#!/bin/bash
# UseGetOpt.sh

# Author: Peggy Russell <prusselltechgroup@gmail.com>

UseGetOpt () {
  declare inputOptions
  declare -r E_OPTERR=85
  declare -r ScriptName=${0##*/}
  declare -r ShortOpts="adf:hlt"
  declare -r LongOpts="aoption,debug,file:,help,log,test"

DoSomething () {
    echo "The function name is '${FUNCNAME}'"
    #  Recall that $FUNCNAME is an internal variable
    #+ holding the name of the function it is in.
  }

  inputOptions=$(getopt -o "${ShortOpts}" --long \
              "${LongOpts}" --name "${ScriptName}" -- "${@}")

  if [[ ($? -ne 0) || ($# -eq 0) ]]; then
    echo "Usage: ${ScriptName} [-dhlt] {OPTION...}"
    exit $E_OPTERR
  fi

  eval set -- "${inputOptions}"

  # Only for educational purposes. Can be removed.
  #-----------------------------------------------
  echo "++ Test: Number of arguments: [$#]"
  echo '++ Test: Looping through "$@"'
  for a in "$@"; do
    echo "  ++ [$a]"
  done
  #-----------------------------------------------

  while true; do
    case "${1}" in
      --aoption | -a)  # Argument found.
        echo "Option [$1]"
        ;;

      --debug | -d)    # Enable informational messages.
        echo "Option [$1] Debugging enabled"
        ;;

      --file | -f)     #  Check for optional argument.
        case "$2" in   #+ Double colon is optional argument.
          "")          #  Not there.
              echo "Option [$1] Use default"
              shift
              ;;

          *) # Got it
             echo "Option [$1] Using input [$2]"
             shift
             ;;

        esac
        DoSomething
        ;;

      --log | -l) # Enable Logging.
        echo "Option [$1] Logging enabled"
        ;;

      --test | -t) # Enable testing.
        echo "Option [$1] Testing enabled"
        ;;

      --help | -h)
        echo "Option [$1] Display help"
        break
        ;;

      --)   # Done! $# is argument number for "--", $@ is "--"
        echo "Option [$1] Dash Dash"
        break
        ;;

       *)
        echo "Major internal error!"
        exit 8
        ;;

    esac
    echo "Number of arguments: [$#]"
    shift
  done

  shift
  # Only for educational purposes. Can be removed.
  #----------------------------------------------------------------------
  echo "++ Test: Number of arguments after \"--\" is [$#] They are: [$@]"
  echo '++ Test: Looping through "$@"'
  for a in "$@"; do
    echo "  ++ [$a]"
  done
  #----------------------------------------------------------------------
  
}

################################### M A I N ########################
#  If you remove "function UseGetOpt () {" and corresponding "}",
#+ you can uncomment the "exit 0" line below, and invoke this script
#+ with the various options from the command-line.
#-------------------------------------------------------------------
# exit 0

echo "Test 1"
UseGetOpt -f myfile one "two three" four

echo;echo "Test 2"
UseGetOpt -h

echo;echo "Test 3 - Short Options"
UseGetOpt -adltf myfile  anotherfile

echo;echo "Test 4 - Long Options"
UseGetOpt --aoption --debug --log --test --file myfile anotherfile

exit