#!/usr/bin/env bash
# bash strict mode http://redsymbol.net/articles/unofficial-bash-strict-mode/
set -euo pipefail
IFS=$'\n\t'

# This script verifies that the postgresql data directory has been correctly
# initialized.  We do not want to automatically initdb it, because that has
# a risk of catastrophic failure (ie, overwriting a valuable database) in
# corner cases, such as a remotely mounted database on a volume that's a
# bit slow to mount.  But we can at least emit a message advising newbies
# what to do.

# PGMAJORVERSION is major version
PGMAJORVERSION=9.4
# PREVMAJORVERSION is the previous major version, e.g., 8.4, for upgrades
PREVMAJORVERSION=9.3

if [ ! -z "$1" ]; then
	PGDATA=$1
fi
if [ ! -d "$PGDATA" ]; then
	echo "Usage: $0 database-path"
	exit 1
fi
export PGDATA

# Check for the PGDATA structure
if [ ! -f "$PGDATA/PG_VERSION" ] || [ ! -d "$PGDATA/base" ]; then
	# No existing PGDATA! Warn the user to initdb it.
	cat <<-EOF
		$PGDATA is missing or empty. Use a command like
		  sudo -u postgres initdb --locale en_US.UTF-8 -D '$PGDATA'
		with relevant options, to initialize the database cluster.
	EOF
	exit 1
fi


current_version=$(cat "$PGDATA/PG_VERSION")
case $current_version in
	$PGMAJORVERSION)
		;;
	$PREVMAJORVERSION)
		cat <<-EOF
			An old version of the database format was found.
			See https://wiki.archlinux.org/index.php/PostgreSQL#Upgrading_PostgreSQL
		EOF
		exit 1
		;;
	*)
		cat <<-EOF
			An old version of the database format was found.
			You need to dump and reload before using PostgreSQL $PGMAJORVERSION.
			See http://www.postgresql.org/docs/$PGMAJORVERSION/static/upgrading.html
		EOF
		exit 1
esac

# Tabs are significant for `<<-`
# vim: noexpandtab