// Copyright (C) 2026 SharpEmu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

using SharpEmu.Libs.Gpu.Buffers;
using SharpEmu.Libs.Gpu.Images;
using Silk.NET.Vulkan;
using Xunit;

namespace SharpEmu.Libs.Tests.Gpu.Images;

public sealed class CachedImageFormatSupportTests
{
    private const ImageCreateFlags OriginalFlags = ImageCreateFlags.CreateMutableFormatBit |
                                                   ImageCreateFlags.CreateExtendedUsageBit |
                                                   ImageCreateFlags.CreateBlockTexelViewCompatibleBit;
    private const ImageUsageFlags SampledUsage = ImageUsageFlags.TransferSrcBit | ImageUsageFlags.TransferDstBit | ImageUsageFlags.SampledBit;

    private sealed class TestImageFormatSupport(bool supportsBlockViews, bool supportsSampling = true, SampleCountFlags supportedSampleCounts = SampleCountFlags.Count1Bit) : IImageFormatSupport
    {
        public int FormatQueryCount { get; private set; }

        public bool TryGetImageFormatProperties(Format format, ImageType type, ImageTiling tiling, ImageUsageFlags usage, ImageCreateFlags flags, out ImageFormatProperties properties)
        {
            FormatQueryCount++;
            properties = new ImageFormatProperties { SampleCounts = supportedSampleCounts };
            return (flags & ImageCreateFlags.CreateBlockTexelViewCompatibleBit) != 0
                ? supportsBlockViews
                : supportsSampling && (usage & ImageUsageFlags.StorageBit) == 0;
        }
    }

    private static ImageCreateInfo CreateCompressedImageConfiguration(Format format) => new()
    {
        SType = StructureType.ImageCreateInfo,
        Format = format,
        ImageType = ImageType.Type2D,
        Tiling = ImageTiling.Optimal,
        Extent = new Extent3D(512, 256, 1),
        MipLevels = 10,
        ArrayLayers = 1,
        Samples = SampleCountFlags.Count1Bit,
        Usage = SampledUsage | ImageUsageFlags.StorageBit,
        Flags = OriginalFlags,
    };

    [Theory]
    [InlineData(Format.BC1RgbaUnormBlock)]
    [InlineData(Format.BC7SrgbBlock)]
    public void MacOsFallbackPreservesCompressedImageSampling(Format format)
    {
        var device = new TestImageFormatSupport(supportsBlockViews: false);
        var configuration = CreateCompressedImageConfiguration(format);

        Assert.True(CachedImage.TrySelectSupportedImageConfiguration(device, ref configuration, allowCompressedImageFallback: true));

        Assert.Equal(2, device.FormatQueryCount);
        Assert.Equal(OriginalFlags & ~ImageCreateFlags.CreateBlockTexelViewCompatibleBit, configuration.Flags);
        Assert.Equal(SampledUsage, configuration.Usage);
        Assert.Equal(format, configuration.Format);
        Assert.Equal(512u, configuration.Extent.Width);
        Assert.Equal(256u, configuration.Extent.Height);
        Assert.Equal(10u, configuration.MipLevels);
    }

    [Theory]
    [InlineData(false)]
    [InlineData(true)]
    public void SupportedImageConfigurationRemainsUnchanged(bool allowCompressedImageFallback)
    {
        var device = new TestImageFormatSupport(supportsBlockViews: true);
        var configuration = CreateCompressedImageConfiguration(Format.BC1RgbaUnormBlock);

        Assert.True(CachedImage.TrySelectSupportedImageConfiguration(device, ref configuration, allowCompressedImageFallback));
        Assert.Equal(1, device.FormatQueryCount);
        Assert.Equal(OriginalFlags, configuration.Flags);
        Assert.Equal(SampledUsage | ImageUsageFlags.StorageBit, configuration.Usage);
    }

    [Fact]
    public void DisabledFallbackDoesNotRetryUnsupportedImage()
    {
        var device = new TestImageFormatSupport(supportsBlockViews: false);
        var configuration = CreateCompressedImageConfiguration(Format.BC1RgbaUnormBlock);

        Assert.False(CachedImage.TrySelectSupportedImageConfiguration(device, ref configuration, allowCompressedImageFallback: false));
        Assert.Equal(1, device.FormatQueryCount);
        Assert.Equal(OriginalFlags, configuration.Flags);
        Assert.Equal(SampledUsage | ImageUsageFlags.StorageBit, configuration.Usage);
    }

    [Theory]
    [InlineData(false, SampleCountFlags.Count1Bit)]
    [InlineData(true, SampleCountFlags.Count4Bit)]
    public void UnsupportedFallbackKeepsOriginalImageConfiguration(bool supportsSampling, SampleCountFlags supportedSampleCounts)
    {
        var device = new TestImageFormatSupport(supportsBlockViews: false, supportsSampling, supportedSampleCounts);
        var configuration = CreateCompressedImageConfiguration(Format.BC7SrgbBlock);

        Assert.False(CachedImage.TrySelectSupportedImageConfiguration(device, ref configuration, allowCompressedImageFallback: true));
        Assert.Equal(OriginalFlags, configuration.Flags);
        Assert.Equal(SampledUsage | ImageUsageFlags.StorageBit, configuration.Usage);
    }

    [Fact]
    public void UncompressedImageDoesNotUseCompressedFallback()
    {
        var device = new TestImageFormatSupport(supportsBlockViews: false);
        var configuration = CreateCompressedImageConfiguration(Format.R8G8B8A8Unorm);
        configuration.Flags &= ~ImageCreateFlags.CreateBlockTexelViewCompatibleBit;

        Assert.False(CachedImage.TrySelectSupportedImageConfiguration(device, ref configuration, allowCompressedImageFallback: true));
        Assert.Equal(1, device.FormatQueryCount);
        Assert.Equal(SampledUsage | ImageUsageFlags.StorageBit, configuration.Usage);
    }

    [Theory]
    [InlineData(Format.BC1RgbaUnormBlock, Format.BC1RgbaSrgbBlock, true)]
    [InlineData(Format.BC7SrgbBlock, Format.BC7UnormBlock, true)]
    [InlineData(Format.BC1RgbaUnormBlock, Format.R32G32Uint, false)]
    [InlineData(Format.BC7SrgbBlock, Format.R32G32B32A32Uint, false)]
    public void FallbackAllowsCompressedViewsAndRejectsUncompressedBlockViews(Format image, Format view, bool allowedWithoutBlockViews)
    {
        Assert.True(ViewFormatRules.AreImageViewFormatsCompatible(image, view, OriginalFlags));
        Assert.Equal(allowedWithoutBlockViews, ViewFormatRules.AreImageViewFormatsCompatible(image, view, OriginalFlags & ~ImageCreateFlags.CreateBlockTexelViewCompatibleBit));
    }
}