<?php
/*
Dit programma laat 1 willekeurig plaatje zien uit gespecificeerde folder.
Met extra parameters via _GET is je afbeelding extra in te stellen.
*/

class random_image
	{
	/* Variables that cannot be changed through superglobals. */
	private $relative_path = './';
	private $font = 2;
	private $max_height = 60;
	private $max_width = 60;
	private $allowed_formats = array('jpg', 'jpeg', 'gif', 'png');

	/* Variables that can be changed through superglobals. */
	private $text = '!';
	private $vertical_align = 'center';
	private $horizontal_align = 'center';
	private $text_color = array(255, 255, 255);

	/* Image resource variable. This is where the image gets stored in before it is displayed. */
	private $image;

	/* Main method, calls the rest of the methods. */
	public function run()
		{
		header('Content-type: image/png');

		$image_names = $this->find_images();
		if(count($image_names) === 0)
			{
			$this->report_error('No images found.');
			}

		$image_file_name = $this->pick_random($image_names);
		if($this->make_image($image_file_name) === false)
			{
			$this->report_error('Error loading '.$this->relative_path.$image_file_name.'.');
			}

		$this->load_superglobals();
		$this->resize_image();
		$this->draw_text();
		$this->finish_up();
		}

	/* Finds all allowed images in specified folder. */
	private function find_images()
		{
		$folder_handle = opendir($this->relative_path);
		if($folder_handle === false)
			{
			$this->report_error('Error opening folder '.$this->relative_path.'.');
			}

		$image_names = array();

		while(($current_file = readdir($folder_handle)) !== false)
			{
			$format = explode('.', $current_file);
			$format = strtolower(end($format));
			if(in_array($format, $this->allowed_formats))
				{
				array_push($image_names, $current_file);
				}
			}

		return $image_names;
		}

	/* Randomly picks one image from the found images. */
	private function pick_random($image_names)
		{
		$image_count = count($image_names);
		return $image_names[rand(0, $image_count - 1)];
		}

	/* Reads the _GET superglobals, checks them and stores them into instance variables. */
	private function load_superglobals()
		{
		if(isset($_GET['nick']))
			{
			if((imagefontwidth($this->font) * strlen($_GET['nick'])) < $this->max_width)
				{
				$this->text = $_GET['nick'];
				}
			else
				{
				$this->report_error('Text is too long!');
				}
			}

		if(isset($_GET['align']))
			{
			$align = strtolower($_GET['align']);
			if($align == 'left' or $align == 'center' or $align == 'right')
				{
				$this->horizontal_align = $align;
				}
			}

		if(isset($_GET['valign']))
			{
			$align = strtolower($_GET['valign']);
			if($align == 'top' or $align == 'center' or $align == 'bottom')
				{
				$this->vertical_align = $align;
				}
			}

		if(isset($_GET['fontcolor']))
			{
			$fontcolor = $_GET['fontcolor'];

			if(preg_match('/[a-f0-9]{6}$/i', $fontcolor))
				{
				$this->text_color = array(hexdec(substr($fontcolor, 0, 2)), hexdec(substr($fontcolor, 2, 2)), hexdec(substr($fontcolor, 4, 2)));
				}
			else
				{
				$this->report_error('Incorrect color '.$_GET['fontcolor'].'. Format: FF0000.');
				}
			}
		}

	/* Reads the image into a variable. */
	private function make_image($image_file_name)
		{
		$format = explode('.', $image_file_name);
		$format = strtolower(end($format));

		switch($format)
			{
			case 'jpg':
			case 'jpeg':
				if(($this->image = imagecreatefromjpeg($image_file_name)) == false)
					return false;
				break;
			case 'gif':
				if(($this->image = imagecreatefromgif($image_file_name)) == false)
					return false;
				break;
			case 'png':
				if(($this->image = imagecreatefrompng($image_file_name)) == false)
					return false;
				break;
			}
		}

	/* Resizing the resource image, so that it fits within the maximum width and height. */
	private function resize_image()
		{
		$width = imagesx($this->image);
		$height = imagesy($this->image);

		if($width > $this->max_width or $height > $this->max_height)
			{
			$max_ratio = $this->max_width/ $this->max_height;
			$image_ratio = $width / $height;

			if($image_ratio > $max_ratio)
				{
				$width = $this->max_width;
				$height = $width / $image_ratio;
				}
			else
				{
				$height = $this->max_height;
				$width = $height * $image_ratio;
				}

			$old_image = $this->image;
			$this->image = imagecreatetruecolor($width, $height);
			imagecopyresampled($this->image, $old_image, 0, 0, 0, 0, $width, $height, imagesx($old_image), imagesy($old_image));
			}
		}

	/* Draws the text on top of the image. */
	private function draw_text()
		{
		$text_color = imagecolorallocate($this->image, $this->text_color[0], $this->text_color[1], $this->text_color[2]);

		switch($this->horizontal_align)
			{
			case 'left':
				$x_coordinate = 0.5 * imagefontwidth($this->font);
				break;
			case 'right':
				$x_coordinate = imagesx($this->image) - (strlen($this->text) + 0.5) * imagefontwidth($this->font);
				break;
			default:
				$x_coordinate = 0.5 * imagesx($this->image) - 0.5 * strlen($this->text) * imagefontwidth($this->font);
				break;
			}

		switch($this->vertical_align)
			{
			case 'top':
				$y_coordinate = 2;
				break;
			case 'center':
				$y_coordinate = 0.5 * imagesy($this->image) - 0.5 * imagefontheight($this->font);
				break;
			default:
				$y_coordinate = imagesy($this->image) - imagefontheight($this->font) - 2;
				break;
			}

		imagestring($this->image, $this->font, $x_coordinate, $y_coordinate, $this->text, $text_color);
		}

	/* Show the image. */
	private function finish_up()
		{
		imagepng($this->image);
		imagedestroy($this->image);
		}

	/* Error handling. Prints the error and dies. */
	private function report_error($error)
		{
		$image = imagecreate(400,200);
		$background_color = imagecolorallocate($image, 0, 0, 0);
		$text_color = imagecolorallocate($image, 255, 0, 0);
		imagestring($image, 4, 5, 5, 'Fatal Error!', $text_color);
		imagestring($image, 4, 5, 55, $error, $text_color);
		imagepng($image);
		imagedestroy($image);
		die();
		}
	}

$image = new random_image;
$image->run();
?>