#!/bin/bash
#########################################################
# 							#
# This is BashStyle-NG  				#
#							#
# Licensed under GNU GENERAL PUBLIC LICENSE v3    	#
#							#
# Copyright 2007 - 2017 Christopher Bratusek		#
#							#
#########################################################

fill_zeros () {
	current_len=${#1}
	diff_string=""

	if [[ ${current_len} -ne ${count_len} ]]; then
		diff_len=$((count_len-current_len))
		while test ${diff_len} -ne 0; do
			diff_string="${diff_string}0"
			diff_len=$((diff_len-1))
		done
		echo ${diff_string}
	fi
}

rename_files () {
	mkdir "${directory}"/tmp

	count_max=$(($(find "${directory}" -maxdepth 1 -type f | wc -l)))
	count_len=${#count_max}
	count_now=1

	OLD_IFS="${IFS}"
	export IFS=$'\n'

	files=$(find "${directory}" -maxdepth 1 -type f)

	for image in ${files[@]}; do
		suffix=$(fill_zeros ${count_now})${count_now}.${image##*.}
		mv "${image}" "${directory}"/tmp/"${prefix}"-"${suffix}"
		count_now=$((count_now+1))
	done

	mv "${directory}"/tmp/* "${directory}"/
	rmdir "${directory}"/tmp

	export IFS="${OLD_IFS}"
}


if [[ $# -ne 2 ]]; then
	bashstyle-help -a "Christopher Roy Bratusek" -e "nano@jpberlin.de" \
		-h "http://www.nanolx.org/" -l "GNU GPL v3" -n "batchrename" \
		-s "batch rename files in NNN-NAME.SUFFIX scheme" \
		-v "${BSNG_VERSION}" -y "${BSNG_YEAR}"\
		-o "directory:/home/test/mypictures|directory containing files"\
		-o "prefix:MyPictures2016|NAME part of the NNN-NAME.SUFFIX scheme"
else
	directory="${1}"
	if [[ ! -d "${directory}" ]]; then
		echo "directory ${directory} does not exist!"
		exit 1
	elif [[ ! -w "${directory}" ]]; then
		echo "directory ${directory} is not writeable!"
		exit 1
	fi

	prefix="${2}"
	rename_files
fi
