#!/usr/bin/env bash
# converts all .flac files to .mp3 and copies them to the
# OUT directory; copies all .mp3 files to the OUT directory.

LAMEOPTS="-V0 --quiet"

if [ "$#" -ne 2 ]
then
echo "usage: $0 MUSIC_DIR OUTPUT_DIR"
exit 1
fi

IN=$1
if [ ! -d "$IN" ]
then
echo "$IN is not a directory"
exit 1
fi

OUT=$2
if [ ! -d "$OUT" ]
then
mkdir "$OUT"
fi

# first, find all .mp3s and copy them to the OUT dir
# unless they are already there
find "$IN" -iname "*.mp3" | while read mp3;
do
OF=`echo "$mp3" | sed s,"$IN","$OUT\/",g`
dir=`dirname "$OF"`
if [ ! -d "$dir" ]
then
mkdir -p "$dir"
fi
if [ ! -e "$OF" ]
then
echo "copying $mp3 to $OF"
cp "$mp3" "$OF"
fi
done

# now, find all .flacs and convert them to .mp3
# unless they have already been converted
find "$IN" -iname "*.flac" | while read flac;
do
OF=`echo "$flac" | sed s/\.flac/\.mp3/g | sed s,"$IN","$OUT\/",g`
dir=`dirname "$OF"`
if [ ! -d "$dir" ]
then
mkdir -p "$dir"
fi
if [ ! -e "$OF" ]
then
# retrieve ID3 tags
ARTIST=`metaflac "$flac" --show-tag=ARTIST | sed s/.*=//g`
TITLE=`metaflac "$flac" --show-tag=TITLE | sed s/.*=//g`
ALBUM=`metaflac "$flac" --show-tag=ALBUM | sed s/.*=//g`
GENRE=`metaflac "$flac" --show-tag=GENRE | sed s/.*=//g`
TRACKNUMBER=`metaflac "$flac" --show-tag=TRACKNUMBER | sed s/.*=//g`
DATE=`metaflac "$flac" --show-tag=DATE | sed s/.*=//g`

# convert to MP3, preserving ID3 tags
echo "encoding $flac to $OF"
flac -c -dF --silent "$flac" | lame $LAMEOPTS \
--add-id3v2 --pad-id3v2 --ignore-tag-errors --tt "$TITLE" --tn "${TRACKNUMBER:-0}" --ta "$ARTIST" --tl "$ALBUM" --ty "$DATE" --tg "${GENRE:-12}" \
- "$OF"
fi
done