#!/usr/bin/perl

# Written by Paul Rogers. (C) 2007 and All Rights Reserved.
#
# This is open source and can be re-used, modified and included in other works, providing
# credit is given to the original author on code or ideas used.
#
# I also make no guarantees or warranties on this program - you use it at your own risk.
#
# You will need to download metamp3 (only available for Windows as there is no source code).
# Obviously, if a similar tool to metamp3 can be found on other platforms, please feel free
# to modify this so it runs accordingly.
#
# http://home.broadpark.no/~tylovset/files/metamp3v092b5.zip
#
# Also, the Perl library MP3::Tag needs to be installed so tags can be read / written to.
#
# the_uhu@hotmail.com

use MP3::Tag;
use Getopt::Long;

$_ = 1;

$optDebug = 0;
$optDir = "";
$optHelp = 0;
$optRescan = 0;
$optUpdMP3s = 0;

GetOptions( 'directory=s'	=> \$optDir,
	    'debug'		=> \$optDebug,
	    'help'		=> \$optHelp,
	    'rescan'		=> \$optRescan,
	    'update'		=> \$optUpdMP3s );

if ($optHelp)
{
	&funcDisplayHelp();
	exit (0);
}

# Location of the metamp3.exe command to scan and set the volume information

$glbStrMetaMP3Loc = ".";
$glbStrMetaMP3Cmd = "metamp3.exe";
$glbStrMetaMP3Args = "--replay-gain";

$strDir="";
@arrDirList;

if ($^O eq "MSWin32")
{
	$strDirSep = "\\";
}
else
{
	$strDirSep = "/";
}

if ($optDir)
{
	$optDir =~ s/\\+$//;
	$optDir =~ s/\/+$//;
	$strDir=$optDir.$strDirSep;
}
else { $strDir=".".$strDirSep; }

if (!$optUpdMP3s) { &funcPrintMsg(2, "Only scanning MP3s - will NOT update files. Use --update switch if otherwise required"); }

if ($optDebug) { &funcPrintMsg(0,"strDir: $strDir"); }

# Excluded albums titles from album gain tagging:

@arrAlbumExclusions = ( "",
			"\"Live tracks\"" );

# Read list of *.mp3 files from ./

&funcPrintMsg(1, "Reading list of MP3 files from $strDir");

opendir(HNDDIR, $strDir) or die "ERROR! Can't open $strDir: $!";

$tmpIntCnt=0;

while( defined ($strFile = readdir HNDDIR) )
{
	if ($strFile =~ /\.mp3$/)
	{
		if ($optDebug) { &funcPrintMsg(0,"Found $strFile"); }

		push (@arrDirList, $strFile);
		$tmpIntCnt++;
	}
}
closedir(HNDDIR);

&funcPrintMsg(1, "Found $tmpIntCnt MP3 files");

if ($tmpIntCnt == 0)
{
	&funcPrintMsg(2,"There are no MP3 files in $strDir. Quitting");

	exit(0);
}

# Open each file and pull Album Artist, Album Title, Track Title, Filename and whether gain info is present
# (used later if a command line switch is present to ignore files with gain info already) with a unique ID number into an array

@arrMP3List;
$intI = 0;
$intUniqID = 1;

&funcPrintMsg(1, "Reading ID3v2 tags...");

foreach $tmpStrFile (@arrDirList)
{
	$#arrMP3Info = -1;

	$strFileChk = $strDir.$tmpStrFile;

	$objMP3 = MP3::Tag->new($strFileChk);
	$objMP3->get_tags();

	if (exists $objMP3->{ID3v2})
	{
		$objMP3ID3v2 = $objMP3->{ID3v2};
	}
	else
	{
		&funcPrintMsg(2, "$tmpStrFile does not have any ID3v2 tags - skipping");
		next;
	}

	($tmpStrAlbumArtist, $tmpStrLong) = $objMP3ID3v2->get_frame("TPE2");
	($tmpStrAlbumTitle, $tmpStrLong) = $objMP3ID3v2->get_frame("TALB");
	($tmpStrTitle, $tmpStrLong) = $objMP3ID3v2->get_frame("TIT2");
	($tmpHashGainInfo1, $tmpStrLong, @tmpHashGainInfoRest) = $objMP3ID3v2->get_frame("TXXX");

	$objMP3->close();

	if ($tmpStrAlbumArtist eq "")
	{
		&funcPrintMsg(2, "$tmpStrFile does not have an Album Artist set (frame TPE2) - skipping.");
		next;
	}
	
	$tmpIntGainInfoFound = 0;
	$tmpStrAlbumGain = "";
	$tmpStrAlbumPeak = "";

	if ($optDebug) { &funcPrintMsg(0,"Reading ID3v2 tags from $tmpStrFile"); }
	if ($optDebug) { &funcPrintMsg(0,"Filename: $tmpStrFile | AlbumArtist: $tmpStrAlbumArtist | AlbTit: $tmpStrAlbumTitle | Title: $tmpStrTitle"); }

	$tmpIntGainInfo = 0;

	while(my ($tmpGainKey,$tmpGainVal)=each %$tmpHashGainInfo1)
	{
		if ($optDebug) { &funcPrintMsg(0,"* $tmpGainKey => $tmpGainVal"); }

		if ($tmpGainKey eq "Description")
		{
			if ($tmpGainVal =~ /^replaygain_/) { $tmpIntGainInfoFound++; }
			if ($tmpGainVal =~ /_album_gain$/) { $tmpIntGainInfo = 1; }
			elsif ($tmpGainVal =~ /_album_peak$/) { $tmpIntGainInfo = 2; }
		}
		elsif ($tmpGainKey eq "Text")
		{
			if ($tmpIntGainInfo == 1) { $tmpStrAlbumGain = $tmpGainVal; }
			elsif ($tmpIntGainInfo == 2) { $tmpStrAlbumPeak = $tmpGainVal; }
		}		
	}

	foreach $tmpHashGainInfo (@tmpHashGainInfoRest)
	{
		$tmpIntGainInfo = 0;

		while (my ($tmpGainKey,$tmpGainVal)=each %$tmpHashGainInfo)
		{
			if ($optDebug) { &funcPrintMsg(0,"$tmpGainKey => $tmpGainVal"); }

			if ($tmpGainKey eq "Description")
			{
				if ($tmpGainVal =~ /^replaygain_/) { $tmpIntGainInfoFound++; }
				if ($tmpGainVal =~ /_album_gain$/) { $tmpIntGainInfo = 1; }
				elsif ($tmpGainVal =~ /_album_peak$/) { $tmpIntGainInfo = 2; }
			}
			elsif ($tmpGainKey eq "Text")
			{
				if ($tmpIntGainInfo == 1) { $tmpStrAlbumGain = $tmpGainVal; }
				elsif ($tmpIntGainInfo == 2) { $tmpStrAlbumPeak = $tmpGainVal; }
			}		
		}
	}

	if ($optDebug) { &funcPrintMsg(0,"| AlbumGain: $tmpStrAlbumGain | AlbumPeak: $tmpStrAlbumPeak | GainInfoCount: $tmpIntGainInfoFound"); }

	push (@arrMP3Info, $intUniqID, $tmpStrAlbumArtist, $tmpStrAlbumTitle, $tmpStrTitle, $tmpIntGainInfoFound, $tmpStrAlbumGain, $tmpStrAlbumPeak, $tmpStrFile);
	push (@arrMP3List, [ @arrMP3Info ]);

	if ($optDebug)
	{
		&funcPrintMsg(0,"arrMP3Info: ",1);
		foreach $tmpStrPrint (@arrMP3Info)
		{
			&funcPrintMsg(-1,"| $tmpStrPrint ",1);
		}
		&funcPrintMsg(-1,"|");
	}

	$intUniqID++;
	$intI++;
}

# Sort the array by Album Artist and Album Title

&funcPrintMsg(1, "Sorting list of MP3s found by Album Artist and Album Title");

@arrMP3ListSorted = sort { $a->[1] cmp $b->[1] || $a->[2] cmp $b->[2] } @arrMP3List;

if ($optDebug)
{
	&funcPrintMsg(0, "Size of sorted array is ".@arrMP3ListSorted);
	foreach $tmpRefList (@arrMP3ListSorted)
	{
		&funcPrintMsg(0, "@$tmpRefList");
	}
}

# Create a blank second arrary

@arrToBeVolumeTagged;

# Loop through each second dimension items in the sorted array and add the filename, gain info count, album gain and album peak info to the second array.

$tmpStrPrevAlbumArtist = "";
$tmpStrPrevAlbumTitle = "";
$tmpIntI = 0;

foreach $tmpRefList (@arrMP3ListSorted)
{
	$#arrVolumeTaggedInfo = -1;

	&funcCheckIfTagReqd();

	if ($optDebug) { &funcPrintMsg(0, "Adding to be tagged list: @$tmpRefList[1] | @$tmpRefList[2] | @$tmpRefList[7] | @$tmpRefList[4] | @$tmpRefList[5] | @$tmpRefList[6]"); }

	push (@arrVolumeTaggedInfo, @$tmpRefList[1], @$tmpRefList[2], @$tmpRefList[7], @$tmpRefList[4], @$tmpRefList[5], @$tmpRefList[6]);
	push (@arrToBeVolumeTagged, [ @arrVolumeTaggedInfo ]);

	$tmpStrPrevAlbumArtist = @$tmpRefList[1];
	$tmpStrPrevAlbumTitle = @$tmpRefList[2];

	$tmpIntI++;
}

$tmpRefList = $arrMP3ListSorted[$tmpIntI - 1];

if ($optDebug) { &funcPrintMsg(0, "Test if we have rolled back to the last item (should be non-blank): @$tmpRefList[2]"); }

&funcCheckIfTagReqd();

&funcPrintMsg(1, "All done!");

exit(0);

# Tagging function - loop through the array passed to us and build a command line to run metamp3.exe to set the gain
# correctly.
# If a command line switch is present, do NOT remove the gain ID3v2 and APEv2 tags within this loop.

# Execute the metamp3.exe command line

sub funcTagAlbum
{
	@arrToTag = @_;
	$tmpStrCmdLine = $glbStrMetaMP3Loc.$strDirSep.$glbStrMetaMP3Cmd;
	$tmpStrCmdArgs = "";

	if ($optRescan) { &funcPrintMsg(1, "Removing existing volume gain information so the files can be rescanned"); }

	foreach $tmpRefToTagList (@arrToTag)
	{
		$strFileChk = $strDir.@$tmpRefToTagList[2];

		if ($optRescan)
		{
			$objMP3 = MP3::Tag->new($strFileChk);
			$objMP3->get_tags();

			if (exists $objMP3->{ID3v2})
			{
				if ($optDebug) { &funcPrintMsg(0, "Deleting TXXX frame from ID3v2 tag within @$tmpRefToTagList[2]",1); }

				if ($optUpdMP3s)
				{
				# This is really crap. All PERL MP3 libraries can only remove one tag name in one instance of the parent object.
				# Which means when you have multiple tags using the same name (like the gain information [TXXX]) you have to
				# create a new object each time to remove an instance of the multiple tag name. GRRRRRRRRRR.

					$objMP3ID3v2 = $objMP3->{ID3v2};
					$objMP3ID3v2->remove_frame("TXXX");
					$objMP3ID3v2->write_tag();
					$objMP3->close();

					$objMP3 = MP3::Tag->new($strFileChk);
					$objMP3->get_tags();
					$objMP3ID3v2 = $objMP3->{ID3v2};
					$objMP3ID3v2->remove_frame("TXXX");
					$objMP3ID3v2->write_tag();
					$objMP3->close();

					$objMP3 = MP3::Tag->new($strFileChk);
					$objMP3->get_tags();
					$objMP3ID3v2 = $objMP3->{ID3v2};
					$objMP3ID3v2->remove_frame("TXXX");
					$objMP3ID3v2->write_tag();
					$objMP3->close();

					$objMP3 = MP3::Tag->new($strFileChk);
					$objMP3->get_tags();
					$objMP3ID3v2 = $objMP3->{ID3v2};
					$objMP3ID3v2->remove_frame("TXXX");
					$objMP3ID3v2->write_tag();
					$objMP3->close();

					if ($optDebug) { &funcPrintMsg(-1, " - DELETED"); }
				}
				else { if ($optDebug) { &funcPrintMsg(-1, " - NOT deleted, re-run with --update"); } }
			}
			else { &funcPrintMsg(2, "@$tmpRefToTagList[2] does not have any ID3v2 tags - skipping"); }
		}

		$tmpStrCmdArgs .= " \"".$strFileChk."\"";
	}

	$tmpIntErrCode = 0;
	$tmpStrErr = "";

	if ($optUpdMP3s)
	{
		&funcPrintMsg(1, "Executing Tagging utility...");
		if ($optDebug) { &funcPrintMsg(0, "Command line: $tmpStrCmdLine $glbStrMetaMP3Args$tmpStrCmdArgs"); }

		$tmpIntErrCode = system($tmpStrCmdLine, $glbStrMetaMP3Args, $tmpStrCmdArgs);

		if ($tmpIntErrCode == 256) { $tmpStrErr = "Cannot find / access '$tmpStrCmdLine'. Please check"; }
	}

	return ($tmpIntErrCode, $tmpStrErr);
}

# This function USES GLOBAL VARIABLES to work out if tagging is required or if the process should skip as we are in the same album still

sub funcCheckIfTagReqd
{ 
	if ($optDebug) { &funcPrintMsg(0, "Loop counter: $tmpIntI"); }

	# Check if the previous track's album is in the excluded album list.

	$tmpBoolExclAlbum = 0;

	foreach $tmpStrAlbumExclude (@arrAlbumExclusions)
	{
		if ((($tmpStrPrevAlbumTitle eq $tmpStrAlbumExclude) && ($tmpIntI > 0)) || ((@$tmpRefList[2] eq $tmpStrAlbumExclude) && ($tmpIntI == 0)))
		{
			$tmpBoolExclAlbum = 1;

			&funcPrintMsg(1, "Album in the Exclusion list");

			last;
		}
	}

	# If the previous second dimenstion item in the array doesn't have a matching Album Artist OR Album Title and is not the first iteration
	# OR the previous track is in the excluded album list OR it's the last item in the to be sorted list,

	if ((((@$tmpRefList[1] ne $tmpStrPrevAlbumArtist) || (@$tmpRefList[2] ne $tmpStrPrevAlbumTitle)) && ($tmpIntI > 0)) || ($tmpBoolExclAlbum || ($tmpIntI == @arrMP3ListSorted)))
	{
		&funcPrintMsg(1, "Reached the end of '$tmpStrPrevAlbumArtist | $tmpStrPrevAlbumTitle'. ",1);

		# then loop around the second array and check if the album gain and album peak figures match and that no track has a gain info count < 4
		# (providing the album is NOT in the exclusion list).

		# If they don't OR the size of the second array is 1 OR one or more tracks has a gain info count < 4,
		# pass the second array to a tagging function.
		# Otherwise do nothing as the list of tracks has the same album volume tag info and are fully populated.

		$tmpBoolEnoughGainInfo = 1;
		$tmpBoolAlbumGainInfoMatches = 1;
		$tmpStrCheckAlbumGain = "";
		$tmpStrCheckAlbumPeak = "";

		foreach $tmpRefTBTList (@arrToBeVolumeTagged)
		{
			if (($tmpBoolExclAlbum) || (@arrToBeVolumeTagged == 1))
			{
				if (@$tmpRefTBTList[3] != 2) { $tmpBoolEnoughGainInfo = 0; }
			}
			else
			{
				if (@$tmpRefTBTList[3] < 4) { $tmpBoolEnoughGainInfo = 0; }
				if ((($tmpStrCheckAlbumGain ne @$tmpRefTBTList[4]) && ($tmpStrCheckAlbumGain ne "")) || (($tmpStrCheckAlbumPeak ne @$tmpRefTBTList[5]) && ($tmpStrCheckAlbumPeak ne ""))) { $tmpBoolAlbumGainInfoMatches = 0; }

				$tmpStrCheckAlbumGain = @$tmpRefTBTList[4];
				$tmpStrCheckAlbumPeak = @$tmpRefTBTList[5];
			}
		}

		if (!$tmpBoolEnoughGainInfo || !$tmpBoolAlbumGainInfoMatches || $optRescan)
		{
			&funcPrintMsg(-1, "Tags need updating...");

			($tmpIntErrCode, $tmpStrErr) = &funcTagAlbum(@arrToBeVolumeTagged);

			if ($tmpIntErrCode != 0)
			{
				&funcPrintMsg(3, "Unable to tag the track(s). Error: $tmpIntErrCode $tmpStrErr");
				exit(1);
			}
		}
		else { &funcPrintMsg(-1, "Tags do NOT need updating..."); }

		# Blank the second array at the end of the above IF block.

		$#arrVolumeTaggedInfo = -1;
		$#arrToBeVolumeTagged = -1;
	}
}

# Displays help on the console

sub funcDisplayHelp
{
	print "Usage:\n";
	print "======\n\n";
	print " $0 [--debug] [--directory=<path>] [--rescan] [--update]|--help\n\n";
	print " --debug               Displays debug processing information\n";
	print " --directory=<path>    Script will search <path> for MP3s to analyse their\n";
	print "                       volume gain information. By default, we use the current\n";
	print "                       directory\n";
	print " --help                Displays this help information\n";
	print " --rescan              If volume gain information is found, instead of skipping\n";
	print "                       the tracks, they will have the tag information deleted\n";
	print "                       before scanning / updates take place (it's a limitation\n";
	print "                       in metamp3.exe unfortunately)\n";
	print " --update              Updates the MP3s with volume gain information if it\n";
	print "                       is found to be missing or inconsistent within the\n";
	print "                       MP3s. It will also set Album Gain details for tracks\n";
}

sub funcPrintMsg
{
	($tmpIntType, $tmpStrMessage, $tmpBoolNoNewline) = ($_[0], $_[1], $_[2]);

	if ($tmpIntType >= 0)
	{
		if ($tmpIntType == 0) { $tmpStrType = "DEBUG"; }
		elsif ($tmpIntType == 1) { $tmpStrType = "INFO"; }
		elsif ($tmpIntType == 2) { $tmpStrType = "WARNING"; }
		elsif ($tmpIntType == 3) { $tmpStrType = "ERROR!"; }
		else { $tmpStrType = "UNKNOWN"; }

		($tmpIntSec,$tmpIntMin,$tmpIntHour,$tmpIntMDay,$tmpIntMon,$tmpIntYear,$tmpIntWDay,$tmpIntYDay,$tmpBoolDst)=localtime(time);
		printf "%4d-%02d-%02d %02d:%02d:%02d",$tmpIntYear+1900,$tmpIntMon+1,$tmpIntMDay,$tmpIntHour,$tmpIntMin,$tmpIntSec;
		print " - ";

		printf "%-7s", $tmpStrType;
		print " - ";
	}
	print "$tmpStrMessage";
	if (!$tmpBoolNoNewline) { print "\n"; }
}