#!/usr/bin/perl
use strict;

my $ScreenHSize = 1280;
my $ScreenVSize = 1024;
my $Source = "/home/exodist/Backgrounds";
my $Tempdir = "/tmp/backswitch";
my $Formats = "jpg,png,jpeg,bmp,tif,tiff";
my $BGName = "$Tempdir/End.jpg";
my $ChangeTime = "30";

my @List;

sub Main();
sub GenerateList();
sub Shuffle();
sub SizeImage($);
sub Combine($$);
sub SetBG($);
	
MAIN:
{
	system("rm -rf \"$Tempdir\"") if (-d "$Tempdir");
	mkdir($Tempdir) || die ("$!\n");
	Main();
}

sub Main()
{
	my @Images; #Where the image names are stored during modification.
	
	GenerateList(); #Generate a list of files from the source directory
	
	while (1) #infinite loop
	{
		Shuffle(); #Shuffle the files
		my $I = 0; #Start at file 0
		while ($I < @List) #Until we hit the end of the list
		{
			foreach my $J (0 .. 1) #we need 2 files
			{
				$Images[$J] = undef; #clear this index
				while ((!($Images[$J])) && ($I < @List)) #Cycle until we get a good image (SizeImage return 0 if the image it was given could not be used) also make sure we do not go beyond the list resulting in an infinite loop
				{
					$Images[$J] = SizeImage($List[$I]); #Try this image
					$I++; #Incriment to next file
				}
			}
			if (($Images[0]) && ($Images[1])) #If we got 2 images that work
			{
				SetBG(Combine($Images[0], $Images[1])); #Set the background
				unlink($Images[0]);
				unlink($Images[1]);
				sleep($ChangeTime); #Wait until next cycle
				#We do not want it to wait if it did not find 2 good images, we want it to try again.
			}
		}
	}
}

sub GenerateList()
{
	my $Ext; #Variable for use in finding files extension.
	opendir(SOURCE, "$Source") || die ("$!\n"); #Open the source directory or die.
	foreach my $I (readdir(SOURCE))
	{
		if ($I =~ m/\..{1,4}$/ig) #Find the extension
		{
			$Ext = $&;
			$Ext =~ s/\.//ig; #Remove . from ext
		}
		else
		{
			next; #Next file
		}
		next if (!($Formats =~ m/$Ext/ig)); #Make sure the ext is in the list or go to next
		push(@List, $I); #Add the file to the list
	}
	closedir(SOURCE); #Close the source dir.
}

sub Shuffle()
{
	my $Temp; #Temporary variable for random number
	my @List2; #Second list, data is shuffled into this list
	my $Size = (@List * 2); #We use double the list size to ensure there is never a lack of slots, if we use exactly the number of files than the script will take a long time possibly forever to find the only remaining slot.
	foreach my $I (@List) #For each file
	{
		do #Do it at least once
		{
			$Temp = rand($Size); #Find a random slot
		} while ($List2[$Temp]); #get a new number if the slot is already full
		$List2[$Temp] = $I; #Place the file into the slot
	}
	@List = (); #Clear the list
	foreach my $I (@List2) #For each element of the second list
	{
		next if (!($I)); #Next element if this one is empty (list should be half full, half empty.)
		push(@List, $I); #Add the file to the end of the main list.
	}
}

sub SizeImage($)
{
	my $HSize;
	my $VSize;

	my ($Image) = @_;
	print("$Image.");
	system("nice -n 19 cp \"$Source/$Image\" \"$Tempdir/$Image\""); #Copy from source to temp, we do not want to modify the original
	my $ImageInfo = `nice -n 19 /usr/bin/identify "$Tempdir/$Image"`; #Get the info for the image
	if ($ImageInfo =~ m/ \d+x\d+ /i) #Find the dimensions from the info, we use space before and after to select the correct one, rather than the offset info
	{
		$ImageInfo = $&; #Use the found dimensions
	}
	$ImageInfo =~ s/ //ig; #Strip spaces from dimensions
	($HSize, $VSize) = split(/x/i, $ImageInfo); #seperate verticle and Horizontal dims
	
	return 0 if ((!($HSize)) || (!($VSize))); #If we did nto get both dims there is a problem, next file.
	
	if (($HSize > $ScreenHSize) || ($VSize > $ScreenVSize)) #If the image is too large in any dimension, fix it
	{
		return 0 if (system("nice -n 19 /usr/bin/convert -resize ${ScreenHSize}x${ScreenVSize} \"$Tempdir/$Image\" \"$Tempdir/$Image\"")); #Attemtp to scale image down
		print(".");
		
		#We need to get the new sizes
		$ImageInfo = `nice -n 19 /usr/bin/identify "$Tempdir/$Image"`;
		if ($ImageInfo =~ m/ \d+x\d+ /i)
		{
			$ImageInfo = $&;
		}
		$ImageInfo =~ s/ //ig;
		($HSize, $VSize) = split(/x/i, $ImageInfo);
		#------------------
	}
	
	if (($HSize < $ScreenHSize) || ($VSize < $ScreenVSize)) #If the image is smaller than the screen size, add a border
	{
		$HSize = ($ScreenHSize - $HSize) / 2; #get half the difference between the image size and the screen size on the H
		$VSize = ($ScreenVSize - $VSize) / 2; #get half the difference between the image size and the screen size on the V
		return 0 if (system("nice -n 19 /usr/bin/convert -bordercolor \"#000000\" -border ${HSize}x${VSize} \"$Tempdir/$Image\" \"$Tempdir/$Image\"")); #Attempt to add the border
		print(".");
	}
	
	print("\t");
	return "$Tempdir/$Image";
}

sub Combine($$)
{
	my ($I1, $I2) = @_;
	print("Combine.");
	
	print(".");
	system("nice -n 19 /usr/bin/convert -verbose +append \"$I1\" \"$I2\" \"$BGName\""); #Combine the 2 images
	print(".\t");
	return $BGName;
}

sub SetBG($)
{
	my ($bg) = @_;
	print(".");
	system("nice -n 19 /usr/bin/Esetroot -center \"$bg\""); #Set the background
	print(".Set\n");
}