#!/bin/bash
#
# Source:
# https://gitea.evolix.org/evolix/ansible-roles/src/branch/stable/nagios-nrpe
#

readonly VERSION="21.04"

# Location of disable files
readonly base_dir="/var/lib/monitoringctl"

# If no datetime is found in file, this value is used
readonly default_disabled_time="1d"


show_version() {
    cat <<END
alerts_wrapper version ${VERSION}

Copyright 2018-2021 Evolix <info@evolix.fr>,
                    Jérémy Lecour <jlecour@evolix.fr>
                    and others.

alerts_wrapper comes with ABSOLUTELY NO WARRANTY.This is free software,
and you are welcome to redistribute it under certain conditions.
See the GNU General Public License v3.0 for details.
END
}

show_help() {
    cat <<END
alerts_wrapper wraps an NRPE command and overrides the return code.

Usage: alerts_wrapper --name <CHECK_NAME> <CHECK_COMMAND>
Usage: alerts_wrapper <CHECK_NAME> <CHECK_COMMAND> (deprecated)

Options
  --name               Check name (like load, disk1…)
                       Special name: 'all' is already hard-coded.
  -h, --help           Print this message and exit.
  -V, --version        Print version and exit.
END
}

time_to_seconds() {
    # $1: formated time string
    if echo "${1}" | grep -E -q '^([0-9]+[wdhms])+$'; then
        echo "${1}" | sed 's/w/ * 604800 + /g; s/d/ * 86400 + /g; s/h/ * 3600 + /g; s/m/ * 60 + /g; s/s/ + /g; s/+ $//' | xargs expr
    elif echo "${1}" | grep -E -q '^([0-9]+$)'; then
        echo "${1} * 3600" | xargs expr
    else
        return 1
    fi
}

delay_from_disable_file() {
    # $1: disabled file containing the re-enable time in sec
    enable_secs=$(grep -v -E "^\s*#" "${1}" | grep -E "[0-9]+" | head -n1 | awk '{print $1}')
    # If file is empty, use file last change date plus default disabled time
    if [ -z "${enable_secs}" ]; then
        file_last_change_secs=$(stat -c %Z "$1")
        default_disabled_time_secs="$(time_to_seconds "${default_disabled_time}")"
        enable_secs="$(( file_last_change_secs + default_disabled_time_secs))"
    fi

    now_secs=$(date +"%s")
    echo $(( enable_secs - now_secs ))
}

delay_to_string() {
    #$1 delay in secs
    delay_days="$(( delay /86400 ))"
    if [ "${delay_days}" -eq 0 ]; then delay_days=""
    else delay_days="${delay_days}d "; fi

    delay_hours="$(( (delay %86400) /3600 ))"
    if [ "${delay_hours}" -eq 0 ]; then delay_hours=""
    else delay_hours="${delay_hours}h "; fi

    delay_minutes="$(( ((delay %86400) %3600) /60 ))"
    if [ "${delay_minutes}" -eq 0 ]; then delay_minutes=""
    else delay_minutes="${delay_minutes}m "; fi

    delay_seconds="$(( ((delay %86400) %3600) %60 ))"
    if [ "${delay_seconds}" -eq 0 ]; then delay_seconds=""
    else delay_days="${delay_days}s "; fi

    echo "${delay_days}${delay_hours}${delay_minutes}${delay_seconds}"
}

is_disabled() {
    # $1: disabled file containing the re-enable time in sec
    if [ -e "$1" ]; then
        delay=$(delay_from_disable_file "$1")
        if [ "${delay}" -le "0" ]; then
            echo "False"
            enable_check "${check_name}"
        else
            echo "True"
        fi
    else
        echo False
    fi
}

enable_check() {
    # $1: check name
    if [ "$(id -u)" -eq "0" ] ; then
        /usr/local/bin/alerts_switch enable "$1"
    else
        sudo /usr/local/bin/alerts_switch enable "$1"
    fi
}

main() {
    is_disabled=$(is_disabled "${disable_file}")

    timeout_command=""
    if [ "${is_disabled}" == "True" ]; then
        timeout_command="timeout 9"
    fi

    check_stdout=$(${timeout_command} "${check_command}")
    check_rc=$?

    if [ "${is_disabled}" == "True" ] && [ "${check_rc}" -eq 124 ] && [ -z "${check_stdout}" ]; then
        check_stdout="Check timeout (9 sec)"
    fi

    if [ "${is_disabled}" == "True" ]; then
        delay=$(delay_from_disable_file "${disable_file}")
        delay_str="$(delay_to_string "${delay}")"
        echo "ALERTS DISABLED for ${check_name} until ${delay_str}."
    fi

    echo "${check_stdout}"

    if [ "${is_disabled}" == "True" ]; then
        if [ ${check_rc} = 0 ]; then
            exit 0  # Nagios OK
        else
            exit 1  # Nagios WARNING
        fi
    else
        exit ${check_rc}
    fi
}


if [[ "${1}" =~ -.* ]]; then
    # parse options
    # based on https://gist.github.com/deshion/10d3cb5f88a21671e17a
    while :; do
        case $1 in
            -h|-\?|--help)
                show_help
                exit 0
                ;;
            -V|--version)
                show_version
                exit 0
                ;;
            -n|--name)
                # with value separated by space
                if [ -n "$2" ]; then
                    check_name=$2
                    shift
                else
                    printf 'ERROR: "--name" requires a non-empty option argument.\n' >&2
                    exit 1
                fi
                ;;
            -n|--name=?*)
                # with value separated by =
                check_name=${1#*=}
                ;;
            -n|--name=)
                # without value
                printf 'ERROR: "--name" requires a non-empty option argument.\n' >&2
                exit 1
                ;;

            --)
                # End of all options.
                shift
                break
                ;;
            -?*)
                # ignore unknown options
                printf 'WARN: Unknown option : %s\n' "$1" >&2
                exit 1
                ;;
            *)
                # Default case: If no more options then break out of the loop.
                break
                ;;
        esac

        shift
    done
    # The rest is the command
    check_command="$*"
else
    # no option is passed (backward compatibility with previous version)
    # treat the first argument as check_name and the rest as the command
    check_name="${1}"
    shift
    check_command="$*"
fi

if [ -z "${check_name}" ]; then
    printf 'ERROR: You must specify a check name, with --names.\n' >&2
    exit 1
fi
if [ -z "${check_command}" ]; then
    printf 'ERROR: You must specify a command to execute.\n' >&2
    exit 1
fi

readonly check_name
readonly check_command
readonly disable_file="${base_dir}/${check_name}_alerts_disabled"

main