#!/bin/bash
[ -z "${MYSQL_USER}" ] && { echo "=> MYSQL_USER cannot be empty" && exit 1; }
[ -z "${MYSQL_PASS:=$MYSQL_PASSWORD}" ] && { echo "=> MYSQL_PASS cannot be empty" && exit 1; }
[ -z "${GZIP_LEVEL}" ] && { GZIP_LEVEL=6; }

DATE=$(date +%Y%m%d%H%M)
date=$(date +%Y%m%d)
dateValue=`date -R`
contentType="application/x-compressed-tar"
echo "=> [Backup MYSQL] started at $(date "+%Y-%m-%d %H:%M:%S")"
DATABASES=${MYSQL_DATABASE:-${MYSQL_DB:-$(mysql -h "$MYSQL_HOST" -P "$MYSQL_PORT" -u "$MYSQL_USER_ROOT" -p"$MYSQL_ROOT_PASSWORD" -e "SHOW DATABASES;" | tr -d "| " | grep -v Database)}}
DB_COUNTER=0
for db in ${DATABASES}
do
  if [[ "$db" != "information_schema" ]] && [[ "$db" != "performance_schema" ]] && [[ "$db" != "mysql" ]] && [[ "$db" != "sys" ]] && [[ "$db" != _* ]] 
  then
    echo "==> Dumping database: $db"
    FILENAME=/backup/$DATE.$db.sql
    LATEST=/backup/latest.$db.sql.gz
    if mysqldump --no-tablespaces -h "$MYSQL_HOST" -P "$MYSQL_PORT" -u "$MYSQL_USER_ROOT" -p"$MYSQL_ROOT_PASSWORD" $db $MYSQLDUMP_OPTS > "$FILENAME"
    then
      gzip "-$GZIP_LEVEL" -f "$FILENAME"
      if [ -n "$S3_BACKUP" ]
      then
        fname=$(basename "$FILENAME".gz)
        echo "Start sending $fname to S3"
        resource="/${S3_BUCKET}/${S3_LOCATION}/${date}/${db}/${fname}"
        stringToSign="PUT\n\n${contentType}\n${dateValue}\n${resource}"
        signature=`echo -en ${stringToSign} | openssl sha1 -hmac ${S3_SECRET} -binary | base64`
        curl -X PUT -T "${FILENAME}.gz" \
        -H "Host: ${S3_BUCKET}.s3.amazonaws.com" \
        -H "Date: ${dateValue}" \
        -H "Content-Type: ${contentType}" \
        -H "Authorization: AWS ${S3_KEY}:${signature}" \
          https://${S3_BUCKET}.s3.amazonaws.com/${S3_LOCATION}/${date}/${db}/${fname}
        echo "$fname has been sent to S3 successfully."
      fi
      echo "==> Creating symlink to latest backup: $(basename "$FILENAME".gz)"
      rm "$LATEST" 2> /dev/null
      cd /backup && ln -s $(basename "$FILENAME".gz) $(basename "$LATEST") && cd -
      DB_COUNTER=$(( DB_COUNTER + 1 ))
    else
      rm -rf "$FILENAME"
    fi
  fi
done

if [ -n "$MAX_BACKUPS" ]
then
  MAX_FILES=$(( MAX_BACKUPS * DB_COUNTER ))
  while [ "$(find /backup -maxdepth 1 -name "*.sql.gz" -type f | wc -l)" -gt "$MAX_FILES" ]
  do
    TARGET=$(find /backup -maxdepth 1 -name "*.sql.gz" -type f | sort | head -n 1)
    echo "==> Max number of backups ($MAX_BACKUPS) reached. Deleting ${TARGET} ..."
    rm -rf "${TARGET}"
    echo "==> Backup ${TARGET} deleted"
  done
fi

echo "=> [Backup MYSQL] process finished at $(date "+%Y-%m-%d %H:%M:%S")"