using System.Linq;
using Age.Engine.Model;
using Xunit;

public class AnimInterpolatorTests
{
    private static GfxState VisibleObj(long handle)
    {
        var g = new GfxState();
        g.SetSurface(1, resId: 5, colorKey: -1);
        g.BindDraw(handle, 1, 0, 0, 64, 64, 100, 100);   // one 64x64 cell, base pos (100,100)
        return g;
    }

    [Fact]
    public void PingPong_FoldsAtHalfPeriod()
    {
        Assert.Equal(0,   BlendMath.PingPong(now: 0,    start: 0, period: 1000));
        Assert.Equal(500, BlendMath.PingPong(now: 500,  start: 0, period: 1000));   // peak at half
        Assert.Equal(0,   BlendMath.PingPong(now: 1000, start: 0, period: 1000));   // back to base
    }

    [Fact]
    public void SrcRect_StaticCell_SelectsSubRect()
    {
        var g = VisibleObj(0x100);
        g.SetSrcRect(0x100, frameCount: 4, columns: 4, cell: 2, period: 0);
        var ro = g.SnapshotVisibleObjects(0).Single();
        Assert.Equal(128, ro.SrcX);   // cell 2 * 64
        Assert.Equal(64, ro.W);
    }

    [Fact]
    public void SrcRect_Animated_AdvancesOneCellPerPeriodAndWraps()
    {
        var g = VisibleObj(0x100);
        g.SetSrcRect(0x100, frameCount: 4, columns: 4, cell: 0, period: 100);
        g.SnapshotVisibleObjects(0);                       // seeds start=0
        var second = g.SnapshotVisibleObjects(100).Single();
        Assert.Equal(64, second.SrcX);
        var fourth = g.SnapshotVisibleObjects(300).Single();
        Assert.Equal(192, fourth.SrcX);
        var wrapped = g.SnapshotVisibleObjects(400).Single();
        Assert.Equal(0, wrapped.SrcX);
    }

    [Fact]
    public void ColorAnim_Mode0Textured_UsesRgbModulationAndIgnoresAlpha()
    {
        var g = VisibleObj(0x100);
        g.SetColorAnim(0x100, period: 1000, target: GfxState.PackColor(0x80, 0xFF0000));
        g.SnapshotVisibleObjects(0);                       // seeds start=0
        var baseFrame = g.SnapshotVisibleObjects(0).Single();
        var peak = g.SnapshotVisibleObjects(500).Single();
        Assert.Equal((255, 0xffffffL, 0, true),
            (baseFrame.Alpha, baseFrame.Tint, baseFrame.TintStrength, baseFrame.MultiplyTint));
        Assert.Equal((255, 0xff0000L, 0, true),
            (peak.Alpha, peak.Tint, peak.TintStrength, peak.MultiplyTint));
    }

    [Fact]
    public void ColorAnim_Mode1_UsesSampledAlphaAsOpacity()
    {
        var g = VisibleObj(0x100);
        g.SetStaticObjectColorResolved(0x100, mode: 1, alpha: 255, rgb: 0xffffff);
        g.SetColorAnim(0x100, period: 1000, target: GfxState.PackColor(0x80, 0xffffff));
        g.SnapshotVisibleObjects(0);
        var peak = g.SnapshotVisibleObjects(500).Single();
        Assert.Equal(0x80, peak.Alpha);
        Assert.Equal(0, peak.TintStrength);
        Assert.True(peak.MultiplyTint);
    }

    [Fact]
    public void Ae001hMode0AlphaCycle_IsVisuallyInert()
    {
        var g = VisibleObj(0x100);
        g.SetColorAnimResolved(0x100, period: 1200, alpha: 224, rgb: -1);
        var start = g.SnapshotVisibleObjects(1000).Single();
        var peak = g.SnapshotVisibleObjects(1600).Single();
        Assert.Equal(0xe0ffffff, g.TryGet(0x100)!.ColorTarget);
        Assert.Equal((255, 0xffffffL, 0, true),
            (start.Alpha, start.Tint, start.TintStrength, start.MultiplyTint));
        Assert.Equal((start.Alpha, start.Tint, start.TintStrength, start.MultiplyTint),
            (peak.Alpha, peak.Tint, peak.TintStrength, peak.MultiplyTint));
    }
}