avd/avds

#!/usr/bin/env bash

USAGE="
USAGE: avds <mod_list|-h|-[-]help> [<when>] [<repeat>]

        mod_list
                A comma or space separated list of modules to request that
                the daemon execute. If mod_list begins this '>>* ', then
                requests are sent to all running daemons.

        when    The integer number of milliseconds to wait before sending the
                request, or one of the following values:
                  - m to send the update request at the top of the next minute
                  - h to send the update request at the top of the next hour
                  - d to send the update request at the top of the next day
                If not present, the request will be sent immediately.

        repeat  If present, the request will be sent repeatedly according
                to <when>.

EXAMPLES:

        Any of these will display this help message.

                avds -h
                avds -help
                avds --help

        If there are volume and backlight modules named 'vol' and 'bl' that
        update the volume and backlight statuses, send a requst to update
        both of those statuses immediately.

                avds 'vol,bl'

        Send the previous requests to all running daemons.

                avds '>>* vol,bl'

        If there are cpu and memory usage modules named 'cpu' and 'mem'
        that update the cpu and memory usage statuses, send a requst to
        update both of those statuses every 5 seconds.

                avds 'cpu,mem' 5000 1

        If there are battery and date/time modules named 'bat' and 'dt'
        that update the battery and date/time statuses, send a requst to
        update both of those statuses at the top of every minute.

                avds 'bat,dt' m true
"
DAEMON=avdd

# Convert integer milliseconds to floating point seconds
ms_to_s() {
  printf '%.3f' "${1}e-3"
}

# Validate the number arguments
if [[ "$#" -lt 1 || "$#" -gt 3 ]]; then
  printf '%s' "${USAGE}" 1>&2
  exit 128
fi

mod_list="$1"

# Check if the user needs help
if [[ "${mod_list}" =~ ^(-h|-(-)?help)$ ]]; then
  printf '%s' "${USAGE}" 1>&2
  exit 0
fi

# Check if we will be sending requests to all daemons, or set the named pipe
# for this login session
if [[ "${mod_list}" =~ ^\>\>\*\  ]]; then
  mod_list="${mod_list:4}"
  is_request_all=1
else
  fifo="/tmp/${DAEMON}-fifo-$("$(dirname "$0")/rpid" $$)"
fi

when="${2:-0}"

# Validate when
if [[ ! "${when}" =~ ^[0-9]+|[mhd]$ ]]; then
  printf 'Invalid argument <when>: %s\n' "${when}" 1>&2
  exit 128
fi

repeat="$3"

# Write to the pipe if this is the first run or if repeat is on
first_run=1
while [[ "${first_run}" -eq 1 || -n "${repeat}" ]]; do
  first_run=0

  # Sleep until it's time to write to the pipe
  if [[ "${when}" != '0' ]]; then
    if [[ "${when}" =~ ^[0-9]+$ ]]; then
      sleep "$(ms_to_s "${when}")"
    else
      case "${when}" in
        m)
          sleep $((60 - 10#$(date +%S)))
          ;;
        h)
          readarray -t ms < <(date +'%M%n%S')
          sleep $((3600 - ms[0] * 60 - ms[1]))
          ;;
        d)
          readarray -t hms < <(date +'%H%n%M%n%S')
          sleep $(((24 - hms[0]) * 3600 - hms[1] * 60 - hms[2]))
          ;;
        *)
          ;;
      esac
    fi
  fi

  # Write each command to the named pipe for this login session
  if [[ ! -v is_request_all ]]; then
    if [[ ! -p "${fifo}" ]]; then
      printf 'The daemon %s is not running\n' "${DAEMON}" 1>&2
      exit 1
    fi
    printf '%s\n' "${mod_list}" >> "${fifo}"
  # Write each command to all the daemon named pipes
  else
    readarray -d '' fifos \
      < <(find /tmp -maxdepth 1 -type p -name "${DAEMON}-fifo-*" -print0)
    if [[ "${#fifos[@]}" -eq 0 ]]; then
      printf 'There are no daemons running\n' 1>&2
      exit 1
    fi
    for fifo in "${fifos[@]}"; do
      printf '%s\n' "${mod_list}" >> "${fifo}"
    done
  fi
done