/*
 * 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;
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 */

#ifndef TALK_P2P_BASE_SESSION_H_
#define TALK_P2P_BASE_SESSION_H_

#include <list>
#include <map>
#include <string>
#include <vector>

#include "talk/p2p/base/sessionmessages.h"
#include "talk/p2p/base/sessionmanager.h"
#include "talk/base/socketaddress.h"
#include "talk/p2p/base/sessionclient.h"
#include "talk/p2p/base/parsing.h"
#include "talk/p2p/base/port.h"
#include "talk/xmllite/xmlelement.h"
#include "talk/xmpp/constants.h"

namespace cricket {

class P2PTransportChannel;
class Transport;
class TransportChannel;
class TransportChannelProxy;
class TransportChannelImpl;

// Used for errors that will send back a specific error message to the
// remote peer.  We add "type" to the errors because it's needed for
// SignalErrorMessage.
struct MessageError : ParseError {
  buzz::QName type;

  // if unset, assume type is a parse error
  MessageError() : ParseError(), type(buzz::QN_STANZA_BAD_REQUEST) {}

  void SetType(const buzz::QName type) {
    this->type = type;
  }
};

// Used for errors that may be returned by public session methods that
// can fail.
// TODO: Use this error in Session::Initiate and
// Session::Accept.
struct SessionError : WriteError {
};

// Bundles a Transport and ChannelMap together. ChannelMap is used to
// create transport channels before receiving or sending a session
// initiate, and for speculatively connecting channels.  Previously, a
// session had one ChannelMap and transport.  Now, with multiple
// transports per session, we need multiple ChannelMaps as well.
class TransportProxy {
 public:
  TransportProxy(const std::string& content_name, Transport* transport)
      : content_name_(content_name),
        transport_(transport),
        state_(STATE_INIT),
        sent_candidates_(false) {}
  ~TransportProxy();

  std::string content_name() const { return content_name_; }
  Transport* impl() const { return transport_; }
  std::string type() const;
  bool negotiated() const { return state_ == STATE_NEGOTIATED; }
  const Candidates& sent_candidates() const { return sent_candidates_; }

  TransportChannel* GetChannel(const std::string& name);
  TransportChannel* CreateChannel(const std::string& name,
                                  const std::string& content_type);
  void DestroyChannel(const std::string& name);
  void AddSentCandidates(const Candidates& candidates);
  void ClearSentCandidates() { sent_candidates_.clear(); }
  void SpeculativelyConnectChannels();
  void CompleteNegotiation();

 private:
  enum TransportState {
    STATE_INIT,
    STATE_CONNECTING,
    STATE_NEGOTIATED
  };

  typedef std::map<std::string, TransportChannelProxy*> ChannelMap;

  TransportChannelProxy* GetProxy(const std::string& name);
  TransportChannelImpl* GetOrCreateImpl(const std::string& name,
                                        const std::string& content_type);
  void SetProxyImpl(const std::string& name, TransportChannelProxy* proxy);

  std::string content_name_;
  Transport* transport_;
  TransportState state_;
  ChannelMap channels_;
  Candidates sent_candidates_;
};

typedef std::map<std::string, TransportProxy*> TransportMap;

// TODO: Consider simplifying the dependency from Voice/VideoChannel
// on Session. Right now the Channel class requires a BaseSession, but it only
// uses CreateChannel/DestroyChannel. Perhaps something like a
// TransportChannelFactory could be hoisted up out of BaseSession, or maybe
// the transports could be passed in directly.

// A BaseSession manages general session state. This includes negotiation
// of both the application-level and network-level protocols:  the former
// defines what will be sent and the latter defines how it will be sent.  Each
// network-level protocol is represented by a Transport object.  Each Transport
// participates in the network-level negotiation.  The individual streams of
// packets are represented by TransportChannels.  The application-level protocol
// is represented by SessionDecription objects.
class BaseSession : public sigslot::has_slots<>,
                    public talk_base::MessageHandler {
 public:
  enum State {
    STATE_INIT = 0,
    STATE_SENTINITIATE,       // sent initiate, waiting for Accept or Reject
    STATE_RECEIVEDINITIATE,   // received an initiate. Call Accept or Reject
    STATE_SENTACCEPT,         // sent accept. begin connecting transport
    STATE_RECEIVEDACCEPT,     // received accept. begin connecting transport
    STATE_SENTMODIFY,         // sent modify, waiting for Accept or Reject
    STATE_RECEIVEDMODIFY,     // received modify, call Accept or Reject
    STATE_SENTREJECT,         // sent reject after receiving initiate
    STATE_RECEIVEDREJECT,     // received reject after sending initiate
    STATE_SENTREDIRECT,       // sent direct after receiving initiate
    STATE_SENTTERMINATE,      // sent terminate (any time / either side)
    STATE_RECEIVEDTERMINATE,  // received terminate (any time / either side)
    STATE_INPROGRESS,         // session accepted and in progress
    STATE_DEINIT,             // session is being destroyed
  };

  enum Error {
    ERROR_NONE = 0,      // no error
    ERROR_TIME = 1,      // no response to signaling
    ERROR_RESPONSE = 2,  // error during signaling
    ERROR_NETWORK = 3,   // network error, could not allocate network resources
    ERROR_CONTENT = 4,   // channel errors in SetLocalContent/SetRemoteContent
  };

  explicit BaseSession(talk_base::Thread *signaling_thread);
  virtual ~BaseSession();

  // Updates the state, signaling if necessary.
  void SetState(State state);

  // Updates the error state, signaling if necessary.
  virtual void SetError(Error error);

  // Handles messages posted to us.
  virtual void OnMessage(talk_base::Message *pmsg);

  // Returns the current state of the session.  See the enum above for details.
  // Each time the state changes, we will fire this signal.
  State state() const { return state_; }
  sigslot::signal2<BaseSession *, State> SignalState;

  // Returns the last error in the session.  See the enum above for details.
  // Each time the an error occurs, we will fire this signal.
  Error error() const { return error_; }
  sigslot::signal2<BaseSession *, Error> SignalError;

  sigslot::signal1<TransportChannel*> SignalWritableState;
  sigslot::signal3<TransportChannel*, const char*, size_t> SignalReadPacket;


  // Creates a new channel with the given names.  This method may be called
  // immediately after creating the session.  However, the actual
  // implementation may not be fixed until transport negotiation completes.
  // This will usually be called from the worker thread, but that
  // shouldn't be an issue since the main thread will be blocked in
  // Send when doing so.
  virtual TransportChannel* CreateChannel(const std::string& content_name,
                                          const std::string& channel_name) = 0;

  // Returns the channel with the given names.
  virtual TransportChannel* GetChannel(const std::string& content_name,
                                       const std::string& channel_name) = 0;

  // Destroys the channel with the given names.
  // This will usually be called from the worker thread, but that
  // shouldn't be an issue since the main thread will be blocked in
  // Send when doing so.
  virtual void DestroyChannel(const std::string& content_name,
                              const std::string& channel_name) = 0;

  // Invoked when we notice that there is no matching channel on our peer.
  sigslot::signal2<Session*, const std::string&> SignalChannelGone;

  // Returns the application-level description given by our client.
  // If we are the recipient, this will be NULL until we send an accept.
  const SessionDescription* local_description() const {
    return local_description_;
  }
  // Takes ownership of SessionDescription*
  bool set_local_description(const SessionDescription* sdesc) {
    if (sdesc != local_description_) {
      delete local_description_;
      local_description_ = sdesc;
    }
    return true;
  }

  // Returns the application-level description given by the other client.
  // If we are the initiator, this will be NULL until we receive an accept.
  const SessionDescription* remote_description() const {
    return remote_description_;
  }
  // Takes ownership of SessionDescription*
  bool set_remote_description(const SessionDescription* sdesc) {
    if (sdesc != remote_description_) {
      delete remote_description_;
      remote_description_ = sdesc;
    }
    return true;
  }

  // When we receive an initiate, we create a session in the
  // RECEIVEDINITIATE state and respond by accepting or rejecting.
  // Takes ownership of session description.
  virtual bool Accept(const SessionDescription* sdesc) = 0;
  virtual bool Reject(const std::string& reason) = 0;
  bool Terminate() {
    return TerminateWithReason(STR_TERMINATE_SUCCESS);
  }
  virtual bool TerminateWithReason(const std::string& reason) = 0;

  // The worker thread used by the session manager
  virtual talk_base::Thread *worker_thread() = 0;

  talk_base::Thread *signaling_thread() {
    return signaling_thread_;
  }

  // Returns the JID of this client.
  const std::string& local_name() const { return local_name_; }

  // Returns the JID of the other peer in this session.
  const std::string& remote_name() const { return remote_name_; }

  // Set the JID of the other peer in this session.
  // Typically the remote_name_ is set when the session is initiated.
  // However, sometimes (e.g when a proxy is used) the peer name is
  // known after the BaseSession has been initiated and it must be updated
  // explicitly.
  void set_remote_name(const std::string& name) { remote_name_ = name; }

  const std::string& id() const { return sid_; }

 protected:
  State state_;
  Error error_;
  const SessionDescription* local_description_;
  const SessionDescription* remote_description_;
  std::string sid_;
  // We don't use buzz::Jid because changing to buzz:Jid here has a
  // cascading effect that requires an enormous number places to
  // change to buzz::Jid as well.
  std::string local_name_;
  std::string remote_name_;
  talk_base::Thread *signaling_thread_;
};

// A specific Session created by the SessionManager, using XMPP for protocol.
class Session : public BaseSession {
 public:
  // Returns the manager that created and owns this session.
  SessionManager* session_manager() const { return session_manager_; }

  // the worker thread used by the session manager
  talk_base::Thread *worker_thread() {
    return session_manager_->worker_thread();
  }

  // Returns the XML namespace identifying the type of this session.
  const std::string& content_type() const { return content_type_; }

  // Returns the client that is handling the application data of this session.
  SessionClient* client() const { return client_; }

  SignalingProtocol current_protocol() const { return current_protocol_; }

  void set_current_protocol(SignalingProtocol protocol) {
    current_protocol_ = protocol;
  }

  // Indicates whether we initiated this session.
  bool initiator() const { return initiator_; }

  const SessionDescription* initiator_description() const {
    if (initiator_) {
      return local_description_;
    } else {
      return remote_description_;
    }
  }

  // Fired whenever we receive a terminate message along with a reason
  sigslot::signal2<Session*, const std::string&> SignalReceivedTerminateReason;

  void set_allow_local_ips(bool allow);

  // Returns the transport that has been negotiated or NULL if
  // negotiation is still in progress.
  Transport* GetTransport(const std::string& content_name);

  // Takes ownership of session description.
  // TODO: Add an error argument to pass back to the caller.
  bool Initiate(const std::string& to,
                const SessionDescription* sdesc);

  // When we receive an initiate, we create a session in the
  // RECEIVEDINITIATE state and respond by accepting or rejecting.
  // Takes ownership of session description.
  // TODO: Add an error argument to pass back to the caller.
  virtual bool Accept(const SessionDescription* sdesc);
  virtual bool Reject(const std::string& reason);
  virtual bool TerminateWithReason(const std::string& reason);

  // The two clients in the session may also send one another
  // arbitrary XML messages, which are called "info" messages. Sending
  // takes ownership of the given elements.  The signal does not; the
  // parent element will be deleted after the signal.
  bool SendInfoMessage(const XmlElements& elems);
  sigslot::signal2<Session*, const buzz::XmlElement*> SignalInfoMessage;

  // Maps passed to serialization functions.
  TransportParserMap GetTransportParsers();
  ContentParserMap GetContentParsers();

  // Creates a new channel with the given names.  This method may be called
  // immediately after creating the session.  However, the actual
  // implementation may not be fixed until transport negotiation completes.
  virtual TransportChannel* CreateChannel(const std::string& content_name,
                                          const std::string& channel_name);

  // Returns the channel with the given names.
  virtual TransportChannel* GetChannel(const std::string& content_name,
                                       const std::string& channel_name);

  // Destroys the channel with the given names.
  virtual void DestroyChannel(const std::string& content_name,
                              const std::string& channel_name);

  // Updates the error state, signaling if necessary.
  virtual void SetError(Error error);

  // Handles messages posted to us.
  virtual void OnMessage(talk_base::Message *pmsg);

 private:
  // Creates or destroys a session.  (These are called only SessionManager.)
  Session(SessionManager *session_manager,
          const std::string& local_name, const std::string& initiator_name,
          const std::string& sid, const std::string& content_type,
          SessionClient* client);
  ~Session();

  // Get a TransportProxy by content_name or transport. NULL if not found.
  TransportProxy* GetTransportProxy(const std::string& content_name);
  TransportProxy* GetTransportProxy(const Transport* transport);
  TransportProxy* GetFirstTransportProxy();
  // TransportProxy is owned by session.  Return proxy just for convenience.
  TransportProxy* GetOrCreateTransportProxy(const std::string& content_name);
  // For each transport info, create a transport proxy.  Can fail for
  // incompatible transport types.
  bool CreateTransportProxies(const TransportInfos& tinfos,
                              SessionError* error);
  void SpeculativelyConnectAllTransportChannels();
  bool OnRemoteCandidates(const TransportInfos& tinfos,
                          ParseError* error);
  // Returns a TransportInfo without candidates for each content name.
  // Uses the transport_type_ of the session.
  TransportInfos GetEmptyTransportInfos(const ContentInfos& contents) const;

  // Called when the first channel of a transport begins connecting.  We use
  // this to start a timer, to make sure that the connection completes in a
  // reasonable amount of time.
  void OnTransportConnecting(Transport* transport);

  // Called when a transport changes its writable state.  We track this to make
  // sure that the transport becomes writable within a reasonable amount of
  // time.  If this does not occur, we signal an error.
  void OnTransportWritable(Transport* transport);

  // Called when a transport requests signaling.
  void OnTransportRequestSignaling(Transport* transport);

  // Called when a transport signals that it has a message to send.   Note that
  // these messages are just the transport part of the stanza; they need to be
  // wrapped in the appropriate session tags.
  void OnTransportCandidatesReady(Transport* transport,
                                  const Candidates& candidates);

  // Called when a transport signals that it found an error in an incoming
  // message.
  void OnTransportSendError(Transport* transport,
                            const buzz::XmlElement* stanza,
                            const buzz::QName& name,
                            const std::string& type,
                            const std::string& text,
                            const buzz::XmlElement* extra_info);

  // Called when we notice that one of our local channels has no peer, so it
  // should be destroyed.
  void OnTransportChannelGone(Transport* transport, const std::string& name);

  // When the session needs to send signaling messages, it beings by requesting
  // signaling.  The client should handle this by calling OnSignalingReady once
  // it is ready to send the messages.
  // (These are called only by SessionManager.)
  sigslot::signal1<Session*> SignalRequestSignaling;
  void OnSignalingReady();

  // Send various kinds of session messages.
  bool SendInitiateMessage(const SessionDescription* sdesc,
                           SessionError* error);
  bool SendAcceptMessage(const SessionDescription* sdesc, SessionError* error);
  bool SendRejectMessage(const std::string& reason, SessionError* error);
  bool SendTerminateMessage(const std::string& reason, SessionError* error);
  bool SendTransportInfoMessage(const TransportInfo& tinfo,
                                SessionError* error);
  bool ResendAllTransportInfoMessages(SessionError* error);

  // Both versions of SendMessage send a message of the given type to
  // the other client.  Can pass either a set of elements or an
  // "action", which must have a WriteSessionAction method to go along
  // with it.  Sending with an action supports sending a "hybrid"
  // message.  Sending with elements must be sent as Jingle or Gingle.

  // When passing elems, must be either Jingle or Gingle protocol.
  // Takes ownership of action_elems.
  bool SendMessage(ActionType type, const XmlElements& action_elems,
                   SessionError* error);
  // When passing an action, may be Hybrid protocol.
  template <typename Action>
  bool SendMessage(ActionType type, const Action& action,
                   SessionError* error);

  // Helper methods to write the session message stanza.
  template <typename Action>
  bool WriteActionMessage(ActionType type, const Action& action,
                          buzz::XmlElement* stanza, WriteError* error);
  template <typename Action>
  bool WriteActionMessage(SignalingProtocol protocol,
                          ActionType type, const Action& action,
                          buzz::XmlElement* stanza, WriteError* error);

  // Sending messages in hybrid form requires being able to write them
  // on a per-protocol basis with a common method signature, which all
  // of these have.
  bool WriteSessionAction(SignalingProtocol protocol,
                          const SessionInitiate& init,
                          XmlElements* elems, WriteError* error);
  bool WriteSessionAction(SignalingProtocol protocol,
                          const TransportInfo& tinfo,
                          XmlElements* elems, WriteError* error);
  bool WriteSessionAction(SignalingProtocol protocol,
                          const SessionTerminate& term,
                          XmlElements* elems, WriteError* error);

  // Sends a message back to the other client indicating that we have received
  // and accepted their message.
  void SendAcknowledgementMessage(const buzz::XmlElement* stanza);

  // Once signaling is ready, the session will use this signal to request the
  // sending of each message.  When messages are received by the other client,
  // they should be handed to OnIncomingMessage.
  // (These are called only by SessionManager.)
  sigslot::signal2<Session *, const buzz::XmlElement*> SignalOutgoingMessage;
  void OnIncomingMessage(const SessionMessage& msg);

  void OnFailedSend(const buzz::XmlElement* orig_stanza,
                    const buzz::XmlElement* error_stanza);

  // Invoked when an error is found in an incoming message.  This is translated
  // into the appropriate XMPP response by SessionManager.
  sigslot::signal6<BaseSession*,
                   const buzz::XmlElement*,
                   const buzz::QName&,
                   const std::string&,
                   const std::string&,
                   const buzz::XmlElement*> SignalErrorMessage;

  // Handlers for the various types of messages.  These functions may take
  // pointers to the whole stanza or to just the session element.
  bool OnInitiateMessage(const SessionMessage& msg, MessageError* error);
  bool OnAcceptMessage(const SessionMessage& msg, MessageError* error);
  bool OnRejectMessage(const SessionMessage& msg, MessageError* error);
  bool OnInfoMessage(const SessionMessage& msg);
  bool OnTerminateMessage(const SessionMessage& msg, MessageError* error);
  bool OnTransportInfoMessage(const SessionMessage& msg, MessageError* error);
  bool OnTransportAcceptMessage(const SessionMessage& msg, MessageError* error);
  bool OnUpdateMessage(const SessionMessage& msg, MessageError* error);
  bool OnRedirectError(const SessionRedirect& redirect, SessionError* error);

  // Verifies that we are in the appropriate state to receive this message.
  bool CheckState(State state, MessageError* error);

  SessionManager *session_manager_;
  bool initiator_;
  std::string initiator_name_;
  std::string content_type_;
  SessionClient* client_;
  std::string transport_type_;
  TransportParser* transport_parser_;
  // This is transport-specific but required so much by unit tests
  // that it's much easier to put it here.
  bool allow_local_ips_;
  TransportMap transports_;
  // Keeps track of what protocol we are speaking.
  SignalingProtocol current_protocol_;

  friend class SessionManager;  // For access to constructor, destructor,
                                // and signaling related methods.
};

}  // namespace cricket

#endif  // TALK_P2P_BASE_SESSION_H_