#!/usr/bin/perl
# Change hash size for an MGMapsCache folder by moving files around
# script version 1.01

#Externals
use POSIX;
use File::Find;
use Cwd;

#OS Specific Variables 
$linuxDirDivider = "\/"; $linuxMoveCommand = "mv"; $linuxDeleteCommand = "rm"; $linuxRmdirCommand = "rmdir"; $linuxMkdirCommand = "mkdir -p";
$windowsDirDivider = "\\"; $windowsMoveCommand = "move"; $windowsDeleteCommand = "del"; $windowsRmdirCommand = "rd"; $windowsMkdirCommand = "md";
print "Detected OS: $^O\n\n";
if($^O ge "linux" || $^O ge "cygwin" ) 
{
	$systemDirDivider = $linuxDirDivider;
	$systemDirDividerRegex = $linuxDirDivider;
	$systemMoveCommand = $linuxMoveCommand;
	$systemDeleteCommand = $linuxDeleteCommand;
	$systemRmdirCommand = $linuxRmdirCommand;
	$systemMkdirCommand = $linuxMkdirCommand;
}
elsif($^O ge "MSWin")
{
	$systemDirDivider = $windowsDirDivider;
	$systemDirDividerRegex = "$windowsDirDivider$windowsDirDivider";
	$systemMoveCommand = $windowsMoveCommand;
	$systemDeleteCommand = $windowsDeleteCommand;
	$systemRmdirCommand = $windowsRmdirCommand;
	$systemMkdirCommand = $windowsMkdirCommand;
}
if($^O eq "darwin")
{
	$systemDirDivider = $linuxDirDivider;
	$systemDirDividerRegex = $linuxDirDivider;
	$systemMoveCommand = $linuxMoveCommand;
	$systemDeleteCommand = $linuxDeleteCommand;
	$systemRmdirCommand = $linuxRmdirCommand;
	$systemMkdirCommand = $linuxMkdirCommand;
}

my $dn = "";
my $fn;
$oldSize = 0;
$newSize = 0;
$file_CacheConf = "cache.conf";

while ($dn eq "") {
	# Read cache folder name
	print "Enter the name of the cache folder (default \"MGMapsCache\"): ";
	chomp($dn = <>);
	if ($dn eq "") {
		$dn = "MGMapsCache";
	}
	
	# Open cache.conf
	$fn = $dn.$systemDirDivider.$file_CacheConf;
	if (!open(F, "<".$fn)) {
		print "$fn not found (invalid cache folder name).\n";
		$dn = "";
		next;
	}
	
	# Get old hash size
	while ($line = <F>) {
		@splits = split('=', $line);
		if (($splits[0] eq 'tiles_per_file') && (int($splits[1]) != 1)) {
			print "At this time you cannot re-hash cache folders with multiple tiles per file.\n";
			exit 1;
		}
		if ($splits[0] eq 'hash_size') {
			$oldSize = int($splits[1]);
		}
		elsif (($splits[0] eq 'version') && (int($splits[1]) < 3)) {
			$oldSize = 97;
		}
	}
	close(F);
	
	if ($oldSize < 1 || $oldSize >= 100) {
		print "Unknown existing cache size, invalid $file_CacheConf file.\n";
		exit 1;
	}
	
}

# Get new hash size
while ($newSize < 1 || $newSize >= 100) {
	print "New hash size (examples: 11, 23, 47, 97 or 1 to disable hashing): ";
	chomp($newSize = <>);
	next if ($newSize eq "");
	$newSize = int($newSize);
	if ($newSize < 1 || $newSize >= 100) {
		print "Please enter a number between 1 and 100 (the prime numbers above give best results).\n";
		next;
	}
}

# Nothing to do? Actually we may have to move _some_ files but not all if downloaded with different tools.
if ($oldSize == $newSize) {
	print "Warning: Old hash size is the same as new hash size, nothing to do.\n";
}

# Get base directory
$baseDir = getcwd().$systemDirDivider;
if ($dn =~ /^$systemDirDividerRegex/) {
	$baseDir = "";
}

# Do the rename/move around
finddepth(\&recursiveMove, $dn);

# Remove the unused folders
finddepth(\&recursiveRmdir, $dn);

# update the cache configuration file
print "Moving $file_CacheConf to $file_CacheConf.old\n";
my $cmd = $systemMoveCommand." ".$fn." ".$fn.".old";
system($cmd);
print "Updating $file_CacheConf\n";
open(F, "<".$fn.".old") or die("Cannot read $file_CacheConf.old");
open(F2, ">".$fn) or die("Cannot write $file_CacheConf");
$found = 0;
print F2 "version=3\n";
while($line = <F>) {
	@splits = split('=', $line);
	if ($splits[0] eq 'hash_size') {
		print F2 "hash_size=".$newSize."\n";
		$found = 1;
	}
	elsif ($splits[0] ne 'version') {
		print F2 $line;
	}
}
if ($found == 0) {
	print F2 "hash_size=".$newSize."\n";
}
close(F2);
close(F);
print "Removing $file_CacheConf.old\n";
$cmd = $systemDeleteCommand." ".$fn.".old";
system($cmd);

# done
exit;


sub recursiveMove {
	# only mgm files
	if (/^([0-9]+)_([0-9]+)\.mgm$/) {
		my $oldName = $File::Find::name;
		my $newName = $oldName;
		my $oldHashVal = ($1*256+$2) % $oldSize;
		my $newHashVal = ($1*256+$2) % $newSize;
		if ($oldSize > 1 && $newSize > 1) {
			$newName =~ s/\/$oldHashVal\/([0-9]+_[0-9]+\.mgm)$/\/$newHashVal\/$1/;
		}
		elsif ($oldSize == 1 && $newSize == 1) {
		}
		elsif ($oldSize == 1) {
			$newName =~ s/\/([0-9]+_[0-9]+\.mgm)$/\/$newHashVal\/$1/;
		}
		else {
			$newName =~ s/\/$oldHashVal\/([0-9]+_[0-9]+\.mgm)$/\/$1/;
		}
		
		# mkdir if needed
		if ($newSize > 1) {
			my $newDir = $newName;
			$newDir =~ s/\/[0-9]+_[0-9]+\.mgm$//;
			if (!(-d $baseDir.$newDir)) {
				print "Creating directory ".$newDir."\n";
				my $cmd = $systemMkdirCommand." ".$baseDir.$newDir;
				system($cmd);
			}
		}
		
		if ($oldName ne $newName) {
			print "Moving ".$oldName." to ".$newName."\n";
			my $cmd = $systemMoveCommand." ".$baseDir.$oldName." ".$baseDir.$newName;
			system($cmd);
		}
		else {
			print "Not moving ".$oldName."\n";
		}
	}
}

sub recursiveRmdir {
	# only folders with names like numbers that are empty
	if (/^([0-9]+)$/) {
		opendir(DIR, $_);
		my @dir = readdir(DIR);
		closedir(DIR);
		# only . and ..
		if ($#dir < 2) {
			print "Removing directory ".$File::Find::name."\n";
			my $cmd = $systemRmdirCommand." ".$baseDir.$File::Find::name;
			system($cmd);
		}
	}
}