#!/usr/bin/env bash
# 2025 Hyperling
# Clean up a music library. Improved version of rename_music_files.sh.

# Steps:
# 0) Ensure an OLD folder exists, it is what will be refactored.
# 1) Convert all non-mp3 files to mp3 and put them in an INTERIM folder.
# 2) Loop over all OLD and INTERIM's mp3 files and move them to NEW based on data.
#    - Name the file as "${ZERO_LED_TRACK_NUMBER}. ${SONG_TITLE}
#    - Name parent folder as "${YEAR} - ${ALBUM}" if both exist, otherwise just one or the other "${YEAR}${ALBUM}".
#    - Name grandparent folder as "${ARTIST} - ${GENRE}" if both exist, otherwise "${ARTIST}${GENRE}".

# TODO list:
# - Organize tracks by Artist + Album folders.
# - Name parent folder as "$YEAR - $ALBUM" if both exist, otherwise just one or the other.
# - Name grandparent folder as ARTIST if it exists, otherwise GENRE.

## Facts and Variables ##

DIR="`pwd`"
PROG="$(basename -- "${BASH_SOURCE[0]}")"

FAIL=".$PROG.exit-error"

OLD="$DIR/OLD"
NEW="$DIR/NEW"
INT="$DIR/INTERIM"

## Checks and Setup ##

# System Packages #
echo "* Checking if necessary tools are installed."
function needed_progs {
	cat <<- EOF
		ffmpeg
		exiftool
	EOF
}
needed_progs | while read prog; do
	if [[ -z "`which $prog`" ]]; then
		echo "ERROR: $prog not found, please install."
		touch $FAIL
	fi
done
if [[ -e $FAIL ]]; then
	rm -fv $FAIL
	exit 1
fi
echo "** Tools are available."

# Old Directory #
echo "* Checking whether OLD directory exists."
if [[ "`pwd`" == *"/OLD" ]]; then
	echo "** We are in the folder, moving up a directory."
	cd ..
fi
if [[ ! -d "OLD" ]]; then
	echo "ERROR: Could not find a folder named 'OLD'."
	echo "       Please create it and add your library there."
fi
echo "** Folder exists appropriately."

# Other Directories #
echo "* Ensuring working directories NEW and INTERIM exist."
mkdir -pv "$NEW" "$INT"

## Convert Media ##

echo "* Convert all files to mp3."
find "$OLD" ! -name "*".mp3 | while read file; do
	ffmpeg -nostdin -hide_banner -loglevel quiet -i "$file" "$file".converted.mp3
done
echo "** Done converting mp3s."

## Transform Media ##

function migrate_music {
	file="$1"
	command="$2"

	if [[ -z $file ]]; then
		echo "ERROR: No filename retrieved, cannot migrate."
		return 1
	fi
	if [[ -z "$command" ]]; then
		command="cp"
	fi

	echo "** $file **"

	# Retrieve and clean the Title
	title=""
	title="`exiftool -Title "$file"`"
	title="${title//Title   /}"
	title="${title//   : /}"
	title="${title//[^[:alnum:][:space:].]/}"
	title="`echo $title`"
	while [[ "$title" == *"  "* ]]; do
		title="${title//  / }"
	done
	echo "*** Title=$title"

	new_file="$title$EXT"

	# Retrieve and clean the Track#
	track=""
	# Get raw value
	track="`exiftool -Track "$file"`"
	# Filter the header
	track="${track//Track   /}"
	track="${track//   : /}"
	# Remove disk designations
	track="${track%%/*}"
	# Remove any whitespace before/after
	track="`echo $track`"
	# Add a leading 0 to single digits.
	[[ ${#track} == 1 ]] && track="0$track"
	echo "*** Track=$track"

	new_file="$track. $new_file"

	# Add the Album and Year.


	new_file="$parent/$new_file"

	# Add the Artist and Genre.


	new_file="$grandparent/$new_file"

	# Move the file.
	new_file="$NEW/$new_file"
	$command "$file" "$new_file"

}

echo "* Moving INTERIM files to NEW."
find "$INT" -name "*".mp3 | while read file; do
	migrate_music "$file" mv
done

echo "** Done with INTERIM, deleting."
rm -rfv "$INT"

echo "* Copying OLD files to NEW."
find "$OLD" -name "*".mp3 | while read file; do
	migrate_music "$file" cp
done