#!/bin/sh

# Configuration
# Files will be named BASE_DIR/PREFIXEbasenameSUFFIXE
BASE_DIR="/var/backups/bdd"
MYSQL_EXTRA_ARGS=""
MYSQLDUMP_EXTRA_ARGS="--add-drop-table"
PREFIXE="sauv_mysql_"
SUFFIXE=_$( date +%Y%m%d-%H%M%S ).sql.gz
NB_DAYS_BEFORE_DELETION="30"
BASES_EXCLUDED="mysql
information_schema
performance_schema"

# Small note for a backup of a random directory in crontab
#  test -d /var/backups/www && cd /var/www && tar -czf /var/backups/www/www_$( date +\%Y\%m\%d-\%H\%M\%S ).tar.gz ./ && find /var/backups/www -maxdepth 1 -name 'www_*' -mtime +10 -delete

# Stop at first non-catched error
set -e

#
# Help function
#
usage() {
	TMP_BASES_EXCLUDED="$( echo "$BASES_EXCLUDED" | tr '\n' " " )"
	cat <<EOF
Usage :
  $0 [ -x mysql_extra_arg ] [ -X mysqldump_extra_args ] [ -d nb_days_before_deletion ] [ -B base_dir ] [ -p prefix ] [ -z -e base_excluded ] [ base base...]

Example :
  $0 -e mysql -e information_schema -e performance_schema -d 10

Default values :
	mysql_extra_args: "$MYSQL_EXTRA_ARGS"  (for ex.: "--defaults-extra-file=/var/backup/my.cnf" )
	mysqldump_extra_args: "$MYSQLDUMP_EXTRA_ARGS"  (for ex.: "--defaults-extra-file=/var/backup/my.cnf --add-drop-table" )
	nb_days_before_deletion : "$NB_DAYS_BEFORE_DELETION" (if <0 deactivate)
	base_dir : "$BASE_DIR"
	prefix : "$PREFIXE"
	base_excluded : "$TMP_BASES_EXCLUDED"
	base base ... : by default, take every base shown by SHOW DATABASES
EOF
}

# Lower script priority
renice -n 20 $$ >/dev/null 2>&1

#
# Parameters management
#
while getopts hd:B:p:ze:x:X: f; do
	case "$f" in
		'h')
			usage
			exit
			;;

		'd')
			NB_DAYS_BEFORE_DELETION="$OPTARG"
			;;

		'B')
			BASE_DIR="$OPTARG"
			;;

		'p')
			PREFIXE="$OPTARG"
			;;

		'z')
			BASES_EXCLUDED=""
			;;

		'e')
			if [ -z "$BASES_EXCLUDED" ]; then
				BASES_EXCLUDED="$OPTARG"
			else
				BASES_EXCLUDED="$( printf "%s\n%s" "$BASES_EXCLUDED" "$OPTARG" )"
			fi
			;;

		'x')
			MYSQL_EXTRA_ARGS="$OPTARG"
			;;

		'X')
			MYSQLDUMP_EXTRA_ARGS="$OPTARG"
			;;

		\?)
			usage
			exit 1
			;;

	esac
done
shift $( expr $OPTIND - 1 )

# Initial checks
if [ ! -d "$BASE_DIR" ]; then
	echo "ERREUR : répertoire de sauvegarde inexistant : $BASE_DIR ." >&2
	exit 1
fi

if [ -z "$@" ]; then
	# Listing des bases à sauvegarder
	BASES="$( mysql $MYSQL_EXTRA_ARGS -Bse "SHOW DATABASES;" )"
else
	BASES="$@"
fi

# Loop on bases' names
# We try to have a little fun here : MySQL can be quite laxist
# on base names, so we use <newline> as a separator. Quite a gymnastic
# ensue :)
printf "%s\n" "$BASES" | while read BASENAME; do
	IFS="
"
	for EXCLUDED_NAME in $BASES_EXCLUDED; do
		if [ "$BASENAME" = "$EXCLUDED_NAME" ]; then
			unset IFS
			continue 2
		fi
	done
	unset IFS
	mysqldump $MYSQL_EXTRA_ARGS "$BASENAME" | gzip -c > "$BASE_DIR/$PREFIXE$BASENAME$SUFFIXE"
done


# Deletion of old backups
if [ "$NB_DAYS_BEFORE_DELETION" -gt "0" ]; then
	find $BASE_DIR -maxdepth 1 -name "$PREFIXE*" -mtime +$NB_DAYS_BEFORE_DELETION -delete
fi