#!/bin/sh

set -e

# depends on https://git.sr.ht/~trinity/utilities (particularly fdivide(1),
# gt(1), and stris(1)) unless POSIXLY_CORRECT is set (not tested)

# these files (separated by newlines) will have the current CPU temperature
# multiplied by $CPU_TEMP_SCALE. this script divides the file contents by scale
# and displays that temperature (assumed to be in Celsius units)
CPU_TEMP_FILES="/sys/devices/platform/coretemp.0/hwmon/hwmon4/temp2_input
/sys/devices/platform/coretemp.0/hwmon/hwmon4/temp3_input"
CPU_TEMP_SCALE=1000

# format for the date (by default in this script, ISO 8601)
alias date="date '+%Y-%m-%dT%T'"

DELIMITER=" || "

# how fast to refresh the display (in seconds, will be substituted with 1 if
# not an integer)
INTERVAL=1

# enable if you have issues with missing `stris` etc. will save negligible time
# with shells that don't spawn new processes for test(1)
# fdivide_posix() may not be fully working yet, so it's not enabled by default
#POSIXLY_CORRECT=1

# this URL will have in plain text the public IP address from which it was
# accessed
PUBLIC_IP_FETCH_URL="http://ifconfig.io/"

get_battery_status() {
	if [ "$(uname)" = "Linux" ]; then
		# this is a dirty hack.
		# acpi | awk '{print $4}' will print the battery percentage,
		# and s/,$// strips the trailing comma.
		# acpi -a will just print the power adapter status.
		printf "%b" "$(acpi | awk '{print $4}' | sed 's/,$//') ($(acpi -a))"
		return
	fi
}

get_cpu_temp() {
	if [ "$(uname)" = "Linux" ]; then
		RETVAL=""
		# iterate over files, adjust, print out "%dC "
		for file in $CPU_TEMP_FILES;
			do RETVAL="$RETVAL$(fdivide $(cat $file) $CPU_TEMP_SCALE)C "
		done
		# in-line python (bet you've never seen that before) that
		# strips off trailing whitespace. could be done with sed but
		# this was more fun
		printf "%b" "$RETVAL" \
			| python -c "from sys import stdin; print(stdin.read().rstrip() + '\n')"
		return
	elif [ "$(uname)" = "NetBSD" ]; then
		printf "%bC" "$(envstat -s coretemp0:'cpu0 temperature' \
			| sed 1,2d \
			| cut -d ':' -f 2 \
			| awk '{print $1}' \
			| cut -d '.' -f 1)"
	fi
}

get_current_desktop() {
	case "$WM" in
	(bspwm) printf "[%b] " "$(bspc query -D -d focused --names)" ;;
	esac
}

get_memory_usage() {
	if [ "$(uname)" = "Linux" ]; then
		printf "%b" \
			"$(free | head -n 2 | tail -n 1 \
				| awk '{print $3 " used / " $2 " total"}')"
		return
	fi
}

get_public_ip() {
	curl "$PUBLIC_IP_FETCH_URL" --no-progress-meter 2>/dev/null \
		|| printf "[error fetching IP]\n"
	return
}

# slow, so fetch it in advance
PUBLIC_IP="$(get_public_ip)"

printbar() {
	printf "%b" "$(get_current_desktop)"
	printf "%b" "$(date)"
	#printf "%b" "$DELIMITER"
	#printf "%b" "BAT: $(get_battery_status)"
	printf "%b" "$DELIMITER"
	printf "%b" "CPU: $(get_cpu_temp)"
	printf "%b" "$DELIMITER"
	printf "%b" "PuIP: $PUBLIC_IP"
	#printf "%b" "$DELIMITER"
	#printf "%b" "MEM: $(get_memory_usage)"
	printf "\n"
	return
}

###############################################################################
#    the following is for error prevention and doesn't need to be changed     #
###############################################################################

# POSIX shell version of fdivide
fdivide_posix() {
	[ -n "$2" ] && [ -n "$1" ] && [ -z "$3" ] \
		|| return 1
	printf "%b\n" "$(($1/$2))"
	return
}

# [ -gt ] with better syntax
gt_posix() {
	while [ -n "$2" ]; do
		[ "$1" -gt "$2" ] \
			|| return 1
		shift 1
	done
	return 0
}

# limited POSIX shell version of stris
# BROKEN REGEX. MUSTFIX.
stris_posix() {
	[ -n "$2" ] || return 1
	case "$1" in
	(int)
		# https://stackoverflow.com/questions/2210349/test-whether-string-is-a-valid-integer
		printf "$2" | grep '^-?[0-9]+$' >/dev/null \
			&& return 0 \
			|| return 1
		;;
	(uint)
		printf "$2" | grep '^[0-9]+$' >/dev/null \
			&& return 0 \
			|| return 1
		;;
	(*)
		return 1
		;;
	esac
	return
}

# check to make sure we have non-standard utilities

[ -n "$POSIXLY_CORRECT" ] || ! which fdivide >/dev/null 2>&1 \
	&& alias fdivide="fdivide_posix" \
	|| true

[ -n "$POSIXLY_CORRECT" ] || ! which gt >/dev/null 2>&1 \
	&& alias gt="gt_posix" \
	|| true

[ -n "$POSIXLY_CORRECT" ] || ! which stris >/dev/null 2>&1 \
	&& alias stris="stris_posix" \
	|| true

# check to make sure customizeable vars are in proper format

[ -n "$INTERVAL" ] && stris int "$INTERVAL" \
	|| INTERVAL=1

[ -n "$CPU_TEMP_SCALE" ] && stris int "$CPU_TEMP_SCALE" \
		&& gt "$CPU_TEMP_SCALE" 0 \
	|| CPU_TEMP_SCALE=1

[ -n "$CPU_TEMP_FILES" ] \
	|| alias get_cpu_temp="printf '[no temperature files specified]\n'"

# main loop

while true; do
	printbar
	sleep "$INTERVAL"
done