rename-tracks

#!/bin/sh

usage()
{
    cat >&2 <<__EOF__
Usage: $(basename $0) [-n]

Arguments:
  -n            -- Dry run mode. Don't actually modify any files.
__EOF__
    exit ${1-1}
}

log()
{
    echo "$(basename $0): $1" >&2
}

digits()
{
    local i count

    i=0
    count=$1
    while [ $count -gt 0 ]; do
        count=$(($count / 10))
        i=$((i + 1))
    done

    echo $i
}

while [ $# -gt 0 ]; do
    case $1 in
    -n)
        dryrun=yes
        ;;
    *)
        usage
        ;;
    esac
    shift
done

: ${dryrun=no}

if ! which audget >/dev/null 2>&1; then
    log "audget is not available"
    exit 1
fi

OLDIFS=$IFS
IFS='
'
count=$(digits $(find . -depth 1 -name \*.mp3 -o -name \*.flac | wc -l))
for file in $(find . -depth 1 -name \*.mp3 -o -name \*.flac); do
    track=$(audget --track "$file" | awk '{print $NF}')
    if [ $? -ne 0 ]; then
        log "failed to obtain track number for '$file', skipping"
        continue
    fi
    ext=${file##*.}
    new=track$(printf "%0${count}d" $track).cdda.$ext

    log "renaming '"$(basename "$file")"' to '$new'"
    [ $dryrun = no ] && mv "$file" "$new"
done
IFS=$OLDIFS