#!/usr/bin/env bash

function help() {
    echo "Check the number of proftpd user with 'ftpcount' output."
    echo "Usage:"
    echo "    check_proftpd_user -w|warning <WARN_THRESHOLD> -c|critical <CRITICAL_THRESHOLD>"
}


warn="-1"
crit="-1"

while [ $# -gt 0 ]; do
    case "${1}" in
        -h|--help)
            show_help
            exit 0
            ;;
        -c|--critical)
            crit="${2}"
            shift
            shift
            ;;
        -w|--warning)
            warn="${2}"
            shift
            shift
            ;;
        *)
            >&2 echo "Error: unknown argument ${1}, exit."
            help
            exit 3
    esac
done

if [ "${warn}" == "-1" ]; then
    echo "Error: warning threshold no defined, exit."
    help
    exit 3
fi

if [ "${crit}" == "-1" ]; then
    echo "Error: critical threshold no defined, exit."
    help
    exit 3
fi
if [[ "${warn}" =~ [^0-9] ]]; then
    echo "Error: warning threshold must be an integer, exit."
    help
    exit 3
fi
if [[ "${crit}" =~ [^0-9] ]]; then
    echo "Error: critical threshold must be an integer, exit."
    help
    exit 3
fi

if ! command -v ftpcount > /dev/null; then
    echo "Error: missing 'ftpcount' command, cannot check users count."
    exit 3
fi

n_users="$(ftpcount | awk '/users/{print $4}')"

if [ "${n_users}" -gt "${crit}" ]; then
    echo "CRITICAL - ${n_users} ftp users connected (warning: ${warn}, critical: ${crit})"
    exit 2
elif [ "${n_users}" -gt "${warn}" ]; then
    echo "WARNING - ${n_users} ftp users connected (warning: ${warn}, critical: ${crit})"
    exit 1
else
    echo "OK - ${n_users} ftp users connected (warning: ${warn}, critical: ${crit})"
    exit 0
fi