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

vergte() {
    [ "$1" = "`echo -e "$1\n$2" | sort -V | tail -n1`" ]
}

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

cd /
if [ "$EUID" -eq 0 ]; then
    version=$(sudo -u "$DEFAULT_USER"  sh -c 'psql -A -t -d postgres -c "show server_version"')
else
    version=$(psql -A -t -d postgres -c "show server_version")
fi

major=$(echo $version | cut -d. -f1,2)
username=$1

shift
tables=$(echo "'$@'" | sed "s/ /','/g")
if vergte "$major" "9.2"; then
    pidname="pid"
else
    pidname="procpid"
fi

if [ "$EUID" -eq 0 ]; then
    sudo -u "$DEFAULT_USER" sh -c "psql postgres '$DEFAULT_USER'" <<EOF
SELECT pg_terminate_backend($pidname) FROM pg_stat_activity WHERE datname IN ($tables);
EOF
else
    psql -h localhost postgres "$username" <<EOF
SELECT pg_terminate_backend($pidname) FROM pg_stat_activity WHERE datname IN ($tables);
EOF
fi