#!/bin/sh

# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero 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 Affero General Public License for more
# details.

readonly PROGRAM_NAME="$(basename "$0")"

main()
{
	# Handle opts
	while getopts ":PS:d:hpt:v" opt
	do
		case "$opt" in
			P) unpause=1 ;;
			S) rundir=$OPTARG ;;
			d) command_dir=$OPTARG ;;
			h) usage && exit 0 ;;
			p) pause=1 ;;
			t) trigger=$OPTARG ;;
			v) verbose=1 ;;
			*)
				printf "Invalid option passed: %s\n" "$OPTARG" >&2
				;;
		esac
	done

	shift $(( OPTIND - 1 ))

	# Set default values
	[ -z "$rundir" ] && rundir="$XDG_RUNTIME_DIR/$PROGRAM_NAME"

	time_old=0
	time_now="$(xprintidle)"

	# Set some environment variables, for exposing to the scripts ran
	export XBLANK_STATESD="$rundir/states.d"

	if [ -n "$unpause" ]
	then
		printf "0\n" > "$rundir/paused"
		return 0
	fi

	if [ -n "$pause" ]
	then
		printf "1\n" > "$rundir/paused"
		return 0
	fi

	if [ -n "$trigger" ]
	then
		cmd=$(get_script "$trigger")

		if [ "$cmd" = "" ]
		then
			log "No executable found for activation"

			return 5
		fi

		$cmd
	fi

	# Check availability of dependencies
	for i in xprintidle xset
	do
		command -v "$i" >/dev/null && continue

		log "Missing dependency $i"
		return 3
	done

	# Ensure $DISPLAY is set
	if [ -z "$DISPLAY" ]
	then
		log "\$DISPLAY is unset"
		return 4
	fi

	# Initialize the rundir
	log "Create rundir ($rundir)"
	mkdir -p -- "$rundir"
	mkdir -p -- "$XBLANK_STATESD"

	printf "0\n" > "$rundir/paused"
	[ ! -f "$rundir/state" ] && printf "active\n" > "$rundir/state"

	# Enter the loop
	while :
	do
		# Do nothing if the program is paused
		if is_paused
		then
			log "$PROGRAM_NAME is paused ($rundir)"

			sleep 1
			continue
		fi

		# Get the time the system has been idle in milliseconds
		time_old=$time_now
		time_now="$(($(xprintidle) / 1000))"

		# Run command_active upon detecting activity
		if [ "$((time_now))" -lt "$((time_old))" ]
		then
			log "Detected activity ($time_now < $time_old)"
			cmd="$(get_script active)"

			if [ "$cmd" = "" ]
			then
				log "No executable found for activation"

				sleep 1
				continue
			fi

			log "> $cmd"
			$cmd
		fi

		# Run command based on inactivity duration
		loop_index=$(($time_old))

		log "Running (potential) scripts $time_old through $time_now"

		while [ "$(($loop_index))" -lt "$(($time_now))" ]
		do
			loop_index="$(($loop_index + 1))"

			log "Running script for $loop_index"

			cmd=$(get_script idle_$loop_index)

			if [ "$cmd" = "" ]
			then
				log "No executable found for idling (${loop_index}s)"

				continue
			fi

			log "> $cmd"
			$cmd
		done

		# Sleep to not burn your CPU
		sleep 1
	done
}

get_script()
{
	if [ -n "$command_dir" ]
	then
		if [ -x "$command_dir/$1" ]
		then
			printf "%s\n" "$command_dir/$1"
			return
		fi

		# Don't continue if a command_dir was explicitly set
		return
	fi

	set -f
	OIFS=$IFS
	IFS=:

	dirs="$XDG_CONFIG_HOME:$XDG_CONFIG_DIRS:$HOME/.config"

	for dir in $dirs
	do
		[ "$dir" = "" ] && continue

		if [ -x "$dir/$PROGRAM_NAME/$1" ]
		then
			printf "%s\n" "$dir/$PROGRAM_NAME/$1"
			return
		fi
	done

	IFS=$OIFS
	set +f
}

is_paused()
{
	if [ "$(head -n 1 "$rundir/paused")" = "0" ]
	then
		return 1
	fi

	return 0
}

log()
{
	[ -z "$verbose" ] && return

	printf "[%s] %s\n" "$(prettify_time "$time_now")" "$*" >&2
}

prettify_time()
{
	printf "%03dh %02dm %02ds\n" \
		"$(( $1 / 60 / 60 ))" \
		"$(( $1 / 60 % 60 ))" \
		"$(( $1 % 60 ))"
}

usage()
{
	cat <<EOF
Usage:
	${0##*/} -h
	${0##*/} [-C <command>] [-R <path>] [-c <command>] [-t <timeout>] [-v]

Force-blank the screen after a certain timeout.

Options:
	-C  Set the command to run when X is becoming active.
	-R  Set the location of the rundir.
	-c  Set the command to run when X is going idle.
	-h  Show this help text and exit.
	-t  Set the timeout in seconds. Defaults to 60.
	-v  Add verbosity.
EOF
}

main "$@"