#!/usr/bin/env bash

set -o pipefail

PATH="$PATH:/usr/local/bin:/usr/local/sbin"

SCRIPT_LOG=/var/log/backup_mysql.log

DB_USER=""

DB_PASSWORD=""

DB_HOST=""

DB_LIST=()

DUMP_OPTIONS="--single-transaction --quick --no-autocommit --force --add-drop-table --skip-add-locks"

DUMP_FOLDER=/backups/tmp

ARCHIVE_NAME=archive.tar.gz

DESTINATION_FOLDER=/backups


function LOG()
{
	local msg="$1"
	date=$(date '+%Y-%m-%d %H:%M:%S')
	echo "[$date]	$msg" >> $SCRIPT_LOG
}

function DELETE_TMP_FOLDER()
{
	if [ -d "${DUMP_FOLDER}" ]; then
		rm -rf "${DUMP_FOLDER}" &> /dev/null
		if [ $? -ne 0 ]; then
		    LOG "ERROR: Can not delete ${DUMP_FOLDER}"
		    exit 2
		else 
		    LOG "SUCCESS: Delete ${DUMP_FOLDER}"
		fi
	fi
}

function CREATE_TMP_FOLDER()
{
	if [ -d "${DUMP_FOLDER}" ]; then
		LOG "ERROR: Dump folder ${DUMP_FOLDER} exists."
		exit 2
	else
		mkdir -p "${DUMP_FOLDER}" &> /dev/null
		if [ $? -ne 0 ]; then
			LOG "ERROR: Create dump folder ${DUMP_FOLDER} failed."
			DELETE_TMP_FOLDER
			exit 2
		else
			LOG "SUCCESS: ${DUMP_FOLDER} is created."
		fi
	fi
}

function READ_DBS()
{

	sql="SHOW DATABASES WHERE \`Database\` NOT IN('information_schema', 'performance_schema', 'mysql')"

	DB_LIST=$(mysql -N --host=${DB_HOST} --user=${DB_USER} --password=${DB_PASSWORD} -e "$sql") &> /dev/null
	if [ $? -ne 0 ]; then
	    LOG "ERROR: Getting list of databases failed."
            DELETE_TMP_FOLDER	    
	    exit 2
	else
		if [[ -n $DB_LIST ]]; then
		        LOG "SUCCESS: Getting list of databases success."
		else
			LOG "ERROR: List of databases is empty."
			DELETE_TMP_FOLDER
			exit 2
		fi
	fi
}


function CHECK_DISK_USAGE()
{
	sql="SELECT table_schema , ROUND(SUM(data_length + index_length) / 1024 / 1024, 0)  FROM information_schema.TABLES;"
	
        DBS_SIZE=$(mysql -N --host=${DB_HOST} --user=${DB_USER} --password=${DB_PASSWORD} -e "$sql"| awk '{print $2}') &> /dev/null
	if [ $? -eq 0 ] ; then
	    LOG "SUCCESS: Determining the size of MySQL databases."
	else
	    LOG "ERROR: Determining the size of MySQL databases failed."
	    exit 2
	fi        
	
	DST_AVAIL_SIZE=$(df -m ${DESTINATION_FOLDER} | awk 'NR==2{print $4}') &> /dev/null
	if [ $? -eq 0 ] ; then
	    LOG "SUCCESS: Determining the amount of available disk space on ${DESTINATION_FOLDER} partition."
	else
	    LOG "ERROR: Determining the amount of available disk space on ${DESTINATION_FOLDER} partition failed."
	    exit 2
	fi        

	
	if [ $DST_AVAIL_SIZE -lt $DBS_SIZE ] ; then
	    LOG "ERROR: There is not ${DESTINATION_FOLDER} enough available disk space."
	    exit 2
	else
	    LOG "SUCCESS: There is ${DESTINATION_FOLDER} enough available disk space."
	fi
}

function DUMP_DBS()
{
	for DB_NAME in $DB_LIST
	do
		LOG "Dumping ${DB_NAME}..."
		mysqldump --host=${DB_HOST} --user=${DB_USER} --password=${DB_PASSWORD} ${DUMP_OPTIONS} ${DB_NAME} > ${DUMP_FOLDER}/${DB_NAME}.sql

		if [ $? -eq 0 ] ; then
		    LOG "SUCCESS: Dump ${DB_NAME} is created."
		else
		    LOG "ERROR: Dump ${DB_NAME} is failed."
		    DELETE_TMP_FOLDER
		    exit 2
		fi
	done
}

function COMPRESS_DUMPS()
{
	(cd ${DUMP_FOLDER} && tar cf - *.sql) | gzip -9 > ${DUMP_FOLDER}/${ARCHIVE_NAME}

	if [ $? -eq 0 ] ; then
	    LOG "SUCCESS: Archive has been created."
	else
	    LOG "ERROR: Archive creation failed."
	    DELETE_TMP_FOLDER
	    exit 2
	fi	
}

function CHECK_ARCHIVE()
{
	tar -tf ${DUMP_FOLDER}/${ARCHIVE_NAME} &> /dev/null;
	if [ $? -eq 0 ] ; then
		LOG "SUCCESS: Archive verification completed."
	else
		LOG "ERROR: Archive verification failed"
		DELETE_TMP_FOLDER
		exit 2
	fi
}

function MOVE_ARCHIVE()
{
	date=$(date '+%Y-%m-%d_%H-%M')
	mv ${DUMP_FOLDER}/${ARCHIVE_NAME} ${DESTINATION_FOLDER}/${DB_HOST}_${date}.tar.gz &> /dev/null
	if [ $? -eq 0 ] ; then
		LOG "SUCCESS: Archive has been moved."
	else
		LOG "ERROR: Archive moving failed"
		DELETE_TMP_FOLDER
		exit 2
	fi
	
}


LOG "### Backup mysql started ###"
LOG "Checking the amount of available disk space on ${DESTINATION_FOLDER} partition."
CHECK_DISK_USAGE
LOG "Creatting temporary folder:"
CREATE_TMP_FOLDER
LOG "Getting list of databases:"
READ_DBS
LOG "Dump databases:"
DUMP_DBS
LOG "Compressing dumps:"
COMPRESS_DUMPS
LOG "Checking  archive:"
CHECK_ARCHIVE
LOG "Moving archive:"
MOVE_ARCHIVE
DELETE_TMP_FOLDER
LOG "### Backup mysql ended ###"