagnostic"
	"git.stormux.org/storm/fenrir/internal/i18n"
	"git.stormux.org/storm/fenrir/internal/interaction"
	"git.stormux.org/storm/fenrir/internal/notifications"
	"git.stormux.org/storm/fenrir/internal/presentation"
)

const notificationLimit = notifications.Limit
const notificationSoundInterval = notifications.SoundInterval

// The speech worker and muted notifications on the event loop share this gate.
// Check at playback admission so queued messages cannot accumulate sound waits.
type notificationSoundGate struct {
	mu       sync.Mutex
	lastPlay time.Time
}

func (g *notificationSoundGate) allow(now time.Time) bool {
	g.mu.Lock()
	defer g.mu.Unlock()
	if !g.lastPlay.IsZero() && now.Sub(g.lastPlay) < notificationSoundInterval {
		return false
	}
	g.lastPlay = now
	return true
}

type notification struct {
	text     string
	received time.Time
}

// Share only the active console account's history with its terminal readers.
// On graphical VTs keep the previous account until a text console is active.
func (a *application) share_notification_history(terminal int, active bool) {
	if !a.options.SharedNotifications {
		return
	}
	uid := os.Geteuid()
	if uid == 0 && !a.options.TerminalMode {
		if !active && a.notificationHistory != nil {
			return
		}
		info, err := os.Stat(fmt.Sprintf("/dev/tty%d", terminal))
		if err != nil {
			a.clear_notification_user()
			return
		}
		stat, ok := info.Sys().(*syscall.Stat_t)
		if !ok {
			a.clear_notification_user()
			return
		}
		uid = int(stat.Uid)
	}
	a.select_notification_user(uid)
}

func (a *application) select_notification_user(uid int) {
	if previous := a.notificationHistory; previous != nil && previous.UID == uid {
		return
	}
	a.clear_notification_user()
	a.notificationHistory = notifications.New(a.ctx, uid, a.options.NotificationNamespace)
}

func (a *application) clear_notification_user() {
	if previous := a.notificationHistory; previous != nil {
		a.voice.Interrupt()
		a.ui.close()
		a.notificationClosers.Go(previous.Close)
	}
	a.notifications = nil
	a.notificationHistory = nil
}

// Snapshot updates are deliberately silent: never call notify, present, or the
// sound service while incorporating another reader's history.
func (a *application) refresh_notification_history() {
	if a.notificationHistory == nil {
		return
	}
	state := a.notificationHistory.Snapshot()
	a.notifications = make([]notification, 0, len(state.Entries))
	for _, entry := range state.Entries {
		a.notifications = append(a.notifications, notification{text: entry.Text, received: entry.Received.In(time.Local)})
	}
}

// Only a targeted notification calls this method. Shared snapshots update
// history separately, without automatic speech or sound.
func (a *application) notify(text string, received time.Time) {
	text = strings.TrimSpace(text)
	if text == "" {
		return
	}
	a.share_notification_history(a.lastTerminal, a.lastActive)
	if a.notificationHistory != nil {
		a.notificationHistory.Publish(text, received)
		a.refresh_notification_history()
	} else {
		if len(a.notifications) == notificationLimit {
			copy(a.notifications, a.notifications[1:])
			a.notifications = a.notifications[:notificationLimit-1]
		}
		a.notifications = append(a.notifications, notification{text: text, received: received})
	}
	diagnostic.Record("notification received", "length", len(text), "retained", len(a.notifications))
	if a.settings.live.Presentation.Sound.Enabled && a.settings.live.Presentation.Sound.Volume > 0 && a.cues != nil {
		cues := a.cues
		history := a.notificationHistory
		if a.temporarySilence || a.muted {
			if history != nil {
				history.Sound(func(ctx context.Context) { play_notification(ctx, cues) })
			} else if a.notificationSound.allow(time.Now()) {
				a.play(presentation.Notification)
			}
			return
		}
		gate := &a.notificationSound
		a.voice.Say_after(text, func(ctx context.Context) {
			if ctx.Err() != nil {
				return
			}
			if history != nil {
				if !history.Claim_sound(ctx) {
					return
				}
			} else if !gate.allow(time.Now()) {
				return
			}
			play_notification(ctx, cues)
		})
		return
	}
	a.present(text, "")
}

func play_notification(ctx context.Context, cues SoundPlayer) {
	if err := cues.Play_wait(ctx, presentation.Notification); err != nil && ctx.Err() == nil {
		slog.Warn("notification sound incomplete", "error", err, "at", time.Now())
	}
}

func (a *application) last_notification() {
	a.share_notification_history(a.lastTerminal, a.lastActive)
	a.refresh_notification_history()
	if len(a.notifications) == 0 {
		a.present(i18n.T("No notifications"), "")
		return
	}
	a.present(a.notifications[len(a.notifications)-1].text, "")
}

func (a *application) open_notifications() {
	a.share_notification_history(a.lastTerminal, a.lastActive)
	a.refresh_notification_history()
	if len(a.notifications) == 0 {
		a.present(i18n.T("No notifications"), "")
		return
	}
	// A snapshot keeps the selected item stable while new notifications arrive.
	items := make([]string, 0, len(a.notifications))
	for index := len(a.notifications) - 1; index >= 0; index-- {
		entry := a.notifications[index]
		timestamp, _ := datetime.Format_time(a.settings.live.Presentation.DateTime.TimeFormat, entry.received)
		items = append(items, entry.text+" "+timestamp)
	}
	session, err := interaction.New_session(interaction.Form{Type: interaction.TabForm, Title: "Notifications", Tabs: []interaction.Tab{
		{ID: "notifications", Label: "Notifications", Controls: []interaction.Control{
			{ID: "history", Label: "Notifications", Kind: interaction.List, Items: items, Action: "repeat_notification"},
			{ID: "close", Label: "Close", Kind: interaction.Button, Action: "cancel"},
		}},
	}})
	if err != nil {
		a.ui.failed("Could not open Notifications: {0}", err)
		return
	}
	if _, err := a.ui.begin("Notifications"); err != nil {
		a.ui.failed("Could not open Notifications: {0}", err)
		return
	}
	session.Handle(interaction.Key{Name: "tab"})
	a.ui.session = session
	a.ui.action = func(action string, session *interaction.Session) {
		if action == "repeat_notification" {
			control := session.Values()["notifications.history"]
			a.present(control.Items[control.Selected], "")
		}
	}
	a.ui.voice.Say(session.Open())
}