#!/bin/sh
ending() {
	echo "$1" |awk -F . '{print $NF}'
}

checkMetadata() {
	ffprobe "$1" 2>&1 | grep -ie artist -e title
	while true; do
		printf "correct metadata? [Y] | [n]: "
		read -r yn < /dev/tty
		case "$yn" in
			[Nn]* ) return 1;;
			* ) return 0;;
		esac
	done
}

download_dir="$(mktemp -d)"
temp_dir="$(mktemp -d)"
downloadSong() {
	filepath="$(youtube-dl "ytsearch:$1 lyrics" \
		-f bestaudio/best \
		--output "$download_dir/%(title)s.%(ext)s" \
		--metadata-from-title "%(artist)s - %(title)s" \
		--add-metadata \
		|awk '$1 == "[download]" && $2 == "Destination:" {print substr($0, index($0,$3))}')"
			case "$filepath" in
				*.webm)
					new_filename="${filepath%.*}".opus
					ffmpeg -i "$filepath" -codec copy "$new_filename" 2> /dev/null
					filepath="$new_filename"
					;;
				*.m4a)
					;;
				*)
					echo "unsupported file type" > /dev/stderr
					exit 1
					;;
			esac
			r128gain "$filepath" 2> /dev/null
			echo "$filepath"
}

changeMetadata() {
	filepath="$1"
	artist="$2"
	title="$3"
	dir="$4"
	case "$filepath" in
		*.opus)
			metadata_track=":s:a:0"
			title_tag="TITLE"
			artist_tag="ARTIST"
			;;
		*.m4a)
			title_tag="title"
			artist_tag="artist"
			;;
	esac
	metadata="-metadata$metadata_track"
	output_path="$dir/$artist-$title.$(ending "$filepath")"
	ffmpeg -i "$filepath" -codec copy "$metadata" "$title_tag=$title" "$metadata" \
		"$artist_tag=$artist" "$output_path" 2> /dev/null
	echo "$output_path"
}

while getopts "a:t:mp" c; do
	case $c in
		a) artist="$OPTARG";;
		t) title="$OPTARG";;
		m)
			dir="$MUSIC_DIR/$(date +%Y)"
			mkdir -p "$dir"
			;;
		p) print_path=0;;
		*) echo "invalid flag" > /dev/stderr;;
	esac
done
shift $(("$OPTIND" - 1))
if [ ! "$dir" ]; then
	dir="$(pwd)"
fi
if [ "$artist" ] && [ "$title" ]; then
	echo 1
	filepath="$(downloadSong "$artist" "$title")"
	output_path="$(changeMetadata "$filepath" "$artist" "$title" "$dir")"
	if [ "$print_path" ]; then
		echo "$output_path"
	fi
else
	for song in "$@"; do
		filepath="$(downloadSong "$song")"
		filename="$(basename "$filepath")"
		if checkMetadata "$filepath"; then
			mv "$filepath" "$dir"
			if [ "$print_path" ]; then
				echo "$dir/$filename"
			fi
		else
			printf "artist: "
			read -r artist
			printf "title: "
			read -r title
			output_path="$(changeMetadata "$filepath" "$artist" "$title" "$dir")"
			if [ "$print_path" ]; then
				echo "$output_path"
			fi
		fi
	done
fi
rm -rf "$temp_dir" "$download_dir"
mpc update > /dev/null