{ pkgs ? import <nixpkgs> { } }:

with pkgs;

let
  mysql_file = "mysql.sql";
  psql_file = "psql.sql";
  mysql_dir = "$(pwd)/.mysql";
  psql_dir = "$(pwd)/.pgdata";
  socket = "${mysql_dir}/mysql.sock";

in mkShell {
  buildInputs = [ mysql57 postgresql pgloader ];

  shellHook = ''
    trap "kill 0" EXIT
    export PGDATA="${psql_dir}"
    export PGHOST="${psql_dir}"

    # MySQL initialization
    if [ ! -d ${mysql_dir} ]; then
      mysqld --datadir="${mysql_dir}" --socket="${socket}" --initialize-insecure
    fi
    mysqld --datadir="${mysql_dir}" --socket="${socket}" --skip-networking &
    sleep 1

    # PostgreSQL initialization
    if [ ! -d ${psql_dir} ]; then
      initdb --auth-local=trust --no-locale --encoding=UTF8
    fi
    pg_ctl start -o "--unix_socket_directories=${psql_dir} --listen_addresses='''"

    mysql --socket="${socket}" -u root < ${mysql_file}
    psql -d postgres -f ${psql_file}

    alias mysql='mysql --socket="${socket}" -u root'
    alias psql='psql -d postgres'
  '';
}