#!/bin/sh
# Program:
# 	* rename file while removing [:punct:], replace [:upper:] with
#	  [:lower:], replace "${sep}" with '_'
# 	* while given '-d' , do not rename file, only print new
# 	  file name
# Dependency:
# 	* err.sh
# Author:
# 	* Chang, Chu-Kuan <cckuan@changchukuan.name>

#
# Setting
#

# Characters which will be replaced by '_', other [:punct:] not presented here
# will be deleted
readonly sep='[]()._-[:blank:]'

. err.sh

help_msg()
{
	cat << EOF
Usage:
  ${progname} [-hd] file... - format filename

Options:
  -d                   Perform a 'dry run'. Do not actually rename file.
  -h                   Show this message and exit.

EOF
}

process_file()
{
	file="$1"
	dir="$(dirname "${file}")"
	base="$(basename "${file}")"

	# Return if there is error parsing file name
	if test -z "${file}" || test -z "${dir}" || test -z "${base}"; then
		printf '%s: error parsing file: %s\n' "${progname}" "${file}" 1>&2
		return 1
	fi

	case "${base}" in
	# file name with extension
	*.*)
		# get file extension
		extension="${base##*.}"
		# process file name
		new_base="$(printf '%s' "${base%.*}" \
		    | iconv --to-code=utf-8 \
		    | tr "${sep}" ' ' \
		    | tr -d '[:punct:]' \
		    | tr '[:upper:]' '[:lower:]' \
		    | tr -s ' ' '_' \
		    | sed 's/^_//; s/_$//'
		).${extension}"
		;;
	# file name without extension
	*)
		new_base="$(printf '%s' "${base}" \
		    | iconv --to-code=utf-8 \
		    | tr "${sep}" ' ' \
		    | tr -d '[:punct:]' \
		    | tr '[:upper:]' '[:lower:]' \
		    | tr -s ' ' '_' \
		    | sed 's/^_//; s/_$//'
		)"
		;;
	esac

	if test "${base}" = "${new_base}"; then
		clean_file_cnt="$((clean_file_cnt + 1))"
		printf '%s: file %s require no rename\n' "${progname}" \
		    "${base}"
		return 0
	fi

	case "${d_flag}" in
	'1')
		# While given '-d', do not rename file, only
		# print new file name
		printf '%s -> %s\n' "${base}" "${new_base}"
		;;
	*)
		# Rename file (prompt before overwrite)
		mv -iv "${dir}/${base}" "${dir}/${new_base}" \
		    && success_file_cnt="$((success_file_cnt + 1))"
		;;
	esac
}

readonly progname="$(basename "$0")"
d_flag='0'
total_file_cnt='0'
success_file_cnt='0'
clean_file_cnt='0'

while getopts 'dh' opt; do
	case "${opt}" in
	'd')
		readonly d_flag='1'
		;;
	'h')
		help_msg
		exit 0
		;;
	*)
		err '1' 'invalid option\n'
		;;
	esac
done

shift "$((OPTIND - 1))"

for arg; do
	total_file_cnt="$((total_file_cnt + 1))"
	process_file "${arg}"
done

# Report status
printf '\n%s: renamed %d, clean %d, total %d/%d\n' "${progname}" \
    "${success_file_cnt}" "${clean_file_cnt}" \
    "$((success_file_cnt + clean_file_cnt))" "${total_file_cnt}"