#!/bin/sh

set -eu

XDG_DATA_HOME=
XDG_CONFIG_HOME=
XDG_DATA_DIRS=
XDG_CONFIG_DIRS=
XDG_CACHE_HOME=
PIDDIR=
SERVICES=

# TODO: "[....] service" output if attached to a tty

load_service()
{
	local service="${1}"
	shift 1

	XDG_DATA_HOME="${XDG_DATA_HOME:-${HOME}/.local/share}"
	XDG_CONFIG_HOME="${XDG_CONFIG_HOME:-${HOME}/.config}"
	XDG_DATA_DIRS="${XDG_DATA_DIRS:-/usr/local/share/:/usr/share/}"
	XDG_CONFIG_DIRS="${XDG_CONFIG_DIRS:-/etc/xdg}"
	XDG_CACHE_HOME="${XDG_CACHE_HOME:-${HOME}/.cache}"
	PIDDIR="${XDG_CACHE_HOME}/homerc"

	# Default functions
	stop() { :; }
	restart() { stop; start; }
	status() { :; }

	# TODO: Errors
	. "${XDG_CONFIG_HOME}/homerc/${service}"
}

act()
{
	local action="${1}"
	shift 1

	"${action}"
	return ${?}
}

match_session()
{
	local needle="${1}"
	local haystack="${2}"
	shift 2
	local hay=

	IFS=','
	for hay in ${haystack}; do
		unset IFS
		case "${hay}" in
			'') continue;;
			"${needle}" | "${needle}:"*) return 0;;
		esac
	done
	unset IFS

	return 1
}

chg_sessions()
{
	local old_sessions="${1}"
	local new_sessions="${2}"
	shift 2
	local is_running=
	local should_run=

	is_running=false
	should_run=false
	for session in ${SESSIONS}; do
		if match_session "${session}" "${old_sessions}"; then
			is_running=true
		fi
		if match_session "${session}" "${new_sessions}"; then
			should_run=true
		fi
	done

	if ${is_running} && ! ${should_run}; then
		act 'stop'
		return ${?}
	fi
	if ! ${is_running} && ${should_run}; then
		act 'start'
		return ${?}
	fi

	# No change.
	return 0
}

usage()
{
	printf 'Usage: %s <service> {start|stop|restart|status}\n' "${progname}"

	return 0
}

main()
{
	local service=
	local action=

	if [ ${#} -ne 2 ]; then
		usage 1>&2
		return 1
	fi
	service="${1}"
	action="${2}"

	case "${action}" in
		'start' | 'stop' | 'restart' | 'status')
			load_service "${service}" || return 1
			act "${action}"
			;;
		*';'*)
			load_service "${service}" || return 1
			chg_sessions "${action%%;*}" "${action#*;}"
			;;
		*)
			usage 1>&2
			return 1
			;;
	esac

	return 0
}

main "${@}"