// 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 "DawnWireServerFuzzer.h"

#include "common/Assert.h"
#include "common/Log.h"
#include "common/SystemUtils.h"
#include "dawn/dawn_proc.h"
#include "dawn/webgpu_cpp.h"
#include "dawn_native/DawnNative.h"
#include "dawn_wire/WireServer.h"
#include "utils/SystemUtils.h"

#include <fstream>
#include <vector>

namespace {

    class DevNull : public dawn::wire::CommandSerializer {
      public:
        size_t GetMaximumAllocationSize() const override {
            // Some fuzzer bots have a 2GB allocation limit. Pick a value reasonably below that.
            return 1024 * 1024 * 1024;
        }
        void* GetCmdSpace(size_t size) override {
            if (size > buf.size()) {
                buf.resize(size);
            }
            return buf.data();
        }
        bool Flush() override {
            return true;
        }

      private:
        std::vector<char> buf;
    };

    std::unique_ptr<dawn::native::Instance> sInstance;
    WGPUProcDeviceCreateSwapChain sOriginalDeviceCreateSwapChain = nullptr;

    bool sCommandsComplete = false;

    WGPUSwapChain ErrorDeviceCreateSwapChain(WGPUDevice device,
                                             WGPUSurface surface,
                                             const WGPUSwapChainDescriptor*) {
        WGPUSwapChainDescriptor desc = {};
        // A 0 implementation will trigger a swapchain creation error.
        desc.implementation = 0;
        return sOriginalDeviceCreateSwapChain(device, surface, &desc);
    }

}  // namespace

int DawnWireServerFuzzer::Initialize(int* argc, char*** argv) {
    // TODO(crbug.com/1038952): The Instance must be static because destructing the vkInstance with
    // Swiftshader crashes libFuzzer. When this is fixed, move this into Run so that error injection
    // for adapter discovery can be fuzzed.
    sInstance = std::make_unique<dawn::native::Instance>();
    sInstance->DiscoverDefaultAdapters();

    return 0;
}

int DawnWireServerFuzzer::Run(const uint8_t* data,
                              size_t size,
                              MakeDeviceFn MakeDevice,
                              bool supportsErrorInjection) {
    // We require at least the injected error index.
    if (size < sizeof(uint64_t)) {
        return 0;
    }

    // Get and consume the injected error index.
    uint64_t injectedErrorIndex = *reinterpret_cast<const uint64_t*>(data);
    data += sizeof(uint64_t);
    size -= sizeof(uint64_t);

    if (supportsErrorInjection) {
        dawn::native::EnableErrorInjector();

        // Clear the error injector since it has the previous run's call counts.
        dawn::native::ClearErrorInjector();

        dawn::native::InjectErrorAt(injectedErrorIndex);
    }

    DawnProcTable procs = dawn::native::GetProcs();

    // Swapchains receive a pointer to an implementation. The fuzzer will pass garbage in so we
    // intercept calls to create swapchains and make sure they always return error swapchains.
    // This is ok for fuzzing because embedders of dawn_wire would always define their own
    // swapchain handling.
    sOriginalDeviceCreateSwapChain = procs.deviceCreateSwapChain;
    procs.deviceCreateSwapChain = ErrorDeviceCreateSwapChain;

    dawnProcSetProcs(&procs);

    wgpu::Device device = MakeDevice(sInstance.get());
    if (!device) {
        // We should only ever fail device creation if an error was injected.
        ASSERT(supportsErrorInjection);
        return 0;
    }

    DevNull devNull;
    dawn::wire::WireServerDescriptor serverDesc = {};
    serverDesc.procs = &procs;
    serverDesc.serializer = &devNull;

    std::unique_ptr<dawn::wire::WireServer> wireServer(new dawn_wire::WireServer(serverDesc));
    wireServer->InjectDevice(device.Get(), 1, 0);

    wireServer->HandleCommands(reinterpret_cast<const char*>(data), size);

    // Wait for all previous commands before destroying the server.
    // TODO(enga): Improve this when we improve/finalize how processing events happens.
    {
        device.GetQueue().OnSubmittedWorkDone(
            0u, [](WGPUQueueWorkDoneStatus, void*) { sCommandsComplete = true; }, nullptr);
        while (!sCommandsComplete) {
            device.Tick();
            utils::USleep(100);
        }
    }

    wireServer = nullptr;
    return 0;
}