# $Id$
# vim:et:ft=sh:sts=2:sw=2
#
# Copyright 2008 Kate Ward. All Rights Reserved.
# Released under the LGPL (GNU Lesser General Public License)
#
# shFlags -- Advanced command-line flag library for Unix shell scripts.
# http://code.google.com/p/shflags/
#
# Author: kate.ward@forestent.com (Kate Ward)
#
# This module implements something like the google-gflags library available
# from http://code.google.com/p/google-gflags/.
#
# FLAG TYPES: This is a list of the DEFINE_*'s that you can do.  All flags take
# a name, default value, help-string, and optional 'short' name (one-letter
# name).  Some flags have other arguments, which are described with the flag.
#
# DEFINE_string: takes any input, and intreprets it as a string.
#
# DEFINE_boolean: does not take any arguments. Say --myflag to set
#   FLAGS_myflag to true, or --nomyflag to set FLAGS_myflag to false. For short
#   flags, passing the flag on the command-line negates the default value, i.e.
#   if the default is true, passing the flag sets the value to false.
#
# DEFINE_float: takes an input and intreprets it as a floating point number. As
#   shell does not support floats per-se, the input is merely validated as
#   being a valid floating point value.
#
# DEFINE_integer: takes an input and intreprets it as an integer.
#
# SPECIAL FLAGS: There are a few flags that have special meaning:
#   --help (or -?)  prints a list of all the flags in a human-readable fashion
#   --flagfile=foo  read flags from foo.  (not implemented yet)
#   --              as in getopt(), terminates flag-processing
#
# EXAMPLE USAGE:
#
#   -- begin hello.sh --
#   #! /bin/sh
#   . ./shflags
#   DEFINE_string name 'world' "somebody's name" n
#   FLAGS "$@" || exit $?
#   eval set -- "${FLAGS_ARGV}"
#   echo "Hello, ${FLAGS_name}."
#   -- end hello.sh --
#
#   $ ./hello.sh -n Kate
#   Hello, Kate.
#
# CUSTOMIZABLE BEHAVIOR:
#
# A script can override the default 'getopt' command by providing the path to
# an alternate implementation by defining the FLAGS_GETOPT_CMD variable.
#
# NOTES:
#
# * Not all systems include a getopt version that supports long flags. On these
#   systems, only short flags are recognized.

#==============================================================================
# shFlags
#
# Shared attributes:
#   flags_error:  last error message
#   flags_output: last function output (rarely valid)
#   flags_return: last return value
#
#   __flags_longNames: list of long names for all flags
#   __flags_shortNames: list of short names for all flags
#   __flags_boolNames: list of boolean flag names
#
#   __flags_opts: options parsed by getopt
#
# Per-flag attributes:
#   FLAGS_<flag_name>: contains value of flag named 'flag_name'
#   __flags_<flag_name>_default: the default flag value
#   __flags_<flag_name>_help: the flag help string
#   __flags_<flag_name>_short: the flag short name
#   __flags_<flag_name>_type: the flag type
#
# Notes:
# - lists of strings are space separated, and a null value is the '~' char.

# return if FLAGS already loaded
[ -n "${FLAGS_VERSION:-}" ] && return 0
FLAGS_VERSION='1.0.4pre'

# return values that scripts can use
FLAGS_TRUE=0
FLAGS_FALSE=1
FLAGS_ERROR=2

# determine some reasonable command defaults
__FLAGS_UNAME_S=`uname -s`
case "${__FLAGS_UNAME_S}" in
  BSD) __FLAGS_EXPR_CMD='gexpr' ;;
  *) __FLAGS_EXPR_CMD='expr' ;;
esac

# commands a user can override if needed
FLAGS_EXPR_CMD=${FLAGS_EXPR_CMD:-${__FLAGS_EXPR_CMD}}
FLAGS_GETOPT_CMD=${FLAGS_GETOPT_CMD:-getopt}

# specific shell checks
if [ -n "${ZSH_VERSION:-}" ]; then
  setopt |grep "^shwordsplit$" >/dev/null
  if [ $? -ne ${FLAGS_TRUE} ]; then
	_flags_fatal 'zsh shwordsplit option is required for proper zsh operation'
  fi
  if [ -z "${FLAGS_PARENT:-}" ]; then
	_flags_fatal "zsh does not pass \$0 through properly. please declare' \
\"FLAGS_PARENT=\$0\" before calling shFlags"
  fi
fi

# can we use built-ins?
( echo "${FLAGS_TRUE#0}"; ) >/dev/null 2>&1
if [ $? -eq ${FLAGS_TRUE} ]; then
  __FLAGS_USE_BUILTIN=${FLAGS_TRUE}
else
  __FLAGS_USE_BUILTIN=${FLAGS_FALSE}
fi

#
# constants
#

# reserved flag names
__FLAGS_RESERVED_LIST=' ARGC ARGV ERROR FALSE GETOPT_CMD HELP PARENT TRUE '
__FLAGS_RESERVED_LIST="${__FLAGS_RESERVED_LIST} VERSION "

# getopt version
__FLAGS_GETOPT_VERS_STD=0
__FLAGS_GETOPT_VERS_ENH=1
__FLAGS_GETOPT_VERS_BSD=2

${FLAGS_GETOPT_CMD} >/dev/null 2>&1
case $? in
  0) __FLAGS_GETOPT_VERS=${__FLAGS_GETOPT_VERS_STD} ;;  # bsd getopt
  1)
    # Probably BusyBox. Getting a return of 4 with -T will confirm
    ${FLAGS_GETOPT_CMD} -T >/dev/null 2>&1
    if [ "$?" == 4 ] ; then
      __FLAGS_GETOPT_VERS=${__FLAGS_GETOPT_VERS_ENH}
    else
      _flags_fatal 'unable to determine getopt version'
    fi
    ;;
  2)
	# TODO(kward): look into '-T' option to test the internal getopt() version
	if [ "`${FLAGS_GETOPT_CMD} --version`" = '-- ' ]; then
	  __FLAGS_GETOPT_VERS=${__FLAGS_GETOPT_VERS_STD}
	else
	  __FLAGS_GETOPT_VERS=${__FLAGS_GETOPT_VERS_ENH}
	fi
	;;
  *) _flags_fatal 'unable to determine getopt version' ;;
esac

# getopt optstring lengths
__FLAGS_OPTSTR_SHORT=0
__FLAGS_OPTSTR_LONG=1

__FLAGS_NULL='~'

# flag info strings
__FLAGS_INFO_DEFAULT='default'
__FLAGS_INFO_HELP='help'
__FLAGS_INFO_SHORT='short'
__FLAGS_INFO_TYPE='type'

# flag lengths
__FLAGS_LEN_SHORT=0
__FLAGS_LEN_LONG=1

# flag types
__FLAGS_TYPE_NONE=0
__FLAGS_TYPE_BOOLEAN=1
__FLAGS_TYPE_FLOAT=2
__FLAGS_TYPE_INTEGER=3
__FLAGS_TYPE_STRING=4

# set the constants readonly
__flags_constants=`set |awk -F= '/^FLAGS_/ || /^__FLAGS_/ {print $1}'`
for __flags_const in ${__flags_constants}; do
  # skip certain flags
  case ${__flags_const} in
	FLAGS_HELP) continue ;;
	FLAGS_PARENT) continue ;;
  esac
  # set flag readonly
  if [ -z "${ZSH_VERSION:-}" ]; then
	readonly ${__flags_const}
  else  # handle zsh
	case ${ZSH_VERSION} in
	  [123].*) readonly ${__flags_const} ;;
	  *) readonly -g ${__flags_const} ;;  # declare readonly constants globally
	esac
  fi
done
unset __flags_const __flags_constants

#
# internal variables
#

# space separated lists
__flags_boolNames=' '  # boolean flag names
__flags_longNames=' '  # long flag names
__flags_shortNames=' '  # short flag names
__flags_definedNames=' ' # defined flag names (used for validation)
__flags_nonegateNames=' '

__flags_columns=''  # screen width in columns
__flags_opts=''  # temporary storage for parsed getopt flags

#------------------------------------------------------------------------------
# private functions
#

# logging functions
_flags_debug() { echo "flags:DEBUG $@" >&2; }
_flags_warn() { echo "flags:WARN $@" >&2; }
_flags_error() { echo "flags:ERROR $@" >&2; }
_flags_fatal() { echo "flags:FATAL $@" >&2; exit ${FLAGS_ERROR}; }

# Define a flag.
#
# Calling this function will define the following info variables for the
# specified flag:
#   FLAGS_flagname - the name for this flag (based upon the long flag name)
#   __flags_<flag_name>_default - the default value
#   __flags_flagname_help - the help string
#   __flags_flagname_short - the single letter alias
#   __flags_flagname_type - the type of flag (one of __FLAGS_TYPE_*)
#
# Args:
#   _flags__type: integer: internal type of flag (__FLAGS_TYPE_*)
#   _flags__name: string: long flag name
#   _flags__default: default flag value
#   _flags__help: string: help string
#   _flags__short: string: (optional) short flag name
# Returns:
#   integer: success of operation, or error
_flags_define()
{
  if [ $# -lt 4 ]; then
	flags_error='DEFINE error: too few arguments'
	flags_return=${FLAGS_ERROR}
	_flags_error "${flags_error}"
	return ${flags_return}
  fi

  _flags_type_=$1
  _flags_name_=$2
  _flags_default_=$3
  _flags_help_=$4
  _flags_short_=${5:-${__FLAGS_NULL}}

  _flags_return_=${FLAGS_TRUE}
  _flags_usName_=`_flags_removeExclamationName ${_flags_name_}`
  _flags_usName_=`_flags_underscoreName ${_flags_usName_}`

  # check whether the flag name is reserved
  _flags_itemInList ${_flags_usName_} "${__FLAGS_RESERVED_LIST}"
  if [ $? -eq ${FLAGS_TRUE} ]; then
	flags_error="flag name (${_flags_name_}) is reserved"
	_flags_return_=${FLAGS_ERROR}
  fi

  # require short option for getopt that don't support long options
  if [ ${_flags_return_} -eq ${FLAGS_TRUE} \
	  -a ${__FLAGS_GETOPT_VERS} -ne ${__FLAGS_GETOPT_VERS_ENH} \
	  -a "${_flags_short_}" = "${__FLAGS_NULL}" ]
  then
	flags_error="short flag required for (${_flags_name_}) on this platform"
	_flags_return_=${FLAGS_ERROR}
  fi

  # check for existing long name definition
  if [ ${_flags_return_} -eq ${FLAGS_TRUE} ]; then
	if _flags_itemInList ${_flags_usName_} ${__flags_definedNames}; then
	  flags_error="definition for ([no]${_flags_name_}) already exists"
	  _flags_warn "${flags_error}"
	  _flags_return_=${FLAGS_FALSE}
	fi
  fi

  # check for existing short name definition
  if [ ${_flags_return_} -eq ${FLAGS_TRUE} \
	  -a "${_flags_short_}" != "${__FLAGS_NULL}" ]
  then
	if _flags_itemInList "${_flags_short_}" ${__flags_shortNames}; then
	  flags_error="flag short name (${_flags_short_}) already defined"
	  _flags_warn "${flags_error}"
	  _flags_return_=${FLAGS_FALSE}
	fi
  fi

  # handle default value. note, on several occasions the 'if' portion of an
  # if/then/else contains just a ':' which does nothing. a binary reversal via
  # '!' is not done because it does not work on all shells.
  if [ ${_flags_return_} -eq ${FLAGS_TRUE} ]; then
	_flags_isNegate_=${FLAGS_FALSE}
	case ${_flags_type_} in
	  ${__FLAGS_TYPE_BOOLEAN})
		if _flags_validBool "${_flags_default_}"; then
		  case ${_flags_default_} in
			true|t|0) _flags_default_=${FLAGS_TRUE} ;;
			false|f|1) _flags_default_=${FLAGS_FALSE} ;;
		  esac
		  _flags_isNegate ${_flags_name_}
		  _flags_isNegate_=$?
		else
		  flags_error="invalid default flag value '${_flags_default_}'"
		  _flags_return_=${FLAGS_ERROR}
		fi
		;;

	  ${__FLAGS_TYPE_FLOAT})
		if _flags_validFloat "${_flags_default_}"; then
		  :
		else
		  flags_error="invalid default flag value '${_flags_default_}'"
		  _flags_return_=${FLAGS_ERROR}
		fi
		;;

	  ${__FLAGS_TYPE_INTEGER})
		if _flags_validInt "${_flags_default_}"; then
		  :
		else
		  flags_error="invalid default flag value '${_flags_default_}'"
		  _flags_return_=${FLAGS_ERROR}
		fi
		;;

	  ${__FLAGS_TYPE_STRING}) ;;  # everything in shell is a valid string

	  *)
		flags_error="unrecognized flag type '${_flags_type_}'"
		_flags_return_=${FLAGS_ERROR}
		;;
	esac
  fi

  if [ ${_flags_return_} -eq ${FLAGS_TRUE} ]; then
	# store flag information
	eval "FLAGS_${_flags_usName_}='${_flags_default_}'"
	eval "__flags_${_flags_usName_}_${__FLAGS_INFO_TYPE}=${_flags_type_}"
	eval "__flags_${_flags_usName_}_${__FLAGS_INFO_DEFAULT}=\
\"${_flags_default_}\""
	eval "__flags_${_flags_usName_}_${__FLAGS_INFO_HELP}=\"${_flags_help_}\""
	eval "__flags_${_flags_usName_}_${__FLAGS_INFO_SHORT}='${_flags_short_}'"

	# append flag names to name lists
	__flags_shortNames="${__flags_shortNames}${_flags_short_} "
	__flags_longNames="${__flags_longNames}`_flags_removeExclamationName ${_flags_name_}` "
	if [ ${_flags_type_} -eq ${__FLAGS_TYPE_BOOLEAN} \
	  -a  ${_flags_isNegate_} -eq ${FLAGS_TRUE} ]; then
		__flags_boolNames="${__flags_boolNames}no${_flags_name_} "
	fi

	# append flag names to defined names for later validation checks
	__flags_definedNames="${__flags_definedNames}${_flags_usName_} "
	if [ ${_flags_type_} -eq ${__FLAGS_TYPE_BOOLEAN} ]; then
	  if [ ${_flags_isNegate_} -eq ${FLAGS_TRUE} ]; then
		__flags_definedNames="${__flags_definedNames}no${_flags_usName_} "
	  fi
	fi

	# append flag names to nonegateNames names for later validation checks
	__flags_definedNames="${__flags_definedNames}${_flags_usName_} "
	if [ ${_flags_type_} -eq ${__FLAGS_TYPE_BOOLEAN} ]; then
	  if [ ${_flags_isNegate_} -eq ${FLAGS_FALSE} ]; then
		__flags_nonegateNames="${__flags_nonegateNames}`_flags_removeExclamationName ${_flags_name_}` "
	  fi
	fi

  fi

  flags_return=${_flags_return_}
  unset _flags_default_ _flags_help_ _flags_name_ _flags_return_ \
	  _flags_short_ _flags_type_ _flags_usName_ _flags_isNegate_
  [ ${flags_return} -eq ${FLAGS_ERROR} ] && _flags_error "${flags_error}"
  return ${flags_return}
}

# Underscore a flag name by replacing dashes with underscores.
#
# Args:
#   unnamed: string: log flag name
# Output:
#   string: underscored name
_flags_underscoreName()
{
  echo $1 |tr '-' '_'
}

# Strip potential exclamation mark
#
# Args:
#   unnamed: string: log flag name
# Output:
#   string: exclamation stripped from name
_flags_removeExclamationName()
{
  _flags_opt_=$1
  if _flags_isNegate "${_flags_opt_}"; then
	echo ${_flags_opt_}
  else
	  if _flags_useBuiltin; then
		echo ${_flags_opt_%!*}
	  else
		echo ${_flags_opt_}|sed 's/!$//'
	  fi
  fi
  unset _flags_opt_
  return ${FLAGS_TRUE}
}

# Check if a flag ends in an exclamation mark,
#  if it does, there will not be a negate option
# Args:
#   unnamed: string: flag name
# return:
#   boolean
_flags_isNegate()
{
  case $1 in
	*!) flags_return=${FLAGS_FALSE} ;;
	*) flags_return=${FLAGS_TRUE} ;;
  esac
  return ${flags_return}
}


# Return valid getopt options using currently defined list of long options.
#
# This function builds a proper getopt option string for short (and long)
# options, using the current list of long options for reference.
#
# Args:
#   _flags_optStr: integer: option string type (__FLAGS_OPTSTR_*)
# Output:
#   string: generated option string for getopt
# Returns:
#   boolean: success of operation (always returns True)
_flags_genOptStr()
{
  _flags_optStrType_=$1

  _flags_opts_=''

  for _flags_name_ in ${__flags_longNames}; do
	_flags_usName_=`_flags_removeExclamationName ${_flags_name_}`
	_flags_usName_=`_flags_underscoreName ${_flags_usName_}`
	_flags_type_=`_flags_getFlagInfo ${_flags_usName_} ${__FLAGS_INFO_TYPE}`
	[ $? -eq ${FLAGS_TRUE} ] || _flags_fatal 'call to _flags_type_ failed'
	case ${_flags_optStrType_} in
	  ${__FLAGS_OPTSTR_SHORT})
		_flags_shortName_=`_flags_getFlagInfo \
			${_flags_usName_} ${__FLAGS_INFO_SHORT}`
		if [ "${_flags_shortName_}" != "${__FLAGS_NULL}" ]; then
		  _flags_opts_="${_flags_opts_}${_flags_shortName_}"
		  # getopt needs a trailing ':' to indicate a required argument
		  [ ${_flags_type_} -ne ${__FLAGS_TYPE_BOOLEAN} ] && \
			  _flags_opts_="${_flags_opts_}:"
		fi
		;;

	  ${__FLAGS_OPTSTR_LONG})
		_flags_opts_="${_flags_opts_:+${_flags_opts_},}`_flags_removeExclamationName ${_flags_name_}`"
		# getopt needs a trailing ':' to indicate a required argument
		[ ${_flags_type_} -ne ${__FLAGS_TYPE_BOOLEAN} ] && \
			_flags_opts_="${_flags_opts_}:"
		;;
	esac
  done

  echo "${_flags_opts_}"
  unset _flags_name_ _flags_opts_ _flags_optStrType_ _flags_shortName_ \
	  _flags_type_ _flags_usName_
  return ${FLAGS_TRUE}
}

# Returns flag details based on a flag name and flag info.
#
# Args:
#   string: underscored flag name
#   string: flag info (see the _flags_define function for valid info types)
# Output:
#   string: value of dereferenced flag variable
# Returns:
#   integer: one of FLAGS_{TRUE|FALSE|ERROR}
_flags_getFlagInfo()
{
  # note: adding gFI to variable names to prevent naming conflicts with calling
  # functions
  _flags_gFI_usName_=$1
  _flags_gFI_info_=$2

  _flags_infoVar_="__flags_${_flags_gFI_usName_}_${_flags_gFI_info_}"
  _flags_strToEval_="_flags_infoValue_=\"\${${_flags_infoVar_}:-}\""
  eval "${_flags_strToEval_}"
  if [ -n "${_flags_infoValue_}" ]; then
	flags_return=${FLAGS_TRUE}
  else
	# see if the _flags_gFI_usName_ variable is a string as strings can be
	# empty...
	# note: the DRY principle would say to have this function call itself for
	# the next three lines, but doing so results in an infinite loop as an
	# invalid _flags_name_ will also not have the associated _type variable.
	# Because it doesn't (it will evaluate to an empty string) the logic will
	# try to find the _type variable of the _type variable, and so on. Not so
	# good ;-)
	_flags_typeVar_="__flags_${_flags_gFI_usName_}_${__FLAGS_INFO_TYPE}"
	_flags_strToEval_="_flags_typeValue_=\"\${${_flags_typeVar_}:-}\""
	eval "${_flags_strToEval_}"
	if [ "${_flags_typeValue_}" = "${__FLAGS_TYPE_STRING}" ]; then
	  flags_return=${FLAGS_TRUE}
	else
	  flags_return=${FLAGS_ERROR}
	  flags_error="missing flag info variable (${_flags_infoVar_})"
	fi
  fi

  echo "${_flags_infoValue_}"
  unset _flags_gFI_usName_ _flags_gfI_info_ _flags_infoValue_ _flags_infoVar_ \
	  _flags_strToEval_ _flags_typeValue_ _flags_typeVar_
  [ ${flags_return} -eq ${FLAGS_ERROR} ] && _flags_error "${flags_error}"
  return ${flags_return}
}

# Check for presense of item in a list.
#
# Passed a string (e.g. 'abc'), this function will determine if the string is
# present in the list of strings (e.g.  ' foo bar abc ').
#
# Args:
#   _flags_str_: string: string to search for in a list of strings
#   unnamed: list: list of strings
# Returns:
#   boolean: true if item is in the list
_flags_itemInList() {
  _flags_str_=$1
  shift
  _flags_list_=" ${*:-} "

  case ${_flags_list_} in
	  *\ ${_flags_str_}\ *)
	  flags_return=$FLAGS_TRUE
	  ;;
	*)
	  flags_return=$FLAGS_FALSE
	  ;;
  esac

  unset _flags_str_ _flags_list_
  return ${flags_return}
}

# Returns the width of the current screen.
#
# Output:
#   integer: width in columns of the current screen.
_flags_columns()
{
  if [ -z "${__flags_columns}" ]; then
	# determine the value and store it
	if eval stty size >/dev/null 2>&1; then
	  # stty size worked :-)
	  set -- `stty size`
	  __flags_columns=$2
	elif eval tput cols >/dev/null 2>&1; then
	  set -- `tput cols`
	  __flags_columns=$1
	else
	  __flags_columns=80  # default terminal width
	fi
  fi
  echo ${__flags_columns}
}

# Validate a boolean.
#
# Args:
#   _flags__bool: boolean: value to validate
# Returns:
#   bool: true if the value is a valid boolean
_flags_validBool()
{
  _flags_bool_=$1

  flags_return=${FLAGS_TRUE}
  case "${_flags_bool_}" in
	true|t|0) ;;
	false|f|1) ;;
	*) flags_return=${FLAGS_FALSE} ;;
  esac

  unset _flags_bool_
  return ${flags_return}
}

# Validate a float.
#
# Args:
#   _flags_float_: float: value to validate
# Returns:
#   bool: true if the value is a valid integer
_flags_validFloat()
{
  flags_return=${FLAGS_FALSE}
  [ -n "$1" ] || return ${flags_return}
  _flags_float_=$1

  if _flags_validInt ${_flags_float_}; then
	flags_return=${FLAGS_TRUE}
  elif _flags_useBuiltin; then
	_flags_float_whole_=${_flags_float_%.*}
	_flags_float_fraction_=${_flags_float_#*.}
	if _flags_validInt ${_flags_float_whole_:-0} -a \
	  _flags_validInt ${_flags_float_fraction_}; then
	  flags_return=${FLAGS_TRUE}
	fi
	unset _flags_float_whole_ _flags_float_fraction_
  else
	flags_return=${FLAGS_TRUE}
	case ${_flags_float_} in
	  -*)  # negative floats
		_flags_test_=`${FLAGS_EXPR_CMD} -- "${_flags_float_}" :\
			'\(-[0-9]*\.[0-9]*\)'`
		;;
	  *)  # positive floats
		_flags_test_=`${FLAGS_EXPR_CMD} -- "${_flags_float_}" :\
			'\([0-9]*\.[0-9]*\)'`
		;;
	esac
	[ "${_flags_test_}" != "${_flags_float_}" ] && flags_return=${FLAGS_FALSE}
	unset _flags_test_
  fi

  unset _flags_float_ _flags_float_whole_ _flags_float_fraction_
  return ${flags_return}
}

# Validate an integer.
#
# Args:
#   _flags_int_: integer: value to validate
# Returns:
#   bool: true if the value is a valid integer
_flags_validInt()
{
  flags_return=${FLAGS_FALSE}
  [ -n "$1" ] || return ${flags_return}
  _flags_int_=$1

  case ${_flags_int_} in
	-*.*) ;;  # ignore negative floats (we'll invalidate them later)
	-*)  # strip possible leading negative sign
	  if _flags_useBuiltin; then
		_flags_int_=${_flags_int_#-}
	  else
		_flags_int_=`${FLAGS_EXPR_CMD} -- "${_flags_int_}" : '-\([0-9][0-9]*\)'`
	  fi
	  ;;
  esac

  case ${_flags_int_} in
	*[!0-9]*) flags_return=${FLAGS_FALSE} ;;
	*) flags_return=${FLAGS_TRUE} ;;
  esac

  unset _flags_int_
  return ${flags_return}
}

# Parse command-line options using the standard getopt.
#
# Note: the flag options are passed around in the global __flags_opts so that
# the formatting is not lost due to shell parsing and such.
#
# Args:
#   @: varies: command-line options to parse
# Returns:
#   integer: a FLAGS success condition
_flags_getoptStandard()
{
  flags_return=${FLAGS_TRUE}
  _flags_shortOpts_=`_flags_genOptStr ${__FLAGS_OPTSTR_SHORT}`

  # check for spaces in passed options
  for _flags_opt_ in "$@"; do
	# note: the silliness with the x's is purely for ksh93 on Ubuntu 6.06
	_flags_match_=`echo "x${_flags_opt_}x" |sed 's/ //g'`
	if [ "${_flags_match_}" != "x${_flags_opt_}x" ]; then
	  flags_error='the available getopt does not support spaces in options'
	  flags_return=${FLAGS_ERROR}
	  break
	fi
  done

  if [ ${flags_return} -eq ${FLAGS_TRUE} ]; then
	__flags_opts=`getopt ${_flags_shortOpts_} $@ 2>&1`
	_flags_rtrn_=$?
	if [ ${_flags_rtrn_} -ne ${FLAGS_TRUE} ]; then
	  _flags_warn "${__flags_opts}"
	  flags_error='unable to parse provided options with getopt.'
	  flags_return=${FLAGS_ERROR}
	fi
  fi

  unset _flags_match_ _flags_opt_ _flags_rtrn_ _flags_shortOpts_
  return ${flags_return}
}

# Parse command-line options using the enhanced getopt.
#
# Note: the flag options are passed around in the global __flags_opts so that
# the formatting is not lost due to shell parsing and such.
#
# Args:
#   @: varies: command-line options to parse
# Returns:
#   integer: a FLAGS success condition
_flags_getoptEnhanced()
{
  flags_return=${FLAGS_TRUE}
  _flags_shortOpts_=`_flags_genOptStr ${__FLAGS_OPTSTR_SHORT}`
  _flags_boolOpts_=`echo "${__flags_boolNames}" \
	  |sed 's/^ *//;s/ *$//;s/ /,/g'`
  _flags_longOpts_=`_flags_genOptStr ${__FLAGS_OPTSTR_LONG}`

  __flags_opts=`${FLAGS_GETOPT_CMD} \
	  -o ${_flags_shortOpts_} \
	  -l "${_flags_longOpts_},${_flags_boolOpts_}" \
	  -- "$@" 2>&1`
  _flags_rtrn_=$?
  if [ ${_flags_rtrn_} -ne ${FLAGS_TRUE} ]; then
	_flags_warn "${__flags_opts}"
	flags_error='unable to parse provided options with getopt.'
	flags_return=${FLAGS_ERROR}
  fi

  unset _flags_boolOpts_ _flags_longOpts_ _flags_rtrn_ _flags_shortOpts_
  return ${flags_return}
}

# Dynamically parse a getopt result and set appropriate variables.
#
# This function does the actual conversion of getopt output and runs it through
# the standard case structure for parsing. The case structure is actually quite
# dynamic to support any number of flags.
#
# Args:
#   argc: int: original command-line argument count
#   @: varies: output from getopt parsing
# Returns:
#   integer: a FLAGS success condition
_flags_parseGetopt()
{
  _flags_argc_=$1
  shift

  flags_return=${FLAGS_TRUE}

  if [ ${__FLAGS_GETOPT_VERS} -ne ${__FLAGS_GETOPT_VERS_ENH} ]; then
	set -- $@
  else
	# note the quotes around the `$@' -- they are essential!
	eval set -- "$@"
  fi

  # Provide user with the number of arguments to shift by later.
  # NOTE: the FLAGS_ARGC variable is obsolete as of 1.0.3 because it does not
  # properly give user access to non-flag arguments mixed in between flag
  # arguments. Its usage was replaced by FLAGS_ARGV, and it is being kept only
  # for backwards compatibility reasons.
  FLAGS_ARGC=`_flags_math "$# - 1 - ${_flags_argc_}"`

  # handle options. note options with values must do an additional shift
  while true; do
	_flags_opt_=$1
	_flags_arg_=${2:-}
	_flags_type_=${__FLAGS_TYPE_NONE}
	_flags_name_=''

	# determine long flag name
	case "${_flags_opt_}" in
	  --) shift; break ;;  # discontinue option parsing

	  --*)  # long option
		if _flags_useBuiltin; then
		  _flags_opt_=${_flags_opt_#*--}
		else
		  _flags_opt_=`${FLAGS_EXPR_CMD} -- "${_flags_opt_}" : '--\(.*\)'`
		fi
		_flags_len_=${__FLAGS_LEN_LONG}
		if _flags_itemInList "${_flags_opt_}" ${__flags_longNames}; then
		  _flags_name_=${_flags_opt_}
		else
		  # check for negated long boolean version
		  if _flags_itemInList "${_flags_opt_}" ${__flags_boolNames}; then
			if _flags_useBuiltin; then
			  _flags_name_=${_flags_opt_#*no}
			else
			  _flags_name_=`${FLAGS_EXPR_CMD} -- "${_flags_opt_}" : 'no\(.*\)'`
			fi
			_flags_type_=${__FLAGS_TYPE_BOOLEAN}
			_flags_arg_=${__FLAGS_NULL}
		  fi
		fi
		;;

	  -*)  # short option
		if _flags_useBuiltin; then
		  _flags_opt_=${_flags_opt_#*-}
		else
		  _flags_opt_=`${FLAGS_EXPR_CMD} -- "${_flags_opt_}" : '-\(.*\)'`
		fi
		_flags_len_=${__FLAGS_LEN_SHORT}
		if _flags_itemInList "${_flags_opt_}" ${__flags_shortNames}; then
		  # yes. match short name to long name. note purposeful off-by-one
		  # (too high) with awk calculations.
		  _flags_pos_=`echo "${__flags_shortNames}" \
			  |awk 'BEGIN{RS=" ";rn=0}$0==e{rn=NR}END{print rn}' \
				  e=${_flags_opt_}`
		  _flags_name_=`echo "${__flags_longNames}" \
			  |awk 'BEGIN{RS=" "}rn==NR{print $0}' rn="${_flags_pos_}"`
		fi
		;;
	esac

	# die if the flag was unrecognized
	if [ -z "${_flags_name_}" ]; then
	  flags_error="unrecognized option (${_flags_opt_})"
	  flags_return=${FLAGS_ERROR}
	  break
	fi

	# set new flag value
	_flags_usName_=`_flags_removeExclamationName ${_flags_name_}`
	_flags_usName_=`_flags_underscoreName ${_flags_usName_}`
	[ ${_flags_type_} -eq ${__FLAGS_TYPE_NONE} ] && \
		_flags_type_=`_flags_getFlagInfo \
			"${_flags_usName_}" ${__FLAGS_INFO_TYPE}`
	case ${_flags_type_} in
	  ${__FLAGS_TYPE_BOOLEAN})
		if [ ${_flags_len_} -eq ${__FLAGS_LEN_LONG} ]; then
		  if [ "${_flags_arg_}" != "${__FLAGS_NULL}" ]; then
			eval "FLAGS_${_flags_usName_}=${FLAGS_TRUE}"
		  else
			eval "FLAGS_${_flags_usName_}=${FLAGS_FALSE}"
		  fi
		else
		  _flags_strToEval_="_flags_val_=\
\${__flags_${_flags_usName_}_${__FLAGS_INFO_DEFAULT}}"
		  eval "${_flags_strToEval_}"
		  if [ ${_flags_val_} -eq ${FLAGS_FALSE} ]; then
			eval "FLAGS_${_flags_usName_}=${FLAGS_TRUE}"
		  else
			eval "FLAGS_${_flags_usName_}=${FLAGS_FALSE}"
		  fi
		fi
		;;

	  ${__FLAGS_TYPE_FLOAT})
		if _flags_validFloat "${_flags_arg_}"; then
		  eval "FLAGS_${_flags_usName_}='${_flags_arg_}'"
		else
		  flags_error="invalid float value (${_flags_arg_})"
		  flags_return=${FLAGS_ERROR}
		  break
		fi
		;;

	  ${__FLAGS_TYPE_INTEGER})
		if _flags_validInt "${_flags_arg_}"; then
		  eval "FLAGS_${_flags_usName_}='${_flags_arg_}'"
		else
		  flags_error="invalid integer value (${_flags_arg_})"
		  flags_return=${FLAGS_ERROR}
		  break
		fi
		;;

	  ${__FLAGS_TYPE_STRING})
		eval "FLAGS_${_flags_usName_}='${_flags_arg_}'"
		;;
	esac

	# handle special case help flag
	if [ "${_flags_usName_}" = 'help' ]; then
	  if [ ${FLAGS_help} -eq ${FLAGS_TRUE} ]; then
		flags_help
		flags_error='help requested'
		flags_return=${FLAGS_TRUE}
		break
	  fi
	fi

	# shift the option and non-boolean arguements out.
	shift
	[ ${_flags_type_} != ${__FLAGS_TYPE_BOOLEAN} ] && shift
  done

  # give user back non-flag arguments
  FLAGS_ARGV=''
  while [ $# -gt 0 ]; do
	FLAGS_ARGV="${FLAGS_ARGV:+${FLAGS_ARGV} }'$1'"
	shift
  done

  unset _flags_arg_ _flags_len_ _flags_name_ _flags_opt_ _flags_pos_ \
	  _flags_strToEval_ _flags_type_ _flags_usName_ _flags_val_ \
	  _flags_argc_
  return ${flags_return}
}

# Perform some path using built-ins.
#
# Args:
#   $@: string: math expression to evaluate
# Output:
#   integer: the result
# Returns:
#   bool: success of math evaluation
_flags_math()
{
  if [ $# -eq 0 ]; then
	flags_return=${FLAGS_FALSE}
  elif _flags_useBuiltin; then
	# Variable assignment is needed as workaround for Solaris Bourne shell,
	# which cannot parse a bare $((expression)).
	_flags_expr_='$(($@))'
	eval echo ${_flags_expr_}
	flags_return=$?
	unset _flags_expr_
  else
	eval expr $@
	flags_return=$?
  fi

  return ${flags_return}
}

# Cross-platform strlen() implementation.
#
# Args:
#   _flags_str: string: to determine length of
# Output:
#   integer: length of string
# Returns:
#   bool: success of strlen evaluation
_flags_strlen()
{
  _flags_str_=${1:-}

  if [ -z "${_flags_str_}" ]; then
	flags_output=0
  elif _flags_useBuiltin; then
	flags_output=${#_flags_str_}
  else
	flags_output=`${FLAGS_EXPR_CMD} -- "${_flags_str_}" : '.*'`
  fi
  flags_return=$?

  unset _flags_str_
  echo ${flags_output}
  return ${flags_return}
}

# Use built-in helper function to enable unit testing.
#
# Args:
#   None
# Returns:
#   bool: true if built-ins should be used
_flags_useBuiltin()
{
  return ${__FLAGS_USE_BUILTIN}
}

#------------------------------------------------------------------------------
# public functions
#
# A basic boolean flag. Boolean flags do not take any arguments, and their
# value is either 1 (false) or 0 (true). For long flags, the false value is
# specified on the command line by prepending the word 'no'. With short flags,
# the presense of the flag toggles the current value between true and false.
# Specifying a short boolean flag twice on the command results in returning the
# value back to the default value.
#
# A default value is required for boolean flags.
#
# For example, lets say a Boolean flag was created whose long name was 'update'
# and whose short name was 'x', and the default value was 'false'. This flag
# could be explicitly set to 'true' with '--update' or by '-x', and it could be
# explicitly set to 'false' with '--noupdate'.
DEFINE_boolean() { _flags_define ${__FLAGS_TYPE_BOOLEAN} "$@"; }

# Other basic flags.
DEFINE_float()   { _flags_define ${__FLAGS_TYPE_FLOAT} "$@"; }
DEFINE_integer() { _flags_define ${__FLAGS_TYPE_INTEGER} "$@"; }
DEFINE_string()  { _flags_define ${__FLAGS_TYPE_STRING} "$@"; }

# Parse the flags.
#
# Args:
#   unnamed: list: command-line flags to parse
# Returns:
#   integer: success of operation, or error
FLAGS()
{
  # define a standard 'help' flag if one isn't already defined
  [ -z "${__flags_help_type:-}" ] && \
	  DEFINE_boolean 'help!' false 'show this help' 'h'

  # parse options
  if [ $# -gt 0 ]; then
	if [ ${__FLAGS_GETOPT_VERS} -ne ${__FLAGS_GETOPT_VERS_ENH} ]; then
	  _flags_getoptStandard "$@"
	else
	  _flags_getoptEnhanced "$@"
	fi
	flags_return=$?
  else
	# nothing passed; won't bother running getopt
	__flags_opts='--'
	flags_return=${FLAGS_TRUE}
  fi

  if [ ${flags_return} -eq ${FLAGS_TRUE} ]; then
	_flags_parseGetopt $# "${__flags_opts}"
	flags_return=$?
  fi

  [ ${flags_return} -eq ${FLAGS_ERROR} ] && _flags_fatal "${flags_error}"
  return ${flags_return}
}

# This is a helper function for determining the 'getopt' version for platforms
# where the detection isn't working. It simply outputs debug information that
# can be included in a bug report.
#
# Args:
#   none
# Output:
#   debug info that can be included in a bug report
# Returns:
#   nothing
flags_getoptInfo()
{
  # platform info
  _flags_debug "uname -a: `uname -a`"
  _flags_debug "PATH: ${PATH}"

  # shell info
  if [ -n "${BASH_VERSION:-}" ]; then
	_flags_debug 'shell: bash'
	_flags_debug "BASH_VERSION: ${BASH_VERSION}"
  elif [ -n "${ZSH_VERSION:-}" ]; then
	_flags_debug 'shell: zsh'
	_flags_debug "ZSH_VERSION: ${ZSH_VERSION}"
  fi

  # getopt info
  ${FLAGS_GETOPT_CMD} >/dev/null
  _flags_getoptReturn=$?
  _flags_debug "getopt return: ${_flags_getoptReturn}"
  _flags_debug "getopt --version: `${FLAGS_GETOPT_CMD} --version 2>&1`"

  unset _flags_getoptReturn
}

# Returns whether the detected getopt version is the enhanced version.
#
# Args:
#   none
# Output:
#   none
# Returns:
#   bool: true if getopt is the enhanced version
flags_getoptIsEnh()
{
  test ${__FLAGS_GETOPT_VERS} -eq ${__FLAGS_GETOPT_VERS_ENH}
}

# Returns whether the detected getopt version is the standard version.
#
# Args:
#   none
# Returns:
#   bool: true if getopt is the standard version
flags_getoptIsStd()
{
  test ${__FLAGS_GETOPT_VERS} -eq ${__FLAGS_GETOPT_VERS_STD}
}

# This is effectively a 'usage()' function. It prints usage information and
# exits the program with ${FLAGS_FALSE} if it is ever found in the command line
# arguments. Note this function can be overridden so other apps can define
# their own --help flag, replacing this one, if they want.
#
# Args:
#   none
# Returns:
#   integer: success of operation (always returns true)
flags_help()
{
  if [ -n "${FLAGS_HELP:-}" ]; then
	echo "${FLAGS_HELP}" >&2
  else
	echo "USAGE: ${FLAGS_PARENT:-$0} [flags] args" >&2
  fi
  if [ -n "${__flags_longNames}" ]; then
	echo 'flags:' >&2
	for flags_name_ in ${__flags_longNames}; do
	  flags_flagStr_=''
	  flags_boolStr_=''
	  flags_usName_=`_flags_underscoreName ${flags_name_}`

	  flags_default_=`_flags_getFlagInfo \
		  "${flags_usName_}" ${__FLAGS_INFO_DEFAULT}`
	  flags_help_=`_flags_getFlagInfo \
		  "${flags_usName_}" ${__FLAGS_INFO_HELP}`
	  flags_short_=`_flags_getFlagInfo \
		  "${flags_usName_}" ${__FLAGS_INFO_SHORT}`
	  flags_type_=`_flags_getFlagInfo \
		  "${flags_usName_}" ${__FLAGS_INFO_TYPE}`

	  [ "${flags_short_}" != "${__FLAGS_NULL}" ] && \
		  flags_flagStr_="-${flags_short_}"

	  if [ ${__FLAGS_GETOPT_VERS} -eq ${__FLAGS_GETOPT_VERS_ENH} ]; then
		[ "${flags_short_}" != "${__FLAGS_NULL}" ] && \
			flags_flagStr_="${flags_flagStr_},"
		# add [no] to long boolean flag names, except the 'help' flag
		if [ ${flags_type_} -eq ${__FLAGS_TYPE_BOOLEAN} ]; then
		  _flags_itemInList "${flags_name_}" ${__flags_nonegateNames}
		   if [ $? -eq ${FLAGS_FALSE} ]; then
			  flags_boolStr_='[no]'
		   fi
		fi
		flags_flagStr_="${flags_flagStr_}--${flags_boolStr_}${flags_name_}:"
	  fi

	  case ${flags_type_} in
		${__FLAGS_TYPE_BOOLEAN})
		  if [ ${flags_default_} -eq ${FLAGS_TRUE} ]; then
			flags_defaultStr_='true'
		  else
			flags_defaultStr_='false'
		  fi
		  ;;
		${__FLAGS_TYPE_FLOAT}|${__FLAGS_TYPE_INTEGER})
		  flags_defaultStr_=${flags_default_} ;;
		${__FLAGS_TYPE_STRING}) flags_defaultStr_="'${flags_default_}'" ;;
	  esac
	  flags_defaultStr_="(default: ${flags_defaultStr_})"

	  flags_helpStr_="  ${flags_flagStr_}  ${flags_help_} ${flags_defaultStr_}"
	  _flags_strlen "${flags_helpStr_}" >/dev/null
	  flags_helpStrLen_=${flags_output}
	  flags_columns_=`_flags_columns`

	  if [ ${flags_helpStrLen_} -lt ${flags_columns_} ]; then
		echo "${flags_helpStr_}" >&2
	  else
		echo "  ${flags_flagStr_}  ${flags_help_}" >&2
		# note: the silliness with the x's is purely for ksh93 on Ubuntu 6.06
		# because it doesn't like empty strings when used in this manner.
		flags_emptyStr_="`echo \"x${flags_flagStr_}x\" \
			|awk '{printf "%"length($0)-2"s", ""}'`"
		flags_helpStr_="  ${flags_emptyStr_}  ${flags_defaultStr_}"
		_flags_strlen "${flags_helpStr_}" >/dev/null
		flags_helpStrLen_=${flags_output}

		if [ ${__FLAGS_GETOPT_VERS} -eq ${__FLAGS_GETOPT_VERS_STD} \
			-o ${flags_helpStrLen_} -lt ${flags_columns_} ]; then
		  # indented to match help string
		  echo "${flags_helpStr_}" >&2
		else
		  # indented four from left to allow for longer defaults as long flag
		  # names might be used too, making things too long
		  echo "    ${flags_defaultStr_}" >&2
		fi
	  fi
	done
  fi

  unset flags_boolStr_ flags_default_ flags_defaultStr_ flags_emptyStr_ \
	  flags_flagStr_ flags_help_ flags_helpStr flags_helpStrLen flags_name_ \
	  flags_columns_ flags_short_ flags_type_ flags_usName_
  return ${FLAGS_TRUE}
}

# Reset shflags back to an uninitialized state.
#
# Args:
#   none
# Returns:
#   nothing
flags_reset()
{
  for flags_name_ in ${__flags_longNames}; do
	flags_usName_=`_flags_removeExclamationName ${flags_name_}`
	flags_usName_=`_flags_underscoreName ${flags_usName_}`
	flags_strToEval_="unset FLAGS_${flags_usName_}"
	for flags_type_ in \
		${__FLAGS_INFO_DEFAULT} \
		${__FLAGS_INFO_HELP} \
		${__FLAGS_INFO_SHORT} \
		${__FLAGS_INFO_TYPE}
	do
	  flags_strToEval_=\
"${flags_strToEval_} __flags_${flags_usName_}_${flags_type_}"
	done
	eval ${flags_strToEval_}
  done

  # reset internal variables
  __flags_boolNames=' '
  __flags_longNames=' '
  __flags_shortNames=' '
  __flags_definedNames=' '

  unset flags_name_ flags_type_ flags_strToEval_ flags_usName_
}