// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_CRYPTO_AES_DECRYPTOR_H_
#define MEDIA_CRYPTO_AES_DECRYPTOR_H_

#include <string>

#include "base/basictypes.h"
#include "base/hash_tables.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
#include "media/base/decryptor.h"
#include "media/base/media_export.h"

namespace crypto {
class SymmetricKey;
}

namespace media {

class DecryptorClient;

// Decryptor implementation that decrypts AES-encrypted buffer.
class MEDIA_EXPORT AesDecryptor : public Decryptor {
 public:
  // The AesDecryptor does not take ownership of the |client|. The |client|
  // must be valid throughout the lifetime of the AesDecryptor.
  explicit AesDecryptor(DecryptorClient* client);
  virtual ~AesDecryptor();

  // Decryptor implementation.
  virtual void GenerateKeyRequest(const std::string& key_system,
                                  const uint8* init_data,
                                  int init_data_length) OVERRIDE;
  virtual void AddKey(const std::string& key_system,
                      const uint8* key,
                      int key_length,
                      const uint8* init_data,
                      int init_data_length,
                      const std::string& session_id) OVERRIDE;
  virtual void CancelKeyRequest(const std::string& key_system,
                                const std::string& session_id) OVERRIDE;
  virtual void Decrypt(const scoped_refptr<DecoderBuffer>& encrypted,
                       const DecryptCB& decrypt_cb) OVERRIDE;

 private:
  // KeyMap owns the crypto::SymmetricKey* and must delete them when they are
  // not needed any more.
  typedef base::hash_map<std::string, crypto::SymmetricKey*> KeyMap;

  // Since only Decrypt() is called off the renderer thread, we only need to
  // protect |key_map_|, the only member variable that is shared between
  // Decrypt() and other methods.
  KeyMap key_map_;  // Protected by the |key_map_lock_|.
  base::Lock key_map_lock_;  // Protects the |key_map_|.

  // Make session ID unique per renderer by making it static.
  // TODO(xhwang): Make session ID more strictly defined if needed:
  // https://www.w3.org/Bugs/Public/show_bug.cgi?id=16739#c0
  static uint32 next_session_id_;

  DecryptorClient* const client_;

  DISALLOW_COPY_AND_ASSIGN(AesDecryptor);
};

}  // namespace media

#endif  // MEDIA_CRYPTO_AES_DECRYPTOR_H_