#!/usr/bin/env bash
set -e

POSTGRES_USER="postgres"
if [ "$(uname)" = "OpenBSD" ]; then
  POSTGRES_USER="_postgresql"
fi

cd /

username=$1

shift
tables="$(printf "'%s'," "${@//\'/\'\'}")"
tables="${tables%,}"

case "$(id -un)" in
root)
    psql=(su -s /usr/bin/env - -- "$POSTGRES_USER" psql postgres "$POSTGRES_USER")
    ;;
"$POSTGRES_USER")
    psql=(psql postgres "$POSTGRES_USER")
    ;;
*)
    psql=(psql -h localhost postgres "$username")
    ;;
esac

"${psql[@]}" -v ON_ERROR_STOP=1 <<EOF
SELECT pg_terminate_backend(s.pid)
    FROM pg_stat_activity s, pg_roles r
    WHERE
        s.datname IN ($tables)
        AND r.rolname = CURRENT_USER
        AND (s.usename = r.rolname OR r.rolsuper = 't');
EOF