using OpenTK.Mathematics;
using VoxelEngine.Core;
using VoxelEngine.World;
using VoxelEngine.World.Blocks;
using VoxelEngine.World.Chunk;
using VoxelEngine.World.Persistence;
using VoxelEngine.World.Streaming;
using VoxelEngine.World.WorldGen;
using Xunit;

namespace VoxelEngine.Tests.Streaming;

public class StreamingIntegrationTests
{
    private static (ChunkStreamer streamer, World.World world, InMemoryChunkModificationStore store)
        BuildRealStack(Configuration cfg)
    {
        var registry = new BlockRegistry();
        var store = new InMemoryChunkModificationStore();
        var world = new World.World(registry, store);
        var gen = new WorldGenerator(seed: 1337, blocks: registry, cfg: new Configuration());
        var mesher = new ChunkMesher(atlasWidthPixels: 128, atlasHeightPixels: 32);
        var executor = new SynchronousJobExecutor();
        Func<float[], IChunkRenderer> factory = m => new FakeRenderer(m);
        var streamer = new ChunkStreamer(cfg, world, gen.Generate, mesher, registry, executor, factory);
        return (streamer, world, store);
    }

    [Fact]
    public void PlayerWalksAcrossWorld_LoadBoxFollowsPlayer()
    {
        var cfg = new Configuration
        {
            RenderDistanceHorizontal = 1,
            RenderDistanceVertical = 0,
            MaxGenerateJobsInFlight = 100,
            MaxMeshUploadsPerFrame = 100,
        };
        var (streamer, world, _) = BuildRealStack(cfg);

        for (int step = 0; step < 5; step++)
        {
            streamer.Tick(new Vector3i(step, 0, 0));

            for (int dx = -1; dx <= 1; dx++)
            for (int dz = -1; dz <= 1; dz++)
            {
                var pos = new Vector3i(step + dx, 0, dz);
                Assert.NotNull(world.GetChunk(pos));
                Assert.True(streamer.IsReady(pos));
            }
        }
    }

    [Fact]
    public void ModificationStore_SurvivesUnloadReload()
    {
        var cfg = new Configuration
        {
            RenderDistanceHorizontal = 0,
            RenderDistanceVertical = 0,
            MaxGenerateJobsInFlight = 100,
            MaxMeshUploadsPerFrame = 100,
        };
        var (streamer, world, store) = BuildRealStack(cfg);

        // Use a block id that differs from what WorldGenerator places at
        // world (0,0,0). At y=0 every biome's "Under" block is Stone (id 1),
        // so SetBlock(..., Stone) would hit World.SetBlock's no-op guard and
        // skip the diff record. Dirt (id 2) is always a real change.
        var pos = new Vector3i(0, 0, 0);
        streamer.Tick(pos);
        Assert.True(streamer.IsReady(pos));
        Assert.True(world.SetBlock(0, 0, 0, /*Dirt*/ (ushort)2));

        streamer.Tick(new Vector3i(50, 0, 0));
        Assert.Null(world.GetChunk(pos));
        Assert.True(store.HasDiff(pos));

        streamer.Tick(pos);
        Assert.NotNull(world.GetChunk(pos));
        Assert.Equal((ushort)2, world.GetBlock(0, 0, 0).Id);
    }
}