#!/bin/bash
set -e

DB_NAME=$1
MAX_BACKUPS=${MAX_BACKUPS:-30}
DB_USER=${DB_USER:-"postgres"}
DB_HOST=${DB_HOST:-""}
PGPASSWORD=$DB_PASSWORD
BACKUP_DIR=${BACKUP_DIR:-"backups"}
BACKUP_FILE=$BACKUP_DIR/$DB_NAME'_'$(date +%F_%T).pgdump

if [[ ! -d $BACKUP_DIR ]]; then
    echo "Creating backup dir"
    mkdir -p $BACKUP_DIR
fi

echo "Creating backup of $DB_NAME"
pg_dump\
    --format=custom\
    --host=$DB_HOST\
    --username=$DB_USER\
    --file=$BACKUP_FILE\
    --dbname=$DB_NAME

echo "Removing old backups"
offset=$(($MAX_BACKUPS + 1))  # tail needs N+1 offset
old_backups=$(find "$BACKUP_DIR" -type f -name "$DB_NAME"_* | sort -r | tail -n +$offset)
if [[ $old_backups != "" ]]; then
    echo $old_backups | xargs rm
fi

echo "Done"