<?php
class DataModel {
	private $db;

	private $groupCache = array();
	private $imageCache = array();
	private $imageTagsCache = array();
	private $groupImagesCache = array();
	private $albumCache = array();

	/**
	 * Call this method to get singleton
	 *
	 * @return DataModel
	 */
	public static function getInstance() {
		static $inst = null;

		if ($inst === null) {
			$inst = new DataModel();
		}
		return $inst;
	}

	private function __clone() {}

	private function __construct() {
		$this->db = new DatabaseConnection();
	}

	public function isAlbumGroup( $groupPath ) {
		if( !array_key_exists( $groupPath , $this->groupCache ) ) {
			$this->groupCache["$groupPath"] = $this->db->isAlbumGroup( $groupPath );
		}
		return $this->groupCache["$groupPath"];
	}

	public function getImageById( $imageId) {
		if( !array_key_exists( $imageId , $this->imageCache ) ) {
			$this->imageCache["$imageId"] = $this->db->getImageById( $imageId );
		}
		return $this->imageCache["$imageId"];
	}

	public function getImageTags ( $albumId, $tagId, $imageId ) {
		$key = "$albumId-$tagId-$imageId" ;
		if( !array_key_exists( "$key" , $this->imageTagsCache ) ) {
			$this->imageTagsCache["$key"] = $this->db->getImageTags ( $albumId, $tagId, $imageId );
		}
		return $this->imageTagsCache["$key"];
	}

	public function getImages( $groupAlbumId, $tagId, $limit, $offset ) {
		$key = "$groupAlbumId-$tagId-$limit-$offset" ;
		if( !array_key_exists( "$key" , $this->groupImagesCache ) ) {
			$this->groupImagesCache["$key"] = $this->db->getImages( $groupAlbumId, $tagId, $limit, $offset);
		}
		return $this->groupImagesCache["$key"];
	}

	public function getAlbum( $groupAlbumId, $exact, $limit, $offset ) {
		$key = "single-$groupAlbumId-$exact-$limit-$offset" ;
		if( !array_key_exists( "$key" , $this->albumCache ) ) {
			$this->albumCache["$key"] = $this->db->getAlbum( $groupAlbumId, $exact, $limit, $offset);
		}
		return $this->albumCache["$key"];
	}

}
?>