mp3tag

#!/bin/bash

# Copy filename in the form of "artist - title.mp3" to mp3 tags,
# or vice versa.
#
# mp3tag {-t | -f} filename [filename ...]

EYED3=$(which eyed3 2>/dev/null)$(which eyeD3 2>/dev/null)

function usage {
	echo "mp3tag {-t | -f} [-a album] filename [filename ...]"
}

while getopts "tfa:" OPT; do
	case $OPT in
		t ) TO_TAG=1 ;;
		f ) TO_FN=1 ;;
        a ) ALBUM=$OPTARG ;;
	esac
done

[[ !($TO_TAG || $TO_FN) || ($TO_TAG && $TO_FN) ]] && {
	usage;
	echo "Please specify one of -t (write tags), -f (write filename)." >&2
	exit 1;
}

[[ -n "$ALBUM" ]] && ALBUMOPTS="-A \"$ALBUM\""

while [[ $1 ]]; do	
	FN=$(echo $1 | egrep '\.mp3$'); shift
	[[ ! "$FN" ]] && continue	
	
	# Write tags based on filename
	
	if [ $TO_TAG ]; then
		[ -w "$FN" ] || {
			echo "$FN is not writable!" >&2
			continue;
		}
		
		ARTIST=$(echo "$FN" | perl -nle '/^(.*?)-/; $a = $1; $a =~ s/(^\s+|\s+$)//g; print $a;')
		TITLE=$(echo "$FN" | perl -nle '/^.*?-(.*?)\.mp3$/; $a = $1; $a =~ s/(^\s+|\s+$)//g; print $a;')
		
		if [[ "$TITLE" && "$ARTIST" ]]; then
			CMD="$EYED3 --no-color -a \"$ARTIST\" -t \"$TITLE\"" 
            [[ -n "$ALBUMOPTS" ]] && CMD="$CMD $ALBUMOPTS"
            eval "$CMD \"$FN\"" >/dev/null
		else
			echo "Cannot write tag for $FN!" >&2
		fi
		
	# Write filename based on tags
		
	elif [ $TO_FN ]; then		
		TA=$($EYED3 --no-color "$FN" 2>/dev/null | egrep 'title\:.*artist\:')
		TITLE=$(echo "$TA" | perl -nle '/title\: (.*?)artist\:/; $a = $1; $a =~ s/(^\s+|\s+$)//g; print $a;')
		ARTIST=$(echo "$TA" | perl -nle '/title\: .*?artist\:(.*)$/; $a = $1; $a =~ s/(^\s+|\s+$)//g; print $a;')
		
		if [[ "$TITLE" && "$ARTIST" ]]; then
			mv "$FN" "$ARTIST - $TITLE.mp3"
			echo "Renamed \"$FN\" to \"$ARTIST - $TITLE.mp3\"" >&2
		else
			echo "Cannot rename $FN!" >&2
		fi
	fi	
done