using FluentAssertions;
using Sand.ChunkPrototype;

namespace Sand.ChunkPrototype.Tests;

public sealed class PrototypeChunkResidencyWorldTests
{
    [Fact]
    public void MoveOccupiedAcrossChunkBoundaryUpdatesCountsAndDirtyChunks()
    {
        var world = new PrototypeChunkResidencyWorld(new ChunkResidencyConfig(4, 4, Capacity: 16));
        world.SetOccupied(3, 1);
        world.ClearDirtyChunks();

        var moved = world.MoveOccupied(3, 1, 4, 1);

        moved.Should().BeTrue();
        world.IsOccupied(3, 1).Should().BeFalse();
        world.IsOccupied(4, 1).Should().BeTrue();
        world.GetChunkOccupancyCount(0, 0).Should().Be(0);
        world.GetChunkOccupancyCount(1, 0).Should().Be(1);
        world.DirtyChunks.Should().BeEquivalentTo([(0, 0), (1, 0)]);
    }

    [Fact]
    public void UnloadEmptyChunksRemovesChunksAfterClearingOccupancy()
    {
        var world = new PrototypeChunkResidencyWorld(new ChunkResidencyConfig(4, 4, Capacity: 16));
        world.SetOccupied(1, 1);
        world.SetOccupied(9, 1);

        world.ClearOccupied(1, 1);

        var unloaded = world.UnloadEmptyChunks();

        unloaded.Should().Be(1);
        world.IsChunkLoaded(0, 0).Should().BeFalse();
        world.IsChunkLoaded(2, 0).Should().BeTrue();
        world.ActiveChunkCount.Should().Be(1);
    }

    [Fact]
    public void UnloadInactiveChunksKeepsActiveNeighborsWithinMargin()
    {
        var world = new PrototypeChunkResidencyWorld(new ChunkResidencyConfig(4, 4, Capacity: 32));
        world.SetOccupied(4, 4);
        world.SetOccupied(20, 20);
        world.ClearOccupied(20, 20);
        world.SetOccupied(8, 4);

        var unloaded = world.UnloadInactiveChunks(marginChunks: 1);

        unloaded.Should().BeGreaterThanOrEqualTo(1);
        world.IsChunkLoaded(1, 1).Should().BeTrue();
        world.IsChunkLoaded(2, 1).Should().BeTrue();
        world.IsChunkLoaded(5, 5).Should().BeFalse();
    }

    [Fact]
    public void ClearDirtyChunksResetsDirtyChunkTracking()
    {
        var world = new PrototypeChunkResidencyWorld();
        world.SetOccupied(2, 2);
        world.SetOccupied(40, 2);
        world.DirtyChunkCount.Should().Be(2);

        world.ClearDirtyChunks();

        world.DirtyChunkCount.Should().Be(0);
        world.DirtyChunks.Should().BeEmpty();
    }
}