/*
 * libjingle
 * Copyright 2004--2005, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef TALK_BASE_VIRTUALSOCKETSERVER_H_
#define TALK_BASE_VIRTUALSOCKETSERVER_H_

#include <cassert>
#include <deque>
#include <map>

#include "talk/base/messagequeue.h"
#include "talk/base/socketserver.h"

namespace talk_base {

class VirtualSocket;
class SocketAddressPair;

// Simulates a network in the same manner as a loopback interface.  The
// interface can create as many addresses as you want.  All of the sockets
// created by this network will be able to communicate with one another.
class VirtualSocketServer : public SocketServer, public sigslot::has_slots<> {
 public:
  // TODO: Add "owned" parameter.
  // If "owned" is set, the supplied socketserver will be deleted later.
  explicit VirtualSocketServer(SocketServer* ss);
  virtual ~VirtualSocketServer();

  SocketServer* socketserver() { return server_; }

  // Limits the network bandwidth (maximum bytes per second).  Zero means that
  // all sends occur instantly.  Defaults to 0.
  uint32 bandwidth() const { return bandwidth_; }
  void set_bandwidth(uint32 bandwidth) { bandwidth_ = bandwidth; }

  // Limits the amount of data which can be in flight on the network without
  // packet loss (on a per sender basis).  Defaults to 64 KB.
  uint32 network_capacity() const { return network_capacity_; }
  void set_network_capacity(uint32 capacity) {
    network_capacity_ = capacity;
  }

  // The amount of data which can be buffered by tcp on the sender's side
  uint32 send_buffer_capacity() const { return send_buffer_capacity_; }
  void set_send_buffer_capacity(uint32 capacity) {
    send_buffer_capacity_ = capacity;
  }

  // The amount of data which can be buffered by tcp on the receiver's side
  uint32 recv_buffer_capacity() const { return recv_buffer_capacity_; }
  void set_recv_buffer_capacity(uint32 capacity) {
    recv_buffer_capacity_ = capacity;
  }

  // Controls the (transit) delay for packets sent in the network.  This does
  // not inclue the time required to sit in the send queue.  Both of these
  // values are measured in milliseconds.  Defaults to no delay.
  uint32 delay_mean() const { return delay_mean_; }
  uint32 delay_stddev() const { return delay_stddev_; }
  uint32 delay_samples() const { return delay_samples_; }
  void set_delay_mean(uint32 delay_mean) { delay_mean_ = delay_mean; }
  void set_delay_stddev(uint32 delay_stddev) {
    delay_stddev_ = delay_stddev;
  }
  void set_delay_samples(uint32 delay_samples) {
    delay_samples_ = delay_samples;
  }

  // If the (transit) delay parameters are modified, this method should be
  // called to recompute the new distribution.
  void UpdateDelayDistribution();

  // Controls the (uniform) probability that any sent packet is dropped.  This
  // is separate from calculations to drop based on queue size.
  double drop_probability() { return drop_prob_; }
  void set_drop_probability(double drop_prob) {
    assert((0 <= drop_prob) && (drop_prob <= 1));
    drop_prob_ = drop_prob;
  }

  // SocketFactory:
  virtual Socket* CreateSocket(int type);
  virtual AsyncSocket* CreateAsyncSocket(int type);

  // SocketServer:
  virtual void SetMessageQueue(MessageQueue* queue);
  virtual bool Wait(int cms, bool process_io);
  virtual void WakeUp();

  typedef std::pair<double, double> Point;
  typedef std::vector<Point> Function;

  static Function* CreateDistribution(uint32 mean, uint32 stddev,
                                      uint32 samples);

  // Similar to Thread::ProcessMessages, but it only processes messages until
  // there are no immediate messages or pending network traffic.  Returns false
  // if Thread::Stop() was called.
  bool ProcessMessagesUntilIdle();

 protected:
  // Returns a new IP not used before in this network.
  uint32 GetNextIP();
  uint16 GetNextPort();

  VirtualSocket* CreateSocketInternal(int type);

  // Binds the given socket to addr, assigning and IP and Port if necessary
  int Bind(VirtualSocket* socket, SocketAddress* addr);

  // Binds the given socket to the given (fully-defined) address.
  int Bind(VirtualSocket* socket, const SocketAddress& addr);

  // Find the socket bound to the given address
  VirtualSocket* LookupBinding(const SocketAddress& addr);

  int Unbind(const SocketAddress& addr, VirtualSocket* socket);

  // Adds a mapping between this socket pair and the socket.
  void AddConnection(const SocketAddress& client,
                     const SocketAddress& server,
                     VirtualSocket* socket);

  // Find the socket pair corresponding to this server address.
  VirtualSocket* LookupConnection(const SocketAddress& client,
                                  const SocketAddress& server);

  void RemoveConnection(const SocketAddress& client,
                        const SocketAddress& server);

  // Connects the given socket to the socket at the given address
  int Connect(VirtualSocket* socket, const SocketAddress& remote_addr,
              bool use_delay);

  // Sends a disconnect message to the socket at the given address
  bool Disconnect(VirtualSocket* socket);

  // Sends the given packet to the socket at the given address (if one exists).
  int SendUdp(VirtualSocket* socket, const char* data, size_t data_size,
              const SocketAddress& remote_addr);

  // Moves as much data as possible from the sender's buffer to the network
  void SendTcp(VirtualSocket* socket);

  // Places a packet on the network.
  void AddPacketToNetwork(VirtualSocket* socket, VirtualSocket* recipient,
                          uint32 cur_time, const char* data, size_t data_size,
                          size_t header_size, bool ordered);

  // Removes stale packets from the network
  void PurgeNetworkPackets(VirtualSocket* socket, uint32 cur_time);

  // Computes the number of milliseconds required to send a packet of this size.
  uint32 SendDelay(uint32 size);

  // Returns a random transit delay chosen from the appropriate distribution.
  uint32 GetRandomTransitDelay();

  // Basic operations on functions.  Those that return a function also take
  // ownership of the function given (and hence, may modify or delete it).
  static Function* Accumulate(Function* f);
  static Function* Invert(Function* f);
  static Function* Resample(Function* f, double x1, double x2, uint32 samples);
  static double Evaluate(Function* f, double x);

  // NULL out our message queue if it goes away. Necessary in the case where
  // our lifetime is greater than that of the thread we are using, since we
  // try to send Close messages for all connected sockets when we shutdown.
  void OnMessageQueueDestroyed() { msg_queue_ = NULL; }

 private:
  friend class VirtualSocket;

  typedef std::map<SocketAddress, VirtualSocket*> AddressMap;
  typedef std::map<SocketAddressPair, VirtualSocket*> ConnectionMap;

  SocketServer* server_;
  bool server_owned_;
  MessageQueue* msg_queue_;
  bool stop_on_idle_;
  uint32 network_delay_;
  uint32 next_ip_;
  uint16 next_port_;
  AddressMap* bindings_;
  ConnectionMap* connections_;

  uint32 bandwidth_;
  uint32 network_capacity_;
  uint32 send_buffer_capacity_;
  uint32 recv_buffer_capacity_;
  uint32 delay_mean_;
  uint32 delay_stddev_;
  uint32 delay_samples_;
  Function* delay_dist_;
  CriticalSection delay_crit_;

  double drop_prob_;
  DISALLOW_EVIL_CONSTRUCTORS(VirtualSocketServer);
};

}  // namespace talk_base

#endif  // TALK_BASE_VIRTUALSOCKETSERVER_H_