// Copyright 2019 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "dawn_native/Format.h"

#include "dawn_native/Device.h"
#include "dawn_native/EnumMaskIterator.h"
#include "dawn_native/Extensions.h"
#include "dawn_native/Texture.h"

#include <bitset>

namespace dawn_native {

    // Format

    // TODO(dawn:527): Remove when unused.
    SampleTypeBit ToSampleTypeBit(wgpu::TextureComponentType type) {
        switch (type) {
            case wgpu::TextureComponentType::Float:
                return SampleTypeBit::Float;
            case wgpu::TextureComponentType::Sint:
                return SampleTypeBit::Sint;
            case wgpu::TextureComponentType::Uint:
                return SampleTypeBit::Uint;
            case wgpu::TextureComponentType::DepthComparison:
                return SampleTypeBit::Depth;
        }
    }

    SampleTypeBit SampleTypeToSampleTypeBit(wgpu::TextureSampleType sampleType) {
        switch (sampleType) {
            case wgpu::TextureSampleType::Float:
            case wgpu::TextureSampleType::UnfilterableFloat:
            case wgpu::TextureSampleType::Sint:
            case wgpu::TextureSampleType::Uint:
            case wgpu::TextureSampleType::Depth:
            case wgpu::TextureSampleType::Undefined:
                // When the compiler complains that you need to add a case statement here, please
                // also add a corresponding static assert below!
                break;
        }

        static_assert(static_cast<uint32_t>(wgpu::TextureSampleType::Undefined) == 0, "");
        if (sampleType == wgpu::TextureSampleType::Undefined) {
            return SampleTypeBit::None;
        }

        // Check that SampleTypeBit bits are in the same position / order as the respective
        // wgpu::TextureSampleType value.
        static_assert(SampleTypeBit::Float ==
                          static_cast<SampleTypeBit>(
                              1 << (static_cast<uint32_t>(wgpu::TextureSampleType::Float) - 1)),
                      "");
        static_assert(
            SampleTypeBit::UnfilterableFloat ==
                static_cast<SampleTypeBit>(
                    1 << (static_cast<uint32_t>(wgpu::TextureSampleType::UnfilterableFloat) - 1)),
            "");
        static_assert(SampleTypeBit::Uint ==
                          static_cast<SampleTypeBit>(
                              1 << (static_cast<uint32_t>(wgpu::TextureSampleType::Uint) - 1)),
                      "");
        static_assert(SampleTypeBit::Sint ==
                          static_cast<SampleTypeBit>(
                              1 << (static_cast<uint32_t>(wgpu::TextureSampleType::Sint) - 1)),
                      "");
        static_assert(SampleTypeBit::Depth ==
                          static_cast<SampleTypeBit>(
                              1 << (static_cast<uint32_t>(wgpu::TextureSampleType::Depth) - 1)),
                      "");
        return static_cast<SampleTypeBit>(1 << (static_cast<uint32_t>(sampleType) - 1));
    }

    bool Format::IsColor() const {
        return aspects == Aspect::Color;
    }

    bool Format::HasDepth() const {
        return (aspects & Aspect::Depth) != 0;
    }

    bool Format::HasStencil() const {
        return (aspects & Aspect::Stencil) != 0;
    }

    bool Format::HasDepthOrStencil() const {
        return (aspects & (Aspect::Depth | Aspect::Stencil)) != 0;
    }

    bool Format::IsMultiPlanar() const {
        return (aspects & (Aspect::Plane0 | Aspect::Plane1)) != 0;
    }

    const AspectInfo& Format::GetAspectInfo(wgpu::TextureAspect aspect) const {
        return GetAspectInfo(SelectFormatAspects(*this, aspect));
    }

    const AspectInfo& Format::GetAspectInfo(Aspect aspect) const {
        ASSERT(HasOneBit(aspect));
        ASSERT(aspects & aspect);
        const size_t aspectIndex = GetAspectIndex(aspect);
        ASSERT(aspectIndex < GetAspectCount(aspects));
        return aspectInfo[aspectIndex];
    }

    size_t Format::GetIndex() const {
        return ComputeFormatIndex(format);
    }

    // Implementation details of the format table of the DeviceBase

    // For the enum for formats are packed but this might change when we have a broader extension
    // mechanism for webgpu.h. Formats start at 1 because 0 is the undefined format.
    size_t ComputeFormatIndex(wgpu::TextureFormat format) {
        // This takes advantage of overflows to make the index of TextureFormat::Undefined outside
        // of the range of the FormatTable.
        static_assert(static_cast<uint32_t>(wgpu::TextureFormat::Undefined) - 1 > kKnownFormatCount,
                      "");
        return static_cast<size_t>(static_cast<uint32_t>(format) - 1);
    }

    FormatTable BuildFormatTable(const DeviceBase* device) {
        FormatTable table;
        std::bitset<kKnownFormatCount> formatsSet;

        static constexpr SampleTypeBit kAnyFloat =
            SampleTypeBit::Float | SampleTypeBit::UnfilterableFloat;

        auto AddFormat = [&table, &formatsSet](Format format) {
            size_t index = ComputeFormatIndex(format.format);
            ASSERT(index < table.size());

            // This checks that each format is set at most once, the first part of checking that all
            // formats are set exactly once.
            ASSERT(!formatsSet[index]);

            // Vulkan describes bytesPerRow in units of texels. If there's any format for which this
            // ASSERT isn't true, then additional validation on bytesPerRow must be added.
            const bool hasMultipleAspects = !HasOneBit(format.aspects);
            ASSERT(hasMultipleAspects ||
                   (kTextureBytesPerRowAlignment % format.aspectInfo[0].block.byteSize) == 0);

            table[index] = format;
            formatsSet.set(index);
        };

        auto AddColorFormat = [&AddFormat](wgpu::TextureFormat format, bool renderable,
                                           bool supportsStorageUsage, uint32_t byteSize,
                                           SampleTypeBit sampleTypes) {
            Format internalFormat;
            internalFormat.format = format;
            internalFormat.isRenderable = renderable;
            internalFormat.isCompressed = false;
            internalFormat.isSupported = true;
            internalFormat.supportsStorageUsage = supportsStorageUsage;
            internalFormat.aspects = Aspect::Color;
            AspectInfo* firstAspect = internalFormat.aspectInfo.data();
            firstAspect->block.byteSize = byteSize;
            firstAspect->block.width = 1;
            firstAspect->block.height = 1;
            if (HasOneBit(sampleTypes)) {
                switch (sampleTypes) {
                    case SampleTypeBit::Float:
                    case SampleTypeBit::UnfilterableFloat:
                        firstAspect->baseType = wgpu::TextureComponentType::Float;
                        break;
                    case SampleTypeBit::Sint:
                        firstAspect->baseType = wgpu::TextureComponentType::Sint;
                        break;
                    case SampleTypeBit::Uint:
                        firstAspect->baseType = wgpu::TextureComponentType::Uint;
                        break;
                    default:
                        UNREACHABLE();
                }
            } else {
                ASSERT((sampleTypes & SampleTypeBit::Float) != 0);
                firstAspect->baseType = wgpu::TextureComponentType::Float;
            }
            firstAspect->supportedSampleTypes = sampleTypes;
            firstAspect->format = format;
            AddFormat(internalFormat);
        };

        auto AddDepthFormat = [&AddFormat](wgpu::TextureFormat format, uint32_t byteSize) {
            Format internalFormat;
            internalFormat.format = format;
            internalFormat.isRenderable = true;
            internalFormat.isCompressed = false;
            internalFormat.isSupported = true;
            internalFormat.supportsStorageUsage = false;
            internalFormat.aspects = Aspect::Depth;
            AspectInfo* firstAspect = internalFormat.aspectInfo.data();
            firstAspect->block.byteSize = byteSize;
            firstAspect->block.width = 1;
            firstAspect->block.height = 1;
            firstAspect->baseType = wgpu::TextureComponentType::Float;
            firstAspect->supportedSampleTypes = kAnyFloat | SampleTypeBit::Depth;
            firstAspect->format = format;
            AddFormat(internalFormat);
        };

        auto AddStencilFormat = [&AddFormat](wgpu::TextureFormat format) {
            Format internalFormat;
            internalFormat.format = format;
            internalFormat.isRenderable = true;
            internalFormat.isCompressed = false;
            internalFormat.isSupported = false;
            internalFormat.supportsStorageUsage = false;
            internalFormat.aspects = Aspect::Stencil;
            AspectInfo* firstAspect = internalFormat.aspectInfo.data();
            firstAspect->block.byteSize = 1;
            firstAspect->block.width = 1;
            firstAspect->block.height = 1;
            firstAspect->baseType = wgpu::TextureComponentType::Uint;
            firstAspect->supportedSampleTypes = SampleTypeBit::Uint;
            firstAspect->format = format;
            AddFormat(internalFormat);
        };

        auto AddCompressedFormat = [&AddFormat](wgpu::TextureFormat format, uint32_t byteSize,
                                                uint32_t width, uint32_t height, bool isSupported) {
            Format internalFormat;
            internalFormat.format = format;
            internalFormat.isRenderable = false;
            internalFormat.isCompressed = true;
            internalFormat.isSupported = isSupported;
            internalFormat.supportsStorageUsage = false;
            internalFormat.aspects = Aspect::Color;
            AspectInfo* firstAspect = internalFormat.aspectInfo.data();
            firstAspect->block.byteSize = byteSize;
            firstAspect->block.width = width;
            firstAspect->block.height = height;
            firstAspect->baseType = wgpu::TextureComponentType::Float;
            firstAspect->supportedSampleTypes = kAnyFloat;
            firstAspect->format = format;
            AddFormat(internalFormat);
        };

        auto AddMultiAspectFormat = [&AddFormat, &table](wgpu::TextureFormat format, Aspect aspects,
                                                         wgpu::TextureFormat firstFormat,
                                                         wgpu::TextureFormat secondFormat,
                                                         bool isRenderable, bool isSupported) {
            Format internalFormat;
            internalFormat.format = format;
            internalFormat.isRenderable = isRenderable;
            internalFormat.isCompressed = false;
            internalFormat.isSupported = isSupported;
            internalFormat.supportsStorageUsage = false;
            internalFormat.aspects = aspects;

            const size_t firstFormatIndex = ComputeFormatIndex(firstFormat);
            const size_t secondFormatIndex = ComputeFormatIndex(secondFormat);

            internalFormat.aspectInfo[0] = table[firstFormatIndex].aspectInfo[0];
            internalFormat.aspectInfo[1] = table[secondFormatIndex].aspectInfo[0];

            AddFormat(internalFormat);
        };

        // clang-format off
        // 1 byte color formats
        AddColorFormat(wgpu::TextureFormat::R8Unorm, true, false, 1, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::R8Snorm, false, false, 1, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::R8Uint, true, false, 1, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::R8Sint, true, false, 1, SampleTypeBit::Sint);

        // 2 bytes color formats
        AddColorFormat(wgpu::TextureFormat::R16Uint, true, false, 2, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::R16Sint, true, false, 2, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::R16Float, true, false, 2, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RG8Unorm, true, false, 2, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RG8Snorm, false, false, 2, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RG8Uint, true, false, 2, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::RG8Sint, true, false, 2, SampleTypeBit::Sint);

        // 4 bytes color formats
        AddColorFormat(wgpu::TextureFormat::R32Uint, true, true, 4, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::R32Sint, true, true, 4, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::R32Float, true, true, 4, SampleTypeBit::UnfilterableFloat);
        AddColorFormat(wgpu::TextureFormat::RG16Uint, true, false, 4, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::RG16Sint, true, false, 4, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::RG16Float, true, false, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RGBA8Unorm, true, true, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RGBA8UnormSrgb, true, false, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RGBA8Snorm, false, true, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RGBA8Uint, true, true, 4, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::RGBA8Sint, true, true, 4, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::BGRA8Unorm, true, false, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::BGRA8UnormSrgb, true, false, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RGB10A2Unorm, true, false, 4, kAnyFloat);

        AddColorFormat(wgpu::TextureFormat::RG11B10Ufloat, false, false, 4, kAnyFloat);
        AddColorFormat(wgpu::TextureFormat::RGB9E5Ufloat, false, false, 4, kAnyFloat);

        // 8 bytes color formats
        AddColorFormat(wgpu::TextureFormat::RG32Uint, true, true, 8, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::RG32Sint, true, true, 8, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::RG32Float, true, true, 8, SampleTypeBit::UnfilterableFloat);
        AddColorFormat(wgpu::TextureFormat::RGBA16Uint, true, true, 8, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::RGBA16Sint, true, true, 8, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::RGBA16Float, true, true, 8, kAnyFloat);

        // 16 bytes color formats
        AddColorFormat(wgpu::TextureFormat::RGBA32Uint, true, true, 16, SampleTypeBit::Uint);
        AddColorFormat(wgpu::TextureFormat::RGBA32Sint, true, true, 16, SampleTypeBit::Sint);
        AddColorFormat(wgpu::TextureFormat::RGBA32Float, true, true, 16, SampleTypeBit::UnfilterableFloat);

        // Depth-stencil formats
        AddDepthFormat(wgpu::TextureFormat::Depth32Float, 4);
        // TODO(crbug.com/dawn/843): This is 4 because we read this to perform zero initialization,
        // and textures are always use depth32float. We should improve this to be more robust. Perhaps,
        // using 0 here to mean "unsized" and adding a backend-specific query for the block size.
        AddDepthFormat(wgpu::TextureFormat::Depth24Plus, 4);
        // TODO(dawn:666): Implement the stencil8 format
        AddStencilFormat(wgpu::TextureFormat::Stencil8);
        AddMultiAspectFormat(wgpu::TextureFormat::Depth24PlusStencil8,
                              Aspect::Depth | Aspect::Stencil, wgpu::TextureFormat::Depth24Plus, wgpu::TextureFormat::Stencil8, true, true);
        // TODO(dawn:690): Implement Depth16Unorm, Depth24UnormStencil8, Depth32FloatStencil8.

        // BC compressed formats
        bool isBCFormatSupported = device->IsExtensionEnabled(Extension::TextureCompressionBC);
        AddCompressedFormat(wgpu::TextureFormat::BC1RGBAUnorm, 8, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC1RGBAUnormSrgb, 8, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC4RSnorm, 8, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC4RUnorm, 8, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC2RGBAUnorm, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC2RGBAUnormSrgb, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC3RGBAUnorm, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC3RGBAUnormSrgb, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC5RGSnorm, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC5RGUnorm, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC6HRGBFloat, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC6HRGBUfloat, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC7RGBAUnorm, 16, 4, 4, isBCFormatSupported);
        AddCompressedFormat(wgpu::TextureFormat::BC7RGBAUnormSrgb, 16, 4, 4, isBCFormatSupported);

        // multi-planar formats
        const bool isMultiPlanarFormatSupported = device->IsExtensionEnabled(Extension::MultiPlanarFormats);
        AddMultiAspectFormat(wgpu::TextureFormat::R8BG8Biplanar420Unorm, Aspect::Plane0 | Aspect::Plane1,
            wgpu::TextureFormat::R8Unorm, wgpu::TextureFormat::RG8Unorm, false, isMultiPlanarFormatSupported);

        // clang-format on

        // This checks that each format is set at least once, the second part of checking that all
        // formats are checked exactly once.
        ASSERT(formatsSet.all());

        return table;
    }

}  // namespace dawn_native