#! /bin/sh

# Copyright (c) 2019-2020 Stefan Kreutz <mail@skreutz.com>
#
# Permission to use, copy, modify, and distribute this software for any purpose
# with or without fee is hereby granted, provided that the above copyright
# notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

# Run the PostgreSQL server off a temporary data directory.
#
# Expects exactly two arguments: database name and user name. You may also set
# the port by setting the environment variable PGPORT, see postgres(1).
#
# Exits 0 on SIGINT, and >0 if an error occurs.
#
# First published at https://www.skreutz.com/posts/temporary-postgresql-server/
# on 14 October 2020.

set -o nounset

# Remove the temporary directory before exiting.
trap 'quit' INT
quit() {
  code="${1:-0}"
  trap '' INT TERM
  kill -TERM 0
  wait
  rm -rf "${tmpdir-}" || {
    ( >&2 printf "temp-postgres: failed to remove temporary directory: %s\\n" "${tmpdir}" )
    [ "${code}" -ne 0 ] || code=1
  }
  exit "${code}"
}

# Parse arguments.
[ $# -eq 2 ] || {
  ( >&2 printf "temp-postgres: invalid arguments\\n" )
  printf "Usage: temp-postgres <dbname> <username>\\n"
  quit 1
}
dbname="$1"
username="$2"

# Create a temporary directory
tmpdir="$( mktemp -d )" || {
  ( >&2 printf "temp-postgres: failed to create temporary directory\\n" )
  quit 1
}

# Initialize the directory
initdb --pgdata="${tmpdir}" --username="${username}" || {
  ( >&2 printf "temp-postgres: failed to initialize database\\n" )
  quit 1
}

# Serve the directory
( postgres -k "${tmpdir}" -D "${tmpdir}" </dev/null ) &

# Test the connection
sleep 1
pg_isready --host="${tmpdir}" --dbname="nope" --username="${username}" --timeout=10 || {
  ( >&2 printf "temp-postgres: failed to connect to server\\n" )
  quit 1
}

# Create the database
createdb --host="${tmpdir}" --username="${username}" --no-password "${dbname}" || {
  ( >&2 printf "temp-postgres: failed to create database\\n" )
  quit 1
}

printf '
Connect with the following command:

\tpsql --host=localhost "%s" "%s"

' "${dbname}" "${username}"

wait