#!/usr/bin/env bash

#
# nagios-acknowledge(1) -- Shortcut to acknowledge problems in Nagios, because
# it's annoying to do with the web interface for large sets of hosts or
# services.
#
#     $ nac (<host[/service][,host[/service],...>|-) [optional comment]
#
# You can specify multiple objects by separating them with commas:
#
#     $ nac abc-example-ap-1,abc-example-ap-2/VOLTAGE 'Power problems at abc-example'
#
# Even easier is to pipe them into stdin by specifying - as the object:
#
#     $ nul | grep abc-example | nac - 'Power problems at abc-example'
#
# By default, does not send ACKNOWLEDGEMENT notifications. Use -n if you do
# want that.
#
# Author: Tom Ryder <tom@sanctum.geek.nz>
# Copyright: 2016
#

# Name self
self=nagios-acknowledge

# Usage printing function
usage() {
    printf 'USAGE: %s [-n] (<host[/service][,host[/service],...>|-) [comment]\n' "$self"
}

# Default to not notifying
notify=0

# Figure out whether we should notify
OPTIND=1
while getopts 'hn' opt ; do
    case $opt in
        n)
            notify=1
            ;;
        h)
            usage
            exit 0
            ;;
        '?')
            usage >&2
            exit 1
            ;;
    esac
done
shift "$((OPTIND-1))"

# Bail if no arguments left; we need at least the host/service name
if ! (($#)) ; then
    usage >&2
    exit 1
fi

# Define relatively fixed/guaranteed fields for Nagios command; note that the
# comment has a default of 'no comment given'
now=$(date +%s)
spec=$1
sticky=1
notify=$notify
persistent=1
author=${SUDO_USER:-$USER}
comment=${2:-'no comment given'}
cmdfile=${NAGCMD_FILE:-/usr/local/nagios/var/rw/nagios.cmd}

# How to get the objects depends on the spec (the first argument)
declare -a objects
case $spec in

    # If the spec is just "-", we just read unique objects from stdin
    -)
        while read -r object ; do
            [[ $object ]] || continue
            objects[${#objects[@]}]=$object
        done < <(sort -u)
        ;;

    # If the spec is anything else, we break it up with commas and read the
    # objects that way
    *)
        IFS=, read -a objects -r < <(printf '%s\n' "$spec")
        ;;
esac

# All the hosts or services must exist, just to be strict; they don't
# necessarily have to be in a PROBLEM state though
for object in "${objects[@]}" ; do
    nagios-exists "$object" && continue
    printf '%s: Host/service %s does not seem to exist\n' \
        "$self" "$object" >&2
    exit 1
done

# Quietly replace semicolons in comment with commas
comment=${comment//;/,}

# Write commands to schedule downtime for each of the objects, bail if a single
# one of them fails
for object in "${objects[@]}" ; do
    case $object in
        */*)
            host=${object%/*}
            service=${object##*/}
            cmd=$(printf '[%lu] ACKNOWLEDGE_SVC_PROBLEM;%s;%s;%u;%u;%u;%s;%s' \
                "$now" "$host" "$service" \
                "$sticky" "$notify" "$persistent" "$author" "$comment")
            ;;
        *)
            host=$object
            cmd=$(printf '[%lu] ACKNOWLEDGE_HOST_PROBLEM;%s;%u;%u;%u;%s;%s' \
                "$now" "$host" \
                "$sticky" "$notify" "$persistent" "$author" "$comment")
            ;;
    esac
    printf '%s\n' "$cmd" > "$cmdfile" || exit
done

# Attempt to write command to file
if ! printf '%s\n' "$cmd" > "$cmdfile" ; then
    printf '%s: Failed to write command to file\n' "$self" >&2
    exit 1
fi