#!/bin/sh
#
# df-uptime -- Panel applet to monitor file system free space and system uptime
#
# Copyright (C) 2018  Patrick "P. J." McDermott
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

set -eu

indent=''
le="$(printf '\n.')"; le="${le%.}"

err()
{
	local fmt="${1}"
	shift 1

	printf "Error: ${fmt}\n" "${@}" 1>&2
	return 0
}

gen_indent()
{
	local l=${1}
	shift 1
	local i=

	i=0
	while [ ${i} -lt ${l} ]; do
		indent="${indent} "
		i=$((${i} + 1))
	done

	return 0
}

do_df()
{
	local sed_bre=

	sed_bre='^..*  *..*  *..*  *..*  *\([0-9][0-9]*%\) \(..*\)$'
	df -x devtmpfs -x tmpfs | \
		sed "1d; s/${sed_bre}/${indent}\\1 \\2/;" | tr '\n' "${le}"

	return 0
}

do_uptime()
{
	local up=
	local idle=
	local min=
	local hr=
	local day=

	read -r up idle 0</proc/uptime

	up="${up%.*}"
	min=$((${up} / 60))
	hr=$((${min} / 60))
	day=$((${hr} / 24))

	min=$((${min} % 60))
	hr=$((${hr} % 24))

	printf '%sUp %d d %2d:%02d%c' "${indent}" ${day} ${hr} ${min} "${le}"

	return 0
}

usage()
{
	printf 'Usage: %s [<options>]\n' "${0}"
	printf '\n'
	printf 'Options:\n'
	printf '  -i <num>  Indent lines with <num> spaces\n'
	printf '  -r  Print carriage returns instead of line feeds\n'

	return 0
}

main()
{
	local opt=

	while getopts 'i:r' opt "${@}"; do
		case "${opt}" in
			'i')
				case "${OPTARG}" in *[!0-9]* | '')
					usage 1>&2
					return 1
				esac
				gen_indent ${OPTARG}
				;;
			'r') le="$(printf '\r.')"; le="${le%.}";;
			'?')
				usage 1>&2
				return 1
				;;
		esac
	done
	shift $((${OPTIND} - 1))

	if [ ${#} -ne 0 ]; then
		usage 1>&2
		return 1
	fi

	do_df
	do_uptime

	return 0
}

main "${@}"