#!/bin/bash
set -e

# Get script name
SCRIPT=$(basename "$0")

# Display Help
Help() {
  echo
  echo "$SCRIPT"
  echo
  echo "Description: Backup Docker Postgres database."
  echo "Syntax: $SCRIPT [-d|-a|-o|-c|help]"
  echo "Example: $SCRIPT -d postgres,odoo -o /tmp -c postgres01"
  echo "options:"
  echo "  -d    Comma-separated list of database names."
  echo "  -a    Backup all databases"
  echo "  -o    Output directory. Defaults to '/var/tmp'."
  echo "  -c    Docker container name. Defaults to 'postgres'."
  echo "  help  Show $SCRIPT manual."
  echo
}

# Show help and exit
if [[ "$1" == "help" ]]; then
  Help
  exit
fi

# Initialise option flag with a false value
ALL='false'

# Process params
while getopts ":a :c: :d: :o:" opt; do
  case $opt in
    a) ALL='true'
    ;;
    c) CONTAINER="$OPTARG"
    ;;
    d) DATABASES="$OPTARG"
    ;;
    o) DIR="$OPTARG"
    ;;
    \?) echo "Invalid option -$OPTARG" >&2
    Help
    exit;;
  esac
done

# Fallback to environment vars and default values
: ${DIR:='/var/tmp'}
: ${CONTAINER:='postgres'}

# Verify variables
[[ -z "$DATABASES" ]] && [[ "$ALL" == "false" ]] && { echo "Parameter -d or -a|databases or all must be set" ; exit 1; }
[[ -z "$DIR" ]] && { echo "Parameter -d|dir is empty" ; exit 1; }

if $ALL ; then
  # Get all databases from docker container
  DATABASE_LIST=($(docker exec "$CONTAINER" /bin/bash -c "psql -U \$POSTGRES_USER \
    template1 -q -A -t -c 'SELECT datname FROM pg_database WHERE datistemplate = false;'"))
  # Concate database list
  printf -v DATABASES '%s,' "${DATABASE_LIST[@]}"
  DATABASES="${DATABASES%,}"
fi

if [[ ! -z $DATABASES ]] ; then
  # Split database param values
  DATABASE_LIST=($(echo $DATABASES | tr "," "\n"))
fi

# Create backup folder
mkdir -p ${DIR}/${CONTAINER}

# Cleanup backup folder
rm -rf ${DIR}/${CONTAINER}/*

# Create dump with docker for each database
for DATABASE in "${DATABASE_LIST[@]}"
do
  echo "Run Docker Postgres backup for $DATABASE"
  docker exec $CONTAINER /bin/bash -c "pg_dump -U \$POSTGRES_USER $DATABASE" > "${DIR}/${CONTAINER}/${DATABASE}.sql"
done

# Notify if backup has finished
echo "The Docker Postgres backup has finished: ${DIR}/${CONTAINER}/{${DATABASES}}.sql"