#!/usr/bin/env bash

#IPURL="https://icanhazip.com/ip"
IPURL="https://myip.syndicat.com"

print_usage(){
cat << EOI
Displays IP addresses of the current host used for internet connections.

Usage: myip [options]

Options:

  -6    Show only IPv6 addresses (public ip address by default).
  -4    Show only IPv4 addresses (public ip address by default).
  -h    Show usage help.
  -l    Show local insted of public addresses.
  -g    Show geolocation (using geoiplookup).

No options produces a more verbose output.
EOI
}

check_dependencies(){
  local FAIL=0
  for tool in "$@"
  do
    if ! hash "$tool" &> /dev/null
    then
      echo "The tool $tool does not exist."
      FAIL=1
    fi
  done
  if [[ "$FAIL" == 1 ]]
  then
    exit 1
  fi
}

print_public_ipv4_address(){
  echo "$(curl -s -4 -L $IPURL || echo "")"
}

print_public_ipv6_address(){
  echo "$(curl -s -6 -L $IPURL || echo "")"
}

print_public_ipv4_geolocation(){
  geoiplookup "$PUBLIC_IPV4_ADDRESS" | awk -F": " '{printf($2)}'
}

print_public_ipv6_geolocation(){
  geoiplookup6 "$PUBLIC_IPV6_ADDRESS" | awk -F": " '{printf($2)}'
}

print_local_ipv4_address(){
  echo "$(curl -s -4 -L --write-out %{local_ip} $IPURL -o /dev/null || echo "")"
}

print_local_ipv6_address(){
  echo "$(curl -s -6 -L --write-out %{local_ip} $IPURL -o /dev/null || echo "")"
}

main(){
  while getopts 46ghlv name
  do
    case "$name" in
    4)
      flag_4=1
    ;;
    6)
      flag_6=1
    ;;
    g)
      flag_g=1
    ;;
    h)
      print_usage
      exit
    ;;
    l)
      flag_l=1
    ;;
    ?)
      print_usage >&2
      exit 2
    ;;
    esac
  done

  if [[ -n $flag_l && -n $flag_4 ]]
  then
    print_local_ipv4_address
  fi
  if [[ -n $flag_l && -n $flag_6 ]]
  then
    print_local_ipv6_address
  fi

  if [[ -z $flag_l && -n $flag_4 ]]
  then
    print_public_ipv4_address
  fi
  if [[ -z $flag_l && -n $flag_6 ]]
  then
    print_public_ipv6_address
  fi

  if [[ -z $flag_l && -z $flag_4 && -z $flag_6 ]]
  then
    PUBLIC_IPV4_ADDRESS=$(print_public_ipv4_address)
    PUBLIC_IPV6_ADDRESS=$(print_public_ipv6_address)
    echo -e "Public IPv4 address:  ${PUBLIC_IPV4_ADDRESS:--}"
    echo -e "Public IPv6 address:  ${PUBLIC_IPV6_ADDRESS:--}"
    LOCAL_IPV4_ADDRESS=$(print_local_ipv4_address)
    LOCAL_IPV6_ADDRESS=$(print_local_ipv6_address)
    echo -e "Local IPv4 address:   ${LOCAL_IPV4_ADDRESS:--}"
    echo -e "Local IPv6 address:   ${LOCAL_IPV6_ADDRESS:--}"

    echo ""

    if [[ -n "$PUBLIC_IPV4_ADDRESS" && -n "$LOCAL_IPV4_ADDRESS" ]]
    then
      if [[ "$PUBLIC_IPV4_ADDRESS" != "$LOCAL_IPV4_ADDRESS" ]]
      then
        echo "IPv4: NAT"
      else
        echo "IPv4: No NAT"
      fi
    fi

    if [[ -n "$PUBLIC_IPV6_ADDRESS" && -n "$LOCAL_IPV6_ADDRESS" ]]
    then
      if [[ "$PUBLIC_IPV6_ADDRESS" != "$LOCAL_IPV6_ADDRESS" ]]
      then
        echo "IPv6: NAT"
      else
        echo "IPv6: No NAT"
      fi
    fi

    if [[ -n "$flag_g" ]]
    then
      check_dependencies geoiplookup geoiplookup6
      if [[ -n "$PUBLIC_IPV4_ADDRESS"  ]]
      then
        PUBLIC_IPV4_GEOLOCATION="$(print_public_ipv4_geolocation)"
        echo "Geolocation IPv4: $PUBLIC_IPV4_GEOLOCATION"
      fi

      if [[ -n "$PUBLIC_IPV6_ADDRESS" ]]
      then
        PUBLIC_IPV6_GEOLOCATION="$(print_public_ipv6_geolocation)"
        echo "Geolocation IPv6: $PUBLIC_IPV4_GEOLOCATION"
      fi
    fi

  fi
}

main "$@"