#!/bin/sh

LC_NUMERIC=POSIX; export LC_NUMERIC

#Find the mp3gain executable
MP3GAIN=`which mp3gain`
if [[ $? != 0 ]]; then
	echo "mp3gain executable not found." >&2
	exit 1
fi

#Find the eyeD3 executable
EYED3=`which eyeD3`
if [[ $? != 0 ]]; then
	echo "eyeD3 executable not found." >&2
	exit 1
fi

if [[ $# > 1 || $# == 1 && $1 != "-f" ]] ; then
	echo "Usage: `basename $0` [-f]" >&2
	echo " for ReplayGain'ing all mp3 file into current directory" >&2
	echo " -f -- force re-ReplayGain'ing for already ReplayGain'ed files" >&2
	exit 2
fi

if [[ $# == 0 ]]; then
	$EYED3 --no-color *.mp3 \
	| egrep -i '^UserTextFrame: \[Description: replaygain_album_gain\]$' >/dev/null 2>&1
		if [[ $? == 0 ]]; then
		echo "Files already ReplayGain'ed." >&2
	exit 1
fi
fi

$MP3GAIN *.mp3

TMPFILE=`tempfile`

for n in *.mp3; do
	$MP3GAIN -s c "$n" > $TMPFILE
	$MP3GAIN -s d "$n"
	TRACK_GAIN=`awk '/^Recommended "Track" dB / { printf("%+.2f dB", $5) }' $TMPFILE`
	ALBUM_GAIN=`awk '/^Recommended "Album" dB / { printf("%+.2f dB", $5) }' $TMPFILE`
	TRACK_PEAK=`awk '/^Max PCM / { printf("%.6f", $7/32768) }' $TMPFILE`
	ALBUM_PEAK=`awk '/^Max Album PCM / { printf("%.6f", $8/32768) }' $TMPFILE`
	$EYED3 \
		--set-user-text-frame="replaygain_track_gain:$TRACK_GAIN" \
		--set-user-text-frame="replaygain_track_peak:$TRACK_PEAK" \
		--set-user-text-frame="replaygain_album_gain:$ALBUM_GAIN" \
		--set-user-text-frame="replaygain_album_peak:$ALBUM_PEAK" \
	"$n"
done

rm -f $TMPFILE