using System;
using Xunit;
using ytLive.Models;
using ytLive.Services;

namespace ytLive.Tests;

/// <summary>
/// Take-5 starvation fix (slice 3): the chat layer is rendered ON CHANGE, not on
/// every pump tick — the per-tick WPF raster (FormattedText + RenderTargetBitmap
/// + CopyPixels) was the 25ms render. OBS text sources raster-on-change; this
/// pins that contract with the real renderer on the RealApp STA host: identical
/// inputs reuse the cached frame by identity, and content or config changes force
/// a fresh raster.
/// </summary>
[Collection("RealApp")]
public sealed class ChatOverlayLayerCacheTests
{
    private readonly RealAppHost _app;

    public ChatOverlayLayerCacheTests(RealAppHost app) => _app = app;

    [Fact]
    public void RenderFrame_RastersOnContentOrConfigChange_ReusesCacheOtherwise()
    {
        _app.Run(Run);
    }

    private void Run()
    {
        var layer = new ChatOverlayLayer(new ChatBoxRenderer());
        var box = new Source { Type = SourceType.ChatBox, Name = "YouTube Chat", Width = 220, Height = 160 };

        Assert.Null(layer.RenderFrame(box)); // empty buffer — nothing to rasterize

        layer.Messages.Add(new ChatMessage { AuthorName = "a", Message = "hello", Timestamp = DateTime.Now });
        var first = layer.RenderFrame(box);
        Assert.NotNull(first);

        Assert.Same(first, layer.RenderFrame(box)); // unchanged content + config → the SAME frame
        Assert.Same(first, layer.RenderFrame(box)); // every tick hits the cache, not the raster

        var resized = new Source { Type = SourceType.ChatBox, Width = 300, Height = 160 };
        var reRendered = layer.RenderFrame(resized);
        Assert.NotNull(reRendered);
        Assert.NotSame(first, reRendered); // config change → fresh raster

        layer.Messages.Add(new ChatMessage { AuthorName = "b", Message = "second", Timestamp = DateTime.Now });
        var grown = layer.RenderFrame(box);
        Assert.NotNull(grown);
        Assert.NotSame(reRendered, grown); // new message → fresh raster

        layer.Messages.Clear(); // the fade path
        Assert.Null(layer.RenderFrame(box));
        Assert.Null(layer.RenderFrame(box));
    }
}