using System;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services;
using ytLive.Services.Compositor;

namespace ytLive.ViewModels;

/// <summary>The scoreboard strip: session tallies rendered as a full-width bar, per scene.
///
/// <para>It is a <see cref="SourceType.Scoreboard"/> layer, so a creator gets the same eye toggle,
/// drag and per-scene presence as every other element — "prominent on BRB, dialled back on Live" is
/// geometry, not a second mechanism.</para></summary>
public partial class MainViewModel
{
    private readonly ScoreboardRecorder _scoreboard = new();
    private ScoreboardTiles _scoreboardTiles = ScoreboardTiles.Default;
    private ScoreboardStyle _scoreboardStyle = new();
    private ScoreboardPresenter? _scoreboardPresenter;
    private WriteableBitmap? _scoreboardPreview;
    private Source? _scoreboardPreviewSource;

    internal ScoreboardRecorder ScoreboardRecorder => _scoreboard;

    internal ScoreboardTiles ScoreboardTilesState => _scoreboardTiles;

    /// <summary>Composited strip frame for the output path (cached by the presenter).</summary>
    internal VideoFrame? ScoreboardFrame => _scoreboardPresenter?.Frame;

    internal void StartScoreboardSession()
    {
        _scoreboard.StartSession();
        RefreshScoreboardPreviews();
    }

    internal void EndScoreboardSession()
    {
        _scoreboard.EndSession();
        RefreshScoreboardPreviews();
    }

    private void InitScoreboard()
    {
        _scoreboardPresenter = new ScoreboardPresenter(_scoreboard, _scoreboardStyle)
        {
            // placeholder so SetTiles below drives the first render
        };
        _scoreboardPresenter.SetTiles(_scoreboardTiles);
        _scoreboardPresenter.SetStyle(_scoreboardStyle);
        _scoreboard.Changed += RefreshScoreboardPreviews;
    }

    /// <summary>Snapshot of the strip presenters as themed properties, for the properties panel
    /// (unit 7) — kept here so the panel binds one object instead of six primitives.</summary>
    internal ScoreboardStyle ScoreboardStyleState => _scoreboardStyle;

    /// <summary>Publishes the strip to every scoreboard layer's preview element. The pump thread
    /// must never touch a WriteableBitmap, so this runs on the UI thread only.</summary>
    private void RefreshScoreboardPreviews()
    {
        var frame = _scoreboardPresenter?.Frame;
        foreach (var scene in Scenes)
        foreach (var source in scene.Elements.OfType<Source>().Where(s => s.IsScoreboard))
        {
            if (frame is null) { source.VideoImageSource = null; continue; }
            if (_scoreboardPreview is null || _scoreboardPreview.PixelWidth != frame.Width ||
                _scoreboardPreview.PixelHeight != frame.Height)
            {
                _scoreboardPreview = new WriteableBitmap(frame.Width, frame.Height, 96, 96, PixelFormats.Bgra32, null);
            }
            _scoreboardPreview.WritePixels(new System.Windows.Int32Rect(0, 0, frame.Width, frame.Height),
                frame.BgraPixels, frame.Width * 4, 0);
            source.VideoImageSource = _scoreboardPreview;
            _scoreboardPreviewSource = source;
        }
    }
}