#!/bin/sh
#
# hwmon -- Panel applet to monitor Linux hwmon (temp, fan, and power) sensors
#
# 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

cr=0
debug=0

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

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

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

	case "${debug}" in '1')
		printf "DEBUG: ${fmt}\n" "${@}" 1>&2
	esac

	return 0
}

lookup_chips()
{
	local hwmon_dir=
	local hwmon=
	local name=

	for hwmon_dir in /sys/class/hwmon/hwmon*; do
		hwmon="${hwmon_dir#/sys/class/hwmon/}"
		if [ -f "${hwmon_dir}/name" ]; then
			read -r name <"${hwmon_dir}/name"
		elif [ -f "${hwmon_dir}/device/name" ]; then
			read -r name <"${hwmon_dir}/device/name"
		else
			return 1
		fi
		printf '%s %s\n' "${hwmon}" "${name}"
		dbg 'Chip %s = %s' "${name}" "${hwmon}"
	done

	return 0
}

lookup_chip()
{
	local chip="${1}"
	local chips="${2}"
	shift 2
	local hwmon=
	local name=

	while read -r hwmon name; do
		case "${name}" in "${chip}")
			printf '%s' "${hwmon}"
			return 0
		esac
	done <<-EOF
		${chips}
		EOF

	return 1
}

read_value()
{
	local hwmon="${1}"
	local element="${2}"
	shift 2
	local hwmon_dir=
	local value=

	hwmon_dir="/sys/class/hwmon/${hwmon}"
	if [ -f "${hwmon_dir}/${element}_input" ]; then
		read -r value <"${hwmon_dir}/${element}_input"
	elif [ -f "${hwmon_dir}/device/${element}_input" ]; then
		read -r value <"${hwmon_dir}/device/${element}_input"
	else
		return 1
	fi

	printf '%s' "${value}"
	return 0
}

format_temp()
{
	local hwmon="${1}"
	local element="${2}"
	shift 2
	local value=

	value="$(read_value "${hwmon}" "${element}")" || return 1
	printf '%d C' "${value%???}"

	return 0
}

format_fan()
{
	local hwmon="${1}"
	local element="${2}"
	shift 2
	local value=

	value="$(read_value "${hwmon}" "${element}")" || return 1
	printf '%d RPM' "${value}"

	return 0
}

format_power()
{
	local hwmon="${1}"
	local element="${2}"
	shift 2
	local value=

	value="$(read_value "${hwmon}" "${element}")" || return 1
	printf '%d W' "${value%??????}"

	return 0
}

print_sensor()
{
	local indent=${1}
	local label="${2}"
	local len=${3}
	local chip="${4}"
	local chips="${5}"
	local element="${6}"
	shift 6
	local hwmon=
	local value=
	local i=

	if ! hwmon="$(lookup_chip "${chip}" "${chips}")"; then
		err 'Unknown chip "%s"' "${chip}"
		return 1
	fi

	case "${element}" in
		'temp'*)
			value="$(format_temp "${hwmon}" "${element}")" || \
				return 1
			;;
		'fan'*)
			value="$(format_fan "${hwmon}" "${element}")" || \
				return 1
			;;
		'power'*)
			value="$(format_power "${hwmon}" "${element}")" || \
				return 1
			;;
		*)
			err 'Unsupported type of element "%s"' "${element}"
			return 1
			;;
	esac

	i=0
	while [ ${i} -lt ${indent} ]; do
		printf ' '
		i=$((${i} + 1))
	done
	case "${label}" in ?*)
		printf '%s: ' "${label}"
		i=${#label}
		while [ ${i} -lt ${len} ]; do
			printf ' '
			i=$((${i} + 1))
		done
	esac
	case "${cr}" in
		1) printf '%s\r' "${value}";;
		0) printf '%s\n' "${value}";;
	esac

	return 0
}

usage()
{
	printf 'Usage: %s [<options>] %s [%s ...]\n' "${0}" \
		'<label>:[<chip>/<element>]' '<label>:[<chip>/<element>]'
	printf '\n'
	printf 'Options:\n'
	printf '  -i <num>  Indent label/value lines with <num> spaces\n'
	printf '  -r  Print carriage returns instead of line feeds\n'
	printf '  -d  Enable debugging output\n'
}

main()
{
	local indent=
	local opt=
	local chips=
	local max_len=
	local sensor=
	local label=
	local len=
	local chip=
	local element=

	indent=0
	while getopts 'i:rd' opt "${@}"; do
		case "${opt}" in
			'i')
				case "${OPTARG}" in *[!0-9]* | '')
					usage 1>&2
					return 1
				esac
				indent=${OPTARG}
				;;
			'r') cr=1;;
			'd') debug=1;;
			'?')
				usage 1>&2
				return 1
				;;
		esac
	done
	shift $((${OPTIND} - 1))

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

	chips="$(lookup_chips)" || return 1

	max_len=0
	for sensor in "${@}"; do
		label="${sensor%%:*}"
		len=${#label}
		if [ ${len} -gt ${max_len} ]; then
			max_len=${len}
		fi
	done

	for sensor in "${@}"; do
		label="${sensor%%:*}"
		sensor="${sensor#*:}"
		case "${sensor}" in '')
			case "${cr}" in
				1) printf '%s:\r' "${label}";;
				0) printf '%s:\n' "${label}";;
			esac
			continue
		esac
		chip="${sensor%/*}"
		element="${sensor##*/}"
		print_sensor ${indent} "${label}" ${len} \
			"${chip}" "${chips}" "${element}" || return 1
	done

	return 0
}

main "${@}"