/* <!-- copyright */
/*
 * aria2 - The high speed download utility
 *
 * Copyright (C) 2013 Tatsuhiro Tsujikawa
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 * You must obey the GNU General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
 * version of the file(s), but you are not obligated to do so.  If you
 * do not wish to do so, delete this exception statement from your
 * version.  If you delete this exception statement from all source
 * files in the program, then also delete it here.
 */
/* copyright --> */
#ifndef D_UDP_TRACKER_CLIENT_H
#define D_UDP_TRACKER_CLIENT_H

#include "common.h"

#include <string>
#include <deque>
#include <map>
#include <memory>

#include "TimerA2.h"

namespace aria2 {

#define UDPT_INITIAL_CONNECTION_ID 0x41727101980LL

struct UDPTrackerRequest;

enum UDPTrackerConnectionState {
  UDPT_CST_CONNECTING,
  UDPT_CST_CONNECTED
};

struct UDPTrackerConnection {
  int state;
  int64_t connectionId;
  Timer lastUpdated;
  UDPTrackerConnection()
    : state(UDPT_CST_CONNECTING),
      connectionId(UDPT_INITIAL_CONNECTION_ID),
      lastUpdated(0)
  {}
  UDPTrackerConnection(int state, int64_t connectionId,
                       const Timer& lastUpdated)
    : state(state),
      connectionId(connectionId),
      lastUpdated(lastUpdated)
  {}
};

class UDPTrackerClient {
public:
  UDPTrackerClient();
  ~UDPTrackerClient();

  int receiveReply
  (const unsigned char* data, size_t length, const std::string& remoteAddr,
   uint16_t remotePort, const Timer& now);

  // Creates data frame for the next pending request. This function
  // always processes first entry of pendingRequests_.  If the data is
  // sent successfully, call requestSent(). Otherwise call
  // requestFail().
  ssize_t createRequest
  (unsigned char* data, size_t length, std::string& remoteAddr,
   uint16_t& remotePort, const Timer& now);

  // Tells this object that first entry of pendingRequests_ is
  // successfully sent.
  void requestSent(const Timer& now);
  // Tells this object that first entry of pendingRequests_ is not
  // successfully sent. The |error| should indicate error situation.
  void requestFail(int error);

  void addRequest(const std::shared_ptr<UDPTrackerRequest>& req);

  // Handles timeout for inflight requests.
  void handleTimeout(const Timer& now);

  const std::deque<std::shared_ptr<UDPTrackerRequest> >&
  getPendingRequests() const
  {
    return pendingRequests_;
  }
  const std::deque<std::shared_ptr<UDPTrackerRequest> >&
  getConnectRequests() const
  {
    return connectRequests_;
  }
  const std::deque<std::shared_ptr<UDPTrackerRequest> >&
  getInflightRequests() const
  {
    return inflightRequests_;
  }

  bool noRequest() const
  {
    return pendingRequests_.empty() && connectRequests_.empty() &&
      getInflightRequests().empty();
  }

  // Makes all contained requests fail.
  void failAll();

  int getNumWatchers() const
  {
    return numWatchers_;
  }

  void increaseWatchers();
  void decreaseWatchers();

  // Actually private function, but made public, to be used by unnamed
  // function.
  void failConnect(const std::string& remoteAddr, uint16_t remotePort,
                   int error);
private:
  std::shared_ptr<UDPTrackerRequest> findInflightRequest
  (const std::string& remoteAddr, uint16_t remotePort, int32_t transactionId,
   bool remove);

  UDPTrackerConnection* getConnectionId
  (const std::string& remoteAddr, uint16_t remotePort, const Timer& now);

  std::map<std::pair<std::string, uint16_t>,
           UDPTrackerConnection> connectionIdCache_;
  std::deque<std::shared_ptr<UDPTrackerRequest> > inflightRequests_;
  std::deque<std::shared_ptr<UDPTrackerRequest> > pendingRequests_;
  std::deque<std::shared_ptr<UDPTrackerRequest> > connectRequests_;
  int numWatchers_;
};

ssize_t createUDPTrackerConnect
(unsigned char* data, size_t length, std::string& remoteAddr,
 uint16_t& remotePort, const std::shared_ptr<UDPTrackerRequest>& req);

ssize_t createUDPTrackerAnnounce
(unsigned char* data, size_t length, std::string& remoteAddr,
 uint16_t& remotePort, const std::shared_ptr<UDPTrackerRequest>& req);

const char* getUDPTrackerActionStr(int action);

const char* getUDPTrackerEventStr(int event);

} // namespace aria2

#endif // D_UDP_TRACKER_CLIENT_H