#!/usr/bin/env sh

get_time(){
	echo "$*" | sed "s/[ \t].*//"
}

get_title(){
	echo "$*" | cut -d ' ' -f 2-
}

reverse_word_order(){
	local result=
	for word in $@; do
		result="$word $result"
	done
	echo "$result" 
}

# bc is mandatory: arythmetic operations are very limited in ash.
get_seconds(){
	local n=0
	local v=0

	values=$(echo "$*" | sed 's/:/\
/g' | sed "s/^0//")
	for i in $(reverse_word_order $values); do
		case $n in
			0) v=$(echo "$v +         $i " | bc);;
			1) v=$(echo "$v + (60   * $i)" | bc);;
			2) v=$(echo "$v + (3600 * $i)" | bc);;
			*) echo "invalid timecode $*"; exit 1;;
		esac

		n=$((n+1))
	done

	echo $v
}

# Get a more usable time representation for the beginning and the end of songs.
get_values(){

	audio_file="$1"
	time_file="$2"
	total_length=$(soxi -D "${audio_file}" | sed "s/\..*//") # integer values only

	n=0

	while read X; do

		if [ $n -ne 0 ]; then
			to=$(get_time $X)
			to_s=$(get_seconds $to)
			echo -e "$from_s\t$to_s\t$title"
		fi

		#echo $X
		from=$(get_time $X)
		from_s=$(get_seconds $from)
		title=$(get_title $X)

		if [ -z "${WITH_NUMBER}" ]; then
			:
		else
			title="${n}${WITH_NUMBER}${title}"
		fi

		n=$(echo $n + 1 | bc)
	done < "${time_file}"

	echo -e "$from_s\t$total_length\t$title"
}

run_ffmpeg(){
	local file=$1
	local from=$2
	local duration=$3
	local title=$4

	if [ "${SIMULATION}" -eq 1 ]; then
		[ -z "${QUIET}" ] && echo "ffmpeg -loglevel error -ss '$from' -t '$duration' -i '${file}' '${title}'"
	else
		[ -z "${QUIET}" ] && echo "ffmpeg -loglevel error -ss '$from' -t '$duration' -i '${file}' '${title}'"
		$(< /dev/null ffmpeg -loglevel quiet -ss "$from" -t "$duration" -i "${file}" "${title}")
	fi
}

rip(){
	n=0
	from=0
	to=0

	audio_file="$1"
	time_file="$2"

	[ "$FORMAT" = "" ] && echo "default format: opus" && FORMAT="opus"

	#echo "from	to	duration	title"
	get_values "$audio_file" "$time_file" | while read LINE; do
		from=$(echo $LINE | cut -d ' ' -f 1)
		to=$(echo $LINE | cut -d ' ' -f 2)
		title=$(echo $LINE | cut -d ' ' -f 3-)
		duration=$(echo "$to - $from" | bc)

		run_ffmpeg "${audio_file}" "${from}" "${duration}" "${title}.${FORMAT}"
		n=$((n + 1))
	done
}

usage(){
	echo "usage: $0 command"
	echo "command: show <single-file-playlist> <song-list>"
	echo "command: rip  <single-file-playlist> <song-list>"
	echo
	echo "song-list line format example: 1:30 My second track of the playlist"
	echo "show output format: start end title"
	echo
	echo "envvar: SIMULATION [0|1] (do not invoke ffmpeg)"
	echo "envvar: FORMAT [mp3,ogg,opus,…] (see the ffmpeg documentation)"
	echo "envvar: WITH_NUMBER [separator] (not null = write song number, with this separator)"
	echo "        example: WITH_NUMBER=_ Song names will be 1_song.opus 2_song.opus…"
	echo "envvar: QUIET (if set to any value, ffmpeg commands are not displayed)"
}

if [ $# -lt 1 ]; then
	usage
	exit 0
fi

command=$1
shift

case "x-${command}" in
	x-show)

		# Takes the audio file in first parameter
		if [ $# -ne 2 ]; then
			echo "Usage: $0 show music-file time-stamps-file"
			exit 1
		fi

		get_values "$1" "$2"
		;;

	x-rip)

		# Takes the audio file in first parameter
		if [ $# -ne 2 ]; then
			echo "Usage: $0 show music-file time-stamps-file"
			exit 1
		fi

		rip "$1" "$2"
		;;
	*)
		usage 1>&2
		exit 1
esac