using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Input;
using Avalonia.Interactivity;
using MediaPlayer.Controls;
using PLib.Desktop.ViewModels;

namespace PLib.Desktop.Views;

/// <summary>
/// Transport controls for the media page.
/// </summary>
/// <remarks>
/// Playback state lives on <see cref="GpuMediaPlayer"/> itself — position, duration and
/// whether it is playing are all its own properties, and seeking is a method call. Mirroring
/// that into the view model would buy nothing but a second copy to keep in sync, so this
/// code-behind wires the buttons straight to the control. Everything the page knows about
/// the video — title, path, the commands around it — stays in the view model.
/// </remarks>
public sealed partial class VideoPlayerView : UserControl
{
    /// <summary>True while the user is dragging the seek bar, so playback must not fight them.</summary>
    private bool _isScrubbing;

    public VideoPlayerView()
    {
        InitializeComponent();

        PlayPauseButton.Click += OnPlayPause;
        MuteButton.Click += OnToggleMute;

        // Tunnelled: the Slider's own handlers mark these as handled on the way back up.
        Seek.AddHandler(PointerPressedEvent, OnScrubStarted, RoutingStrategies.Tunnel);
        Seek.AddHandler(PointerReleasedEvent, OnScrubFinished, RoutingStrategies.Tunnel);

        VolumeSlider.PropertyChanged += OnVolumeChanged;

        Player.GetObservable(GpuMediaPlayer.PositionProperty).Subscribe(OnPositionChanged);
        Player.GetObservable(GpuMediaPlayer.DurationProperty).Subscribe(OnDurationChanged);
        Player.GetObservable(GpuMediaPlayer.IsPlayingProperty).Subscribe(OnIsPlayingChanged);
        Player.GetObservable(GpuMediaPlayer.LastErrorProperty).Subscribe(OnErrorChanged);

    }

    protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
    {
        base.OnDetachedFromVisualTree(e);

        // Leaving the page has to stop the decoder; nothing else will.
        Player.Stop();
    }

    private void OnPlayPause(object? sender, RoutedEventArgs e)
    {
        if (Player.IsPlaying)
        {
            Player.Pause();
        }
        else
        {
            Player.Play();
        }
    }

    private void OnToggleMute(object? sender, RoutedEventArgs e) => Player.IsMuted = !Player.IsMuted;

    private void OnScrubStarted(object? sender, PointerPressedEventArgs e) => _isScrubbing = true;

    private void OnScrubFinished(object? sender, PointerReleasedEventArgs e)
    {
        _isScrubbing = false;
        Player.Seek(TimeSpan.FromSeconds(Seek.Value));
    }

    private void OnVolumeChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
    {
        if (e.Property != RangeBase.ValueProperty)
        {
            return;
        }

        Player.Volume = VolumeSlider.Value;
        MuteIcon.Kind = VolumeIconFor(VolumeSlider.Value, Player.IsMuted);
    }

    private void OnPositionChanged(TimeSpan position)
    {
        PositionText.Text = DisplayText.Duration(position);

        if (!_isScrubbing)
        {
            Seek.Value = position.TotalSeconds;
        }
    }

    private void OnDurationChanged(TimeSpan duration)
    {
        DurationText.Text = DisplayText.Duration(duration);

        // A zero maximum would pin the thumb to the left and swallow every seek.
        Seek.Maximum = duration > TimeSpan.Zero ? duration.TotalSeconds : 1;
        Seek.IsEnabled = duration > TimeSpan.Zero;
    }

    private void OnIsPlayingChanged(bool isPlaying) =>
        PlayPauseIcon.Kind = isPlaying
            ? Material.Icons.MaterialIconKind.Pause
            : Material.Icons.MaterialIconKind.Play;

    private void OnErrorChanged(string? error)
    {
        ErrorText.Text = string.IsNullOrWhiteSpace(error)
            ? null
            : $"Не удалось воспроизвести файл: {error}";

        ErrorText.IsVisible = !string.IsNullOrWhiteSpace(error);
    }

    private static Material.Icons.MaterialIconKind VolumeIconFor(double volume, bool isMuted) =>
        isMuted || volume <= 0.001
            ? Material.Icons.MaterialIconKind.VolumeOff
            : volume < 0.5
                ? Material.Icons.MaterialIconKind.VolumeMedium
                : Material.Icons.MaterialIconKind.VolumeHigh;
}