#!/bin/sh
#$Id$
#Copyright (c) 2020-2021 Pierre Pronchery <khorben@defora.org>
#This file is part of DeforaOS Devel scripts
#
#Redistribution and use in source and binary forms, with or without
#modification, are permitted provided that the following conditions
#are met:
#1. Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
#2. Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
#
#THIS SOFTWARE IS PROVIDED BY THE EDGEBSD PROJECT AND CONTRIBUTORS
#``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
#TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
#PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
#BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
#CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
#SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
#INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
#CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
#ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
#POSSIBILITY OF SUCH DAMAGE.



#variables
#executables
DATABASE="database"
DEBUG="_debug"
LOCK="mkdir"
UNLOCK="rmdir"
SED="sed"
#settings
PROGNAME="deforaos-jobs"

DATABASE_CONFFILE="$PROGNAME.conf"
DATABASE_ENGINE="sqlite3"
DATABASE_FILE="$PROGNAME.db"
DATABASE_INITFILE="$PROGNAME.sql"
DEVNULL="/dev/null"
PREFIX="/usr/local"
QUERY_ADD_BEGIN="INSERT INTO jobs (command) VALUES ('"
QUERY_ADD_END="')"
QUERY_EXEC_SELECT="SELECT jobs_id, command FROM jobs WHERE started IS NULL ORDER BY jobs_id ASC LIMIT 1"
QUERY_INIT="CREATE TABLE jobs (jobs_id INTEGER PRIMARY KEY, timestamp TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, command VARCHAR(255), started TIMESTAMP DEFAULT NULL, pid INTEGER DEFAULT NULL, code INTEGER DEFAULT NULL, completed TIMESTAMP DEFAULT NULL)"
QUERY_LIST="SELECT * FROM jobs"
SYSCONFDIR="$PREFIX/etc"
VENDOR="DeforaOS"
VERBOSE=1
#load local settings
[ -f "$SYSCONFDIR/$VENDOR/$PROGNAME.conf" ] &&
	. "$SYSCONFDIR/$VENDOR/$PROGNAME.conf"
[ -f "$HOME/.config/$VENDOR/$PROGNAME.conf" ] &&
	. "$HOME/.config/$VENDOR/$PROGNAME.conf"

#Error codes:
#  1	Usage error
#  2	Generic error
#  3	Could not lock the database
#  4	Could not unlock the database


#functions
#database_add
_database_add()
{
	if [ $# -ne 1 ]; then
		_usage
		return $?
	fi
	command="$1"
	query="$QUERY_ADD_BEGIN$(echo "$command" | _database_escape)$QUERY_ADD_END"

	_info "Queueing command: $command"
	_database_init						|| return 2
	_database_query "$query" > "$DEVNULL"			|| return 2
}


#database_escape
_database_escape()
{
	$SED -e "s,','',"
}


#database_exec
_database_exec()
{
	if [ $# -ne 0 ]; then
		_usage
		return $?
	fi

	_database_init							|| return 2
	_database_lock "$DATABASE_FILE"					|| return 3
	_database_query "$QUERY_EXEC_SELECT" | (IFS="|"
	read header
	read empty jobs_id command empty
	if [ -z "$jobs_id" ]; then
		_database_unlock "$DATABASE_FILE"			|| return 4
		return 0
	fi
	#XXX TOCTOU
	QUERY="UPDATE jobs SET started=datetime() WHERE jobs_id='$jobs_id'"
	_database_query "$QUERY" > "$DEVNULL"
	_database_unlock "$DATABASE_FILE"
	code=-1
	if [ -n "$command" ]; then
		_info "Executing command: $command"
		$DEBUG sh -c "$command" &
		pid=$!
		QUERY="UPDATE jobs SET pid='$pid' WHERE jobs_id='$jobs_id'"
		_database_query "$QUERY" > "$DEVNULL"
		wait $pid
		code=$?
	fi
	QUERY="UPDATE jobs SET completed=datetime(), code='$code' WHERE jobs_id='$jobs_id'"
	_database_query "$QUERY" > "$DEVNULL")
}


#database_init
_database_init()
{
	ret=0

	if [ ! -f "$DATABASE_CONFFILE" ]; then
		echo "filename=$DATABASE_FILE" > "$DATABASE_CONFFILE"
	fi
	if [ ! -f "$DATABASE_FILE" ]; then
		_info "Initializing the database"
		_database_lock "$DATABASE_FILE"				|| return 3
		_database_query "$QUERY_INIT" > "$DEVNULL"		|| ret=2
		_database_unlock "$DATABASE_FILE"			|| return 4
	fi
	return $ret
}


#database_list
_database_list()
{
	if [ $# -ne 0 ]; then
		_usage
		return $?
	fi
	_database_init						|| return 2
	_info "Listing the jobs"
	_database_query "$QUERY_LIST"				|| return 2
}


#database_lock
_database_lock()
{
	filename="$1"

	$DEBUG $LOCK "$filename.lock"
}


#database_query
_database_query()
{
	$DEBUG $DATABASE -d "$DATABASE_ENGINE" -C "$DATABASE_CONFFILE" "$@"
}


#database_unlock
_database_unlock()
{
	filename="$1"

	$DEBUG $UNLOCK "$filename.lock"
}


#debug
_debug()
{
	[ $VERBOSE -ge 2 ] && echo "$@" 1>&3
	"$@"
}


#error
_error()
{
	echo "$PROGNAME: $@" 1>&2
	return 2
}


#info
_info()
{
	[ $VERBOSE -eq 0 ] || echo "$PROGNAME: $@"
}


#usage
_usage()
{
	echo "Usage: $PROGNAME [-d directory][-qv] add command" 1>&2
	echo "       $PROGNAME [-d directory][-qv] exec" 1>&2
	echo "       $PROGNAME [-d directory][-qv] list" 1>&2
	return 1
}


#main
directory=
while getopts "O:d:qv" name; do
	case "$name" in
		O)
			export "${OPTARG%%=*}"="${OPTARG#*=}"
			;;
		d)
			directory="$OPTARG"
			;;
		q)
			VERBOSE=0
			;;
		v)
			VERBOSE=$((VERBOSE + 1))
			;;
		?)
			_usage
			exit $?
			;;
	esac
done
shift $((OPTIND - 1))
if [ $# -lt 1 ]; then
	_usage
	exit $?
fi

exec 3>&1

method="_usage"
case "$1" in
	add|list|exec)
		method="_database_$1"
		;;
	*)
		_error "$1: Operation not supported"
		;;
esac
shift

if [ -n "$directory" ]; then
	(cd "$directory" && "$method" "$@")
else
	"$method" "$@"
fi