// ------------------------------------------------------------------------
// eca-neteci-server.c: NetECI server implementation.
// Copyright (C) 2002,2004,2009 Kai Vehmanen
//
// Attributes:
//     eca-style-version: 3
//
// 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
// ------------------------------------------------------------------------

#include <cassert>
#include <cstring>        /* memcpy() */
#include <iostream>
#include <string>

#include <fcntl.h>        /* POSIX: fcntl() */
#include <pthread.h>      /* POSIX: pthread_* */
#include <unistd.h>       /* POSIX: fcntl() */
#include <arpa/inet.h>    /* BSD: inet_ntoa() */
#include <netinet/in.h>   /* BSD: inet_ntoa() */
#include <sys/poll.h>     /* POSIX: poll() */
#include <sys/socket.h>   /* BSD: getpeername() */
#include <sys/types.h>    /* OSX: u_int32_t (INADDR_ANY) */

#include <kvu_dbc.h>
#include <kvu_fd_io.h>
#include <kvu_numtostr.h>
#include <kvu_utils.h>

#include <eca-control-mt.h>
#include <eca-logger.h>
#include <eca-logger-wellformed.h>

#include "ecasound.h"
#include "eca-neteci-server.h"

/** 
 * Options
 */
// #define NETECI_DEBUG_ENABLED

#define ECA_NETECI_START_BUFFER_SIZE    128
#define ECA_NETECI_MAX_BUFFER_SIZE      65536

/**
 * Macro definitions
 */

#ifdef NETECI_DEBUG_ENABLED
#define NETECI_DEBUG(x) x
#else
#define NETECI_DEBUG(x) ((void) 0)
#endif

/** 
 * Import namespaces
 */

using namespace std;

ECA_NETECI_SERVER::ECA_NETECI_SERVER(ECASOUND_RUN_STATE* state)
  : state_repp(state),
    srvfd_rep(-1),
    server_listening_rep(false),
    unix_sockets_rep(false),
    cleanup_request_rep(false)
{
}

ECA_NETECI_SERVER::~ECA_NETECI_SERVER(void)
{
  if (server_listening_rep == true) {
    close_server_socket();
  }
}

/**
 * Launches the server thread.
 *
 * @param arg pointer to a ECA_NETECI_SERVER object
 */
void* ECA_NETECI_SERVER::launch_server_thread(void* arg)
{
  ECA_LOG_MSG(ECA_LOGGER::user_objects, "Server thread started");

  ECA_NETECI_SERVER* self = 
    reinterpret_cast<ECA_NETECI_SERVER*>(arg);
  self->run();
  return 0;
}

/**
 * Starts running the NetECI server. 
 *
 * After calling this function, the ECA_CONTROL_MAIN object
 * may be used at any time from the NetECI server thread.
 */ 
void ECA_NETECI_SERVER::run(void)
{
  create_server_socket();
  open_server_socket();
  if (server_listening_rep == true) {
    listen_for_events();
  }
  else {
    ECA_LOG_MSG(ECA_LOGGER::info, 
		"Unable to start NetECI server. Please check that no other program is using the TCP port "
		+ kvu_numtostr(state_repp->neteci_tcp_port)
		+ ".");
  }
  close_server_socket();

  ECA_LOG_MSG(ECA_LOGGER::user_objects, 
	      "server thread exiting");
}

/**
 * Creates a server socket with 'socket()'. Depending on 
 * object configuration either UNIX or IP socket is 
 * created.
 */
void ECA_NETECI_SERVER::create_server_socket(void)
{
  DBC_REQUIRE(server_listening_rep != true);
  DBC_REQUIRE(srvfd_rep <= 0);

  if (unix_sockets_rep == true) {
    srvfd_rep = socket(AF_UNIX, SOCK_STREAM, 0);
    if (srvfd_rep >= 0) {
      /* create a temporary filename for the socket in a secure way */
      socketpath_rep = "/tmp/neteci_server_1";
      addr_un_rep.sun_family = AF_UNIX;
      memcpy(addr_un_rep.sun_path, socketpath_rep.c_str(), socketpath_rep.size() + 1);
      addr_repp = reinterpret_cast<struct sockaddr*>(&addr_un_rep);
    }
  }
  else {
    srvfd_rep = socket(PF_INET, SOCK_STREAM, 0);
    if (srvfd_rep >= 0) {
      addr_in_rep.sin_family = AF_INET;
      addr_in_rep.sin_port = htons(state_repp->neteci_tcp_port);
      addr_in_rep.sin_addr.s_addr = INADDR_ANY;
      
      addr_repp = reinterpret_cast<struct sockaddr*>(&addr_in_rep);
    }
  }
}

/**
 * Opens the server socket for listening. If succesful,
 * 'server_listening_rep' will be true after the call.
 */
void ECA_NETECI_SERVER::open_server_socket(void)
{
  DBC_REQUIRE(server_listening_rep != true);
  DBC_REQUIRE(srvfd_rep > 0);

  int val = 1;
  int ret = setsockopt(srvfd_rep, SOL_SOCKET, SO_REUSEADDR, (void *)&val, sizeof(val));
  if (ret < 0) 
    std::cerr << "setsockopt() failed." << endl;
  
  // int res = bind(srvfd_rep, (struct sockaddr*)addr_repp, sizeof(*addr_repp));
  
  int res = 0;
  if (unix_sockets_rep == true) 
    res = bind(srvfd_rep, (struct sockaddr*)&addr_un_rep, sizeof(addr_un_rep));
  else
    res = bind(srvfd_rep, (struct sockaddr*)&addr_in_rep, sizeof(addr_in_rep));
  
  if (res == 0) {
    res = listen(srvfd_rep, 5);
    if (res == 0) {
      int res = fcntl(srvfd_rep, F_SETFL, O_NONBLOCK);
      if (res == -1) 
	std::cerr << "fcntl() failed." << endl;
      
      NETECI_DEBUG(std::cout << "server socket created." << endl);
      server_listening_rep = true;
    }
    else 
      std::cerr << "listen() failed." << endl;
  }
  else {
    if (unix_sockets_rep == true) {
      unlink(socketpath_rep.c_str());
    }
    socketpath_rep.resize(0);
    std::cerr << "bind() failed." << endl;
  }
  
  DBC_ENSURE((unix_sockets_rep == true && 
	     (((server_listening_rep == true && socketpath_rep.size() > 0) ||
	       (server_listening_rep != true && socketpath_rep.size() == 0)))) ||
	     (unix_sockets_rep != true));
}

/**
 * Closes the server socket.
 */
void ECA_NETECI_SERVER::close_server_socket(void)
{
  DBC_REQUIRE(srvfd_rep > 0);
  DBC_REQUIRE(server_listening_rep == true);

  NETECI_DEBUG(cerr << "closing socket " << kvu_numtostr(srvfd_rep) << "." << endl);
  close(srvfd_rep);
  srvfd_rep = -1;
  server_listening_rep = false;

  DBC_ENSURE(srvfd_rep == -1);
  DBC_ENSURE(server_listening_rep != true);
}

/**
 * Listens for and accepts incoming connections.
 */
void ECA_NETECI_SERVER::listen_for_events(void)
{
  /* 
   * - loop until we get an exit request from network or from
   *   ecasound_state
   */
  
  /* - enter poll
   * - if new connections, accept them and add the new client to
   *   client list
   * - if incoming bytes, grab ecasound_state lock, send command,
   *   store retval, release lock, send the reply to client
   * - return to poll
   */
  while(state_repp->exit_request == 0) {
    // NETECI_DEBUG(cerr << "checking for events" << endl);
    check_for_events(2000);
  }

  if (state_repp->exit_request != 0) {
    NETECI_DEBUG(cerr << "exit_request received" << endl);
  }
}

/**
 * Checks for new connections and messages from 
 * clients.
 * 
 * @param timeout upper-limit in ms for how long 
 *        function waits for events; if -1, 
 *        call will return immediately
 *        (ie. is non-blocking)
 */
void ECA_NETECI_SERVER::check_for_events(int timeout)
{
  int nfds = clients_rep.size() + 1;
  struct pollfd* ufds = new struct pollfd [nfds];

  ufds[0].fd = srvfd_rep;
  ufds[0].events = POLLIN;
  ufds[0].revents = 0;
  
  std::list<struct ecasound_neteci_server_client*>::iterator p = clients_rep.begin();
  for(int n = 1; n < nfds; n++) {
    ufds[n].fd = (*p)->fd;
    ufds[n].events = POLLIN;
    ufds[n].revents = 0;
    ++p;
  }
  DBC_CHECK(nfds == 1 || p == clients_rep.end());

  int ret = poll(ufds, nfds, timeout);
  if (ret > 0) {
    if (ufds[0].revents & POLLIN) {
      /* 1. new incoming connection */
      handle_connection(srvfd_rep);
    }
    p = clients_rep.begin();
    for(int n = 1; n < nfds; n++) {
      if (ufds[n].revents & POLLIN) {
	/* 2. client has sent a message */
	handle_client_messages(*p);
      }
      else if (ufds[n].revents == POLLERR ||
	       ufds[n].revents == POLLHUP ||
	       ufds[n].revents == POLLNVAL) {
	/* 3. error, remove client */
	remove_client(*p);
      }
      if (p != clients_rep.end()) ++p;
    }
  }

  if (cleanup_request_rep == true) {
    clean_removed_clients();
  }

  delete[] ufds;
}

void ECA_NETECI_SERVER::handle_connection(int fd)
{
  socklen_t bytes = 0;
  string peername;
  int connfd = 0;

  if (unix_sockets_rep == true) {
    bytes = static_cast<socklen_t>(sizeof(addr_un_rep));
    connfd = accept(fd, reinterpret_cast<struct sockaddr*>(&addr_un_rep), &bytes);
    peername = "UNIX:" + socketpath_rep;
  }
  else {
    bytes = static_cast<socklen_t>(sizeof(addr_in_rep));
    connfd = accept(fd, reinterpret_cast<struct sockaddr*>(&addr_in_rep), &bytes);

    if (connfd > 0) {
      struct sockaddr_in peeraddr;
      socklen_t peernamelen;
      // struct in_addr peerip;
      peername = "TCP/IP:";
      int res = getpeername(connfd, 
			    reinterpret_cast<struct sockaddr*>(&peeraddr), 
			    reinterpret_cast<socklen_t*>(&peernamelen));
      if (res == 0)
	peername += string(inet_ntoa(peeraddr.sin_addr));
      else
	peername += string(inet_ntoa(addr_in_rep.sin_addr));
    }
  }

  ECA_LOG_MSG(ECA_LOGGER::info,
	      "New connection from " + 
	      peername + ".");


  if (connfd >= 0) {
    NETECI_DEBUG(cerr << "incoming connection accepted" << endl);
    struct ecasound_neteci_server_client* client = new struct ecasound_neteci_server_client; /* add a new client */
    client->fd = connfd; 
    client->buffer_length = ECA_NETECI_START_BUFFER_SIZE;
    client->buffer = new char [client->buffer_length];
    client->buffer_current_ptr = 0;
    client->peername = peername;
    clients_rep.push_back(client);
  }
}

/**
 * Handle incoming messages for client 'client'.
 */
void ECA_NETECI_SERVER::handle_client_messages(struct ecasound_neteci_server_client* client)
{
  char* buf[128];
  int connfd = client->fd;

  NETECI_DEBUG(cerr << "handle_client_messages for fd " 
	       << connfd << endl);

  ssize_t c = kvu_fd_read(connfd, buf, 128, 5000);
  if (c > 0) {
    parse_raw_incoming_data(reinterpret_cast<char*>(buf), c, client);
    while(parsed_cmd_queue_rep.size() > 0) {
      const string& nextcmd = parsed_cmd_queue_rep.front();
      if (nextcmd == "quit" || nextcmd == "q") {
	NETECI_DEBUG(cerr << "client initiated quit, removing client-fd " << connfd << "." << endl);
	remove_client(client);
      }
      else {
	handle_eci_command(nextcmd, client);
      }
      parsed_cmd_queue_rep.pop_front();
    }
    /* ... */
  }
  else {
    /* read() <= 0 */
    NETECI_DEBUG(cerr << "read error, removing client-fd " << connfd << "." << endl);
    remove_client(client);
  }
}

void ECA_NETECI_SERVER::parse_raw_incoming_data(const char* buffer,
						ssize_t bytes,
						struct ecasound_neteci_server_client* client)
{
  DBC_REQUIRE(buffer != 0);
  DBC_REQUIRE(bytes >= 0);
  DBC_REQUIRE(client != 0);
  DBC_DECLARE(int old_client_ptr = client->buffer_current_ptr);
  DBC_DECLARE(unsigned int old_cmd_queue_size = parsed_cmd_queue_rep.size());

  NETECI_DEBUG(cerr << "parse incoming data; "
	       << bytes << " bytes. Buffer length is " 
	       << client->buffer_length << endl);
  
  for(int n = 0; n < bytes; n++) {
    DBC_CHECK(client->buffer_current_ptr <= client->buffer_length);
    if (client->buffer_current_ptr == client->buffer_length) {
      int new_buffer_length = client->buffer_length * 2;
      char *new_buffer = new char [new_buffer_length];

      if (new_buffer_length > ECA_NETECI_MAX_BUFFER_SIZE) {
	cerr << "client buffer overflow, unable to increase buffer size. flushing..." << endl;
	client->buffer_current_ptr = 0;
      }
      else {
	NETECI_DEBUG(cerr << "client buffer overflow, increasing buffer size from "
		     << client->buffer_length << " to " << new_buffer_length << " bytes." << endl);
	
	for(int i = 0; i < client->buffer_length; i++) new_buffer[i] = client->buffer[i];
	
	delete[] client->buffer;
	client->buffer = new_buffer;
	client->buffer_length = new_buffer_length;
      }
    }

    NETECI_DEBUG(cerr << "copying '" << buffer[n] << "'\n");
    client->buffer[client->buffer_current_ptr] = buffer[n];
    if (client->buffer_current_ptr > 0 &&
	client->buffer[client->buffer_current_ptr] == '\n' &&
	client->buffer[client->buffer_current_ptr - 1] == '\r') {

      string cmd (client->buffer, client->buffer_current_ptr - 1);
      NETECI_DEBUG(cerr << "storing command '" <<	cmd << "'" << endl);
      parsed_cmd_queue_rep.push_back(cmd);
      
      NETECI_DEBUG(cerr << "copying " 
		   << client->buffer_length - client->buffer_current_ptr - 1
		   << " bytes from " << client->buffer_current_ptr + 1 
		   << " to the beginning of the buffer."
		   << " Index is " << client->buffer_current_ptr << endl);
      
      DBC_CHECK(client->buffer_current_ptr < client->buffer_length);
      
#if 0
      /* must not use memcpy() as the 
	 affected areas may overlap! */
      for(int o = 0, p = index + 1; 
	  p < client->buffer_length; o++, p++) {
	client->buffer[o] = client->buffer[p];
      }
#endif
      client->buffer_current_ptr = 0;
    }
    else {
      // NETECI_DEBUG(cerr << "crlf not found, index=" << index << ", n=" << n << "cur_ptr=" << client->buffer_current_ptr << ".\n");
      client->buffer_current_ptr++;
    }
  }

  DBC_ENSURE(client->buffer_current_ptr > old_client_ptr ||
	     parsed_cmd_queue_rep.size() > old_cmd_queue_size);
}

void ECA_NETECI_SERVER::handle_eci_command(const string& cmd, struct ecasound_neteci_server_client* client)
{
  ECA_CONTROL_MT* ctrl = state_repp->control;

  NETECI_DEBUG(cerr << "handle eci command: " << cmd << endl);

  assert(ctrl != 0);

  struct eci_return_value retval;
  ctrl->command(cmd, &retval);

  string strtosend =
    ECA_LOGGER_WELLFORMED::create_wellformed_message(ECA_LOGGER::eiam_return_values,
      std::string(ECA_CONTROL_MAIN::return_value_type_to_string(&retval))
      + " " + 
      ECA_CONTROL_MAIN::return_value_to_string(&retval));

  int bytes_to_send = strtosend.size();
  while(bytes_to_send > 0) {
    int ret = kvu_fd_write(client->fd, strtosend.c_str(), strtosend.size(), 5000);
    if (ret < 0) {
      cerr << "error in kvu_fd_write(), removing client.\n";
      remove_client(client);
      break;
    }
    else {
      bytes_to_send -= ret;
    }
  }
}

/**
 * Removes 'client' from list of clients.
 *
 * Note! Internally, the 'fd' field of the deleted client 
 * is marked to be -1.
 *
 * @see clean_removed_clients()
 */
void ECA_NETECI_SERVER::remove_client(struct ecasound_neteci_server_client* client)
{
  NETECI_DEBUG(std::cout << "removing client." << std::endl);

  if (client != 0 && client->fd > 0) {
    ECA_LOG_MSG(ECA_LOGGER::info, 
		"Closing connection " +
		client->peername + ".");
    close(client->fd);
    client->fd = -1;
  }

  cleanup_request_rep = true;
}

/**
 * Cleans the list of clients from removed objects.
 *
 * @see remove_client()
 */
void ECA_NETECI_SERVER::clean_removed_clients(void)
{
  DBC_DECLARE(size_t oldsize = clients_rep.size());
  DBC_DECLARE(size_t counter = 0);

  NETECI_DEBUG(std::cerr << "cleaning removed clients." << std::endl);

  list<struct ecasound_neteci_server_client*>::iterator p = clients_rep.begin();
  while(p != clients_rep.end()) {
    NETECI_DEBUG(std::cerr << "checking for delete, client " << *p << std::endl);
    if (*p != 0 && (*p)->fd == -1) {
      if ((*p)->buffer != 0) {
	delete[] (*p)->buffer;
	(*p)->buffer = 0;
      }
      std::list<struct ecasound_neteci_server_client*>::iterator q = p;
      ++q;
      NETECI_DEBUG(std::cerr << "deleting client " << *p << std::endl);
      delete *p;
      NETECI_DEBUG(std::cerr << "erasing client " << *p << std::endl);
      *p = 0;
      clients_rep.erase(p);
      p = q;
      DBC_DECLARE(++counter);
    }
    else {
      ++p;
    }
  }
  
  cleanup_request_rep = false;

  DBC_ENSURE(clients_rep.size() == oldsize - counter);
}