/*
    Mosh: the mobile shell
    Copyright 2012 Keith Winstein

    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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "config.h"

#include <errno.h>
#include <locale.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <pwd.h>
#include <signal.h>
#include <time.h>

#if HAVE_PTY_H
#include <pty.h>
#elif HAVE_UTIL_H
#include <util.h>
#endif

#include "stmclient.h"
#include "swrite.h"
#include "completeterminal.h"
#include "user.h"
#include "fatal_assert.h"
#include "locale_utils.h"
#include "select.h"

#include "networktransport.cc"

void STMClient::init( void )
{
  if ( !is_utf8_locale() ) {
    LocaleVar native_ctype = get_ctype();
    string native_charset( locale_charset() );

    fprintf( stderr, "mosh-client needs a UTF-8 native locale to run.\n\n" );
    fprintf( stderr, "Unfortunately, the client's environment (%s) specifies\nthe character set \"%s\".\n\n", native_ctype.str().c_str(), native_charset.c_str() );
    int unused __attribute((unused)) = system( "locale" );
    exit( 1 );
  }

  /* Verify terminal configuration */
  if ( tcgetattr( STDIN_FILENO, &saved_termios ) < 0 ) {
    perror( "tcgetattr" );
    exit( 1 );
  }

  /* Put terminal driver in raw mode */
  raw_termios = saved_termios;

#ifdef HAVE_IUTF8
  if ( !(raw_termios.c_iflag & IUTF8) ) {
    //    fprintf( stderr, "Warning: Locale is UTF-8 but termios IUTF8 flag not set. Setting IUTF8 flag.\n" );
    /* Probably not really necessary since we are putting terminal driver into raw mode anyway. */
    raw_termios.c_iflag |= IUTF8;
  }
#endif /* HAVE_IUTF8 */

  cfmakeraw( &raw_termios );

  if ( tcsetattr( STDIN_FILENO, TCSANOW, &raw_termios ) < 0 ) {
      perror( "tcsetattr" );
      exit( 1 );
  }

  /* Put terminal in application-cursor-key mode */
  swrite( STDOUT_FILENO, Terminal::Emulator::open().c_str() );

  /* Add our name to window title */
  if ( !getenv( "MOSH_TITLE_NOPREFIX" ) ) {
    overlays.set_title_prefix( wstring( L"[mosh] " ) );
  }

  wchar_t tmp[ 128 ];
  swprintf( tmp, 128, L"Nothing received from server on UDP port %d.", port );
  connecting_notification = wstring( tmp );
}

void STMClient::shutdown( void )
{
  /* Restore screen state */
  overlays.get_notification_engine().set_notification_string( wstring( L"" ) );
  overlays.get_notification_engine().server_heard( timestamp() );
  overlays.set_title_prefix( wstring( L"" ) );
  output_new_frame();

  /* Restore terminal and terminal-driver state */
  swrite( STDOUT_FILENO, Terminal::Emulator::close().c_str() );
  
  if ( tcsetattr( STDIN_FILENO, TCSANOW, &saved_termios ) < 0 ) {
    perror( "tcsetattr" );
    exit( 1 );
  }

  if ( still_connecting() ) {
    fprintf( stderr, "mosh did not make a successful connection to %s:%d.\n", ip.c_str(), port );
    fprintf( stderr, "Please verify that UDP port %d is not firewalled and can reach the server.\n\n", port );
    fprintf( stderr, "(By default, mosh uses a UDP port between 60000 and 61000. The -p option\nselects a specific UDP port number.)\n" );
  } else if ( network ) {
    if ( !clean_shutdown ) {
      fprintf( stderr, "\n\nmosh did not shut down cleanly. Please note that the\nmosh-server process may still be running on the server.\n" );
    }
  }
}

void STMClient::main_init( void )
{
  Select &sel = Select::get_instance();
  sel.add_signal( SIGWINCH );
  sel.add_signal( SIGTERM );
  sel.add_signal( SIGINT );
  sel.add_signal( SIGHUP );
  sel.add_signal( SIGPIPE );
  sel.add_signal( SIGTSTP );
  sel.add_signal( SIGCONT );

  /* get initial window size */
  if ( ioctl( STDIN_FILENO, TIOCGWINSZ, &window_size ) < 0 ) {
    perror( "ioctl TIOCGWINSZ" );
    return;
  }  

  /* local state */
  local_framebuffer = new Terminal::Framebuffer( window_size.ws_col, window_size.ws_row );
  new_state = new Terminal::Framebuffer( 1, 1 );

  /* initialize screen */
  string init = display.new_frame( false, *local_framebuffer, *local_framebuffer );
  swrite( STDOUT_FILENO, init.data(), init.size() );

  /* open network */
  Network::UserStream blank;
  Terminal::Complete local_terminal( window_size.ws_col, window_size.ws_row );
  network = new Network::Transport< Network::UserStream, Terminal::Complete >( blank, local_terminal,
									       key.c_str(), ip.c_str(), port );

  network->set_send_delay( 1 ); /* minimal delay on outgoing keystrokes */

  /* tell server the size of the terminal */
  network->get_current_state().push_back( Parser::Resize( window_size.ws_col, window_size.ws_row ) );
}

void STMClient::output_new_frame( void )
{
  if ( !network ) { /* clean shutdown even when not initialized */
    return;
  }

  /* fetch target state */
  *new_state = network->get_latest_remote_state().state.get_fb();

  /* apply local overlays */
  overlays.apply( *new_state );

  /* apply any mutations */
  display.downgrade( *new_state );

  /* calculate minimal difference from where we are */
  const string diff( display.new_frame( !repaint_requested,
					*local_framebuffer,
					*new_state ) );
  swrite( STDOUT_FILENO, diff.data(), diff.size() );

  repaint_requested = false;

  /* switch pointers */
  Terminal::Framebuffer *tmp = new_state;
  new_state = local_framebuffer;
  local_framebuffer = tmp;
}

bool STMClient::process_network_input( void )
{
  network->recv();
  
  /* Now give hints to the overlays */
  overlays.get_notification_engine().server_heard( network->get_latest_remote_state().timestamp );
  overlays.get_notification_engine().server_acked( network->get_sent_state_acked_timestamp() );

  overlays.get_prediction_engine().set_local_frame_acked( network->get_sent_state_acked() );
  overlays.get_prediction_engine().set_send_interval( network->send_interval() );
  overlays.get_prediction_engine().set_local_frame_late_acked( network->get_latest_remote_state().state.get_echo_ack() );

  return true;
}

bool STMClient::process_user_input( int fd )
{
  const int buf_size = 16384;
  char buf[ buf_size ];

  /* fill buffer if possible */
  ssize_t bytes_read = read( fd, buf, buf_size );
  if ( bytes_read == 0 ) { /* EOF */
    return false;
  } else if ( bytes_read < 0 ) {
    perror( "read" );
    return false;
  }

  if ( !network->shutdown_in_progress() ) {
    overlays.get_prediction_engine().set_local_frame_sent( network->get_sent_state_last() );

    for ( int i = 0; i < bytes_read; i++ ) {
      char the_byte = buf[ i ];

      overlays.get_prediction_engine().new_user_byte( the_byte, *local_framebuffer );

      if ( quit_sequence_started ) {
	if ( the_byte == '.' ) { /* Quit sequence is Ctrl-^ . */
	  if ( network->has_remote_addr() && (!network->shutdown_in_progress()) ) {
	    overlays.get_notification_engine().set_notification_string( wstring( L"Exiting on user request..." ), true );
	    network->start_shutdown();
	    return true;
	  } else {
	    return false;
	  }
	} else if ( the_byte == '^' ) {
	  /* Emulation sequence to type Ctrl-^ is Ctrl-^ ^ */
	  network->get_current_state().push_back( Parser::UserByte( 0x1E ) );
	} else {
	  /* Ctrl-^ followed by anything other than . and ^ gets sent literally */
	  network->get_current_state().push_back( Parser::UserByte( 0x1E ) );
	  network->get_current_state().push_back( Parser::UserByte( the_byte ) );	  
	}

	quit_sequence_started = false;
	continue;
      }

      quit_sequence_started = (the_byte == 0x1E);
      if ( quit_sequence_started ) {
	continue;
      }

      if ( the_byte == 0x0C ) { /* Ctrl-L */
	repaint_requested = true;
      }

      network->get_current_state().push_back( Parser::UserByte( the_byte ) );		
    }
  }

  return true;
}

bool STMClient::process_resize( void )
{
  /* get new size */
  if ( ioctl( STDIN_FILENO, TIOCGWINSZ, &window_size ) < 0 ) {
    perror( "ioctl TIOCGWINSZ" );
    return false;
  }
  
  /* tell remote emulator */
  Parser::Resize res( window_size.ws_col, window_size.ws_row );
  
  if ( !network->shutdown_in_progress() ) {
    network->get_current_state().push_back( res );
  }

  /* note remote emulator will probably reply with its own Resize to adjust our state */
  
  /* tell prediction engine */
  overlays.get_prediction_engine().reset();

  return true;
}

void STMClient::main( void )
{
  /* initialize signal handling and structures */
  main_init();

  /* prepare to poll for events */
  Select &sel = Select::get_instance();
  sel.add_fd( network->fd() );
  sel.add_fd( STDIN_FILENO );

  while ( 1 ) {
    try {
      output_new_frame();

      int wait_time = min( network->wait_time(), overlays.wait_time() );

      /* Handle startup "Connecting..." message */
      if ( still_connecting() ) {
	wait_time = min( 250, wait_time );
      }

      int active_fds = sel.select( wait_time );
      if ( active_fds < 0 ) {
	perror( "select" );
	break;
      }

      if ( sel.read( network->fd() ) ) {
	/* packet received from the network */
	if ( !process_network_input() ) { return; }
      }
    
      if ( sel.read( STDIN_FILENO ) ) {
	/* input from the user needs to be fed to the network */
	if ( !process_user_input( STDIN_FILENO ) ) {
	  if ( !network->has_remote_addr() ) {
	    break;
	  } else if ( !network->shutdown_in_progress() ) {
	    overlays.get_notification_engine().set_notification_string( wstring( L"Exiting..." ), true );
	    network->start_shutdown();
	  }
	}
      }

      if ( sel.signal( SIGWINCH ) ) {
        /* resize */
        if ( !process_resize() ) { return; }
      }

      if ( sel.signal( SIGTERM )
           || sel.signal( SIGINT )
           || sel.signal( SIGHUP )
           || sel.signal( SIGPIPE )
           || sel.signal( SIGTSTP )
           || sel.signal( SIGCONT ) ) {
        /* shutdown signal */
        if ( !network->has_remote_addr() ) {
          break;
        } else if ( !network->shutdown_in_progress() ) {
          overlays.get_notification_engine().set_notification_string( wstring( L"Signal received, shutting down..." ), true );
          network->start_shutdown();
        }
      }

      if ( sel.error( network->fd() ) ) {
	/* network problem */
	break;
      }

      if ( sel.error( STDIN_FILENO ) ) {
	/* user problem */
	if ( !network->has_remote_addr() ) {
	  break;
	} else if ( !network->shutdown_in_progress() ) {
	  overlays.get_notification_engine().set_notification_string( wstring( L"Exiting..." ), true );
	  network->start_shutdown();
	}
      }

      /* quit if our shutdown has been acknowledged */
      if ( network->shutdown_in_progress() && network->shutdown_acknowledged() ) {
	clean_shutdown = true;
	break;
      }

      /* quit after shutdown acknowledgement timeout */
      if ( network->shutdown_in_progress() && network->shutdown_ack_timed_out() ) {
	break;
      }

      /* quit if we received and acknowledged a shutdown request */
      if ( network->counterparty_shutdown_ack_sent() ) {
	clean_shutdown = true;
	break;
      }

      /* write diagnostic message if can't reach server */
      if ( still_connecting()
	   && (!network->shutdown_in_progress())
	   && (timestamp() - network->get_latest_remote_state().timestamp > 250) ) {
	if ( timestamp() - network->get_latest_remote_state().timestamp > 15000 ) {
	  if ( !network->shutdown_in_progress() ) {
	    network->start_shutdown();
	  }
	}
	overlays.get_notification_engine().set_notification_string( connecting_notification );
      } else if ( (network->get_remote_state_num() != 0)
		  && (overlays.get_notification_engine().get_notification_string()
		      == connecting_notification) ) {
	overlays.get_notification_engine().set_notification_string( L"" );
      }

      network->tick();

      const Network::NetworkException *exn = network->get_send_exception();
      if ( exn ) {
        overlays.get_notification_engine().set_network_exception( *exn );
      } else {
        overlays.get_notification_engine().clear_network_exception();
      }
    } catch ( Network::NetworkException e ) {
      if ( !network->shutdown_in_progress() ) {
        overlays.get_notification_engine().set_network_exception( e );
      }

      struct timespec req;
      req.tv_sec = 0;
      req.tv_nsec = 200000000; /* 0.2 sec */
      nanosleep( &req, NULL );
    } catch ( Crypto::CryptoException e ) {
      if ( e.fatal ) {
        throw;
      } else {
        wchar_t tmp[ 128 ];
        swprintf( tmp, 128, L"Crypto exception: %s", e.text.c_str() );
        overlays.get_notification_engine().set_notification_string( wstring( tmp ) );
      }
    }
  }
}