#!/bin/bash

# flac2mp3 script
# Copyright (C) 2006-2011 Greg Methvin (greg@methvin.net)

# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# This script transcodes FLAC files to MP3. Requires flac, lame and id3v2.

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

EOT
    exit 1;
}

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

bitrate=
CBR_OPTS="--alt-preset cbr"
ABR_OPTS="--alt-preset"
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*\(32\|40\|48\|56\|64\|80\|96\|112\|128\|160\|192\|224\|256\|320\)$')
            [[ -z $bitrate ]] && usage;;
        p) br_opts=$ABR_OPTS
            bitrate=$(echo "$OPTARG" | grep '^\(medium\|standard\|extreme\|insane\)$')
            [[ -z $preset ]] && usage;;
        s) sedarg=$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 $bitrate ]]; then
    lame_opts="$br_opts $bitrate"
else
    lame_opts="$ABR_OPTS $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=${inf%.*}.mp3
    if [[ -n $sedarg ]]; then
        outf=$(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