#!/bin/bash

# Copyright (c) 2002, 2003, 2004, 2005 Peter Palfrader <peter@palfrader.org>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

umask 037

set -e
set -u

DATE=`date "+%Y%m%d-%H%M%S"`
if [ -d /var/backups/local/mysql ]; then
	TARGET=/var/backups/local/mysql
elif [ -d /var/local/backup/mysql ]; then
	TARGET=/var/local/backup/mysql
elif [ -d /aux/dbbackup/mysql ]; then
	TARGET=/aux/dbbackup/mysql
else
	echo "Cannot find a backup target directory" >&2
	exit 1
fi

HOSTS="$@"
if [ -z "$HOSTS" ]; then
	HOSTS="localhost"
fi

if [ -z "${CONCURRENCY_LEVEL:-}" ]; then
	CONCURRENCY_LEVEL=1
fi

for host in $HOSTS; do
	if [ "$host" = "localhost" ]; then
		prefix="";
		postfix="";
	else
		shorthost=`echo "$host" | sed -e 's/\..*//'`
		prefix="$shorthost--";
		postfix="--$shorthost";
	fi
	mysqlcnf="$HOME/.my.cnf$postfix"
	if ! [ -e "$mysqlcnf" ]; then
		echo "Cannot find my.cnf for host $host: $mysqlcnf" >&2
		exit 1
	fi
	if grep '^host=' "$mysqlcnf" > /dev/null; then
		hostarg=""
	else
		hostarg="--host=$host"
	fi

	DBs=$(
	echo 'SHOW DATABASES;' | mysql --defaults-file="$mysqlcnf" ${hostarg:+"$hostarg"} | tail -n +2 |
	while read db; do
		if [ "$db" = "innodb" ] || [ "$db" = "test" ] || [ "$db" = "lost+found" ] ; then
			continue;
		fi
		echo $db;
	done
	);

	for db in $DBs; do
		file="$TARGET/$DATE-$prefix$db"
		mysqldump --defaults-file="$mysqlcnf" ${hostarg:+"$hostarg"} --opt --lock-tables -- "$db" > "$file"
	done

	for db in $DBs; do
		file="$TARGET/$DATE-$prefix$db"
		echo $file
	done | xargs --no-run-if-empty --max-procs "$CONCURRENCY_LEVEL" -n 1 bzip2

	for db in $DBs; do
		file="$TARGET/$DATE-$prefix$db"

		md5=`md5sum -- "$file.bz2" | awk '{print $1}'`
		if [ -e "$TARGET/MD5-$md5" ]; then
			rm -- "$file.bz2"
			ln "$TARGET/MD5-$md5" "$file.bz2"
		else
			ln "$file.bz2" "$TARGET/MD5-$md5"
		fi
	done
done