#!/bin/bash
  
  # Copyright 2012  Johns Hopkins University (Author: Daniel Povey);
  #                 Arnab Ghoshal, Karel Vesely
  
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #  http://www.apache.org/licenses/LICENSE-2.0
  #
  # THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
  # WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
  # MERCHANTABLITY OR NON-INFRINGEMENT.
  # See the Apache 2 License for the specific language governing permissions and
  # limitations under the License.
  
  
  # Parse command-line options.
  # To be sourced by another script (as in ". parse_options.sh").
  # Option format is: --option-name arg
  # and shell variable "option_name" gets set to value "arg."
  # The exception is --help, which takes no arguments, but prints the 
  # $help_message variable (if defined).
  
  
  ###
  ### The --config file options have lower priority to command line 
  ### options, so we need to import them first...
  ###
  
  # Now import all the configs specified by command-line, in left-to-right order
  for ((n=1; n<$#; n++)); do
    if [ "${!n}" == "--config" ]; then
      n_plus1=$((n+1))
      config=${!n_plus1}
      . $config  # source the config file.
    fi
  done
  
  
  ###
  ### No we process the command line options
  ###
  while true; do
    [ -z "${1:-}" ] && break;  # break if there are no arguments
    case "$1" in
      # If the enclosing script is called with --help option, print the help 
      # message and exit.  Scripts should put help messages in $help_message
    --help|-h) if [ -z "$help_message" ]; then echo "No help found." 1>&2;
  	  else printf "$help_message
  " 1>&2 ; fi; 
  	  exit 0 ;; 
      # If the first command-line argument begins with "--" (e.g. --foo-bar), 
      # then work out the variable name as $name, which will equal "foo_bar".
    --*) name=`echo "$1" | sed s/^--// | sed s/-/_/g`; 
      # Next we test whether the variable in question is undefned-- if so it's 
      # an invalid option and we die.  Note: $0 evaluates to the name of the 
      # enclosing script.
      # The test [ -z ${foo_bar+xxx} ] will return true if the variable foo_bar
      # is undefined.  We then have to wrap this test inside "eval" because 
      # foo_bar is itself inside a variable ($name).
        eval '[ -z "${'$name'+xxx}" ]' && echo "$0: invalid option $1" 1>&2 && exit 1;
        
        oldval="`eval echo \\$$name`";
      # Work out whether we seem to be expecting a Boolean argument.
        if [ "$oldval" == "true" ] || [ "$oldval" == "false" ]; then 
  	was_bool=true;
        else 
  	was_bool=false;
        fi
  
      # Set the variable to the right value-- the escaped quotes make it work if
      # the option had spaces, like --cmd "queue.pl -sync y"
        eval $name=\"$2\"; 
          
      # Check that Boolean-valued arguments are really Boolean.
        if $was_bool && [[ "$2" != "true" && "$2" != "false" ]]; then
          echo "$0: expected \"true\" or \"false\": --$name $2" 1>&2
          exit 1;
        fi
        shift 2;
        ;;
    *) break;
    esac
  done
  
  
  # Check for an empty argument to the --cmd option, which can easily occur as a 
  # result of scripting errors.
  [ ! -z "${cmd+xxx}" ] && [ -z "$cmd" ] && echo "$0: empty argument to --cmd option" 1>&2 && exit 1;
  
  
  true; # so this script returns exit code 0.