using System;
using System.Numerics;
using AcDream.Core.Selection;
using AcDream.Core.World;

namespace AcDream.Core.Tests.Selection;

public sealed class WorldPickerRectOverloadTests
{
    private static (Matrix4x4 view, Matrix4x4 proj, Vector2 viewport) StdCam()
    {
        var view     = Matrix4x4.Identity;
        var proj     = Matrix4x4.CreatePerspectiveFieldOfView(
                          MathF.PI * 0.5f, 800f / 600f, 0.1f, 100f);
        var viewport = new Vector2(800, 600);
        return (view, proj, viewport);
    }

    private static WorldEntity MakeEntity(uint serverGuid, Vector3 position) => new()
    {
        Id = serverGuid == 0u ? 1u : serverGuid,
        ServerGuid = serverGuid,
        SourceGfxObjOrSetupId = 0u,
        Position = position,
        Rotation = Quaternion.Identity,
        MeshRefs = Array.Empty<MeshRef>(),
    };

    [Fact]
    public void Pick_RectHitTest_ReturnsHitWhenMouseInsideRect()
    {
        var (view, proj, viewport) = StdCam();
        var e = MakeEntity(0x10001u, new Vector3(0, 0, -10));
        uint? picked = WorldPicker.Pick(
            mouseX: 400f, mouseY: 300f,
            view, proj, viewport,
            new[] { e },
            skipServerGuid: 0u,
            sphereForEntity: x => ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 0f);
        Assert.Equal(0x10001u, picked);
    }

    [Fact]
    public void Pick_RectHitTest_ReturnsNullWhenMouseOutsideRect()
    {
        var (view, proj, viewport) = StdCam();
        var e = MakeEntity(0x10001u, new Vector3(0, 0, -10));
        uint? picked = WorldPicker.Pick(
            mouseX: 50f, mouseY: 50f,
            view, proj, viewport,
            new[] { e },
            skipServerGuid: 0u,
            sphereForEntity: x => ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 0f);
        Assert.Null(picked);
    }

    [Fact]
    public void Pick_RectHitTest_PicksNearerWhenRectsOverlap()
    {
        var (view, proj, viewport) = StdCam();
        var near = MakeEntity(0x10001u, new Vector3(0, 0, -8));
        var far  = MakeEntity(0x10002u, new Vector3(0, 0, -15));
        uint? picked = WorldPicker.Pick(
            mouseX: 400f, mouseY: 300f,
            view, proj, viewport,
            new[] { far, near } /* deliberately reversed */,
            skipServerGuid: 0u,
            sphereForEntity: x => ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 0f);
        Assert.Equal(0x10001u, picked);
    }

    [Fact]
    public void Pick_RectHitTest_NullResolverSkipsCandidates()
    {
        var (view, proj, viewport) = StdCam();
        var e1 = MakeEntity(0x10001u, new Vector3(0, 0, -10));
        var e2 = MakeEntity(0x10002u, new Vector3(0, 0, -20));
        uint? picked = WorldPicker.Pick(
            mouseX: 400f, mouseY: 300f,
            view, proj, viewport,
            new[] { e1, e2 },
            skipServerGuid: 0u,
            sphereForEntity: x => x.ServerGuid == 0x10001u
                ? ((Vector3, float)?)null
                : ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 0f);
        Assert.Equal(0x10002u, picked);
    }

    [Fact]
    public void Pick_RectHitTest_RespectsSkipServerGuid()
    {
        var (view, proj, viewport) = StdCam();
        var player = MakeEntity(0x5000000Au, new Vector3(0, 0, -10));
        var npc    = MakeEntity(0x10002u,    new Vector3(0, 0, -15));
        uint? picked = WorldPicker.Pick(
            mouseX: 400f, mouseY: 300f,
            view, proj, viewport,
            new[] { player, npc },
            skipServerGuid: 0x5000000Au,
            sphereForEntity: x => ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 0f);
        Assert.Equal(0x10002u, picked);
    }

    [Fact]
    public void Pick_RectHitTest_InflateExpandsClickableArea()
    {
        var (view, proj, viewport) = StdCam();
        var e = MakeEntity(0x10001u, new Vector3(0, 0, -10));

        uint? withoutInflate = WorldPicker.Pick(
            mouseX: 400f + 200f, mouseY: 300f,
            view, proj, viewport,
            new[] { e },
            skipServerGuid: 0u,
            sphereForEntity: x => ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 0f);
        Assert.Null(withoutInflate);

        uint? withInflate = WorldPicker.Pick(
            mouseX: 400f + 200f, mouseY: 300f,
            view, proj, viewport,
            new[] { e },
            skipServerGuid: 0u,
            sphereForEntity: x => ((Vector3, float)?)(x.Position, 1.0f),
            inflatePixels: 250f);
        Assert.Equal(0x10001u, withInflate);
    }
}