ID3-Tag-Inator: Automatically populates ID3 tags for all MP3 files in the Tri-State Area

id3-tag-inator

#!/bin/sh
SELF=$(basename $0)

usage () {
    echo "usage: $SELF [-dfhv] [basedir]"
}

help () {
    echo "\
ID3-Tag-inator: Automatically populates ID3 tags for all MP3 files in the
                Tri-State Area."
    usage
    echo '
Options:
    -d
        Dry run (output ID3-editing commands instead of running them)
    -f
        Force updating ID3 tags even if they are already set
    -h
        This help screen
    -v
        Verbose output

Parameters:
    basedir
        A directory with subdirectories for each artist, each with
        subdirectories for each album, each with MP3 files; defaults to the
        current directory

Notes:
    Artist, album, and title values are derived from the folder and file names
    ID3-Tag-inator encounters, which no attempt to clean them up.  It is up to
    the user to rename the corresponding folders and files accordingly
    beforehand.

    Only MP3 files are supported, and their filenames must end in .mp3.

Copyright (C) 2021 Ryan S. Northrup ("RyNo") <northrup@yellowapple.us>

Permission to use, copy, modify, and distribute this software for any purpose
with or without fee is hereby granted, provided that the above copyright notice
and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.'
    exit 0
}

badopt () {
    echo "unknown option -- $1"
    usage
    exit 1
}

dep_not_found () {
    echo "$1 not found; exiting."
    exit 1
}

check_dep () {
    which $1 >/dev/null 2>&1 || dep_not_found $1
}

verbose () {
    test $VERBOSE -gt 0
}

dryrun () {
    test $DRYRUN -gt 0
}

force () {
    test $FORCE -gt 0
}

tag_is_unset () {
    test -z "$(echo $1 | grep $2)"
}

current_tags () {
    id3v2 -l "$1"
}

process_artist () {
    ARTIST="$1"
    verbose && echo "ARTIST: '$ARTIST'"
    cd "$ARTIST"
    pwd
    for ALBUM in */; do
        ALBUM=${ALBUM%*/}
        process_album "$ALBUM" "$ARTIST"
    done
    cd ..
    verbose && echo "================"
}

process_album () {
    ALBUM="$1"
    ARTIST="$2"
    verbose && echo "ALBUM: '$ALBUM'"
    cd "$ALBUM"
    pwd
    for TITLE in *.mp3; do
        TITLE=${TITLE%*.mp3}
        process_song "$TITLE" "$ALBUM" "$ARTIST"
    done
    cd ..
    verbose && echo "----------------"
}

process_song () {
    TITLE="$1"
    ALBUM="$2"
    ARTIST="$3"
    CURRENT_TAGS=`current_tags "$TITLE.mp3"`
    verbose && echo "PROCESS '$TITLE.mp3':"

    COMMAND="id3v2"
    if (force || tag_is_unset "$CURRENT_TAGS" TIT2); then
        COMMAND="$COMMAND -t \"$TITLE\""
        verbose && echo "    SET  title  (TIT2): \"$TITLE\""
    else
        verbose && echo "    SKIP title  (TIT2); already set"
    fi
    if (force || tag_is_unset "$CURRENT_TAGS" TALB); then
        COMMAND="$COMMAND -A \"$ALBUM\""
        verbose && echo "    SET  album  (TALB): \"$ALBUM\""
    else
        verbose && echo "    SKIP album  (TALB); already set"
    fi
    if (force || tag_is_unset "$CURRENT_TAGS" TPE1); then
        COMMAND="$COMMAND -a \"$ARTIST\""
        verbose && echo "    SET  artist (TPE1): \"$ARTIST\""
    else
        verbose && echo "    SKIP artist (TPE1); already set"
    fi

    COMMAND="$COMMAND \"$TITLE.mp3\" >/dev/null 2>&1"

    if dryrun; then
        echo $COMMAND
    else
        eval "$COMMAND"
    fi
}

VERBOSE=0
DRYRUN=0
FORCE=0

while getopts ":vdfh" arg; do
    case $arg in
        v)
            VERBOSE=1
            ;;
        d)
            DRYRUN=1
            ;;
        f)
            FORCE=1
            ;;
        h)
            help
            ;;
        *)
            badopt $OPTARG
            ;;
    esac
done
shift $((OPTIND-1))

check_dep id3v2
BASEPATH=${1:-.}
verbose && echo "Parameters:"
verbose && echo "    BASEPATH: $BASEPATH"
verbose && echo "    VERBOSE: $VERBOSE"
verbose && echo "    DRYRUN: $DRYRUN"
verbose && echo "    FORCE: $FORCE"

cd "$BASEPATH"
for ARTIST in */; do
    pwd
    ARTIST=${ARTIST%*/}
    process_artist "$ARTIST"
done