#!/bin/sh
#
# Shell script to demonstrate built-in getopts for parsing command options.
# - Built-in getopts can only handle one-character options

# Supporting functions, alphabetized...

# Parse the command line and set variables to control logic
parseCommandLine() {
	# Special case that nothing was provided on the command line so print usage
	# - include this if it is desired to print usage by default
	if [ "$#" -eq 0 ]; then
		printUsage
		exit 0
	fi
	local OPTIND opt h i o v
	optstring=":hi:o:v"
	while getopts $optstring opt; do
		#echo "Command line option is $opt"
		case $opt in
			h) # -h  Print usage
				printUsage
				exit 0
				;;
			i) # -i inputFile  Get the input file
				inputFile=$OPTARG
				;;
			o) # -o outputFile  Get the output file
				outputFile=$OPTARG
				;;
			v) # -v  Print the version
				printVersion
				exit 0
				;;
			\?) # Unknown single-character option
				echo ""
				echo "Invalid option:  -$OPTARG" >&2
				printUsage
				exit 1
				;;
			:) # Option is recognized but it is missing an argument
				echo ""
				echo "Option -$OPTARG requires an argument" >&2
				printUsage
				exit 1
				;;
		esac
	done
	# Get a list of all command line options that do not correspond to dash options.
	# - These are "non-option" arguments.
	# - For example, one or more file or folder names that need to be processed.
	# - If multiple values, they will be delimited by spaces.
	# - Command line * will result in expansion to matching files and folders.
	shift $((OPTIND-1))
	additionalOpts=$*
}

# Print the program usage
# - calling code needs to exit with the appropriate status
printUsage() {
	echo ""
	program=$(basename $0)
	echo "$program [options] other-vals"
	echo ""
	echo "Example of how to use built-in getopts."
	echo "Options are:"
	echo ""
	echo "-h               Print help."
	echo "-i inputFile     Specify the input file."
	echo "-o outputFile    Specify the output file."
	echo "-v               Print version."
	echo ""
}

# Print the program version
# - calling code needs to exit with the appropriate status
printVersion() {
	echo ""
	program=$(basename $0)
	echo "$program version:  $version $versionDate"
	echo ""
}

# Main entry point into shell
version="1.1.0"
versionDate="2019-03-24"

# Initialize variables
inputFile=""
outputFile=""
additionalOpts=""

# Parse the command line options
# - pass all arguments to the function
parseCommandLine "$@"

# Print input and output file
echo "Input file:   $inputFile"
echo "Output file:  $outputFile"
echo "Additional options:  $additionalOpts"

exit 0