#!/usr/bin/perl

use 5.14.0;
use strict;
use warnings;
use File::Copy qw(move);
use File::Basename qw(basename dirname);
use File::Path qw(make_path);

#my $library = "/home/sir/Music/Songbird Music";
my $library = "/home/sir/Music/Songbird Music";
my (%t, %files, @files, @dirs);
my $flac_version = '1.2.1';

getdirs($library);

foreach my $dn (sort(@dirs)) {
	#my $ino = (stat($fn))[1];
	#say "$dn has $ino";
	undef %files;
	undef @files;
	getfiles($dn);
	my $fc = @files;
	if ($fc > 0) {
		replaygain($dn);
		for (my $n = 0; $n < $fc; $n++) {
			my $fn = $files[$n];
			undef(%t);
			foreach my $tag (keys($files{$fn})) {
				$t{$tag} = $files{$fn}{$tag}->[0];
				#say "$tag = $t{$tag}";
			}
			vendor($fn);
			rmtag($fn, 'rating');
			albumartist($fn, $fc);
			track($fn);
			spaces($fn);
			totaltracks($fn, $fc);
	#		empty($fn);
			duplicate($fn);
			discnum($fn, $n, $fc);
		}
	}
}
# Make this subroutine and the whole script so that each file name is stored in a hash and that each member contains an anonymous hash with the tags (the alltags hash).
# This means it won't have to look up the tags again for the albumartist subroutine.

sub gettags {
	my $fn = shift;
	my (%alltags, @mflac);
	open(OUTPUT, '-|', qq{metaflac --no-utf8-convert --show-vendor-tag --export-tags-to=- "$fn"}) || die "can't run metaflac: $!";
	chomp(@mflac = (<OUTPUT>));
	foreach (@mflac) {
		my (@tag, $tagname);
		if (/^reference/) {
			@tag = split(' ');
			$tagname = 'vendor_ref';
			$tag[1] = $tag[2];
		} else {
			@tag = split('=');
			$tagname = lc($tag[0]) or next;
		}

		if ($tag[1]) {
			push(@{$alltags{$tagname}}, $tag[1]); }
			else { push(@{$alltags{$tagname}}, 'null'); }
	}
	close(OUTPUT) || die "couldn't close metaflac: $!";
	return %alltags;
}

sub vendor {
	my $fn = shift;

	if ($t{vendor_ref} ne $flac_version) {
		my $newfn = $fn . '.' . int(rand(10000));
		say "$fn: old encoder ($t{vendor_ref}), re-encoding...";
		system('flac', '--silent', '-8', "$fn", '--output-name=' . "$newfn");
		if ($? == 0) {
			move($newfn, $fn) or die "Couldn't rename '$newfn': $!";
		} elsif ($? == 2) {
			say "Interrupted by user!";
			unlink($newfn) if (-f $newfn);
			exit;
		}
	}
}

sub getdirs {

	my $dn = shift;

	open(FIND, '-|', qq(find -L "$dn" -name "*" -type d))
	or die "Can't run 'find': $!";
	chomp(@dirs = (<FIND>));
	close(FIND) or die "Can't close 'find': $!";
}

sub getfiles {
	my $dn = shift;
	my $fn;
	opendir(my $dh, $dn) or die "Can't open directory '$dn': $!";
	foreach (readdir $dh) {
		$fn = $dn . '/' . $_;
		if (/.flac$/ && -f $fn) {
			push(@files, $fn);
			$files{$fn} = { gettags($fn) };
		}
	}
	closedir $dh or die "Can't close directory '$dn': $!";
}

sub replaygain {
	my $dn = shift;
	my %replaygain;
 
	#foreach ('REFERENCE_LOUDNESS', 'TRACK_GAIN', 'TRACK_PEAK', 'ALBUM_GAIN', 'ALBUM_PEAK') {
	#	my $tag = 'REPLAYGAIN_' . $_;
	#	system('metaflac', '--remove-tag=' . $tag, keys(%files));
	#}

	foreach my $fn (sort(keys %files)) {
			if ($files{$fn}{replaygain_album_gain}) {
				$replaygain{$files{$fn}{replaygain_album_gain}->[0]}++;
			}
	}

	if (keys(%replaygain) != 1) {
		print "$dn: adding ReplayGain...";
		system('metaflac', '--add-replay-gain', keys(%files));
		say " done";
	}
}

sub albumartist {
	my $fn = shift;
	my $tracks = shift;

	if (! $t{albumartist} || $t{albumartist} eq 'null') {
		my %artist;
		my $max;
		if ($tracks == 1) { $max = $tracks } else { $max = $tracks / 2 }
		foreach my $fn (sort(keys(%files))) {
			$artist{$t{artist}} = 1;
		}
		if (keys(%artist) > $max) {
			$t{albumartist} = 'Various Artists';
		} else { $t{albumartist} = $t{artist} };

		say "$fn: adding albumartist tag";
		system('metaflac', '--remove-tag=ALBUMARTIST', '--set-tag=ALBUMARTIST=' . $t{albumartist}, "$fn");
	}
}

sub empty {
	my $fn = shift;
	foreach my $tag (sort(keys(%{$files{$fn}}))) {
		foreach (@{$files{$fn}{$tag}}) {
			if ($_ eq 'null') {
				say "$fn: WARNING: empty $tag tag";
			}
		}
	}
}

sub duplicate {
		my $fn = shift;
		my %exists;
		foreach my $field (sort(keys(%{$files{$fn}}))) {
			foreach my $tag (@{$files{$fn}{$field}}) {
				if ($exists{$field} && $exists{$field} eq $tag) {
					say "$fn: removing duplicate $field tag";
					system('metaflac', '--remove-tag=' . $field, '--set-tag=' . $field . '=' . $tag, "$fn");
				} else {
					$exists{$field} = $tag;
				}
			}
		}
}

sub track {
	my $fn = shift;
	if (!$t{tracknumber}) {
		say "$fn: doesn't have any tracknumber tag"
	}
	elsif ($t{tracknumber} =~ m/^0/ && $t{tracknumber} != 0) {
		say "$fn: fixing tracknumber tag";
		$t{tracknumber} =~ s/^0+//;
		system('metaflac', '--remove-tag=TRACKNUMBER', '--set-tag=TRACKNUMBER=' . $t{tracknumber}, "$fn");
	}
}

sub spaces {
	my $fn = shift;
	my %temp;

	foreach my $tag (sort(keys(%t))) {
		$temp{$tag} = $t{$tag};
		$temp{$tag} =~ s/(^\s*)|(\s*$)//g;
	}

	foreach my $tag (sort(keys(%t))) {
		if ($temp{$tag} ne $t{$tag} && "$temp{$tag}") {
			say "$fn: removing leading and trailing whitespaces from tags";
			#say $temp{$tag};
			my $ufield = uc($tag);
			system('metaflac', '--remove-tag=' . $ufield, '--set-tag=' . $ufield . '=' . $temp{$tag}, "$fn");
		}
	}
}

sub totaltracks {
	my $fn = shift;
	my $tracks = shift;
	if (
	!$t{totaltracks} &&
	!$t{tracktotal}
	) {
		say "$fn: adding totaltracks tag";
		system('metaflac', '--set-tag=TOTALTRACKS=' . $tracks, "$fn");
	}
	elsif (
	$t{tracktotal} &&
	!$t{totaltracks}
	) {
		say "$fn: replacing tracktotal tag with totaltracks";
		system('metaflac', '--remove-tag=TRACKTOTAL', '--set-tag=TOTALTRACKS=' . $t{tracktotal}, "$fn");
	}	
}

sub discnum {
	my $fn = shift;
	my $n = shift;
	my $fc = shift;

	my $dn = dirname($fn);
	my ($match, $newfn);
	my $regex = '[[:punct:]]?(cd|disc) ?[0-9]+[[:punct:]]?$';

	if ($t{album} =~ /$regex/i) {
		$t{album} =~ s/.?(${^MATCH}).?//;
		system('metaflac', '--remove-tag=ALBUM', '--set-tag=ALBUM=' . $t{album}, "$fn");
	}

	if (!$t{discnumber}) {
		if (basename($fn) =~ /^[0-9]+-/) {
			$match = ${^MATCH};
			${^MATCH} =~ /([0-9]+)/;
			$t{discnumber} = eval { $1 =~ s/^0+//; };
		}
		elsif ($dn =~ /$regex/i) {
			$match = ${^MATCH};
			${^MATCH} =~ /([0-9]+)/;
			$t{discnumber} = eval { $1 =~ s/^0+//; };

			$dn =~ s/ .?($match).?//;

			make_path($dn) if (! -d $dn);
			$newfn = "${dn}/" . $t{discnumber} . '-' . basename($fn);
			unless (-f $newfn) {
				move($fn, $newfn) or die "Couldn't rename '$fn': $!";
			}
		}
		else {
			$t{discnumber} = 1;
			$newfn = "${dn}/" . $t{discnumber} . '-' . basename($fn);
			unless (-f $newfn) {
				move($fn, $newfn) or die "Couldn't rename '$fn': $!";
			}
		}

		if (!$newfn) { $newfn = $fn }
		say "$newfn: adding discnumber tag";
		system('metaflac', '--set-tag=DISCNUMBER=' . $t{discnumber}, "$newfn");
	}
}

sub rmtag {
	my $fn = shift;
	foreach my $field (@_) {
		if ($t{$field}) {
			say "$fn: removing $field tag";
			system('metaflac', '--remove-tag=' . $field, "$fn");
		}
	}
}