<?php
/*
 * An object representing an entry in the images table. As of 2.2, this no
 * longer necessarily represents an image per se, but could be a video,
 * sound file, or any other supported upload type.
 */
class Image {
	var $config;
	var $database;

	var $id = null;
	var $height, $width;
	var $hash, $filesize;
	var $filename, $ext;
	var $owner_ip;
	var $posted;
	var $source;

	public function Image($row=null) {
		global $config;
		global $database;

		$this->config = $config;
		$this->database = $database;

		if(!is_null($row)) {
			foreach($row as $name => $value) {
				// FIXME: some databases use table.name rather than name
				$this->$name = $value; // hax
			}
			$this->posted_timestamp = strtotime($this->posted); // pray
		}
	}

	public static function by_id(Config $config, Database $database, $id) {
		assert(is_numeric($id));
		$image = null;
		$row = $database->get_row("SELECT * FROM images WHERE images.id=?", array($id));
		return ($row ? new Image($row) : null);
	}
	
	public static function by_hash(Config $config, Database $database, $hash) {
		assert(is_string($hash));
		$image = null;
		$row = $database->db->GetRow("SELECT images.* FROM images WHERE hash=?", array($hash));
		return ($row ? new Image($row) : null);
	}

	public static function by_random(Config $config, Database $database, $tags=array()) {
		$max = Image::count_images($config, $database, $tags);
		$rand = mt_rand(0, $max-1);
		$set = Image::find_images($config, $database, $rand, 1, $tags);
		if(count($set) > 0) return $set[0];
		else return null;
	}
	
	public static function find_images(Config $config, Database $database, $start, $limit, $tags=array()) {
		$images = array();

		assert(is_numeric($start));
		assert(is_numeric($limit));
		if($start < 0) $start = 0;
		if($limit < 1) $limit = 1;
		
		$querylet = Image::build_search_querylet($config, $database, $tags);
		$querylet->append(new Querylet("ORDER BY images.id DESC LIMIT ? OFFSET ?", array($limit, $start)));
		$result = $database->execute($querylet->sql, $querylet->variables);
		
		while(!$result->EOF) {
			$images[] = new Image($result->fields);
			$result->MoveNext();
		}
		return $images;
	}

	public static function count_images(Config $config, Database $database, $tags=array()) {
		if(count($tags) == 0) {
			return $database->db->GetOne("SELECT COUNT(*) FROM images");
		}
		else {
			$querylet = Image::build_search_querylet($config, $database, $tags);
			$result = $database->execute($querylet->sql, $querylet->variables);
			return $result->RecordCount();
		}
	}
	
	public static function count_pages(Config $config, Database $database, $tags=array()) {
		$images_per_page = $config->get_int('index_width') * $config->get_int('index_height');
		return ceil(Image::count_images($config, $database, $tags) / $images_per_page);
	}


	public function get_next($tags=array(), $next=true) {
		assert(is_array($tags));
		assert(is_bool($next));
		
		if($next) {
			$gtlt = "<";
			$dir = "DESC";
		}
		else {
			$gtlt = ">";
			$dir = "ASC";
		}

		if(count($tags) == 0) {
			$row = $this->database->db->GetRow("SELECT images.* FROM images WHERE images.id $gtlt {$this->id} ORDER BY images.id $dir LIMIT 1");
		}
		else {
			$tags[] = "id$gtlt{$this->id}";
			$querylet = Image::build_search_querylet($this->config, $this->database, $tags);
			$querylet->append_sql(" ORDER BY images.id $dir LIMIT 1");
			$row = $this->database->db->GetRow($querylet->sql, $querylet->variables);
		}
		
		return ($row ? new Image($row) : null);
	}

	public function get_prev($tags=array()) {
		return $this->get_next($tags, false);
	}
	
	public function delete() {
		$this->database->execute("DELETE FROM images WHERE id=?", array($this->id));
		
		unlink($this->get_image_filename());
		unlink($this->get_thumb_filename());
	}

	public function get_owner() {
		return User::by_id($this->config, $this->database, $this->owner_id);
	}

	public function get_tag_array() {
		if(!isset($this->tag_array)) {
			$this->tag_array = Array();
			$row = $this->database->Execute("SELECT tag FROM image_tags JOIN tags ON image_tags.tag_id = tags.id WHERE image_id=? ORDER BY tag", array($this->id));
			while(!$row->EOF) {
				$this->tag_array[] = $row->fields['tag'];
				$row->MoveNext();
			}
		}
		return $this->tag_array;
	}

	public function get_tag_list() {
		return implode(' ', $this->get_tag_array());
	}

	public function get_image_link() {
		return $this->parse_link_template($this->config->get_string('image_ilink'));
	}

	public function get_short_link() {
		return $this->parse_link_template($this->config->get_string('image_slink'));
	}

	public function get_thumb_link() {
		return $this->parse_link_template($this->config->get_string('image_tlink'));
	}

	public function get_tooltip() {
		global $config;
		return $this->parse_link_template($config->get_string('image_tip'), "html_escape");
	}

	public function get_image_filename() {
		$hash = $this->hash;
		$ab = substr($hash, 0, 2);
		$ext = $this->ext;
		return "images/$ab/$hash";
	}

	public function get_thumb_filename() {
		$hash = $this->hash;
		$ab = substr($hash, 0, 2);
		return "thumbs/$ab/$hash";
	}

	public function get_filename() {
		return $this->filename;
	}
	
	public function get_mime_type() {
		return "image/".($this->ext);
	}

	public function get_ext() {
		return $this->ext;
	}

	public function get_source() {
		return $this->source;
	}

	public function parse_link_template($tmpl, $_escape="url_escape") {
		// don't bother hitting the database if it won't be used...
		$safe_tags = "";
		if(strpos($tmpl, '$tags') !== false) { // * stabs dynamically typed languages with a rusty spoon *
			$safe_tags = preg_replace(
					"/[^a-zA-Z0-9_\- ]/",
					"", $this->get_tag_list());
		}

		$base_href = $this->config->get_string('base_href');
		$fname = $this->get_filename();
		$base_fname = strpos($fname, '.') ? substr($fname, 0, strrpos($fname, '.')) : $fname;

		$tmpl = str_replace('$id',   $this->id,   $tmpl);
		$tmpl = str_replace('$hash', $this->hash, $tmpl);
		$tmpl = str_replace('$tags', $_escape($safe_tags),  $tmpl);
		$tmpl = str_replace('$base', $base_href,  $tmpl);
		$tmpl = str_replace('$ext',  $this->ext,  $tmpl);
		$tmpl = str_replace('$size', "{$this->width}x{$this->height}", $tmpl);
		$tmpl = str_replace('$filesize', to_shorthand_int($this->filesize), $tmpl);
		$tmpl = str_replace('$filename', $_escape($base_fname), $tmpl);
		$tmpl = str_replace('$title', $_escape($this->config->get_string("title")), $tmpl);

		$plte = new ParseLinkTemplateEvent($tmpl, $this);
		send_event($plte);
		$tmpl = $plte->link;

		return $tmpl;
	}

	private static function build_search_querylet(Config $config, Database $database, $terms) {
		$tag_querylets = array();
		$img_querylets = array();
		$positive_tag_count = 0;

		$stpe = new SearchTermParseEvent(null, $terms);
		send_event($stpe);
		if($stpe->is_querylet_set()) {
			foreach($stpe->get_querylets() as $querylet) {
				$img_querylets[] = new ImgQuerylet($querylet, true);
			}
		}

		// parse the words that are searched for into
		// various types of querylet
		foreach($terms as $term) {
			$positive = true;
			if((strlen($term) > 0) && ($term[0] == '-')) {
				$positive = false;
				$term = substr($term, 1);
			}
			
			$term = $database->resolve_alias($term);

			$stpe = new SearchTermParseEvent($term, $terms);
			send_event($stpe);
			if($stpe->is_querylet_set()) {
				foreach($stpe->get_querylets() as $querylet) {
					$img_querylets[] = new ImgQuerylet($querylet, $positive);
				}
			}
			else {
				$term = str_replace("*", "%", $term);
				$term = str_replace("?", "_", $term);
				if(!preg_match("/^[%_]+$/", $term)) {
					$expansions = $database->resolve_wildcard($term);
					if($positive) $positive_tag_count++;
					foreach($expansions as $term) {
						$tag_querylets[] = new TagQuerylet($term, $positive);
					}
				}
			}
		}


		// merge all the image metadata searches into one generic querylet
		$n = 0;
		$sql = "";
		$terms = array();
		foreach($img_querylets as $iq) {
			if($n++ > 0) $sql .= " AND";
			if(!$iq->positive) $sql .= " NOT";
			$sql .= " (" . $iq->qlet->sql . ")";
			$terms = array_merge($terms, $iq->qlet->variables);
		}
		$img_search = new Querylet($sql, $terms);


		// no tags, do a simple search (+image metadata if we have any)
		if(count($tag_querylets) == 0) {
			$query = new Querylet("SELECT images.* FROM images ");

			if(strlen($img_search->sql) > 0) {
				$query->append_sql(" WHERE ");
				$query->append($img_search);
			}
		}

		// one positive tag (a common case), do an optimised search
		else if(count($tag_querylets) == 1 && $tag_querylets[0]->positive) {
			$query = new Querylet("
				SELECT images.* FROM images
				JOIN image_tags ON images.id = image_tags.image_id
				WHERE tag_id = (SELECT tags.id FROM tags WHERE tag = ?)
				", array($tag_querylets[0]->tag));

			if(strlen($img_search->sql) > 0) {
				$query->append_sql(" AND ");
				$query->append($img_search);
			}
		}

		// more than one positive tag, or more than zero negative tags
		else {
			$positive_tag_id_array = array();
			$negative_tag_id_array = array();
			$tags_ok = true;

			foreach($tag_querylets as $tq) {
				$tag_ids = $database->db->GetCol("SELECT id FROM tags WHERE tag = ?", array($tq->tag));
				if($tq->positive) {
					$positive_tag_id_array = array_merge($positive_tag_id_array, $tag_ids);
					$tags_ok = count($tag_ids) > 0;
					if(!$tags_ok) break;
				}
				else {
					$negative_tag_id_array = array_merge($negative_tag_id_array, $tag_ids);
				}
			}

			if($tags_ok) {
				$have_pos = count($positive_tag_id_array) > 0;
				$have_neg = count($negative_tag_id_array) > 0;

				$sql = "SELECT images.* FROM images WHERE ";
				if($have_pos) {
					$positive_tag_id_list = join(', ', $positive_tag_id_array);
					$sql .= "
						images.id IN (
							SELECT image_id
							FROM image_tags
							WHERE tag_id IN ($positive_tag_id_list)
							GROUP BY image_id
							HAVING COUNT(image_id)>=$positive_tag_count
						)
					";
				}
				if($have_pos && $have_neg) {
					$sql .= " AND ";
				}
				if($have_neg) {
					$negative_tag_id_list = join(', ', $negative_tag_id_array);
					$sql .= "
						images.id NOT IN (
							SELECT image_id
							FROM image_tags
							WHERE tag_id IN ($negative_tag_id_list)
						)
					";
				}
				$query = new Querylet($sql);

				if(strlen($img_search->sql) > 0) {
					$query->append_sql(" AND ");
					$query->append($img_search);
				}
			}
			else {
				# one of the positive tags had zero results, therefor there
				# can be no results; "where 1=0" should shortcut things
				$query = new Querylet("
					SELECT images.*
					FROM images
					WHERE 1=0
				");
			}
		}

		return $query;
	}

}
?>