#!/bin/bash
#
# A utility to execute a command and notify the user upon completion.
#
# Copyright 2009, Victor Chudnovsky <victor.chudnovsky@gmail.com>
# Credits: This work was inspired by http://wagiaalla.com/blog/?p=28 and
# http://emacs-fu.blogspot.com/2009/11/showing-pop-ups.html
#
# 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/>.

basename=$(basename $0)
dbg="$basename: "

# form_option flag value
#
# Returns the string "--flag value" unless value is empty, in which
# case it returns the empty string
function form_option() {
  local flag=$1
  local value=$2
  local option=""
  if [[ -n "$value" ]]
  then
    option="$flag $value"
  fi
  echo $option
}

# set_one_flag_value command_root flag value_root variant
#
# Sets the global script variable ${command_root}_${variant} to be the
# string needed to set a flag called $flag to the global script variable value
# ${value_root}_${variant}.
function set_one_flag_value() {
  local command_root=$1
  local flag=$2
  local value_root=$3
  local variant=$4
  local cmd="${command_root}_${variant}=\$(form_option \"$flag\" \$${value_root}_${variant})" 
  eval $cmd
}

# set_success_failure_flag_variants command_root flag value_root
#
# Sets the global script variable ${command_root}_success and
# ${command_root}_failure to be the strings needed to set a flag
# called $flag to the global script variables ${value_root}_success
# and ${value_root}_failure, respectively.
function set_success_failure_flag_variants() {
  local command_root=$1
  local flag=$2
  local value_root=$3
  set_one_flag_value $command_root $flag $value_root success
  set_one_flag_value $command_root $flag $value_root failure
}

# show_flag_variants command_root
#
# For debugging purposes, displays the global script variables
# ${command_root}_success and ${command_root}_failure.
function show_flag_variants() {
  local command_root=$1
  eval "echo $dbg \"\" ${command_root}_success : \${${command_root}_success}"
  eval "echo $dbg \"\" ${command_root}_failure : \${${command_root}_failure}"
}

# get_argument argument
# 
# If argument is of the form --XXX, returns XXX. Otherwise, returns
# the empty string.
function get_argument() {
  local argument="$1"
  expr "$argument" : "--\([a-z_]\+\)"
}

# debug arg1 arg2...
#
# If debug mode is on, echo arg1, arg2... to stderr.
function debug() {
  if [[ -n "$debug" ]]
  then
    while [[ -n "$1" ]]
    do
      echo "$1" 1>&2
      shift
    done
  fi
}

# show_usage
#
# Echoes usage information for this utility
function show_usage() {
cat <<EOF
$basename Execute a command and notify when finished
Usage: $basename [FLAGS...] COMMAND [ARGS...]
       executes COMMAND ARGS... and sends a notification to the status
       panel upon completion, indicating the result of COMMAND. The
       exit code of COMMAND is the exit of $basename.

Each flag to $basename begins with "--"; flags take zero or one
arguments. The first argument to $basename that is not interpreted as
a flag or value is taken to be the command to execute.

Possible no-argument flags are:
  --help  Show this message
  --debug Print debugging information about $basename

Possible one-argument flags are:
  --title Prefix to the "Success" or "Failure" title of the
    notification

  --command_label Description of the command to be used in the
    notification text in place of the command itself. Useful for
    succinctly describing a long command, or for use with --exit_code
    flag

  --exit_code Simulated exit code from COMMAND to use when generating
    the notification, Setting this flag causes COMMAND to not actually
    execute, and is useful for testing that the notification is
    formatted as desired without actually invoking COMMAND or of the
    form

  --PROPERTY_OUTCOME where PROPERTY is one of "icon", "urgency", or
    "expiration" and OUTCOME is one of "success" or "failure".
    All the properties are used in creating and dispatching the
    notification, but the outcome used depends on the exit code of the
    command being run.
       icon: the icon to be used in the notification
       expiration: the duration of the notification (ms)
       urgency: the notification urgency, as defined by send-notify

Example:
  $basename --icon_success /usr/share/icons/gnome/32x32/emblems/emblem-default.png \\
            --expiration 600000 --title "Directory listing" ls
EOF
}

# Default settings
icon_success="/usr/share/icons/gnome/32x32/emblems/emblem-default.png"
icon_failure="/usr/share/icons/gnome/32x32/emblems/emblem-important.png"
urgency_success=""
urgency_failure="critical"
expiration_success=600000 # ten minutes
expiration_failure=600000 # ten minutes
command_label=""
title=""

# Get arguments to this utility
possible_flag=$(get_argument "$1")
while [[ -n "$possible_flag" ]]
do
  # Process the no-value arguments explictly...
  case "$possible_flag" in
    help)
      show_usage;
      exit 0;
      ;;
    debug)
      debug=1
      debug "$dbg entering debug mode"
      ;;
    *)
      # ...but let the arguments that set state directly set the
      # variables used by this script.
      debug "$dbg setting '${possible_flag}' to '$2'"
      eval "$possible_flag"=\"$2\"
      shift
      ;;
  esac
  shift
  possible_flag=$(get_argument "$1")
done

# If no command_label was specified, use the command itself.
if [[ -z "$command_label" ]]
then
  command_label=$(echo $@)
fi

# Based on the arguments passed in, set the various flags to
# send-notify.
set_success_failure_flag_variants "show_icon" "--icon" "icon"
set_success_failure_flag_variants "expiration" "--expire-time" "expiration"
set_success_failure_flag_variants "urgency" "--urgency" "urgency"

# Echo state in debug mode.
debug "$dbg flags:"
debug "$(show_flag_variants show_icon)"
debug "$(show_flag_variants expiration)"
debug "$(show_flag_variants urgency)"

# If no exit_code was provided, get one (by running the command left
# in argv).
if [[ -z "$exit_code" ]]
then
  ($@)
  exit_code=$?
fi

# Determine success or failure messaging.
if [[ $exit_code = 0 ]]
then
  result="success"
  label_success="$title Success!"
else
  result="failure"
  label_failure="$title Failure ($exit_code)"
fi
content=$(echo -e "${command_label}\n\n<i>`date +%c`</i>")

# Build the appropriate notification command.
cmd="notify-send \$show_icon_$result \$expiration_$result \$urgency_$result \"\$label_$result\""
debug "$dbg $cmd \"$content\""
debug "$dbg $(eval echo $cmd \"$content\")"

# Notify, redirecting any stdout to stderr so as to allow this utility
# to be used in stdout pipes.
eval "$cmd \"$content\"" 1>&2

# Pass along the exit code of the command to the calling process.
exit $exit_code