#!/bin/bash
#
# Ircmsg sends messages to irc servers using bash sockets.
# Copyright (C)  2016  Aaron Ball <nullspoon@oper.io>
#
# 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/>.
#

portfd=''

#
# Takes active file descriptor to irc server and reads until finding a line
# matching "PING". Retrieves value of that line (without the PING prefix), and
# returns so the corresponding PONG can be sent.
#
# Note: This function will timeout when reading from the server 100 times
#
function get_ping {
  local portfd=${1}
  local emptymax=50
  local emptycount=0

  # get ping
  while [[ ${emptycount} -lt ${emptymax} ]]; do
    read ping <&${portfd}

    # If first four match PING, break and process
    [[ ${ping:0:4} == 'PING' ]] && break

    # If response is empty, increment empty counter
    [[ ${ping} == '' ]] && emptycount=$(($emptycount + 1))
  done
  
  ping=${ping:5}
  echo "${ping}"
}


# function connect {
#   local server=${1}
#   local port=${2}
# 
#   # Open the socket
#   exec {portfd}<>/dev/tcp/${server}/${port}
# 
#   # Exit on failure
#   [[ $? -gt 0 ]] && echo "Failed to connect to ${server}:${port}." && exit 1
# 
#   echo "${portfd}"
# }


function close_sock {
  local portfd=${1}

  # Close read
  exec {portfd}<&-
  # Close write
  exec {portfd}>&-
}


function main {
  argv=(${@})

  [[ -z ${1} ]] && echo "Please specify a server." && exit 1
  [[ -z ${2} ]] && echo "Please specify a server port." && exit 1
  [[ -z ${3} ]] && echo "Please specify a channel." && exit 1
  [[ -z ${4} ]] && echo "Please specify a message." && exit 1

  # Config
  nick="ircmsg"
  server="${1}"
  port="${2}"
  chan="${3}"
  msg="${4}"

  # Open the socket
  exec {portfd}<>/dev/tcp/${server}/${port}
  # Exit on failure
  [[ $? -gt 0 ]] && echo "Failed to connect to ${server}:${port}." && exit 1

  # Authenticate
  echo "NICK ${nick}" >&${portfd}
  echo "USER ${nick} 8 * : ${nick}" >&${portfd}

  # Respond to the server with its ping value (ping pong)
  ping=$(get_ping ${portfd})
  if [[ ${ping} == '' ]]; then
    echo "ERROR: No PING response received. Cannot continue."
    exit 1
  fi

  echo "PONG ${ping}" >&${portfd}

  # Send message to specified channel
  echo "PRIVMSG ${chan} ${msg}" >&${portfd}

  # Send quit command
  echo "QUIT :All done!" >&${portfd}

  # Close up shop
  close_sock ${portfd}
}

main "${@}"