#!/bin/bash

# saner programming env: these switches turn some bugs into errors
set -o errexit -o pipefail -o noclobber -o nounset
source="-"
dest="-"
verbose=true
help=false

GetOptions() {

	# https://stackoverflow.com/a/29754866
	! getopt --test > /dev/null 
	if [[ ${PIPESTATUS[0]} -ne 4 ]]; then
		VerboseOutput "Fatal" "\`getopt --test\` failed"
		echo "Sorry, It seems that your shell is not supported"
		echo "If you're using mac or another unix-like system, please install GNU getopt"
		exit 1
	fi
	
	# Parsing style without -s or -d
	source=${*: -2:1}
	dest=${*: -1:1}

	OPTIONS=s:d:vh
	LONGOPTS=source:,dest:,verbose,help

	# -use ! and PIPESTATUS to get exit code with errexit set
	# -temporarily store output to be able to check for errors
	# -activate quoting/enhanced mode (e.g. by writing out “--options”)
	# -pass arguments only via   -- "$@"   to separate them correctly
	! PARSED=$(getopt --options=$OPTIONS --longoptions=$LONGOPTS --name "$0" -- "$@")
	if [[ ${PIPESTATUS[0]} -ne 0 ]]; then
		# e.g. return value is 1
		#  then getopt has complained about wrong arguments to stdout
		Usage
		exit 2
	fi

	# read getopt’s output this way to handle the quoting right:
	eval set -- "$PARSED"

	verbose=false
	# now enjoy the options in order and nicely split until we see --
	while true; do
		case "$1" in
			-v|--verbose)
				verbose=true
				shift
				;;
			-h|--help)
				help=true
				shift
				;;
			-s|--source)
				source="$2"
				shift 2
				;;
			-d|--dest)
				dest="$2"
				shift 2
				;;
			--)
				shift
				break
				;;
			*)
				echo "Programming error"
				return 3
				;;
		esac
	done

}

Usage() {
	echo ""
	echo "Usage:"
	echo "music-sync <options> -s|--source <source> -d|--dest <destination>"
	echo "music-sync <options> <source> <destination>"
	echo ""
	echo "Syncronises music from one folder to another."
	echo ""
	echo "Options:"
	echo " -s, --source <source>     The source folder of the music"
	echo " -d, --dest <destination>  The destionation folder of the music"
	echo " -v, --verbose             Enable verbose output"
	echo " -h, --help                Display this help text"
	echo ""
}

VerboseOutput() {
	if [[ "$verbose" = true ]]; then
		echo "[$1] $2" >&2
	fi
}

GetOptions $@
if [[ "$help" == true ]]; then
	Usage
	exit
fi