#!/bin/bash
# Version: 0.3.0-seeder
# Copyright (c) 2005-2022:
#   Darren 'Tadgy' Austin <darren (at) afterdark.org.uk>
# Licensed under the terms of the GNU General Public License version 3.

SCREEN_EXEC="/usr/bin/screen"
RTORRENTWRAPPER_EXEC='$HOME/bin/rtorrent-wrapper'
DAEMON_EXEC="/usr/bin/daemon"
SCREEN_ARGS=('-c' '~/.screenrc-seeding' '-S' 'seeding')
RUNUSER="seeder"

# Allow configuration in /etc/default to override.
# Additional available variables:
#   ENVIRONMENT=()	# Extra environment passed to $SCREEN_EXEC.  Must be an array.
#   RUNUSER=""		# The username of the seeding user account.  Default: seeder.
#   SEEDS=()		# The seeding sessions to start.  Must be an array.
#   SLAY_DELAY=""	# Delay between the SIGTERM and SIGKILL on a 'stop'.  Default: 2s.
#   RESTART_DELAY=""	# Delay between stopping and starting on a 'restart'.  Default: 2s.
[[ -e "/etc/default/${0##*rc.}" ]] && { source "/etc/default/${0##*rc.}" || return 1 2>/dev/null || exit 1; }

error() {
  printf "%s: %s\\n" "${BASH_SOURCE[0]##*/}" "$*" >&2
}

checkconfigured() {
  # This function can be used to perform any pre-start tests; hopfully to insure the daemon
  # can start correctly, before actually trying to start it.  A return value of 0 means the
  # tests were passed and the daemon should be started.  Any other value prevents the
  # daemon from being started, and an error message will be emitted.
  id "${RUNUSER:-seeder}" >/dev/null 2>&1 || return 1
  return 0
}

checkstatus() {
  # $@ = Name(s) of a seeding session(s) to check.
  local SEED RET=0
  if [[ ! -z "$(su - "${RUNUSER:-seeder}" -c "\"$DAEMON_EXEC\" --list 2>/dev/null")" ]]; then
    for SEED in "$@"; do
      if su - "${RUNUSER:-seeder}" -c "\"$DAEMON_EXEC\" --running -n \"seeder-$SEED\""; then
        printf "%s: %s: %s\\n" "${BASH_SOURCE[0]##*/}" "seed '$SEED'" "running"
        RET=${RET:+2}
      else
        printf "%s: %s: %s\\n" "${BASH_SOURCE[0]##*/}" "seed '$SEED'" "stopped"
        RET=${RET:-1}
      fi
    done
  else
    printf "%s: %s\\n" "${BASH_SOURCE[0]##*/}" "all seeds stopped"
    RET=1
  fi
  return $RET
}

startdaemon() {
  # $@ = Name(s) of a seeding session(s) to start.
  local EXEC SEED ERR RET
  checkconfigured || {
    error "seeding not started - pre-start checks failed"
    return 2
  }
  for EXEC in "$SCREEN_EXEC" "$(su - "${RUNUSER:-seeder}" -c "printf \"%s\" \"$RTORRENTWRAPPER_EXEC\"")"; do
    [[ ! -e "$EXEC" ]] && {
      error "$EXEC:" "not found"
      return 2
    }
    [[ ! -x "$EXEC" ]] && {
      error "$EXEC:" "not executable"
      return 2
    }
  done
  su - "${RUNUSER:-seeder}" -c "${ENVIRONMENT:+declare ${ENVIRONMENT[*]};} \"$SCREEN_EXEC\" ${SCREEN_ARGS[*]} -ls" | grep -iv "dead" >/dev/null || {
    su - "${RUNUSER:-seeder}" -c "${ENVIRONMENT:+declare ${ENVIRONMENT[*]};} \"$SCREEN_EXEC\" ${SCREEN_ARGS[*]} -d -m"
    ERR=$?
    (( ERR != 0 )) && {
      error "failed to start background screen:" "Error code = $ERR"
      return 2
    }
    sleep 2
  }
  for SEED in "$@"; do
    su - "${RUNUSER:-seeder}" -c "${ENVIRONMENT:+declare ${ENVIRONMENT[*]};} \"$SCREEN_EXEC\" ${SCREEN_ARGS[*]} -X screen -t \"$SEED\" \"$RTORRENTWRAPPER_EXEC\" \"$SEED\""
    ERR=$?
    (( ERR != 0 )) && {
      error "failed to add screen for '$SEED':" "Error code = $ERR"
      RET=2
      continue
    }
    sleep 1
  done
  return ${RET:-0}
}

stopdaemon() {
  # $@ = Optional name(s) of a seeding session(s) to stop.
  local SEED
  for SEED in "$@"; do
    su - "${RUNUSER:-seeder}" -c "\"$DAEMON_EXEC\" -n \"seeder-$SEED\" --stop 2>/dev/null"
  done
  sleep "${SLAY_DELAY:-2}"
  for SEED in "$@"; do
    checkstatus >/dev/null && {
      error "seed '$SEED':" "failed to stop gracefully - slaying"
      su - "${RUNUSER:-seeder}" -c "\"$DAEMON_EXEC\" -n \"seeder-$SEED\" --signal=kill 2>/dev/null"
    }
  done
  return 0
}

for EXEC in "$SCREEN_EXEC" "$DAEMON_EXEC"; do
  [[ ! -e "$EXEC" ]] && {
    error "$EXEC:" "not found"
    return 1 2>/dev/null || exit 1
  }
  [[ ! -x "$EXEC" ]] && {
    error "$EXEC:" "not executable"
    return 1 2>/dev/null || exit 1
  }
done

OPT="$1"
shift
[[ -z "${*:-${SEEDS[@]}}" ]] && {
  error "no seeding sessions specified in /etc/default/${0##*rc.} or on command line"
  return 1 2>/dev/null || exit 1
}

case "$OPT" in
  'start')
    if checkstatus "${@:-${SEEDS[@]}}" >/dev/null; then
      error "seeds already running"
      printf "  %s\\n" "Try: ${BASH_SOURCE[0]} status $@" >&2
      RET=1
    else
      startdaemon "${@:-${SEEDS[@]}}"
      RET=$?
    fi
    ;;
  'stop')
    checkstatus "${@:-${SEEDS[@]}}" >/dev/null
    ERR=$?
    if (( ERR == 2 )) || (( ERR == 0 )); then
      stopdaemon "${@:-${SEEDS[@]}}"
      RET=$?
    elif (( ERR == 1 )); then
      error "seeds already stopped"
      printf "  %s\\n" "Try: ${BASH_SOURCE[0]} status" >&2
      RET=1
    else
      error "unhandled status: $ERR"
      RET=1
      break
    fi
    ;;
  'restart')
    checkstatus "${@:-${SEEDS[@]}}" >/dev/null
    ERR=$?
    if (( ERR == 2 )) || (( ERR == 0 )); then
      stopdaemon "${@:-${SEEDS[@]}}"
      sleep "${RESTART_DELAY:-2}"
      startdaemon "${@:-${SEEDS[@]}}"
      RET=$?
    elif (( ERR == 1 )); then
      startdaemon "${@:-${SEEDS[@]}}"
      RET=$?
    else
      error "unhandled status: $ERR"
      RET=1
      break
    fi
    ;;
  'status')
    checkstatus "${@:-${SEEDS[@]}}"
    RET=$?
    ;;
  *)
    printf "%s\\n" "Usage: ${BASH_SOURCE[0]} <start|stop|restart|status> [seeding session] ..." >&2
    RET=1
    ;;
esac

return $RET 2>/dev/null || exit $RET