using AcDream.App.Streaming;
using Xunit;

namespace AcDream.Core.Tests.Streaming;

public class StreamingRegionTwoTierTests
{
    [Fact]
    public void Constructor_TwoRadii_ExposesNearAndFarRadii()
    {
        var region = new StreamingRegion(centerX: 100, centerY: 100, nearRadius: 4, farRadius: 12);

        Assert.Equal(4, region.NearRadius);
        Assert.Equal(12, region.FarRadius);
        Assert.Equal(100, region.CenterX);
        Assert.Equal(100, region.CenterY);
        // Radius (used by existing single-radius hysteresis math) must alias to
        // FarRadius — the outer ring drives "everything currently loaded" bookkeeping.
        // If a future change mistakenly aliases Radius to NearRadius, hysteresis
        // becomes (NearRadius+2) for the far-tier unload, which is wrong.
        Assert.Equal(region.FarRadius, region.Radius);
    }

    [Fact]
    public void RecenterTo_FirstTick_SplitsLoadIntoNearAndFar()
    {
        // near=1, far=3 → near window is 3×3=9, far window is 7×7-3×3=40 LBs.
        var region = new StreamingRegion(centerX: 100, centerY: 100, nearRadius: 1, farRadius: 3);
        var diff = region.ComputeFirstTickDiff();

        Assert.Equal(9,  diff.ToLoadNear.Count);
        Assert.Equal(40, diff.ToLoadFar.Count);
        Assert.Empty(diff.ToPromote);
        Assert.Empty(diff.ToDemote);
        Assert.Empty(diff.ToUnload);
    }
}