using AcDream.Core.Physics;
using Xunit;

namespace AcDream.Core.Tests.Physics;

public class PhysicsEngineIsLandblockLoadedTests
{
    private static TerrainSurface MakeFlatTerrain()
    {
        var heights = new byte[81];
        Array.Fill(heights, (byte)50);
        var heightTable = new float[256];
        for (int i = 0; i < 256; i++) heightTable[i] = i * 1f;
        return new TerrainSurface(heights, heightTable);
    }

    [Fact]
    public void IsLandblockLoaded_AbsentId_ReturnsFalse()
    {
        var engine = new PhysicsEngine();
        Assert.False(engine.IsLandblockLoaded(0xA9B4FFFFu));
    }

    [Fact]
    public void IsLandblockLoaded_AddedId_ReturnsTrue()
    {
        var engine = new PhysicsEngine();
        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
            worldOffsetX: 0f, worldOffsetY: 0f);

        Assert.True(engine.IsLandblockLoaded(0xA9B4FFFFu));
    }

    [Fact]
    public void IsLandblockLoaded_AnotherIdAbsent_ReturnsFalse()
    {
        var engine = new PhysicsEngine();
        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
            worldOffsetX: 0f, worldOffsetY: 0f);

        Assert.False(engine.IsLandblockLoaded(0xDEADBEEFu));
    }

    [Fact]
    public void IsLandblockLoaded_AfterRemove_ReturnsFalse()
    {
        var engine = new PhysicsEngine();
        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
            worldOffsetX: 0f, worldOffsetY: 0f);
        engine.RemoveLandblock(0xA9B4FFFFu);

        Assert.False(engine.IsLandblockLoaded(0xA9B4FFFFu));
    }

    // Regression for the Slice 2 key-mismatch bug (#145 apparatus re-test, 2026-06-21):
    // landblocks are stored under the EncodeLandblockId form (low 16 = 0xFFFF), but the
    // teleport gate (TeleportArrivalReadiness) queries with (destCell & 0xFFFF0000) (low
    // 16 = 0x0000). A raw ContainsKey never matched, so the outdoor gate was permanently
    // NotReady and every outdoor teleport timed out at 10 s. IsLandblockLoaded must
    // normalize so ANY id within the landblock resolves to the stored entry.
    [Theory]
    [InlineData(0xA9B40000u)] // landblock-prefix form — exactly what the gate passes (destCell & 0xFFFF0000)
    [InlineData(0xA9B4000Du)] // an outdoor cell id within the landblock
    [InlineData(0xA9B40143u)] // an indoor cell id within the landblock
    [InlineData(0xA9B4FFFFu)] // the dat-id storage form
    public void IsLandblockLoaded_NormalizesLow16_FindsLandblockForAnyContainedId(uint queryId)
    {
        var engine = new PhysicsEngine();
        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
            worldOffsetX: 0f, worldOffsetY: 0f);

        Assert.True(engine.IsLandblockLoaded(queryId));
    }

    [Fact]
    public void IsLandblockLoaded_DifferentLandblockPrefix_ReturnsFalse()
    {
        var engine = new PhysicsEngine();
        engine.AddLandblock(0xA9B4FFFFu, MakeFlatTerrain(),
            Array.Empty<CellSurface>(), Array.Empty<PortalPlane>(),
            worldOffsetX: 0f, worldOffsetY: 0f);

        // A different landblock prefix must NOT match, even in the 0x..0000 query form.
        Assert.False(engine.IsLandblockLoaded(0xA9B50000u));
    }
}