#!/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

	if [[ $dest == "" ]] || [[ $source == "" ]]; then
		help=true
	fi
}

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
}

CreateFileList() {
	# ${1} /mnt/hdd/Example-Artist/Example-Album
	# ${2} /mnt/mtp/Example-Artist/Example-Album
	# ${3} Example-Artist/Example-Album/
	IFS=""
	sourcepath="${1}/*"
	for file in $sourcepath; do
		relfile="${file#"$1/"}"
		if [[ -d "${1}/$relfile" ]]; then
			newdir="${3}/$relfile"
			newdir=${newdir#"/"}
			VerboseOutput "Info" "Entering $newdir"
			CreateFileList "${1}/$relfile" "${2}/$relfile" "$newdir"
		elif [[ ! -f "${2}/$relfile" || "${1}/$relfile" -nt "${2}/$relfile" ]]; then
			echo ${3}/$relfile >> /tmp/music-sync-filelist
			VerboseOutput "Info" "Added: ${3}/${relfile}"
		fi
	done
}

ConvertFiles() {
	mkdir -p /tmp/converted
	while read -r line
	do
		VerboseOutput "Info" "Converting $line"
		if [[ "/tmp/converted/$line" = */* ]]; then
			mkdir -p "/tmp/converted/${line%/*}";
		fi;
		lame -b 192 $source/$line /tmp/converted/$line 1>/dev/null 2>/dev/null
		VerboseOutput "Info" "Converted $line"
	done < "/tmp/music-sync-filelist"
}

CopyFiles() {
	while read -r line
	do
		VerboseOutput "Info" "Copy $line"
		if [[ "$dest/$line" = */* ]]; then
			mkdir -p "$dest/${line%/*}";
		fi;
		cp -f $source/$line $dest/$line 1>/dev/null 2>/dev/null
	done < "/tmp/music-sync-filelist"
	VerboseOutput "Info" "Copied $line"
}

CleanUp() {
	VerboseOutput "Info" "Cleaning Up"
	rm "/tmp/music-sync-filelist"
	rm -rf "/tmp/converted"
	VerboseOutput "Info" "Done"
}

GetOptions $@
if [[ $help == true ]]; then
	Usage
	exit
fi
CreateFileList $source $dest ""
if [[ ! -f /tmp/music-sync-filelist ]]; then
	VerboseOutput "Info" "Nothing to do!"
	exit 0
fi
ConvertFiles
CopyFiles
CleanUp