#!/bin/sh

set -e

MYSQL_USERNAME='root'
MYSQL_PASSWORD=''
MYSQL_HOST='127.0.0.1'
MYSQL_PORT='3306'

MYSQL_DATADIR='/var/lib/mysql'
MYSQL_BACKUP_BIN="/usr/bin/xtrabackup"
MYSQL_BACKUP_BASEDIR='/nfs/mysql-backup'
MYSQL_BACKUP_POSITION="$(cat "$MYSQL_BACKUP_BASEDIR/position" 2>/dev/null || true)"

if [ -z "$MYSQL_BACKUP_POSITION" ]; then
  MYSQL_BACKUP_INCRDIR="$MYSQL_BACKUP_BASEDIR/base"
  MYSQL_BACKUP_POSITION_NEXT="1"
else
  MYSQL_BACKUP_INCRDIR="$MYSQL_BACKUP_BASEDIR/inc$MYSQL_BACKUP_POSITION"
  MYSQL_BACKUP_POSITION_NEXT="$(expr $MYSQL_BACKUP_POSITION + 1)"
fi
MYSQL_BACKUP_TARGETDIR="$MYSQL_BACKUP_BASEDIR/inc$MYSQL_BACKUP_POSITION_NEXT"

printf "Performing backup to $MYSQL_BACKUP_TARGETDIR based on $MYSQL_BACKUP_INCRDIR\n"
"$MYSQL_BACKUP_BIN" \
  --backup \
  --target-dir="$MYSQL_BACKUP_TARGETDIR" \
  --incremental-basedir="$MYSQL_BACKUP_INCRDIR" \
  --datadir="$MYSQL_DATADIR" \
  --user="$MYSQL_USERNAME" \
  --password="$MYSQL_PASSWORD" \
  --host="$MYSQL_HOST" \
  --port="$MYSQL_PORT"

printf "Updating the incremental backup position\n"
echo "$MYSQL_BACKUP_POSITION_NEXT" > "$MYSQL_BACKUP_BASEDIR/position"

printf "All successful\n"