#!/bin/sh
# See LICENSE file for copyright and license details.

set -e

usage () {
	printf 'usage %s: [-Dry] in-file [out-file]\n' "$0" >&2
	exit 1
}

recursive=no
delete_in_file=no
ffmpeg_flag_y=
status=0

while test "${1::1}" = '-'; do
	if test "${1}" = '--'; then
		shift
		break
	elif test "${1}" = '-'; then
		break
	fi

	arg="${1:1}"
	while test -n "${arg}"; do
		flag="${arg::1}"
		arg="${arg:1}"
		if test "${flag}" = r; then
			recursive=yes
		elif test "${flag}" = D; then
			delete_in_file=yes
		elif test "${flag}" = y; then
			ffmpeg_flag_y=-y
		else
			usage
		fi
	do
done

if test ! $# = 1 && test ! $# = 2; then
	usage
fi

in_file="$1"
if test -z "${in_file}"; then
	usage
fi

out_file=""
if test $# = 2; then
	out_file="$2"
	if test -z "${out_file}"; then
		usage
	fi
fi

getext () {
	ffprobe -v error -select_streams a:0 -show_entries stream=codec_name -of default=noprint_wrappers=1:nokey=1 -- "$1"
}

removeext () {
	printf '%s\n' "$1" | sed 's/\.[^.]*$//'
}

extract () {
	printf '\033[1m%s\033[m\n' "Extracting audio track from ${1}" >&2
	printf '\033[1m%s\033[m\n' "and storing as ${2}" >&2
	if ffmpeg -i "${1}" -vn -acodec copy ${ffmpeg_flag_y} -- "${2}"; then
		if test ${delete_in_file} = yes; then
			unlink -- "${1}"
		fi
	fi
}

if test ${recursive} = no || test ! -d "${in_file}"; then
	if test -z "${out_file}"; then
		out_file="$(removeext "${in_file}").$(getext "${in_file}")"
	fi
	extract "${in_file}" "${out_file}"
	exit $?
fi

recursive () {
	for in_file in "${1}/"*; do
		out_file="$2/$(basename -- "${in_file}")"
		if test -d "$f"; then
			mkdir -p -- "${out_file}"
			recursive "${in_file}" "${out_file}"
		else
			out_file="$(removeext "${out_file}").$(getext "${in_file}")"
			if ! extract "${in_file}" "${out_file}"; then
				status=1
			fi
		fi
	done
	if test ${delete_in_file} = yes; then
		rmdir -- "${1}" 2>/dev/null || :
	fi
}

if test -z "${out_file}"; then
	out_file="${in_file}"
else
	mkdir -p -- "${out_file}"
fi
recursive "${in_file}" "${out_file}"

exit $status