#!/bin/bash
#
# Simple alarm applicaton
# Example run: xalarm 1m mymessage
# See discussion at https://www.reddit.com/r/Gentoo/comments/1rryh1/kalarm_replacement/
#

# Parameters
FULLNAME="$0"
BASENAME="`basename $0`"
XALARMPID="$BASHPID"
XALARMPPID="$PPID"

# Set alarm
function xalarm_set {
  # Delay
  DELAY="${1:-10m}"

  # Message
  shift
  MESSAGE="${*:-Alarm!}"

  # Simple argument checking
  if ! echo $DELAY | grep -q '^[0-9]'; then
    xalarm_usage
  fi

  # Suppor for HH:MM format
  if echo $DELAY | grep -q '[0-9]:[0-9][0-9]'; then
    NOW="`date +%s`"
    LATER="`date -d $DELAY +%s`"
    DELAY="$(($LATER - $NOW))"

    if (($LATER < $NOW)); then
      echo "$BASENAME: deadline must be later than now"
      exit 1
    fi
  fi

  # AT(1) implementation
  # Example run: xalarm 1minute mymessage
  #echo "xmessage $MESSAGE" | at now +$DELAY

  # Sleep implementation
  #
  # We put sleep into background and tell bash to wait it
  # This way we can grab sleep PID and then be able to reset the timer if needed
  sleep $DELAY &
  SLEEP_PID="$!"
  wait

  if [ "$ALARM_RESET" == "1" ]; then
    ALARM_RESET=0
    echo "Resetting alarm..."
    xalarm_set $DELAY $MESSAGE
  else
    if which sm &> /dev/null; then
      #sm -f '#ffffff' -b '#1c1c1c' $MESSAGE
      (timer=0; while sleep 1; do let timer++; echo $MESSAGE - $timer; echo -e '\f'; done) | sm -f '#ffffff' -b '#1c1c1c' -
    else
      xmessage $MESSAGE
    fi
  fi
}

# List alarms
function xalarm_list {
  # Simpler process filtering, but might collide with alarm messages
  #ps -U $USER -o pid,state,lstart,command | grep xalarm | grep -v grep | grep -v list | grep -v cancel | grep -v pause | grep -v resume | grep -v reset | grep -v reset-loop | \
  #  sed -e "s|$FULLNAME||" -e "s|/bin/bash||" | grep -v -- "sed -e"

  # Better, butt more difficult way to filter processes
  THISPID="$BASHPID"
  PARENTPID="$PPID"
  ps -U $USER -o pid,state,lstart,command | grep xalarm | grep -v grep | \
    sed -e "s|$FULLNAME||" -e "s|/bin/bash||" | grep -v -- "sed -e" | grep -v "^ *$THISPID" | grep -v "^ *$PARENTPID" | grep -v "^ *$XALARMPID" | grep -v "^ *$XALARMPPID"
}

# Return xalarm PIDs
function xalarm_pids {
  if [ ! -z "$1" ]; then
    if xalarm_list | awk '{ print $1 }' | grep -q "^$1"; then
      echo $1
    fi
  else
    xalarm_list | awk '{ print $1 }'
  fi
}

# Send a signal to a process
function xalarm_signal {
  local pid="$1"
  local signal="$2"

  if [ -z "$signal" ]; then
    signal="-TERM"
  fi

  if ps $1 &> /dev/null; then
    kill $signal $pid
  fi
}

# Cancel alarms
function xalarm_cancel {
  for pid in `xalarm_pids $1`; do
    xalarm_signal $pid
  done
}

# Pause alarms
function xalarm_pause {
  for pid in `xalarm_pids $1`; do
    xalarm_signal $pid -STOP
  done
}

# Resume alarms
function xalarm_resume {
  for pid in `xalarm_pids $1`; do
    xalarm_signal $pid -CONT
  done
}

# Reset alarms
function xalarm_reset {
  for pid in `xalarm_pids $1`; do
    xalarm_signal $pid -USR1
  done
}

# Reset alarm loop counter
function xalarm_reset_loop {
  for pid in `xalarm_pids $1`; do
    xalarm_signal $pid -USR2
  done
}

# Usage
function xalarm_usage {
  echo "usage: $BASENAME [list|cancel|kill|resume|continue|help|usage|loop|reset|reset-loop] [timedef] [message]"
  echo ""
  echo "timedef: accepts both sleep(1) and date(1) formats"
  exit 1
}

# Respond to SIGUSR1
function xalarm_sigusr1 {
  if [ ! -z "$SLEEP_PID" ]; then
    ALARM_RESET="1"
    kill $SLEEP_PID 2> /dev/null
  fi
}

# Respond to SIGUSR2
function xalarm_sigusr2 {
  if [ ! -z "$COUNT" ]; then
    COUNT=0
  fi
}

# Register traps
trap xalarm_sigusr1 SIGUSR1
trap xalarm_sigusr2 SIGUSR2

# Dispatch
if [ -z "$1" ] || [ "$1" == "list" ]; then
  xalarm_list
elif [ "$1" == "cancel" ] || [ "$1" == "kill" ]; then
  xalarm_cancel $2
elif [ "$1" == "pause" ]; then
  xalarm_pause $2
elif [ "$1" == "resume" ] || [ "$1" == "continue" ]; then
  xalarm_resume $2
elif [ "$1" == "reset" ]; then
  xalarm_reset $2
elif [ "$1" == "reset-loop" ]; then
  xalarm_reset_loop $2
elif [ "$1" == "help" ] || [ "$1" == "usage" ]; then
  xalarm_usage
elif [ "$1" == "loop" ]; then
  COUNT="0"

  shift
  while true; do
    let COUNT++
    xalarm_set $* $COUNT
  done
else
  xalarm_set $*
fi