using XFESystem.Desktop;
using Xunit;

namespace XFESystem.Core.Tests;

public sealed class ChromeRasterTests
{
    private sealed class BitmapCanvas(int scale, uint background) : IDesktopCoverageCanvas
    {
        public int Width => 100;
        public int Height => 80;
        public int NativeWidth => Width * scale;
        public int NativeHeight => Height * scale;
        public int ScalePercent => scale * 100;
        public uint[] Pixels { get; } = Enumerable.Repeat(background, 100 * 80 * scale * scale).ToArray();
        public void Fill(uint rgb, int x, int y, int width, int height)
        {
            for (int py = Math.Max(0, y * scale); py < Math.Min(NativeHeight, (y + height) * scale); py++)
                for (int px = Math.Max(0, x * scale); px < Math.Min(NativeWidth, (x + width) * scale); px++) Pixels[py * NativeWidth + px] = rgb;
        }
        public void BlendCoverage(uint rgb, int x, int y, int width, int height, ReadOnlySpan<byte> alpha)
        {
            Assert.Equal(width * height, alpha.Length);
            for (int row = 0; row < height; row++)
                for (int column = 0; column < width; column++)
                {
                    int px = x + column, py = y + row;
                    if (px < 0 || py < 0 || px >= NativeWidth || py >= NativeHeight) continue;
                    int index = py * NativeWidth + px, a = alpha[row * width + column];
                    uint old = Pixels[index], color = 0;
                    foreach (int shift in new[] { 0, 8, 16 })
                        color |= (uint)(((rgb >> shift & 255) * a + (old >> shift & 255) * (255 - a) + 127) / 255) << shift;
                    Pixels[index] = color;
                }
        }
        public void Line(uint rgb, int x1, int y1, int x2, int y2) => throw new InvalidOperationException("Native coverage must not fall back to aliased lines.");
        public void Text(string text, uint rgb, int x, int y) { }
        public void Present() { }
    }

    [Theory]
    [InlineData(1)]
    [InlineData(2)]
    public void RoundedCornersContainIntermediateCoverageAndPreserveOutsidePixels(int scale)
    {
        const uint background = 0x09121B, foreground = 0xFAFAFE;
        var bitmap = new BitmapCanvas(scale, background);
        DesktopChromeRenderer.RoundedFill(bitmap, foreground, 10, 12, 60, 42, 12);
        Assert.Equal(background, bitmap.Pixels[12 * scale * bitmap.NativeWidth + 10 * scale]);
        Assert.Equal(foreground, bitmap.Pixels[30 * scale * bitmap.NativeWidth + 35 * scale]);
        Assert.Contains(bitmap.Pixels, pixel => pixel != foreground && pixel != background);
        for (int row = 0; row < bitmap.NativeHeight; row++)
            for (int col = 0; col < bitmap.NativeWidth; col++)
                if (col < 10 * scale || col >= 70 * scale || row < 12 * scale || row >= 54 * scale)
                    Assert.Equal(background, bitmap.Pixels[row * bitmap.NativeWidth + col]);
    }

    [Theory]
    [InlineData(1)]
    [InlineData(2)]
    public void DiagonalCaptionStrokesAreAntialiasedAndBlendWithScene(int scale)
    {
        const uint background = 0xEEEFF8, foreground = 0x343C56;
        var bitmap = new BitmapCanvas(scale, background);
        DesktopChromeRenderer.Line(bitmap, foreground, 20, 20, 32, 32);
        Assert.Contains(bitmap.Pixels, pixel => pixel != foreground && pixel != background);
        Assert.Equal(background, bitmap.Pixels[0]);
        Assert.Equal(background, bitmap.Pixels[50 * scale * bitmap.NativeWidth + 50 * scale]);
        Assert.True(bitmap.Pixels.Count(pixel => pixel != background) < 100 * scale * scale);
    }

    [Fact]
    public void NegativeChromeBoundsClipCleanlyAndTinyRadiiDoNotLoseInterior()
    {
        var bitmap = new BitmapCanvas(2, 0x102538);
        DesktopChromeRenderer.RoundedFill(bitmap, 0x75C9F5, -10, -6, 40, 30, 8);
        Assert.Equal(0x75C9F5u, bitmap.Pixels[0]);
        DesktopChromeRenderer.RoundedFill(bitmap, 0xFAFAFE, 50, 50, 3, 2, 20);
        Assert.Equal(0xFAFAFEu, bitmap.Pixels[101 * bitmap.NativeWidth + 102]);
        DesktopChromeRenderer.Line(bitmap, 0x657DE2, -8, -8, 10, 10);
        Assert.Contains(bitmap.Pixels, pixel => pixel == 0x102538);
    }
}