// Copyright 2016 The Cobalt Authors. All Rights Reserved.
//
// 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 COBALT_H5VCC_H5VCC_ACCOUNT_MANAGER_H_
#define COBALT_H5VCC_H5VCC_ACCOUNT_MANAGER_H_

#include <queue>
#include <string>

#include "base/memory/scoped_ptr.h"
#include "base/memory/scoped_vector.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop.h"
#include "base/threading/thread.h"
#include "base/threading/thread_checker.h"
#include "cobalt/account/user_authorizer.h"
#include "cobalt/script/callback_function.h"
#include "cobalt/script/script_value.h"
#include "cobalt/script/wrappable.h"

namespace cobalt {
namespace h5vcc {

// Implementation of the H5vccAccountManager interface. Requests will be handled
// one-at-time on another thread in FIFO order. When a request is complete, the
// AccessTokenCallback will be fired on the thread that the H5vccAccountManager
// was created on.
class H5vccAccountManager : public script::Wrappable,
                            public base::SupportsWeakPtr<H5vccAccountManager> {
 public:
  typedef script::CallbackFunction<bool(const std::string&, uint64_t)>
      AccessTokenCallback;
  typedef script::ScriptValue<AccessTokenCallback> AccessTokenCallbackHolder;

  H5vccAccountManager();
  // H5vccAccountManager interface.
  void GetAuthToken(const AccessTokenCallbackHolder& callback);
  void RequestPairing(const AccessTokenCallbackHolder& callback);
  void RequestUnpairing(const AccessTokenCallbackHolder& callback);

  DEFINE_WRAPPABLE_TYPE(H5vccAccountManager);

 private:
  typedef script::ScriptValue<AccessTokenCallback>::Reference
      AccessTokenCallbackReference;
  enum OperationType {
    kPairing,
    kUnpairing,
    kGetToken,
  };

  ~H5vccAccountManager();

  // Posts an operation to the account manager thread.
  void PostOperation(OperationType operation_type,
                     const AccessTokenCallbackHolder& callback);

  // Processes an operation on the account manager thread. Static because
  // H5vccAccountManager may have been destructed before this runs.
  static void RequestOperationInternal(
      account::UserAuthorizer* user_authorizer, OperationType operation,
      const base::Callback<void(const std::string&, uint64_t)>& post_result);

  // Posts the result of an operation from the account manager thread back to
  // the owning thread. Static because H5vccAccountManager may have been
  // destructed before this runs.
  static void PostResult(
      MessageLoop* message_loop,
      base::WeakPtr<H5vccAccountManager> h5vcc_account_manager,
      AccessTokenCallbackReference* token_callback,
      const std::string& token, uint64_t expiration_in_seconds);

  // Sends the result of an operation to the callback on the owning thread.
  void SendResult(AccessTokenCallbackReference* token_callback,
                  const std::string& token, uint64_t expiration_in_seconds);

  // The platform-specific user authorizer for getting access tokens.
  scoped_ptr<account::UserAuthorizer> user_authorizer_;

  // Scoped holder of the callbacks that are currently waiting for a response.
  ScopedVector<AccessTokenCallbackReference> pending_callbacks_;

  // Thread checker for the thread that creates this instance.
  base::ThreadChecker thread_checker_;

  // The message loop that the H5vccAccountManager was created on. The public
  // interface must be called from this message loop, and callbacks will be
  // fired on this loop as well.
  MessageLoop* owning_message_loop_;

  // Each incoming request will have a corresponding task posted to this
  // thread's message loop and will be handled in a FIFO manner.
  // This is last so that all the other fields are valid before the thread gets
  // constructed, and they remain valid until the thread gets destructed and its
  // message loop gets flushed.
  base::Thread thread_;

  friend class scoped_refptr<H5vccAccountManager>;
  DISALLOW_COPY_AND_ASSIGN(H5vccAccountManager);
};

}  // namespace h5vcc
}  // namespace cobalt

#endif  // COBALT_H5VCC_H5VCC_ACCOUNT_MANAGER_H_