<?php

if( !class_exists( 'LDB_Affiliate_Press' ) ) {

	class LDB_Affiliate_Press {

		/* Set the main variables */
		public $messages = array();
		public $action = false;
		public $titles = array();

		/* Load the custom post type, menu, meta box, stylesheet. Perform actions if needed. And assign something to the cronjob. */
		function __construct() {
			add_action( 'init', array( &$this, 'AP_loadCpt' ) );
			add_action( 'admin_menu', array( &$this, 'AP_menu' ) );
			add_action( 'admin_init', array( &$this, 'AP_addCustomMetaBox' ) );
			add_action( 'admin_print_scripts-post-new.php', array( &$this, 'AP_loadStyle' ) );
			add_action( 'admin_print_scripts-post.php', array( &$this, 'AP_loadStyle' ) );
			add_action( 'admin_init', array( &$this, 'AP_performAction' ) );
			add_action( 'AP_cronjob', array( &$this, 'AP_processAllPrices' ) );
		}

		/* Add the menu items and add some hidden ones. */
		function AP_menu() {
			$pages = array();
			$parent = add_menu_page( __( 'Affiliate Press', 'LDB_AP' ), __( 'Affiliate Press', 'LDB_AP' ), 'manage_options', 'affiliate_press', array( &$this, 'AP_dashboard' ), LDB_AP_URL . 'images/icon16.png' );
			$pages[] = $parent;
			add_submenu_page( 'affiliate_press', __( 'Dashboard', 'LDB_AP' ), __( 'Dashboard', 'LDB_AP' ), 'manage_options', 'affiliate_press' );
			$pages[] = add_submenu_page( 'affiliate_press', __( 'Feeds', 'LDB_AP' ), __( 'Feeds', 'LDB_AP' ), 'manage_options', 'affiliate_press_feeds', array( &$this, 'AP_feeds' ) );
			$pages[] = add_submenu_page( 'affiliate_press', __( 'Add New Feed', 'LDB_AP' ), __( 'Add New Feed', 'LDB_AP' ), 'manage_options', 'affiliate_press_add', array( &$this, 'AP_addFeed' ) );
			$pages[] = add_submenu_page( 'affiliate_press', __( 'Add New Feed Wizard', 'LDB_AP' ), __( 'Add New Feed Wizard', 'LDB_AP' ), 'manage_options', 'affiliate_press_add_wizard', array( &$this, 'AP_addFeedWizard' ) );
			foreach( $pages as $page )
				add_action( 'admin_print_styles-' . $page, array( &$this, 'AP_loadStyle' ) );

			$hiddenpages = array(
				'affiliate_press_edit' => array( array( &$this, 'AP_editFeed' ), __( 'Edit feed', 'LDB_AP' ) ),
				'affiliate_press_view' => array( array( &$this, 'AP_viewFeed' ), __( 'View feed', 'LDB_AP' ) ),
				'affiliate_press_linktoproduct' => array( array( &$this, 'AP_linkToProduct' ), __( 'Link item to an existing product', 'LDB_AP' ) )
			);
			$this->AP_registerHiddenPages( $hiddenpages, $parent );
		}

		/* Function to register the hidden pages */
		function AP_registerHiddenPages( $pages, $parent ) {
			global $_registered_pages;
			foreach( $pages as $slug => $function ) {
				$hookname = get_plugin_page_hookname( $slug, $parent );
				$this->titles[ $slug ] = $function[1];
				if ( !empty( $hookname ) ) {
					add_action( $hookname, $function[0] );
				}
				$_registered_pages[ $hookname ] = true;
				add_action( 'admin_print_styles-' . $hookname, array( &$this, 'AP_loadStyle' ) );
			}
			if( isset( $_GET['page'] ) && isset( $pages[ $_GET['page'] ] ) && isset( $pages[ $_GET['page'] ][1] ) )
				add_filter( 'admin_title', array( &$this, 'AP_changeTitle' ), 10, 2 );
		}

		/* Function to change the title on hidden pages */
		function AP_changeTitle( $admin_title, $title ) {
			if( isset( $_GET['page'] ) && isset( $this->titles[ $_GET['page'] ] ) )
			return $this->titles[ $_GET['page'] ] . $admin_title;
		}

		/* Function to load the stylesheet and some scripts. */
		function AP_loadStyle() {
			wp_enqueue_style( 'APstyle', LDB_AP_URL . 'styles.css' );
			wp_enqueue_script( 'ap_message', LDB_AP_SCRIPTS_URL . 'message.js' );
			wp_enqueue_script( 'postbox' );
			wp_enqueue_script( 'dashboard' );
		}

		/* Function to load the custom post type. */
		function AP_loadCpt() {
			$labels = array(
				'name' => __( 'Products', 'LDB_AP' ),
				'singular_name' => __( 'Product', 'LDB_AP' ),
				'add_new' => __( 'Add New', 'LDB_AP' ),
				'add_new_item' => __( 'Add New Product', 'LDB_AP' ),
				'edit_item' => __( 'Edit Product', 'LDB_AP' ),
				'new_item' => __( 'New Product', 'LDB_AP' ),
				'all_items' => __( 'All Products', 'LDB_AP' ),
				'view_item' => __( 'View Product', 'LDB_AP' ),
				'search_items' => __( 'Search Products', 'LDB_AP' ),
				'not_found' =>	__( 'No products found', 'LDB_AP' ),
				'not_found_in_trash' => __( 'No products found in Trash', 'LDB_AP' ), 
				'parent_item_colon' => '',
				'menu_name' => __( 'Products', 'LDB_AP' )
			);
			$args = array(
				'labels' => $labels,
				'public' => true,
				'publicly_queryable' => true,
				'show_ui' => true, 
				'show_in_menu' => true, 
				'query_var' => true,
				'rewrite' => true,
				'capability_type' => 'post',
				'has_archive' => true, 
				'hierarchical' => false,
				'menu_position' => null,
				'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'excerpt', 'comments', 'custom-fields' )
			);
			register_post_type( 'product', $args );
			add_filter( 'manage_product_posts_columns', array( &$this, 'AP_changeColumns' ) );
			add_filter( 'manage_product_posts_custom_column', array( &$this, 'AP_addColumnContent' ) );
			add_filter( 'manage_edit-product_sortable_columns', array( &$this, 'AP_sortableColumns' ) );
		}

		/* Function that adds additional columns on the products index page. */
		function AP_changeColumns( $cols ) {
			$newcols = array();
			foreach( $cols as $key => $value ) {
				$newcols[ $key ] = $value;
				if( $key === 'title' )
					$newcols['prices'] = __( 'Number of prices', 'LDB_AP' );
			}
			return $newcols;
		}

		/* Function that adds content to the additional columns on the products index page. */
		function AP_addColumnContent( $column_name ) {
			global $post, $wpdb;
			switch ( $column_name ) {
				case 'prices' :
					$results = $wpdb->get_results( 'SELECT apfeeds.title, apfeeds.currency, apprices.price FROM ' . $wpdb->prefix . 'apprices apprices, ' . $wpdb->prefix . 'apfeeds apfeeds WHERE apprices.productID = ' . $post->ID . ' AND apprices.feedID = apfeeds.ID AND apprices.online = 1 ORDER BY apprices.price ASC' );
					echo count( $results );
				break;
			}
		}

		/* Function that determines the sortable columns on the products index page. */
		function AP_sortableColumns() {
			return array(
				'prices' => 'prices',
				'title' => 'title',
				'author' => 'author',
				'date' => 'date',
			);
		}

		/* Function that fetches the current action, partly stolen from core. */
		function AP_currentAction() {
			$action = false;

			if ( isset( $_REQUEST['action'] ) && -1 != $_REQUEST['action'] )
				$action = $_REQUEST['action'];

			if ( isset( $_REQUEST['action2'] ) && -1 != $_REQUEST['action2'] )
				$action = $_REQUEST['action2'];

			if ( !$action && isset( $_GET['action'] ) )
				$action = $_GET['action'];

			return $action;
		}

		/* Function to perform the actions issues by forms. */
		function AP_performAction() {
			global $wpdb;
			$action = $this->AP_currentAction();
			switch( $action ) {
				case 'process':
					if( isset( $_GET['feed'] ) && is_array( $_GET['feed'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( $_GET['_wpnonce'], 'bulk-feeds' ) ) {
						foreach( $_GET['feed'] as $feed ) {
							$this->AP_processPrices( $feed );
						}
						$this->AP_setMessage( __( 'The feeds were processed succesfully.', 'LDB_AP' ), 'success' );
					} else if( isset( $_GET['feed'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( $_GET['_wpnonce'], 'process' . $_GET['feed'] ) ) {
						$this->AP_processPrices( $_GET['feed'] );
						$this->AP_setMessage( __( 'The feed was processed succesfully.', 'LDB_AP' ), 'success' );
					} else {
						wp_die( __( "You're not allowed to perform the requested action." ) );
					}
				break;
				case 'delete':
					if( isset( $_GET['feed'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( $_GET['_wpnonce'], 'bulk-feeds' ) ) {
						$wpdb->query( 'DELETE FROM ' . $wpdb->prefix . 'apfeeds WHERE ID IN (' . implode( ', ', $_GET['feed'] ) . ')' );
						$this->AP_setMessage( __( 'The feeds were succesfully deleted.', 'LDB_AP' ), 'success' );
					}
					if( isset( $_REQUEST['feed'] ) && isset( $_REQUEST['_wpnonce'] ) && wp_verify_nonce( $_REQUEST['_wpnonce'], 'delete' . $_REQUEST['feed'] ) ) {
						$wpdb->query( 'DELETE FROM ' . $wpdb->prefix . 'apfeeds WHERE id=' . $_GET['feed'] );
						$this->AP_setMessage( __( 'The feed was succesfully deleted.', 'LDB_AP' ), 'success' );
					}
				break;
				case 'draft':
					if( isset( $_GET['identifier'] ) && isset( $_GET['feed'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( $_GET['_wpnonce'], 'bulk-feeds' ) ) {
						$items = @$this->AP_processFeed( $_GET['feed'] );
						foreach( $_GET['identifier'] as $identifier ) {
							foreach( $items as $item ) {
								if( $item['identifier'] === $identifier )
									if( $this->AP_createDraft( $item['name'], $item['matches'], $item['identifier'], $item['image'] ) )
										$this->AP_setMessage( sprintf( __( 'The draft for %s was created succesfully.', 'LDB_AP' ), $item['name'] ), 'success' );
							}
						}
						$feed = @$this->AP_getFeed( $_GET['feed'] );
						$this->AP_processPrices( $_GET['feed'] );
						$this->action = 'view';
					} else if( isset( $_GET['identifier'] ) && isset( $_GET['feed'] ) && isset( $_GET['_draftnonce'] ) && wp_verify_nonce( $_GET['_draftnonce'], 'draft' . $_GET['identifier'] ) ) {
						$items = @$this->AP_processFeed( $_GET['feed'] );
						$post = '';
						$postID = false;
						$message = '';
						$messagetype= '';
						foreach( $items as $item ) {
							if( $item['identifier'] === $_GET['identifier'] )
								$postID = $this->AP_createDraft( $item['name'], $item['matches'], $item['identifier'], $item['image'] );
						}
						if( $postID && !is_array( $postID ) )
							$post = '&post=' . $postID;
						$feed = @$this->AP_getFeed( $_GET['feed'] );
						$this->AP_processPrices( $_GET['feed'] );
						$paged = '';
						$orderby = '';
						$order = '';
						if( isset( $_GET['paged'] ) )
							$paged = '&paged=' . $_GET['paged'];
						if( isset( $_GET['orderby'] ) )
							$orderby = '&orderby=' . $_GET['orderby'];
						if( isset( $_GET['order'] ) )
							$order = '&order=' . $_GET['order'];
						header( 'Location:?page=' . $_GET['page'] . '&action=view&feed=' . $_GET['feed'] . '&_viewnonce=' . $_GET['_viewnonce'] . $paged . $orderby . $order . $post );
					}
				break;
				default:
					if( isset( $_POST['wp_nonce_add'] ) && wp_verify_nonce( $_POST['wp_nonce_add'], 'addfeed' ) ) {
						$data = $this->AP_prepareFeedData();
						$wpdb->insert( $wpdb->prefix . 'apfeeds', $data );
						$this->AP_setMessage( __( 'The feed was succesfully saved.', 'LDB_AP' ), 'success' );
					} else if( isset( $_POST['wp_nonce_edit'] ) && wp_verify_nonce( $_POST['wp_nonce_edit'], 'editfeed' ) ) {
						$data = $this->AP_prepareFeedData();
						$wpdb->update( $wpdb->prefix . 'apfeeds', $data, array( 'ID' => $_POST['ID'] ) );
						$this->AP_setMessage( __( 'The feed was succesfully updated.', 'LDB_AP' ), 'success' );
					} else if( isset( $_POST['wp_nonce_linkto'] ) && isset( $_POST['identifier'] ) && wp_verify_nonce( $_POST['wp_nonce_linkto'], 'linkto' . $_POST['identifier'] ) ) {
						add_post_meta( $_POST['product'], $_POST['matches'], $_POST['identifier'] );
						header( 'Location:' . $_POST['view_referer'] . '&linkto=' . $_POST['product'] );
					}
				break;
			}
		}

		/* Function that adds the custom meta box for the products. */
		function AP_addCustomMetaBox() {
			add_meta_box( 'affiliate-press', __( 'Prices from feeds', 'LDB_AP' ), array( &$this, 'AP_pricesBox' ), 'product', 'side', 'default' );
		}

		/* Function that fetches and show the content for the meta box on the edit product page. */
		function AP_pricesBox() {
			global $post, $wpdb;
			$productID = $post->ID;
			$results = $wpdb->get_results( 'SELECT apfeeds.title, apfeeds.currency, apprices.price FROM ' . $wpdb->prefix . 'apprices apprices, ' . $wpdb->prefix . 'apfeeds apfeeds WHERE apprices.productID = ' . $productID . ' AND apprices.feedID = apfeeds.ID AND apprices.online = 1 ORDER BY apprices.price ASC' );
			$pricetable = '<table cellpadding="0" cellspacing="0" border="0" class="pricetable">';
			if( $results ) {
				$r = 1;
				foreach( $results as $result ){
					$class = 'normal';
					if( count( $results ) === 1 ) {
						$class = '';
					} else if( $r === 1 ) {
						$class = 'first';
					} else if( $r === count( $results ) ) {
						$class = 'last';
					}
					$pricetable.= '<tr class="' . $class . '"><th class="feedtitle">' . $result->title . '</th><td class="feedprice">' . $result->currency . ' ' . $result->price . '</td></tr>';
					$r++;
				}
			} else {
				$pricetable.= '<td>' . __( 'No prices were found.', 'LDB_AP' ) . '</td>';
			}
			$pricetable.= '</table>';
			echo $pricetable;
		}

		/* Function that shows the dashboard. */
		function AP_dashboard() {
			include( LDB_AP_VIEW_PATH . 'dashboard.php' );
		}

		/* Function that shows the feed index page. */
		function AP_feeds() {
			include( LDB_AP_VIEW_PATH . 'feed-index.php' );
		}

		/* Function that shows the add feed page. */
		function AP_addFeed() {
			$matches = $this->AP_buildSelect( 'matches', $this->AP_getCustomFields() );
			include( LDB_AP_VIEW_PATH . 'feed-add.php' );
		}

		/* Function that shows the add feed page. */
		function AP_addFeedWizard() {
			$step = 1;
			if( isset( $_POST['step'] ) ) {
				$step = $_POST['step'] + 1;
			}
			if( $step === 2 ) {
				if( $this->AP_issetAndNotEmpty( $_POST, array( 'title', 'currency', 'url' ) ) ) {
					$nodes = $this->AP_fetchNodesWithChildren( $_POST['url'] );
					$item_xpath = $this->AP_buildSelect( 'item_xpath', $nodes, false, true );
				} else {
					$this->AP_setMessage( __( "You didn't fill out all the required fields.", 'LDB_AP' ), 'warning' );
					$step = 1;
				}
			} else if( $step === 3 ) {
				if( $this->AP_issetAndNotEmpty( $_POST, array( 'title', 'currency', 'url', 'item_xpath' ) ) ) {
					$xpath = array();
					$fields = array( 'name', 'image', 'price', 'link', 'identifier' );
					$nodes = $this->AP_fetchChildNodes( $_POST['url'], $_POST['item_xpath'] );
					foreach( $fields as $field ) {
						$xpath[ $field ] = $this->AP_buildSelect( $field . '_xpath', $nodes, false, true );
					}
					$matches = $this->AP_buildSelect( 'matches', $this->AP_getCustomFields() );
				} else {
					$nodes = $this->AP_fetchNodesWithChildren( $_POST['url'] );
					$item_xpath = $this->AP_buildSelect( 'item_xpath', $nodes, false, true );
					$this->AP_setMessage( __( "You didn't fill out all the required fields.", 'LDB_AP' ), 'warning' );
					$step = 2;
				}
			}
			include( LDB_AP_VIEW_PATH . 'feed-add-wizard-step' . $step . '.php' );
		}

		/* Function that check if the data in an array is set and not empty */
		function AP_issetAndNotEmpty( $var, $keys ) {
			$check = true;
			foreach( $keys as $key ) {
				if( !isset( $var[ $key ] ) || empty( $var[ $key ] ) )
					$check = false;

			}
			return $check;
		}

		/* Function that fetches all XPath nodes that have children and occur multiple times. */
		function AP_fetchNodesWithChildren( $url ) {
			$nodes = array();
			$temp = array();
			$data = wp_remote_get( $url );
			$body = new DOMDocument();
			@$body->loadXML( $data['body'] );
			$xpath = new DOMXPath( $body );
			$items = $xpath->query( '//*[count(*)>0]' );
			foreach( $items as $item ) {
				if( in_array( $item->nodeName, $temp ) && !in_array( $item->nodeName, $nodes ) ) {
					$nodes['//' . $item->nodeName] = '//' .$item->nodeName;
				}
				$temp[] = $item->nodeName;
			}
			return $nodes;
		}

		/* Function that fetches the childnodes for the first occurence of a certain node. */
		function AP_fetchChildNodes( $url, $item_xpath ) {
			$nodes = array();
			$data = wp_remote_get( $url );
			$body = new DOMDocument();
			@$body->loadXML( $data['body'] );
			$xpath = new DOMXPath( $body );
			$query = $item_xpath . '[1]/*';
			$items = $xpath->query( $item_xpath . '[1]/*' );
			foreach( $items as $item ) {
				if( !in_array( $item->nodeName, $nodes ) ) {
					$nodes['.//' . $item->nodeName] = './/' .$item->nodeName;
				}
			}
			return $nodes;
		}

		/* Function that shows the edit feed page. */
		function AP_editFeed() {
			wp_enqueue_script( 'ap_expand', LDB_AP_SCRIPTS_URL . 'expand.js' );
			wp_enqueue_script( 'ap_message', LDB_AP_SCRIPTS_URL . 'message.js' );
			if( isset( $_GET['feed'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( $_GET['_wpnonce'], 'edit' . $_GET['feed'] ) ) {
				$feed = @$this->AP_getFeed( $_REQUEST['feed'] );
				$customfields = $this->AP_getCustomFields();
				$matches = $this->AP_buildSelect( 'matches', $this->AP_getCustomFields(), $feed['matches'] );
				include( LDB_AP_VIEW_PATH . 'feed-edit.php' );
			} else {
				wp_die( __( "You're not allowed to perform the requested action." ) );
			}
		}

		/* Function that shows the view feed page. */
		function AP_viewFeed() {
			wp_enqueue_script( 'ap_expand', LDB_AP_SCRIPTS_URL . 'expand.js' );
			wp_enqueue_script( 'ap_message', LDB_AP_SCRIPTS_URL . 'message.js' );
			if( isset( $_GET['post'] ) ) {
				$postinfo = get_post( $_GET['post'] );
				$this->AP_setMessage( sprintf( __( 'The draft for %s was created successfully.', 'LDB_AP' ), $postinfo->post_title ), 'success' );
			} else if( isset( $_GET['linkto'] ) ) {
				$postinfo = get_post( $_GET['linkto'] );
				$this->AP_setMessage( sprintf( __( 'The item was succesfully linked to the product with title "%s".', 'LDB_AP' ), $postinfo->post_title ), 'success' );
			}
			if( isset( $_GET['feed'] ) && isset( $_GET['_viewnonce'] ) && wp_verify_nonce( $_GET['_viewnonce'], 'view' . $_GET['feed'] ) ) {
				$feed = @$this->AP_getFeed( $_GET['feed'] );
				$items = @$this->AP_processFeed( $_GET['feed'] );
				include( LDB_AP_VIEW_PATH . 'feed-view.php' );
			} else {
				wp_die( __( "You're not allowed to perform the requested action." ) );
			}
		}

		/* Function that adds the item data to an existing product. */
		function AP_linkToProduct() {
			wp_enqueue_script( 'ap_expand', LDB_AP_SCRIPTS_URL . 'expand.js' );
			wp_enqueue_script( 'ap_message', LDB_AP_SCRIPTS_URL . 'message.js' );
			if( isset( $_GET['identifier'] ) && isset( $_GET['_wpnonce'] ) && wp_verify_nonce( $_GET['_wpnonce'], 'linkto' . $_GET['identifier'] ) ) {
				$products = array();
				$setproducts = array();
				$productsarray = array();
				$allproducts = get_posts(
					array(
						'post_type' => 'product',
						'post_status' => array( 'publish', 'draft' )
					)
				);
				foreach( $allproducts as $product ) {
					if( !$meta = get_post_meta( $product->ID, $_GET['matches'] ) ) {
						$products[ $product->ID ] = $product->post_title;
					} else {
						if( !in_array( $_GET['identifier'], $meta ) ) {
							$setproducts[ $product->ID ] = $product->post_title;
						}
					}
				}
				if( count( $products ) > 0 )
					$productsarray[ sprintf( __('Products without %s set', 'LDB_AP' ), $_GET['matches'] ) ] = $products;

				if( count( $setproducts ) > 0 )
					$productsarray[ sprintf( __('Products with %s already set', 'LDB_AP' ), $_GET['matches'] ) ] = $setproducts;

				$view_referer = $_SERVER['HTTP_REFERER'];
				$linkto = $this->AP_buildSelect( 'product', $productsarray, false, true );
				include( LDB_AP_VIEW_PATH . 'feed-linkto.php' );
			} else {
				wp_die( __( "You're not allowed to perform the requested action." ) );
			}
		}

		/* Function to show a postbox. */
		function AP_postbox( $id, $title, $content ) {
			$postbox = '<div id="' . $id . '" class="postbox"><div class="handlediv" title="' . __( 'Click to toggle', 'LDB_AP' ) . '"><br /></div><h3 class="hndle"><span>' . $title . '</span></h3><div class="inside">' . $content . '</div></div>';
			echo $postbox;
		}

		/* Function that shows the sidebar. */
		function AP_sidebar() {
			include( LDB_AP_VIEW_PATH . 'sidebar.php' );
		}

		/* Function that catches the attachment id and assigns it as the feature image to it's parent. */
		function AP_catchAttachment( $att_id ){
			$post = get_post( $att_id );
			update_post_meta( $post->post_parent, '_thumbnail_id' , $att_id );
		}

		/* Function that creates a product draft based on the feed item data. */
		function AP_createDraft( $name, $matches, $identifier, $image ) {
			$data = array(
				'post_title' => $name,
				'post_type' => 'product'
			);
			$post = wp_insert_post( $data );
			add_post_meta( $post, $matches, $identifier );
			if( $image && !empty( $image ) ) {
				add_action( 'add_attachment', array( &$this, 'AP_catchAttachment' ) );
				$html = media_sideload_image( $image, $post );
				remove_action( 'add_attachment', array( &$this, 'AP_catchAttachment' ) );
			}
			return $post;
		}

		/* Function that creates a product draft based on the feed item data. */
		function AP_prepareFeedData() {
			$fields = array( 'title', 'currency', 'url', 'item_xpath', 'name_xpath', 'image_xpath', 'price_xpath', 'link_xpath', 'identifier_xpath', 'matches' );
			$data = array();
			foreach( $fields as $key => $value ) {
				if( isset( $_POST[ $value ] ) ) {
					$data[ $value ] = $_POST[ $value ];
				} else {
					$data[ $value ] = '';
				}
				
			}
			if( isset( $_POST['new_matches'] ) && !empty( $_POST['new_matches'] ) ) {
				$data['matches'] = $_POST['new_matches'];
			}
			return $data;
		}

		/* Function that sets a message. */
		function AP_setMessage( $msg, $type ) {
			$this->messages[] = array( $msg, $type );
		}

		/* Function that gets, displays and clears all messages. */
		function AP_getMessage() {
			$messages = '';
			foreach( $this->messages as $message ){
				$messages.= '<div class="message ' . $message[1] . '">' . $message[0] . '<a class="ap_message_close" href="javascript:;">' . __( 'Close', 'LDB_AP' ) . '</a></div>' . "\n";
			}
			$this->messages = array();
			echo $messages;
		}

		/* Function that gets all the info for a feed. */
		function AP_getFeed( $id ) {
			global $wpdb;
			if( $id === null )
				return false;
			$feed = $wpdb->get_row( 'SELECT * FROM ' . $wpdb->prefix . 'apfeeds WHERE id=' . $id, ARRAY_A );
			return $feed;
		}

		/* Function that fetches the custom fields for matching the identifier to. */
		function AP_getCustomFields() {
			$fields = array();
			$products = get_posts(
				array(
					'post_type' => 'product',
					'post_status' => array( 'publish', 'draft' )
				)
			);
			foreach( $products as $product ) {
				$fields = array_merge( $fields, get_post_custom_keys( $product->ID ) );
			}
			foreach( $fields as $key => $field ) {
				if( $field[0] === '_' )
					unset( $fields[ $key ] );
			}
			$fields = array_unique( $fields );
			return $fields;
		}

		/* Function to build a <select>. */
		function AP_buildSelect( $name, $values, $default = false, $split = false ) {
			$select = '<select name="' . $name . '" id="' . $name . '"><option></option>';
			if( $split ) {
				foreach( $values as $key => $value ) {
					if( is_array( $value ) ) {
						$select.= '<optgroup label="' . $key . '">';
						foreach( $value as $subkey => $subvalue ) {
							if( $subkey === $default ) {
								$select.= '<option value="' . $subkey . '" selected="selected">' . $subvalue . '</option>';
							} else {
								$select.= '<option value="' . $subkey . '">' . $subvalue . '</option>';
							}
						}
						$select.= '</optgroup>';
					} else {
						if( $key === $default ) {
							$select.= '<option value="' . $key . '" selected="selected">' . $value . '</option>';
						} else {
							$select.= '<option value="' . $key . '">' . $value . '</option>';
						}
					}
				}
			} else {
				foreach( $values as $value ) {
					if( $value === $default ) {
						$select.= '<option value="' . $value . '" selected="selected">' . $value . '</option>';
					} else {
						$select.= '<option value="' . $value . '">' . $value . '</option>';
					}
				}
			}
			$select.= '</select>';
			return $select;
		}

		/* Function that processes a feed based on a feed ID. */
		function AP_processFeed( $feed ) {
			global $wpdb;
			$info = json_decode( get_option( 'ap_feed_' . $feed, false ), true );
			if( isset( $info['timestamp'] ) && $info['timestamp'] < ( time() - 300 ) ) {
				return $info['data'];
			} else {
				$info = array();
				$feedinfo = $this->AP_getFeed( $feed );
				$data = wp_remote_get( $feedinfo['url'] );
				$body = new DOMDocument();
				@$body->loadXML( $data['body'] );
				$xpath = new DOMXPath( $body );
				$items = $xpath->query( $feedinfo['item_xpath'] );
				foreach ( $items as $item ) {
					$price = @$this->AP_getValue( @$xpath->query( $feedinfo['price_xpath'], $item ) );
					$name = @$this->AP_getValue( @$xpath->query( $feedinfo['name_xpath'], $item ) );
					$image = @$this->AP_getValue( @$xpath->query( $feedinfo['image_xpath'], $item ) );
					$link = @$this->AP_getValue( @$xpath->query( $feedinfo['link_xpath'], $item ) );
					$identifier = @$this->AP_getValue( @$xpath->query( $feedinfo['identifier_xpath'], $item ) );
					$info[] = array(
						'identifier' => $identifier,
						'matches' => $feedinfo['matches'],
						'currency' => $feedinfo['currency'],
						'price' => $price,
						'name' => $name,
						'image' => $image,
						'link' => $link,
						'feed_id' => $feedinfo['ID']
					);
				}
				$option = array(
					'data' => $info,
					'time' => time()
				);
				update_option( 'ap_feed_' . $feed, json_encode( $option ) );
				return $info;
			}
		}

		/* Function that gets the value of an XPath node. */
		function AP_getValue( $e ) {
			if( $e ) {
				return trim( preg_replace( '/\s+/', ' ', @$e->item(0)->nodeValue ) );
			} else {
				return false;
			}
		}

		/* Function that processes the prices found for a product. */
		function AP_processPrices( $feed ) {
			global $wpdb;
			$info = array();
			$feedinfo = $this->AP_getFeed( $feed );
			$wpdb->query( 'UPDATE ' . $wpdb->prefix . 'apprices SET online = 0 WHERE feedID = ' . $feedinfo['ID'] );
			$info = @$this->AP_processFeed( $feed );
			foreach( $info as $item ) {
				$query = 'SELECT wposts.ID FROM ' . $wpdb->posts . ' wposts, ' . $wpdb->postmeta . ' wpostmeta WHERE wposts.ID = wpostmeta.post_id AND wpostmeta.meta_key = "' . $item['matches'] . '" AND wpostmeta.meta_value = "' . $item['identifier'] . '" AND wposts.post_type = "product"';
				$results = $wpdb->get_results( $query );
				foreach( $results as $result ) {
					$data = array(
						'productID' => $result->ID,
						'feedID' => $item['feed_id'],
						'price' => $item['price'],
						'link' => $item['link'],
						'online' => 1
					);
					$update = $wpdb->get_row( 'SELECT * FROM ' . $wpdb->prefix . 'apprices WHERE productID = ' . $result->ID . ' AND feedID = ' . $item['feed_id'] );
					if( $update ) {
						$wpdb->update( $wpdb->prefix . 'apprices', $data, array( 'ID' => $update->ID ) );
					} else {
						$wpdb->insert( $wpdb->prefix . 'apprices', $data );
					}
				}
			}
		}

		/* Function that processes all the prices. For cron purposes. */
		function AP_processAllPrices() {
			global $wpdb;
			$feeds = $wpdb->get_results( 'SELECT ID FROM ' . $wpdb->prefix . 'apfeeds ORDER BY ID ASC', ARRAY_A );
			foreach( $feeds as $feed ) {
				$this->AP_processPrices( $feed['ID'] );
			}
		}

		/* Function that builds a table to display the prices in the front-end. */
		function AP_buildTable( $data ) {
			$table = '<table cellpadding="0" cellspacing="0" border="0" class="aptable">';
			if( $data ) {
				foreach( $data as $row ){
					$table.= '<tr><td><a href="' . $row->link . '" target="_blank">' . $row->title . '</a></td><td>' . $row->price . '</td></tr>';
				}
			} else {
				$table.= '<td>' . __( 'No prices were found.', 'LDB_AP' ) . '</td>';
			}
			$table.= '</table>';
			return $table;
		}

		/* Function that gets the prices to display the prices in the front-end. */
		function AP_getPrices( $table = false ) {
			global $post, $wpdb;
			$results = $wpdb->get_results( 'SELECT apfeeds.title, apprices.price, apprices.link FROM ' . $wpdb->prefix . 'apprices apprices, ' . $wpdb->prefix . 'apfeeds apfeeds WHERE apprices.productID = ' . $post->ID . ' AND apprices.feedID = apfeeds.ID AND apprices.online = 1 ORDER BY apprices.price ASC' );
			if ( $table )
				$results = $this->AP_buildTable( $results );

			return $results;
		}

	}

}