#!/bin/bash


function helpexit() {
    echo "Print your public internet IP address."
    echo "-n  return as host name."
    echo "-l  display only local addresses."
    echo "-j  JSON output from ifconfig.co"
    exit
}
function locals_only() {
  ip -4 -o addr | awk '!/^[0-9]*: ?lo|link\/ether/ {printf "%18s  %s\n", $4, $2}' | sort -k 2
  exit $?
}
function ifconfig_service() {
  which curl &>/dev/null && {
    curl -4 ifconfig.co/json; exit $?
  }
  which wget &>/dev/null && {
    wget -q -O - ifconfig.co/json; exit $?
  }
}

for (( i=1; i<=$#; i++ )); do
  [[ "${!i}" = "--help" ]] && helpexit                                            
  [[ "${!i}" = "-h" ]] && helpexit                                            
done
for (( i=1; i<=1; i++ )); do
  [[ "${!i}" = "-n" ]] && { NAME=1; continue; }
  [[ "${!i}" = "-l" ]] && { LOCAL=1; continue; }
  [[ "${!i}" = "-j" ]] && { JSON=1; continue; }
done                       

if [[ "$LOCAL" -eq 1 ]]; then
  locals_only
fi

if [[ "$JSON" -eq 1 ]]; then
  ifconfig_service
fi

which dig &> /dev/null || {
  echo Install apt dnsutils >&2
  exit 1
} 
   

IP=$( dig +short myip.opendns.com @resolver1.opendns.com )
if [[ -z "$IP" ]]; then
    IP=$( curl -s -4 ifconfig.co/ip )
fi

if [[ "$NAME" -eq 1 ]]; then 
  output=$( dig +short -x "$IP" )
else
  output="$IP"
fi

if [[ -z "$output" ]]; then
  exit 1
fi
echo "$output"