#!/bin/bash

[ "$1" = "set.txt" ] && . set.txt 2> /dev/null

varName="servicedesc"
varDefault=""
myDelim="[ :-]"
myField=""
myHost=""
myService=""
myContact=""
doLower=""
doUpper=""
doVerbose=""
doNCPA=""

do_help() {
cat << HELP_EOF
This utility is designed to be called by the ARGx parameters of a Nagios configuration as one of the following:

  \$\$(\$USER1\$/env [-n <var>] [-t <default>] [-f <field>] [-d <delim>] [-u] [-H|-S|-C <suffix>] [-v]
  \$\$(\$USER1\$/env -N [-H suffix]


Where:

  var     the name of a case-insensitive NAGIOS_variable (defaults to "servicedesc")
  default a default value if \$NAGIOS_var\$ is blank (case sensitive)
  field   an awk-compatible field number (potentially to use with <delim>)
  delim   an awk-compatible field delimiter (defaults to space, dash, and colon)
  -u      Convert the output to uppercase
  -l	  Convert the output to lowercase
  suffix  Take var result and use the it to get NAGIOS__[HOST|SERVICE|CONTACT]<result><suffix>
  -v      Be verbose (only for debugging)
  -N      Look for NAGIOS__HOSTNCPA<suffix> (defaults to TOKEN)
	Can do double lookup if -H is specified directly: -H TOKEN will find NAGIOS__HOSTNCPATOKEN=Level1 which then finds NAGIOS__HOSTLEVEL1TOKEN=Secret
	Or -H PASS will find NAGIOS__HOSTNCPAPASS=Level2 which will then find NAGIOS__HOSTLEVEL2PASS=SuperSecret


The value will always be trimmed of leading and/or trailing spaces/tabs.

If -f is used, then the result will be as if the request were as follows, unless the field starts with a negative, in which case it will read from the last word forward:

  echo \$NAGIOS_var\$ | awk -F <delim> '{print $<field>}'

Examples (service_description is assumed to be "MySQL Check: myDatabase performance"):

  .../env 				Return: "MySQL Check: myDatabase performance"
  .../env -n hostName			Return: "localhost" (or whatever the name of the host is that ran the check)
  .../env -n SERVICESTATE -t 0		Return: current state of the service (0, 1, 2) or 0 if the state is not defined
  .../env -n servicedesc -f 2		Return: "Check" (watch out for defaults!)
  .../env -n servicedesc -f 4		Return: "myDatabase" (watch out for defaults!)
  .../env -n servicedesc -d : -f 2	Return: "myDatabase performance"
  .../env -n servicedesc -d : -f -2 	Return: "MySQL Check" (2nd field from right, split by :)*
  .../env -n servicedesc -f -2 -H pass	Return: the value of \$NAGIOS__HOSTNAGIOSXIPASS\$

see https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/4/en/macrolist.html for possible macro names.
*0 for this field will print the entire line
HELP_EOF
  exit
}

while [ -n "$1" ]; do
  case "$1" in
    -h|--help) do_help;;
    -n) varName="$2"; shift 2;;
    -t) varDefault="$2"; shift 2;;
    -d) myDelim="$2"; shift 2;;
    -f) myField="$2"; shift 2;;
    -H) myHost="$2"; shift 2;;
    -S) myService="$2"; shift 2;;
    -C) myContact="$2"; shift 2;;
    -N) doNCPA="true"; shift 1;;
    -u) doUpper="true"; shift 1;;
    -l) doLower="true"; shift 1;;
    -v) doVerbose="true"; shift 1;;
    *) shift 1;;
  esac
done

do_debug() {
  [ -n "$doVerbose" ] && echo "DEBUG: $*"
}

if [ -n "$doNCPA" ]; then
  do_debug "NCPA mode active. myHost=$myHost"
  varName=`echo "NAGIOS__HOSTNCPA${myHost:-token}" | tr "a-z" "A-Z"`
else
  do_debug "NCPA mode NOT active."
  varName=`echo "NAGIOS_$varName" | tr "a-z" "A-Z"`
fi
do_debug "Looking for $varName..."
varValue="${!varName}"
do_debug "Got varValue=$varValue"
if [ -n "$myField" ]; then
  do_debug "myField=$myField"
  if [ "$myField" -lt 0 ]; then
    varValue=`echo "$varValue" | rev | awk -F "$myDelim" -v f="${myField:1}" '{print $f}' | rev`
  else
    varValue=`echo "$varValue" | awk -F "$myDelim" -v f="$myField" '{print $(f)}'`
  fi
fi
varValue=`echo $varValue | sed -e "s/^[ \t]*//" -e "s/[ \t]*$//"`
do_debug "After processing varValue=$varValue"

[ -n "$doUpper" ] && varValue=`echo "$varValue" | tr "a-z" "A-Z"`
[ -n "$doLower" ] && varValue=`echo "$varValue" | tr "A-Z" "a-z"`

# Check for myHost
if [ -n "$myHost" ]; then
  myHost=`echo "NAGIOS__HOST${varValue}${myHost}" | tr "a-z" "A-Z"`
  do_debug "myHost=$myHost"
  varValue=${!myHost}
fi

# Check for myService
if [ -n "$myService" ]; then
  myService=`echo "NAGIOS__SERVICE${varValue}${myService}" | tr "a-z" "A-Z"`
  do_debug "myService=$myService"
  varValue=${!myService}
fi

# Check for myContact
if [ -n "$myContact" ]; then
  myContact=`echo "NAGIOS__CONTACT${varValue}${myContact}" | tr "a-z" "A-Z"`
  do_debug "myContact=$myContact"
  varValue=${!myContact}
fi

[ -z "$varValue" ] && varValue="$varDefault"
echo "$varValue"

exit 0