/* Copyright (C) 2014 InfiniDB, Inc.

   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; version 2 of
   the License.

   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. */

/******************************************************************************
 * $Id$
 *
 *****************************************************************************/

/** @file umsocketselector.h
 * Used in selecting the "next" socket/port when sending a response message
 * to a UM module.  UmSocketSelector is the public API class.  UmModuleIPs
 * is a supporting class of UmSocketSelector, and UmIPSocketConns is in turn
 * a supporting class of UmModuleIPs.
 */

#pragma once

#include <netinet/in.h>
#include <list>
#include <map>
#include <sstream>
#include <string>
#include <utility>
#include <vector>
#include <boost/shared_ptr.hpp>
#include <boost/thread.hpp>

#include "iosocket.h"

namespace primitiveprocessor
{
class UmModuleIPs;
class UmIPSocketConns;

typedef boost::shared_ptr<UmModuleIPs> SP_UM_MODIPS;
typedef boost::shared_ptr<UmIPSocketConns> SP_UM_IPCONNS;
typedef boost::shared_ptr<messageqcpp::IOSocket> SP_UM_IOSOCK;
typedef boost::shared_ptr<boost::mutex> SP_UM_MUTEX;

//------------------------------------------------------------------------------
/** @brief Public API class used to track and select socket for outgoing msgs.
 *
 * This class maintains a list of UM's and the corresponding IP addresses for
 * each UM.  In addition, a list of socket/port connections are maintained for
 * each IP addresss.  nextIOSocket() can be used to iterate through all the IP
 * addresses and socket/port connections for a given UM, as response messages
 * are sent to the UM.  This action attempts to see that the output network
 * traffic is evenly distributed among all the NIC's for a UM.
 *
 * This class is not entirely thread-safe, as the first call to instance() must
 * be made from a single threaded envirionment as part of initialization. After
 * that, the class is thread-safe through the use of a mutex in UmModuleIPs.
 */
//------------------------------------------------------------------------------
class UmSocketSelector
{
 public:
  typedef std::map<in_addr_t, unsigned int> IpAddressUmMap_t;

  /** @brief Singleton accessor to UmSocketSelector instance.
   *
   * This method should be called once from the main thread to perform
   * initialization from a single threaded environment.
   */
  static UmSocketSelector* instance();

  /** @brief UmSocketSelector destructor
   *
   */
  ~UmSocketSelector() = default;

  /** @brief Accessor to total number of UM IP's in Columnstore.xml.
   *
   * @return Number of UM IP addresses read from Columnstore.xml.
   */
  uint32_t ipAddressCount() const;

  /** @brief Add a socket/port connection to the connection list.
   *
   * @param ios (in) socket/port connection to be added.
   * @param writeLock (in) mutex to use when writing to ios.
   * @return boolean indicating if socket/port connection was added.
   */
  bool addConnection(const SP_UM_IOSOCK& ios, const SP_UM_MUTEX& writeLock);

  /** @brief Delete a socket/port connection from the connection list.
   *
   * @param ios (in) socket/port connection to be removed.
   */
  void delConnection(const messageqcpp::IOSocket& ios);

  /** @brief Get the next output IOSocket to use for the specified ios.
   *
   * @param ios (in) socket/port connection for the incoming message.
   * @param outIos (out) socket/port connection to use for the response.
   * @param writeLock (out) mutex to use when writing to outIos.
   * @return boolean indicating if operation was successful.
   */
  bool nextIOSocket(const messageqcpp::IOSocket& ios, SP_UM_IOSOCK& outIos, SP_UM_MUTEX& writeLock);

  /** @brief toString method used in logging, debugging, etc.
   *
   */
  const std::string toString() const;

 private:
  //...Disable default copy constructor and assignment operator by
  //   declaring but not defining
  UmSocketSelector(const UmSocketSelector& rhs);
  UmSocketSelector& operator=(const UmSocketSelector& rhs);

  UmSocketSelector();
  void loadUMModuleInfo();
  unsigned int findOrAddUm(const std::string& moduleName);

  static UmSocketSelector* fpUmSocketSelector;
  std::vector<SP_UM_MODIPS> fUmModuleIPs;  // UM's and their sockets

  // std::map that maps an IP address to an index into fUmModuleIPs
  IpAddressUmMap_t fIpAddressUmMap;
};

//------------------------------------------------------------------------------
/** @brief Tracks and selects "next" socket/port for a UM module.
 *
 * This is a supporting class to UmSocketSelector.
 * This class maintains a list of IP addresses (and their corrresponding
 * socket/port connections) for a specific UM module.  UmModuleIPs can
 * be used to iterate through the available IP addresses (and socket/port
 * connections) for a UM module, as response messages are sent out by PrimProc.
 *
 * This class is thread-safe.
 */
//------------------------------------------------------------------------------
class UmModuleIPs
{
 public:
  /** @brief UmModuleIPs constructor.
   *
   * @param moduleName (in) UM module name for this UmModuleIPs object.
   */
  explicit UmModuleIPs(std::string moduleName)
   : fUmModuleName(std::move(moduleName)), fNextUmIPSocketIdx(NEXT_IP_SOCKET_UNASSIGNED)
  {
  }

  /** @brief UmModuleIPs destructor.
   *
   */
  ~UmModuleIPs() = default;

  /** @brief Accessor to number of IP's from Columnstore.xml for this UM.
   *
   * @return Number of IP addresses read from Columnstore.xml for this UM.
   */
  uint32_t ipAddressCount() const
  {
    return fUmIPSocketConns.size();
  }

  /** @brief Accessor to the module name for this UmModuleIPs object.
   *
   * @return UM module name.
   */
  const std::string& moduleName() const
  {
    return fUmModuleName;
  }

  /** @brief Add an IP address to this UM module.
   *
   * @param ip (in) IP address to be added (in network byte order)
   */
  void addIP(in_addr_t ip);

  /** @brief Add specified socket/port to the connection list for this UM.
   *
   * @param ioSock (in) socket/port to add to the connection list.
   * @param writeLock (in) mutex to use when writing to ioSock.
   * @return boolean indicating if socket/port connection was added.
   */
  bool addSocketConn(const SP_UM_IOSOCK& ioSock, const SP_UM_MUTEX& writeLock);

  /** @brief Delete specified socket/port from the connection list.
   *
   * @param ioSock (in) socket/port to delete from the connection list.
   */
  void delSocketConn(const messageqcpp::IOSocket& ioSock);

  /** @brief Get the "next" available socket/port for this UM module.
   *
   * @param outIos (out) socket/port connection to use for the response.
   * @param writeLock (out) mutex to use when writing to outIos.
   * @return bool flag indicating whether a socket/port was available.
   */
  bool nextIOSocket(SP_UM_IOSOCK& outIos, SP_UM_MUTEX& writeLock);

  /** @brief toString method used in logging, debugging, etc.
   *
   */
  const std::string toString();

 private:
  void advanceToNextIP();

  static const int32_t NEXT_IP_SOCKET_UNASSIGNED;
  std::string fUmModuleName;   // UM module name
  int32_t fNextUmIPSocketIdx;  // index to "next" IP address
  boost::mutex fUmModuleMutex;

  // collection of IP addresses and their corresponding socket/port conns
  std::vector<SP_UM_IPCONNS> fUmIPSocketConns;
};

//------------------------------------------------------------------------------
/** @brief Tracks and selects "next" socket/port for a UM module IP address.
 *
 * This is a supporting class to UmModuleIPs.
 * This class maintains a list of socket/port connections for a specific UM
 * module IP address.  UmIPSocketConns can be used to iterate through the
 * available connections for an IP address, as response messages are sent out
 * by PrimProc.
 *
 * This class by itself is not thread-safe.  However, UmModulesIPs, which
 * uses UmIPSocketConns, insures thread-safeness.
 */
//------------------------------------------------------------------------------
class UmIPSocketConns
{
 public:
  struct UmIOSocketData
  {
    SP_UM_IOSOCK fSock;  // an output IOSocket
    SP_UM_MUTEX fMutex;  // mutex to be use when writing to fSock
  };

  /** @brief UmIPSocketConns constructor.
   *
   * @param ip (in) IP address for this UmIPSocketConns object.
   */
  explicit UmIPSocketConns(in_addr_t ip) : fIpAddress(ip), fNextIOSocketIdx(NEXT_IOSOCKET_UNASSIGNED)
  {
  }

  /** @brief UmIPSocketConns destructor.
   *
   */
  ~UmIPSocketConns() = default;

  /** @brief Accessor to the IP address for this UmIPSocketConns object.
   *
   * @return IP address (in network byte order).
   */
  in_addr_t ipAddress() const
  {
    return fIpAddress;
  }

  /** @brief Accessor to socket/port connection count for this IP address.
   *
   * @return socket/port connection count.
   */
  uint32_t count()
  {
    return fIOSockets.size();
  }

  /** @brief Add specified socket/port to the connection list.
   *
   * @param ioSock (in) socket/port to add to the connection list.
   * @param writeLock (in) mutex to use when writing to ioSock.
   */
  void addSocketConn(const SP_UM_IOSOCK& ioSock, const SP_UM_MUTEX& writeLock);

  /** @brief Delete specified socket/port from the connection list.
   *
   * @param ioSock (in) socket/port to delete from the connection list.
   */
  void delSocketConn(const messageqcpp::IOSocket& ioSock);

  /** @brief Get the "next" available socket/port for this IP address.
   *
   * @param outIos (out) socket/port connection to use for the response.
   * @param writeLock (out) mutex to use when writing to outIos.
   */
  void nextIOSocket(SP_UM_IOSOCK& outIos, SP_UM_MUTEX& writeLock);

  /** @brief Convert network byte ordered IP address to string
   *
   * @param ipString (out) IP address string;
   *  ipString must be an array of size INET_ADDRSTRLEN.
   * @return IP address string (same as ipString)
   */
  static char* nwToString(in_addr_t addr, char* ipString);

  /** @brief toString method used in logging, debugging, etc.
   *
   */
  const std::string toString() const;

 private:
  static const int32_t NEXT_IOSOCKET_UNASSIGNED;
  in_addr_t fIpAddress;                    // IP address in network byte order
  int32_t fNextIOSocketIdx;                // index to "next" socket/port
  std::vector<UmIOSocketData> fIOSockets;  // socket/port list for fIpAddress
};

}  // namespace primitiveprocessor