<?php
/**
 * Name: Image View Counter
 * Author: Drudex Software <support@drudexsoftware.com>
 * Link: http://www.drudexsoftware.com/
 * License: GPLv2
 * Description: Tracks & displays how many times an image is viewed
 * Documentation:
 *  Whenever anyone views an image, a view will be added to that image.
 *  This extension will also track any username & the IP adress.
 *  This is done to prevent duplicate views. 
 *  A person can only count as a view again 1 hour after viewing the image initially.
 */
class ImageViewCounter extends Extension {    
	private $view_interval = 3600; # allows views to be added each hour
    
	# Add Setup Block with options for view counter
	public function onSetupBuilding(SetupBuildingEvent $event) {
		$sb = new SetupBlock("Image View Counter");
		$sb->add_bool_option("image_viewcounter_adminonly", "Display view counter only to admin");

		$event->panel->add_block($sb);
	}
        
	# Adds view to database if needed
	public function onDisplayingImage(DisplayingImageEvent $event) {
		$imgid = $event->image->id; // determines image id
		$this->addview($imgid); // adds a view
	}
        
	# display views to user or admin below image if allowed
	public function onImageInfoBoxBuilding(ImageInfoBoxBuildingEvent $event) {
		global $user, $config;

		$adminonly = $config->get_bool("image_viewcounter_adminonly"); // todo
		if ($adminonly == false || ($adminonly && $user->is_admin()))
			$event->add_part(
				"<tr><th>Views:</th><td>". 
				$this->get_view_count($event->image->id) .
				"</tr>", 38);
	}

	# Installs DB table
	public function onInitExt(InitExtEvent $event) {
		global $database, $config;

		// if the sql table doesn't exist yet, create it
		if($config->get_bool("image_viewcounter_installed") == false) { //todo
			$database->create_table("image_views","
					id SCORE_AIPK,
					image_id INTEGER NOT NULL,
					user_id INTEGER NOT NULL,
					timestamp INTEGER NOT NULL,
					ipaddress SCORE_INET NOT NULL");
			$config->set_bool("image_viewcounter_installed", true);
		}
	}

	/**
	 * Adds a view to the item if needed
	 */
	private function addview(int $imgid)
	{
		global $database, $user;

		// don't add view if person already viewed recently
		if ($this->can_add_view($imgid) == false) return;

		// Add view for current IP
		$database->execute(
			"
				INSERT INTO image_views (image_id, user_id, timestamp, ipaddress)
				VALUES (:image_id, :user_id, :timestamp, :ipaddress)
			",
			array(
				"image_id" => $imgid,  
				"user_id" => $user->id,
				"timestamp" => time(),
				"ipaddress" => $_SERVER['REMOTE_ADDR'],
			)
		);
	}

	/**
	 * Returns true if this IP hasn't recently viewed this image
	 */
	private function can_add_view(int $imgid)
	{
		global $database;

		// counts views from current IP in the last hour
		$recent_from_ip = (int)$database->get_one(
			"
				SELECT COUNT(*)
				FROM image_views
				WHERE ipaddress=:ipaddress AND timestamp >:lasthour AND image_id =:image_id
			",
			array(
				"ipaddress" => $_SERVER['REMOTE_ADDR'],
				"lasthour" => time() - $this->view_interval,
				"image_id" => $imgid
			)
		);

		// if no views were found with the set criteria, return true
		if($recent_from_ip == 0) return true;
		else return false;
	}

	/**
	 * Returns the int of the view count from the given image id
	 */
	private function get_view_count(int $imgid = 0)
	{
		global $database;

		if ($imgid == 0) // return view count of all images
			$view_count = (int)$database->get_one(
				"SELECT COUNT(*) FROM image_views"
			);
		else // return view count of specified image
			$view_count = (int)$database->get_one(
				"SELECT COUNT(*) FROM image_views WHERE image_id =:image_id",
				array("image_id" => $imgid)
			);

		// returns the count as int
		return $view_count;
	}
}