using System.Numerics;
using AcDream.Core.Physics;
using Xunit;

namespace AcDream.Core.Tests.Physics;

/// <summary>
/// Render Residual A — <see cref="ResolveResult.Ok"/> surfaces the
/// <c>FindTransitionalPosition</c> return (retail <c>find_valid_position != 0</c>,
/// pc:273898) so the camera <c>SweepEye</c> can trigger <c>SmartBox::update_viewer</c>'s
/// fallbacks when the sweep fails. Default <c>true</c> keeps every existing caller
/// (which never reads it) unaffected.
/// </summary>
public class ResolveResultOkTests
{
    [Fact]
    public void NoStartCell_ReportsNotOk()
    {
        var engine = new PhysicsEngine();

        // cellId == 0 → FindTransitionalPosition returns false at its first guard
        // (TransitionTypes.cs:665) → the sweep did not find a valid position.
        var r = engine.ResolveWithTransition(
            currentPos: Vector3.Zero, targetPos: new Vector3(1f, 0f, 0f), cellId: 0u,
            sphereRadius: 0.3f, sphereHeight: 0f, stepUpHeight: 0f, stepDownHeight: 0f,
            isOnGround: false);

        Assert.False(r.Ok);
    }

    [Fact]
    public void ZeroMovementValidCell_ReportsOk()
    {
        var engine = new PhysicsEngine();

        // Zero offset with a non-zero start cell → FindTransitionalPosition's
        // zero-step path returns true (TransitionTypes.cs:718-723), no geometry needed.
        var r = engine.ResolveWithTransition(
            currentPos: new Vector3(5f, 5f, 5f), targetPos: new Vector3(5f, 5f, 5f), cellId: 0xA9B40001u,
            sphereRadius: 0.3f, sphereHeight: 0f, stepUpHeight: 0f, stepDownHeight: 0f,
            isOnGround: false);

        Assert.True(r.Ok);
    }
}