// Copyright 2017 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/utils/BackendBinding.h"

#include "dawn/common/Assert.h"
#include "dawn/common/SwapChainUtils.h"
#include "dawn/native/MetalBackend.h"

#define GLFW_EXPOSE_NATIVE_COCOA
#include "GLFW/glfw3.h"
#include "GLFW/glfw3native.h"

#import <QuartzCore/CAMetalLayer.h>

namespace utils {
class SwapChainImplMTL {
  public:
    using WSIContext = DawnWSIContextMetal;

    SwapChainImplMTL(id nsWindow) : mNsWindow(nsWindow) {}

    ~SwapChainImplMTL() {
        [mCurrentTexture release];
        [mCurrentDrawable release];
    }

    void Init(DawnWSIContextMetal* ctx) {
        mMtlDevice = ctx->device;
        mCommandQueue = ctx->queue;
    }

    DawnSwapChainError Configure(WGPUTextureFormat format,
                                 WGPUTextureUsage usage,
                                 uint32_t width,
                                 uint32_t height) {
        if (format != WGPUTextureFormat_BGRA8Unorm) {
            return "unsupported format";
        }
        ASSERT(width > 0);
        ASSERT(height > 0);

        NSView* contentView = [mNsWindow contentView];
        [contentView setWantsLayer:YES];

        CGSize size = {};
        size.width = width;
        size.height = height;

        mLayer = [CAMetalLayer layer];
        [mLayer setDevice:mMtlDevice];
        [mLayer setPixelFormat:MTLPixelFormatBGRA8Unorm];
        [mLayer setDrawableSize:size];

        constexpr uint32_t kFramebufferOnlyTextureUsages =
            WGPUTextureUsage_RenderAttachment | WGPUTextureUsage_Present;
        bool hasOnlyFramebufferUsages = !(usage & (~kFramebufferOnlyTextureUsages));
        if (hasOnlyFramebufferUsages) {
            [mLayer setFramebufferOnly:YES];
        }

        [contentView setLayer:mLayer];

        return DAWN_SWAP_CHAIN_NO_ERROR;
    }

    DawnSwapChainError GetNextTexture(DawnSwapChainNextTexture* nextTexture) {
        [mCurrentDrawable release];
        mCurrentDrawable = [mLayer nextDrawable];
        [mCurrentDrawable retain];

        [mCurrentTexture release];
        mCurrentTexture = mCurrentDrawable.texture;
        [mCurrentTexture retain];

        nextTexture->texture.ptr = reinterpret_cast<void*>(mCurrentTexture);

        return DAWN_SWAP_CHAIN_NO_ERROR;
    }

    DawnSwapChainError Present() {
        id<MTLCommandBuffer> commandBuffer = [mCommandQueue commandBuffer];
        [commandBuffer presentDrawable:mCurrentDrawable];
        [commandBuffer commit];

        return DAWN_SWAP_CHAIN_NO_ERROR;
    }

  private:
    id mNsWindow = nil;
    id<MTLDevice> mMtlDevice = nil;
    id<MTLCommandQueue> mCommandQueue = nil;

    CAMetalLayer* mLayer = nullptr;
    id<CAMetalDrawable> mCurrentDrawable = nil;
    id<MTLTexture> mCurrentTexture = nil;
};

class MetalBinding : public BackendBinding {
  public:
    MetalBinding(GLFWwindow* window, WGPUDevice device) : BackendBinding(window, device) {}

    uint64_t GetSwapChainImplementation() override {
        if (mSwapchainImpl.userData == nullptr) {
            mSwapchainImpl =
                CreateSwapChainImplementation(new SwapChainImplMTL(glfwGetCocoaWindow(mWindow)));
        }
        return reinterpret_cast<uint64_t>(&mSwapchainImpl);
    }

    WGPUTextureFormat GetPreferredSwapChainTextureFormat() override {
        return WGPUTextureFormat_BGRA8Unorm;
    }

  private:
    DawnSwapChainImplementation mSwapchainImpl = {};
};

BackendBinding* CreateMetalBinding(GLFWwindow* window, WGPUDevice device) {
    return new MetalBinding(window, device);
}
}  // namespace utils