#!/bin/sh
#
# metaflac-field2field.sh, Copyright © 2009 Matteo Cypriani
#
# This program is free software. It comes without any warranty, to
# the extent permitted by applicable law. You can redistribute it
# and/or modify it under the terms of the Do What The Fuck You Want
# To Public License, Version 2, as published by Sam Hocevar. See
# http://sam.zoy.org/wtfpl/COPYING for more details.
#
# This script uses metaflac to process field to field copy/rename on
# FLAC file metadatas.
# Launch this script without arguments to display usage.
# ----
# Ce script utilise metaflac pour effectuer des actions de copie ou
# renommage de champ à champ sur les fichiers FLAC.
# Lancer ce script sans argument pour afficher son utilisation.

#set -x

USAGE=$(cat <<EOF
Usage:
  $0 <ACTION> <SRC_FIELD> <DST_FIELD> <FILE.flac> [ <FILE2.flac> [...] ]

<ACTION> : copy | move | rmcopy | mvcopy
  copy: each occurrence of SRC_FIELD is duplicated to create an occurrence of
        DST_FIELD; all the existing occurrences of SRC_FIELD and DST_FIELD are
        kept.
  move: each occurrence of SRC_FIELD is renamed to create an occurrence of
        DST_FIELD; the existing occurrences of DST_FIELD are kept.
  rmcopy: the existing occurrences of DST_FIELD are deleted, then each
          occurrence of SRC_FIELD is duplicated to create an occurrence
          of DST_FIELD; the occurrences of SRC_FIELD are kept.
  rmmove: the existing occurrences of DST_FIELD are deleted, then each
          occurrence of SRC_FIELD is renamed to create an occurrence of
          DST_FIELD.
EOF
)

# Right number of arguments?
if [ $# -lt 4 ] ; then
    echo "Wrong number of arguments!" >&2
    print_usage
fi

ACTION="$1"
shift

# Known action type?
case "$ACTION" in
    copy) ;;
    move) ;;
    rmcopy) ;;
    rmmove) ;;
    *)
        printf 'Action unknown "%s"!\n\n' "$ACTION" >&2
        printf '%s\n' "$USAGE" >&2
        exit 1
        ;;
esac

SRC_FIELD=$1
shift
DST_FIELD=$1
shift

printf 'Source field: %s\n' "$SRC_FIELD"
printf 'Destination field: %s\n' "$DST_FIELD"
printf 'Action: %s\n' "$ACTION"

echo "Processing files..."

if echo "$ACTION" | grep '^rm' >/dev/null ; then
    printf 'Deleting field "%s" on each file...\n' "$DST_FIELD"
    metaflac --remove-tag="$DST_FIELD" "$@"
fi

for file in "$@" ; do
    printf 'Setting field "%s" on file: "%s"\n' "$DST_FIELD" "$file"
    metaflac --show-tag="$SRC_FIELD" "$file" | sed 's/^[A-Z]\+=//' | while read -r c1 ; do
    printf 'Adding "%s"...\n' "$DST_FIELD=$c1"
    metaflac --set-tag="$DST_FIELD"="$c1" "$file"
done
done

if echo "$ACTION" | grep 'move$' >/dev/null ; then
    printf 'Deleting "%s" on each file...\n' "$SRC_FIELD"
    metaflac --remove-tag="$SRC_FIELD" "$@"
fi

# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4