using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Windows;
using ytLive;
using ytLive.Models;
using ytLive.Services;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    private Scene? _stagedScene;
    private Scene? _liveScene;

    // TASK 20 step 2 — hotkey bindings (custom chord per action)
    private Dictionary<HotkeyId, HotkeyChord> _hotkeyBindings = new();

    // TASK 31: the scene collection is owned by the SceneGraph (single owner of the
    // element inventory + mutation surface). The ViewModel exposes it as-is so the
    // XAML bindings and MainViewModel call sites keep working unchanged.
    public ObservableCollection<Scene> Scenes => _sceneGraph.Scenes;

    public Scene? StagedScene
    {
        get => _stagedScene;
        set
        {
            if (value != null && value.IsHidden) return;
            if (SetProperty(ref _stagedScene, value))
            {
                // Update IsStaged flags for thumbnail glow
                foreach (var s in Scenes)
                    s.IsStaged = s == value;

                SelectedElement = null;
                if (value != null)
                {
                    var background = EnsureBackground(value);
                    if (background != null)
                        StampDefaultBackgroundAsset(background, value.Name);
                    _sceneGraph.InvalidateBake(value);
                }
                OnPropertyChanged(nameof(ShowChatInactiveMessage));
                OnPropertyChanged(nameof(ShowEmptySceneHint));
                OnPropertyChanged(nameof(ShowPreviewPlaceholder));
                OnPropertyChanged(nameof(ShowSourcesEmptyHint));
                OnPropertyChanged(nameof(CanChangeBackground));
                OnPropertyChanged(nameof(CanAddWebcam));
                OnPropertyChanged(nameof(CanAddYouTubeChat));
                OnPropertyChanged(nameof(CanShowWebcamInStagedScene));
                OnPropertyChanged(nameof(WebcamAddToolTip));
                OnPropertyChanged(nameof(IsCountdownAvailable));
                UpdateActiveBackground();
                UpdateBackgroundImage();
                RefreshSnapshotsAsync();
            }
        }
    }

    /// <summary>The scene the encoder outputs. Set on Go Live (StagedScene → LiveScene)
    /// or on transition completion. FramePump reads this every tick.</summary>
    public Scene? LiveScene
    {
        get => _liveScene;
        set
        {
            if (SetProperty(ref _liveScene, value))
            {
                foreach (var s in Scenes)
                    s.IsLive = s == value;
            }
        }
    }

    /// <summary>True when offline — edit mode is available. When live/recording,
    /// all edit operations are locked out (gun safety).</summary>
    public bool IsEditMode => StreamStatus == StreamStatus.Offline && !IsRecording;

    // ─── Transitions (TASK 19/23) ───

    public TransitionType SelectedTransitionType
    {
        get => _selectedTransitionType;
        set => SetProperty(ref _selectedTransitionType, value);
    }
    private TransitionType _selectedTransitionType = TransitionType.Fade;

    public double TransitionDurationMs
    {
        get => _transitionDurationMs;
        set => SetProperty(ref _transitionDurationMs, value);
    }
    private double _transitionDurationMs = 300;

    /// <summary>
    /// Called when a scene thumbnail is clicked. If live, triggers a transition from
    /// LiveScene to the selected StagedScene. Always sets StagedScene first.
    /// </summary>
    public void TransitionToScene(Scene scene)
    {
        if (scene.IsHidden || scene == StagedScene) return;
        StagedScene = scene;
        if (IsLive)
            _transition.Start(SelectedTransitionType, TransitionDurationMs, null);
    }

    /// <summary>
    /// Apply the current transition type to the next StagedScene change while live.
    /// Called from XAML when user picks a transition from the dropdown.
    /// </summary>
    public void ApplyTransitionToLive()
    {
        if (IsLive)
            _transition.Start(SelectedTransitionType, TransitionDurationMs, null);
    }

    // ─── Global hotkeys (TASK 20) — dispatch a registered hotkey to its action ───

    /// <summary>
    /// Callback set by MainWindow so the VM can trigger hotkey re-registration
    /// after the user saves custom bindings from the config dialog.
    /// </summary>
    public Action<Dictionary<HotkeyId, HotkeyChord>>? HotkeyBindingsChanged { get; set; }

    /// <summary>The current hotkey bindings (loaded from DB, updated on dialog save).</summary>
    public Dictionary<HotkeyId, HotkeyChord> CurrentHotkeyBindings => _hotkeyBindings;

    public void HandleHotkey(Services.HotkeyId id)
    {
        switch (id)
        {
            case Services.HotkeyId.SceneStarting: TransitionToCanonical(SceneCatalog.Starting); break;
            case Services.HotkeyId.SceneLive: TransitionToCanonical(SceneCatalog.Live); break;
            case Services.HotkeyId.SceneBrb: TransitionToCanonical(SceneCatalog.Brb); break;
            case Services.HotkeyId.SceneChat: TransitionToCanonical(SceneCatalog.Chat); break;
            case Services.HotkeyId.SceneEnding: TransitionToCanonical(SceneCatalog.Ending); break;
            case Services.HotkeyId.StartStopStream:
                if (IsLive || IsRecording)
                {
                    if (EndStreamCommand.CanExecute(null)) EndStreamCommand.Execute(null);
                }
                else if (StartStreamCommand.CanExecute(null))
                {
                    StartStreamCommand.Execute(null);
                }
                break;
            case Services.HotkeyId.ToggleMicMute: ToggleMicMuteCommand.Execute(null); break;
            case Services.HotkeyId.ToggleGameMute: ToggleGameMuteCommand.Execute(null); break;
            case Services.HotkeyId.TraxPlayPause: TraxLeftClick(); break;
        }
    }

    private void TransitionToCanonical(string name)
    {
        var scene = Scenes.FirstOrDefault(s => SceneCatalog.Is(s.Name, name));
        if (scene != null) TransitionToScene(scene);
    }

    private void OpenHotkeyConfig()
    {
        var vm = new HotkeyConfigViewModel(_layoutStore);
        var dialog = new HotkeyConfigDialog(vm) { Owner = Application.Current.MainWindow };
        if (dialog.ShowDialog() == true)
        {
            // Reload bindings from DB (the dialog already saved them).
            _hotkeyBindings = _layoutStore.LoadHotkeyBindings();
            HotkeyBindingsChanged?.Invoke(_hotkeyBindings);
            RefreshHotkeyLabels();
        }
    }

    private void RefreshHotkeyLabels()
    {
        foreach (var scene in Scenes)
        {
            if (SceneCatalog.SceneHotkeys.TryGetValue(scene.Name, out var hid)
                && _hotkeyBindings.TryGetValue(hid, out var chord))
                scene.HotkeyLabel = chord.ToDisplayString();
            else if (SceneCatalog.SceneHotkeys.TryGetValue(scene.Name, out var defId)
                     && GlobalHotkeyManager.Defaults.TryGetValue(defId, out var defChord))
                scene.HotkeyLabel = defChord.ToDisplayString();
            else
                scene.HotkeyLabel = string.Empty;
        }
    }

    public bool ShowEmptySceneHint => StagedScene != null && StagedScene.Elements.Count == 0;
    public bool ShowSourcesEmptyHint => StagedScene == null || StagedScene.Elements.Count == 0;

    public bool IsCountdownAvailable => StagedScene != null
        && (SceneCatalog.Is(StagedScene.Name, "Starting") || SceneCatalog.Is(StagedScene.Name, "BRB"));

    /// <summary>The canonical scenes (SceneCatalog) not present right now — what the
    /// "+" button may re-add. Work with less, never more.</summary>
    public IEnumerable<string> MissingScenes
        => SceneCatalog.All.Where(canonical => Scenes.All(s => !SceneCatalog.Is(s.Name, canonical)));

    /// <summary>Only show the "+" button when one of the five canonical scenes is missing.</summary>
    public bool ShowAddScene => MissingScenes.Any();

    /// <summary>"Change Capture…"/"Refresh Capture" apply to the active scene's background.</summary>
    // Capture controls (Show Desktop / monitor pick / refresh) exist only on
    // the Live screen's Background. Static-art screens never expose them.
    public bool CanChangeBackground =>
        StagedScene != null && SceneCatalog.Is(StagedScene.Name, SceneCatalog.Live);

    // ─── Auto-save wiring ───
    private void OnScenesChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        if (e.NewItems != null)
            foreach (Scene scene in e.NewItems)
                WireScene(scene);
        if (e.OldItems != null)
            foreach (Scene scene in e.OldItems)
                UnwireScene(scene);
        OnPropertyChanged(nameof(MissingScenes));
        OnPropertyChanged(nameof(ShowAddScene));
        ScheduleSave();
    }

    private void WireScene(Scene scene)
    {
        scene.PropertyChanged += OnScenePropertyChanged;
        scene.Elements.CollectionChanged += OnElementsChanged;
    }

    private void UnwireScene(Scene scene)
    {
        scene.PropertyChanged -= OnScenePropertyChanged;
        scene.Elements.CollectionChanged -= OnElementsChanged;
    }

    private void OnScenePropertyChanged(object? sender, PropertyChangedEventArgs e)
    {
        // A rename can drop a canonical scene in/out of MissingScenes.
        OnPropertyChanged(nameof(MissingScenes));
        OnPropertyChanged(nameof(ShowAddScene));
        ScheduleSave();
    }

    private void OnElementsChanged(object? sender, NotifyCollectionChangedEventArgs e)
    {
        if (e.NewItems != null)
            foreach (SceneElement element in e.NewItems)
                element.PropertyChanged += OnElementPropertyChanged;
        if (e.OldItems != null)
            foreach (SceneElement element in e.OldItems)
                element.PropertyChanged -= OnElementPropertyChanged;
        OnPropertyChanged(nameof(CanAddWebcam));
        OnPropertyChanged(nameof(CanAddYouTubeChat));
        ScheduleSave();
    }

    private void OnElementPropertyChanged(object? sender, PropertyChangedEventArgs e)
    {
        if (sender is WebcamSceneConfig && e.PropertyName == nameof(SceneElement.IsVisible))
            OnPropertyChanged(nameof(CanShowWebcamInStagedScene));

        // A Static element's baked pixels depend on its layout, opacity and
        // visibility — any of those changing invalidates the cached base.
        if (sender is SceneElement { Kind: ElementKind.Static } el)
        {
            var bakedSurface = e.PropertyName is nameof(SceneElement.X) or nameof(SceneElement.Y)
                or nameof(SceneElement.Width) or nameof(SceneElement.Height)
                or nameof(SceneElement.Opacity) or nameof(SceneElement.IsVisible)
                or nameof(SceneElement.ClipShape) or nameof(SceneElement.IsMirrored);
            if (bakedSurface)
            {
                var containingScene = Scenes.FirstOrDefault(s => s.Elements.Contains(el));
                if (containingScene != null)
                    _sceneGraph.InvalidateBake(containingScene);
            }
        }
        ScheduleSave();
    }

    // Adds a canonical scene by name — only when it's actually missing. The
    // background flag follows the policy (Live yes, everyone else no).
    private void AddScene(string name)
    {
        if (!SceneCatalog.IsCanonical(name)) return;
        if (Scenes.Any(s => SceneCatalog.Is(s.Name, name))) return;
        var scene = new Scene
        {
            Name = name.Trim(),
            IsChatScene = SceneCatalog.IsChat(name),
            HasBackground = SceneCatalog.HasBackground(name),
        };
        EnsureBackground(scene);
        Scenes.Add(scene);
        StagedScene = scene;
    }
}