#!/bin/sh

set -e

usage() {
  cat << EOF
Executes a given command if there is an internet connection. Availability of an
connection is tested by (i) the availability of a default route and (ii) the
pingability of a test host.

Usage:
 $0 [OPTIONS]
 $0 -h
 $0 -c "echo 'online'"

OPTIONS:
  -h            Show this text
  -v            Verbose output
  -p HOST       Host for ping test. Default: 8.8.8.8
  -c CMD        Command to execute if online
EOF
}

CMD=""
VERBOSE=0
PINGHOST="8.8.8.8"

while getopts "hvc:p:" OPTION; do
    
  case "${OPTION}" in
    h)
      usage
      exit
      ;;
    v)
      VERBOSE=1
      ;;
    p)
      PINGHOST=${OPTARG}
      ;;
    c)
      CMD=${OPTARG}
      ;;
  esac
done

if [ -z "${CMD}" ]; then
    echo "No command given."
    usage
    exit 2
fi

if [ -z "$(ip r list exact default)" ]; then
  if [ "1" -eq "${VERBOSE}" ];  then
    echo "Not online because no default route."
  fi
  exit
fi


if ! ping -c1 "${PINGHOST}" 2>&1 >/dev/null; then
  if [ "1" -eq "${VERBOSE}" ];  then
    echo "Not online because cannot ping ${PINGHOST}."
  fi
  exit
fi

${CMD}