#!/bin/bash

# flac2mp3 script
# Copyright (C) 2006-2007 Greg Methvin (greg@methvin.net)

# This program is free software. You may distribute it under the terms of
# the GNU General Public License as published by the Free Software
# Foundation, version 2.
# 
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
# 
# This script transcodes FLAC files to MP3.

function usage {
    echo "Usage: $(basename $0) [[-a|-c] -b <kbps> | -p <preset>] [-i <id3>] <file> [<file2>...]"
    echo "options:"
    echo " -b <kbps>    Set average or constant bitrate for mp3 (constant is default)"
    echo "              <kbps>: 32 40 48 56 64 80 96 112 128 160 192 224 256 320"
    echo "   -a         Encode mp3 at a variable bitrate averaging <kbps> kbps"
    echo "   -c         Encode mp3 at a constant bitrate of <kbps> kbps"
    echo " -p <preset>  Use a preset quality value:"
    echo "              \"-p medium\": ~150-180kbps"
    echo "              \"-p standard\": ~170-210kbps"
    echo "              \"-p extreme\": ~200-240kbps (default)"
    echo "              \"-p insane\": 320kbps CBR"
    echo " -s <sed>     Apply sed expression to output filename:"
    echo "              \"-s 's/rip/\/media\/mp3player/'\":"
    echo "                      Replaces 'rip' with '/media/mp3player'"
    exit 1;
}

# Turn off input field separation to allow filenames with spaces
IFS=

bitrate=
CBR_OPTS="--cbr -b"
ABR_OPTS="--abr"
br_opts=
preset=extreme
sedarg=

while getopts ":p:acb:s:" options; do
    case $options in
        a) br_opts=$ABR_OPTS;;
        c) br_opts=$CBR_OPTS;;
        b) bitrate=$(echo "$OPTARG" | grep '^0*\(32\|40\|48\|56\|64\|80\|96\|112\|128\|160\|192\|224\|256\|320\)$')
            if [ -z "$bitrate" ]; then usage; fi;;
        p) preset=$(echo "$OPTARG" | grep '^\(medium\|standard\|extreme\|insane\)$')
            if [ -z "$preset" ]; then usage; fi;;
	    s) sedarg=$OPTARG;;
        *) usage;;
    esac
done

shift $(($OPTIND - 1))

if [ -z "$*" ] || [ -n "$cbr" ] && [ -z "$bitrate" ]; then
    usage
elif [ -z "$br_opts" ] && [ -n "$bitrate" ]; then
    br_opts=$CBR_OPTS
fi

if [ -n "$br_opts" ]; then
    lame_opts="$br_opts $bitrate"
else
    lame_opts="--preset $preset"
fi

function flac2mp3_convert {
    inf="$1"
    outf="$2"

    # Encode to MP3
    echo
    echo "input FLAC file: $inf"
    echo "output MP3 file: $outf"
    bash -c "flac -c -d \"$inf\" | lame $lame_opts - \"$outf\""

    # check if we have an output file
    [ -f "$outf" ] || return 1
    
    # Get ID3 info
    ARTIST=$(metaflac "$inf" --show-tag=ARTIST | sed s/ARTIST=//g)
    TITLE=$(metaflac "$inf" --show-tag=TITLE | sed s/TITLE=//g)
    ALBUM=$(metaflac "$inf" --show-tag=ALBUM | sed s/ALBUM=//g)
    GENRE=$(metaflac "$inf" --show-tag=GENRE | sed s/GENRE=//g)
    TRACKNUMBER=$(metaflac "$inf" --show-tag=TRACKNUMBER \
        | sed s/TRACKNUMBER=//g)
    YEAR=$(metaflac "$inf" --show-tag=DATE \
        | sed s/DATE=//g | cut -b -4)

    # Set ID3 tags (assume id3v2)
    echo
    echo "Setting ID3 tags"
    echo

    id3v2 -t "$TITLE" -T "$TRACKNUMBER" \
        -a "$ARTIST" -A "$ALBUM" -y "$YEAR" -g "$GENRE" \
        "$outf" > /dev/null
    id3v2 -l "$outf"
    return 0
}

count=0
for inf in $*; do
    # Check if the file exists
    if [ ! -f "$inf" ]; then
        echo "$inf: No such file.">&2
        continue
    fi

    # Set output filename   
    outf=$(echo "$inf" | sed 's/\.flac$/.mp3/gi')
    if [ "$sedarg" != "" ]; then
	    outf=$(echo "$outf" | sed "$sedarg")
	    mkdir -p "$(dirname "$outf")"
    fi

    # Do the conversion on this file and increment if we created the file
    if [ "$outf" != "$inf" ]; then
        flac2mp3_convert "$inf" "$outf" && let count++
    fi
done

echo
echo "$count MP3 files created."
echo