// Copyright 2018 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.

#ifndef DAWNNATIVE_DAWNNATIVE_H_
#define DAWNNATIVE_DAWNNATIVE_H_

#include <dawn/dawn.h>
#include <dawn_native/dawn_native_export.h>

#include <string>
#include <vector>

namespace dawn_native {

    struct PCIInfo {
        uint32_t deviceId = 0;
        uint32_t vendorId = 0;
        std::string name;
    };

    enum class BackendType {
        D3D12,
        Metal,
        Null,
        OpenGL,
        Vulkan,
    };

    class InstanceBase;
    class AdapterBase;

    // An adapter is an object that represent on possibility of creating devices in the system.
    // Most of the time it will represent a combination of a physical GPU and an API. Not that the
    // same GPU can be represented by multiple adapters but on different APIs.
    //
    // The underlying Dawn adapter is owned by the Dawn instance so this class is not RAII but just
    // a reference to an underlying adapter.
    class DAWN_NATIVE_EXPORT Adapter {
      public:
        Adapter();
        Adapter(AdapterBase* impl);
        ~Adapter();

        BackendType GetBackendType() const;
        const PCIInfo& GetPCIInfo() const;

        explicit operator bool() const;

        // Create a device on this adapter, note that the interface will change to include at least
        // a device descriptor and a pointer to backend specific options.
        // On an error, nullptr is returned.
        DawnDevice CreateDevice();

      private:
        AdapterBase* mImpl = nullptr;
    };

    // Base class for options passed to Instance::DiscoverAdapters.
    struct DAWN_NATIVE_EXPORT AdapterDiscoveryOptionsBase {
      public:
        const BackendType backendType;

      protected:
        AdapterDiscoveryOptionsBase(BackendType type);
    };

    // Represents a connection to dawn_native and is used for dependency injection, discovering
    // system adapters and injecting custom adapters (like a Swiftshader Vulkan adapter).
    //
    // This is an RAII class for Dawn instances and also controls the lifetime of all adapters
    // for this instance.
    class DAWN_NATIVE_EXPORT Instance {
      public:
        Instance();
        ~Instance();

        Instance(const Instance& other) = delete;
        Instance& operator=(const Instance& other) = delete;

        // Gather all adapters in the system that can be accessed with no special options. These
        // adapters will later be returned by GetAdapters.
        void DiscoverDefaultAdapters();

        // Adds adapters that can be discovered with the options provided (like a getProcAddress).
        // The backend is chosen based on the type of the options used. Returns true on success.
        bool DiscoverAdapters(const AdapterDiscoveryOptionsBase* options);

        // Returns all the adapters that the instance knows about.
        std::vector<Adapter> GetAdapters() const;

      private:
        InstanceBase* mImpl = nullptr;
    };

    // Backend-agnostic API for dawn_native
    DAWN_NATIVE_EXPORT DawnProcTable GetProcs();

}  // namespace dawn_native

#endif  // DAWNNATIVE_DAWNNATIVE_H_