<?php
/*
 * Name: Resize Image
 * Author: jgen <jgen.tech@gmail.com>
 * Description: Allows admins to resize images.
 * License: GPLv2
 * Version: 0.1
 * Notice:
 *  The image resize and resample code is based off of the "smart_resize_image"
 *  function copyright 2008 Maxim Chernyak, released under a MIT-style license.
 * Documentation:
 *  This extension allows admins to resize images.
 */

/**
 * This class is just a wrapper around SCoreException.
 */
class ImageResizeException extends SCoreException {
	public $error;

	/** @param string $error */
	public function __construct($error) {
		$this->error = $error;
	}
}

/**
 *	This class handles image resize requests.
 */
class ResizeImage extends Extension {

	public function onInitExt(InitExtEvent $event) {
		global $config;
		$config->set_default_bool('resize_enabled', true);
		$config->set_default_bool('resize_upload', false);
		$config->set_default_int('resize_default_width', 0);
		$config->set_default_int('resize_default_height', 0);
	}

	public function onImageAdminBlockBuilding(ImageAdminBlockBuildingEvent $event) {
		global $user, $config;
		if($user->is_admin() && $config->get_bool("resize_enabled")) {
			/* Add a link to resize the image */
			$event->add_part($this->theme->get_resize_html($event->image));
		}
	}
	
	public function onSetupBuilding(SetupBuildingEvent $event) {
		$sb = new SetupBlock("Image Resize");
		$sb->add_bool_option("resize_enabled", "Allow resizing images: ");
		$sb->add_bool_option("resize_upload", "<br>Resize on upload: ");
		$sb->add_label("<br>Preset/Default Width: ");
		$sb->add_int_option("resize_default_width");
		$sb->add_label(" px");
		$sb->add_label("<br>Preset/Default Height: ");
		$sb->add_int_option("resize_default_height");
		$sb->add_label(" px");
		$sb->add_label("<br>(enter 0 for no default)");
		$event->panel->add_block($sb);
	}
	
	public function onDataUpload(DataUploadEvent $event) {
		global $config, $page;

		$image_obj = Image::by_id($event->image_id);

		if($config->get_bool("resize_upload") == true && ($image_obj->ext == "jpg" || $image_obj->ext == "png" || $image_obj->ext == "gif")){
			$width = $height = 0;

			if ($config->get_int("resize_default_width") !== 0) {
				$height = $config->get_int("resize_default_width");
			}
			if ($config->get_int("resize_default_height") !== 0) {
				$height = $config->get_int("resize_default_height");
			}
			$isanigif = 0;
			if($image_obj->ext == "gif"){
				$image_filename = warehouse_path("images", $image_obj->hash);
				if(($fh = @fopen($image_filename, 'rb'))) {
					//check if gif is animated (via http://www.php.net/manual/en/function.imagecreatefromgif.php#104473)
					while(!feof($fh) && $isanigif < 2) {
						$chunk = fread($fh, 1024 * 100);
						$isanigif += preg_match_all('#\x00\x21\xF9\x04.{4}\x00(\x2C|\x21)#s', $chunk, $matches);
					}
				}
			}
			if($isanigif == 0){
				try {
					$this->resize_image($image_obj, $width, $height);
				} catch (ImageResizeException $e) {
					$this->theme->display_resize_error($page, "Error Resizing", $e->error);
				}

				//Need to generate thumbnail again...
				//This only seems to be an issue if one of the sizes was set to 0.
				$image_obj = Image::by_id($event->image_id); //Must be a better way to grab the new hash than setting this again..
				send_event(new ThumbnailGenerationEvent($image_obj->hash, $image_obj->ext, true));

				log_info("resize", "Image #{$event->image_id} has been resized to: ".$width."x".$height);
				//TODO: Notify user that image has been resized.
			}
		}
	}

	public function onPageRequest(PageRequestEvent $event) {
		global $page, $user;

		if ( $event->page_matches("resize") && $user->is_admin() ) {
			// Try to get the image ID
			$image_id = int_escape($event->get_arg(0));
			if (empty($image_id)) {
				$image_id = isset($_POST['image_id']) ? int_escape($_POST['image_id']) : null;
			}
			if (empty($image_id)) {
				throw new ImageResizeException("Can not resize Image: No valid Image ID given.");
			}
			
			$image = Image::by_id($image_id);
			if(is_null($image)) {
				$this->theme->display_error(404, "Image not found", "No image in the database has the ID #$image_id");
			} else {
			
				/* Check if options were given to resize an image. */
				if (isset($_POST['resize_width']) || isset($_POST['resize_height'])) {
					
					/* get options */
					
					$width = $height = 0;
					
					if (isset($_POST['resize_width'])) {
						$width = int_escape($_POST['resize_width']);
					}
					if (isset($_POST['resize_height'])) {
						$height = int_escape($_POST['resize_height']);
					}
					
					/* Attempt to resize the image */
					try {
						$this->resize_image($image, $width, $height);
						
						//$this->theme->display_resize_page($page, $image_id);
						
						$page->set_mode("redirect");
						$page->set_redirect(make_link("post/view/".$image_id));
						
					} catch (ImageResizeException $e) {
						$this->theme->display_resize_error($page, "Error Resizing", $e->error);
					}
				}
			}
		}
	}
	
	
	// Private functions
	/* ----------------------------- */

	/**
	 * This function could be made much smaller by using the ImageReplaceEvent
	 * ie: Pretend that we are replacing the image with a resized copy.
	 *
	 * @param Image $image_obj
	 * @param int $width
	 * @param int $height
	 * @throws ImageResizeException
	 */
	private function resize_image(Image $image_obj, /*int*/ $width, /*int*/ $height) {
		global $database;
		
		if ( ($height <= 0) && ($width <= 0) ) {
			throw new ImageResizeException("Invalid options for height and width. ($width x $height)");
		}
		
		$hash = $image_obj->hash;
		$image_filename  = warehouse_path("images", $hash);
		$info = getimagesize($image_filename);
		/* Get the image file type */
		$pathinfo = pathinfo($image_obj->filename);
		$filetype = strtolower($pathinfo['extension']);
		
		if (($image_obj->width != $info[0] ) || ($image_obj->height != $info[1])) {
			throw new ImageResizeException("The current image size does not match what is set in the database! - Aborting Resize.");
		}

		$memory_use = $this->calc_memory_use($info);
		$memory_limit = get_memory_limit();
		if ($memory_use > $memory_limit) {
			throw new ImageResizeException("The image is too large to resize given the memory limits. ($memory_use > $memory_limit)");
		}

		list($new_height, $new_width) = $this->calc_new_size($image_obj, $width, $height);

		/* Attempt to load the image */
		switch ( $info[2] ) {
		  case IMAGETYPE_GIF:   $image = imagecreatefromgif($image_filename);   break;
		  case IMAGETYPE_JPEG:  $image = imagecreatefromjpeg($image_filename);  break;
		  case IMAGETYPE_PNG:   $image = imagecreatefrompng($image_filename);   break;
		  default:
			throw new ImageResizeException("Unsupported image type (Only GIF, JPEG, and PNG are supported).");
		}
		
		// Handle transparent images
		
		$image_resized = imagecreatetruecolor( $new_width, $new_height );
		
		if ($info[2] == IMAGETYPE_GIF) {
			$transparency = imagecolortransparent($image);

			// If we have a specific transparent color
			if ($transparency >= 0) {
				// Get the original image's transparent color's RGB values
				$transparent_color = imagecolorsforindex($image, $transparency);

				// Allocate the same color in the new image resource
				$transparency = imagecolorallocate($image_resized, $transparent_color['red'], $transparent_color['green'], $transparent_color['blue']);

				// Completely fill the background of the new image with allocated color.
				imagefill($image_resized, 0, 0, $transparency);

				// Set the background color for new image to transparent
				imagecolortransparent($image_resized, $transparency);
			}
		} elseif ($info[2] == IMAGETYPE_PNG) {
			// 
			// More info here:  http://stackoverflow.com/questions/279236/how-do-i-resize-pngs-with-transparency-in-php
			// 
			imagealphablending($image_resized, false);
			imagesavealpha($image_resized, true);
			$transparent_color = imagecolorallocatealpha($image_resized, 255, 255, 255, 127);
			imagefilledrectangle($image_resized, 0, 0, $new_width, $new_height, $transparent_color);
		}
		
		// Actually resize the image.
		imagecopyresampled($image_resized, $image, 0, 0, 0, 0, $new_width, $new_height, $image_obj->width, $image_obj->height);
		
		/* Temp storage while we resize */
		$tmp_filename = tempnam("/tmp", 'shimmie_resize');
		if (empty($tmp_filename)) {
			throw new ImageResizeException("Unable to save temporary image file.");
		}
		
		/* Output to the same format as the original image */
		switch ( $info[2] ) {
		  case IMAGETYPE_GIF:   imagegif($image_resized, $tmp_filename);    break;
		  case IMAGETYPE_JPEG:  imagejpeg($image_resized, $tmp_filename);   break;
		  case IMAGETYPE_PNG:   imagepng($image_resized, $tmp_filename);    break;
		  default:
			throw new ImageResizeException("Failed to save the new image - Unsupported image type.");
		}
		
		/* Move the new image into the main storage location */
		$new_hash = md5_file($tmp_filename);
		$new_size = filesize($tmp_filename);
		$target = warehouse_path("images", $new_hash);
		if(!@copy($tmp_filename, $target)) {
			throw new ImageResizeException("Failed to copy new image file from temporary location ({$tmp_filename}) to archive ($target)");
		}
		$new_filename = 'resized-'.$image_obj->filename;
		
		/* Remove temporary file */
		@unlink($tmp_filename);

		/* Delete original image and thumbnail */
		log_debug("image", "Removing image with hash ".$hash);
		$image_obj->remove_image_only();
		
		/* Generate new thumbnail */
		send_event(new ThumbnailGenerationEvent($new_hash, $filetype));
		
		/* Update the database */
		$database->Execute("
			UPDATE images SET filename = :filename, filesize = :filesize, hash = :hash, width = :width, height = :height
			WHERE id = :id
		", array(
			"filename"=>$new_filename, "filesize"=>$new_size, "hash"=>$new_hash,
			"width"=>$new_width, "height"=>$new_height,	"id"=>$image_obj->id
		));
		
		log_info("resize", "Resized Image #{$image_obj->id} - New hash: {$new_hash}");
	}

	/**
	 * Check Memory usage limits
	 *
	 * Old check:   $memory_use = (filesize($image_filename)*2) + ($width*$height*4) + (4*1024*1024);
	 * New check:   $memory_use = $width * $height * ($bits_per_channel) * channels * 2.5
	 *
	 * It didn't make sense to compute the memory usage based on the NEW size for the image. ($width*$height*4)
	 * We need to consider the size that we are GOING TO instead.
	 *
	 * The factor of 2.5 is simply a rough guideline.
	 * http://stackoverflow.com/questions/527532/reasonable-php-memory-limit-for-image-resize
	 *
	 * @param mixed[] $info
	 * @return int
	 */
	private function calc_memory_use($info) {
		if (isset($info['bits']) && isset($info['channels'])) {
			$memory_use = ($info[0] * $info[1] * ($info['bits'] / 8) * $info['channels'] * 2.5) / 1024;
		}
		else {
			// If we don't have bits and channel info from the image then assume default values
			// of 8 bits per color and 4 channels (R,G,B,A) -- ie: regular 24-bit color
			$memory_use = ($info[0] * $info[1] * 1 * 4 * 2.5) / 1024;
		}
		return (int)$memory_use;
	}

	/**
	 * @param Image $image_obj
	 * @param int $width
	 * @param int $height
	 * @return int[]
	 */
	private function calc_new_size(Image $image_obj, $width, $height) {
		/* Calculate the new size of the image */
		if ($height > 0 && $width > 0) {
			$new_height = $height;
			$new_width = $width;
			return array($new_height, $new_width);
		} else {
			// Scale the new image
			if ($width == 0) $factor = $height / $image_obj->height;
			elseif ($height == 0) $factor = $width / $image_obj->width;
			else                  $factor = min($width / $image_obj->width, $height / $image_obj->height);

			$new_width = round($image_obj->width * $factor);
			$new_height = round($image_obj->height * $factor);
			return array($new_height, $new_width);
		}
	}
}