// Copyright 2022 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 SRC_DAWN_NATIVE_BLOBCACHE_H_
#define SRC_DAWN_NATIVE_BLOBCACHE_H_

#include <memory>
#include <mutex>

namespace dawn::platform {
    class CachingInterface;
}

namespace dawn::native {

    class BlobCache;
    class CacheKey;
    class InstanceBase;

    class CachedBlob {
      public:
        explicit CachedBlob(size_t size = 0);

        bool Empty() const;
        const uint8_t* Data() const;
        uint8_t* Data();
        size_t Size() const;
        void Reset(size_t size);

      private:
        std::unique_ptr<uint8_t[]> mData = nullptr;
        size_t mSize = 0;
    };

    // This class should always be thread-safe because it may be called asynchronously. Its purpose
    // is to wrap the CachingInterface provided via a platform.
    class BlobCache {
      public:
        explicit BlobCache(dawn::platform::CachingInterface* cachingInterface = nullptr);

        // Returns empty blob if the key is not found in the cache.
        CachedBlob Load(const CacheKey& key);

        // Value to store must be non-empty/non-null.
        void Store(const CacheKey& key, size_t valueSize, const void* value);
        void Store(const CacheKey& key, const CachedBlob& value);

      private:
        // Non-thread safe internal implementations of load and store. Exposed callers that use
        // these helpers need to make sure that these are entered with `mMutex` held.
        CachedBlob LoadInternal(const CacheKey& key);
        void StoreInternal(const CacheKey& key, size_t valueSize, const void* value);

        // Protects thread safety of access to mCache.
        std::mutex mMutex;

        // TODO(dawn:549): Current CachingInterface declaration requires passing a device to each
        //   call, but this might be unnecessary. This class just passes nullptr for those calls
        //   right now. Eventually we can just change the interface to be more generic.
        dawn::platform::CachingInterface* mCache;
    };

}  // namespace dawn::native

#endif  // SRC_DAWN_NATIVE_BLOBCACHE_H_