$exclude        Comma-separated list of bookmark IDs to exclude. Default empty.
 * }
 * @return array List of bookmark row objects.
 */
function get_bookmarks( $args = '' ) {
	global $wpdb;

	$defaults = array(
		'orderby' => 'name', 'order' => 'ASC',
		'limit' => -1, 'category' => '',
		'category_name' => '', 'hide_invisible' => 1,
		'show_updated' => 0, 'include' => '',
		'exclude' => '', 'search' => ''
	);

	$r = wp_parse_args( $args, $defaults );

	$key = md5( serialize( $r ) );
	$cache = false;
	if ( 'rand' !== $r['orderby'] && $cache = wp_cache_get( 'get_bookmarks', 'bookmark' ) ) {
		if ( is_array( $cache ) && isset( $cache[ $key ] ) ) {
			$bookmarks = $cache[ $key ];
			/**
			 * Filters the returned list of bookmarks.
			 *
			 * The first time the hook is evaluated in this file, it returns the cached
			 * bookmarks list. The second evaluation returns a cached bookmarks list if the
			 * link category is passed but does not exist. The third evaluation returns
			 * the full cached results.
			 *
			 * @since 2.1.0
			 *
			 * @see get_bookmarks()
			 *
			 * @param array $bookmarks List of the cached bookmarks.
			 * @param array $r         An array of bookmark query arguments.
			 */
			return apply_filters( 'get_bookmarks', $bookmarks, $r );
		}
	}

	if ( ! is_array( $cache ) ) {
		$cache = array();
	}

	$inclusions = '';
	if ( ! empty( $r['include'] ) ) {
		$r['exclude'] = '';  //ignore exclude, category, and category_name params if using include
		$r['category'] = '';
		$r['category_name'] = '';
		$inclinks = preg_split( '/[\s,]+/', $r['include'] );
		if ( count( $inclinks ) ) {
			foreach ( $inclinks as $inclink ) {
				if ( empty( $inclusions ) ) {
					$inclusions = ' AND ( link_id = ' . intval( $inclink ) . ' ';
				} else {
					$inclusions .= ' OR link_id = ' . intval( $inclink ) . ' ';
				}
			}
		}
	}
	if (! empty( $inclusions ) ) {
		$inclusions .= ')';
	}

	$exclusions = '';
	if ( ! empty( $r['exclude'] ) ) {
		$exlinks = preg_split( '/[\s,]+/', $r['exclude'] );
		if ( count( $exlinks ) ) {
			foreach ( $exlinks as $exlink ) {
				if ( empty( $exclusions ) ) {
					$exclusions = ' AND ( link_id <> ' . intval( $exlink ) . ' ';
				} else {
					$exclusions .= ' AND link_id <> ' . intval( $exlink ) . ' ';
				}
			}
		}
	}
	if ( ! empty( $exclusions ) ) {
		$exclusions .= ')';
	}

	if ( ! empty( $r['category_name'] ) ) {
		if ( $r['category'] = get_term_by('name', $r['category_name'], 'link_category') ) {
			$r['category'] = $r['category']->term_id;
		} else {
			$cache[ $key ] = array();
			wp_cache_set( 'get_bookmarks', $cache, 'bookmark' );
			/** This filter is documented in wp-includes/bookmark.php */
			return apply_filters( 'get_bookmarks', array(), $r );
		}
	}

	$search = '';
	if ( ! empty( $r['search'] ) ) {
		$like = '%' . $wpdb->esc_like( $r['search'] ) . '%';
		$search = $wpdb->prepare(" AND ( (link_url LIKE %s) OR (link_name LIKE %s) OR (link_description LIKE %s) ) ", $like, $like, $like );
	}

	$category_query = '';
	$join = '';
	if ( ! empty( $r['category'] ) ) {
		$incategories = preg_split( '/[\s,]+/', $r['category'] );
		if ( count($incategories) ) {
			foreach ( $incategories as $incat ) {
				if ( empty( $category_query ) ) {
					$category_query = ' AND ( tt.term_id = ' . intval( $incat ) . ' ';
				} else {
					$category_query .= ' OR tt.term_id = ' . intval( $incat ) . ' ';
				}
			}
		}
	}
	if ( ! empty( $category_query ) ) {
		$category_query .= ") AND taxonomy = 'link_category'";
		$join = " INNER JOIN $wpdb->term_relationships AS tr ON ($wpdb->links.link_id = tr.object_id) INNER JOIN $wpdb->term_taxonomy as tt ON tt.term_taxonomy_id = tr.term_taxonomy_id";
	}

	if ( $r['show_updated'] ) {
		$recently_updated_test = ", IF (DATE_ADD(link_updated, INTERVAL 120 MINUTE) >= NOW(), 1,0) as recently_updated ";
	} else {
		$recently_updated_test = '';
	}

	$get_updated = ( $r['show_updated'] ) ? ', UNIX_TIMESTAMP(link_updated) AS link_updated_f ' : '';

	$orderby = strtolower( $r['orderby'] );
	$length = '';
	switch ( $orderby ) {
		case 'length':
			$length = ", CHAR_LENGTH(link_name) AS length";
			break;
		case 'rand':
			$orderby = 'rand()';
			break;
		case 'link_id':
			$orderby = "$wpdb->links.link_id";
			break;
		default:
			$orderparams = array();
			$keys = array( 'link_id', 'link_name', 'link_url', 'link_visible', 'link_rating', 'link_owner', 'link_updated', 'link_notes', 'link_description' );
			foreach ( explode( ',', $orderby ) as $ordparam ) {
				$ordparam = trim( $ordparam );

				if ( in_array( 'link_' . $ordparam, $keys ) ) {
					$orderparams[] = 'link_' . $ordparam;
				} elseif ( in_array( $ordparam, $keys ) ) {
					$orderparams[] = $ordparam;
				}
			}
			$orderby = implode( ',', $orderparams );
	}

	if ( empty( $orderby ) ) {
		$orderby = 'link_name';
	}

	$order = strtoupper( $r['order'] );
	if ( '' !== $order && ! in_array( $order, array( 'ASC', 'DESC' ) ) ) {
		$order = 'ASC';
	}

	$visible = '';
	if ( $r['hide_invisible'] ) {
		$visible = "AND link_visible = 'Y'";
	}

	$query = "SELECT * $length $recently_updated_test $get_updated FROM $wpdb->links $join WHERE 1=1 $visible $category_query";
	$query .= " $exclusions $inclusions $search";
	$query .= " ORDER BY $orderby $order";
	if ( $r['limit'] != -1 ) {
		$query .= ' LIMIT ' . absint( $r['limit'] );
	}

	$results = $wpdb->get_results( $query );

	if ( 'rand()' !== $orderby ) {
		$cache[ $key ] = $results;
		wp_cache_set( 'get_bookmarks', $cache, 'bookmark' );
	}

	/** This filter is documented in wp-includes/bookmark.php */
	return apply_filters( 'get_bookmarks', $results, $r );
}

/**
 * Sanitizes all bookmark fields
 *
 * @since 2.3.0
 *
 * @param stdClass|array $bookmark Bookmark row
 * @param string $context Optional, default is 'display'. How to filter the
 *		fields
 * @return stdClass|array Same type as $bookmark but with fields sanitized.
 */
function sanitize_bookmark($bookmark, $context = 'display') {
	$fields = array('link_id', 'link_url', 'link_name', 'link_image', 'link_target', 'link_category',
		'link_description', 'link_visible', 'link_owner', 'link_rating', 'link_updated',
		'link_rel', 'link_notes', 'link_rss', );

	if ( is_object($bookmark) ) {
		$do_object = true;
		$link_id = $bookmark->link_id;
	} else {
		$do_object = false;
		$link_id = $bookmark['link_id'];
	}

	foreach ( $fields as $field ) {
		if ( $do_object ) {
			if ( isset($bookmark->$field) )
				$bookmark->$field = sanitize_bookmark_field($field, $bookmark->$field, $link_id, $context);
		} else {
			if ( isset($bookmark[$field]) )
				$bookmark[$field] = sanitize_bookmark_field($field, $bookmark[$field], $link_id, $context);
		}
	}

	return $bookmark;
}

/**
 * Sanitizes a bookmark field.
 *
 * Sanitizes the bookmark fields based on what the field name is. If the field
 * has a strict value set, then it will be tested for that, else a more generic
 * filtering is applied. After the more strict filter is applied, if the `$context`
 * is 'raw' then the value is immediately return.
 *
 * Hooks exist for the more generic cases. With the 'edit' context, the {@see 'edit_$field'}
 * filter will be called and passed the `$value` and `$bookmark_id` respectively.
 *
 * With the 'db' context, the {@see 'pre_$field'} filter is called and passed the value.
 * The 'display' context is the final context and has the `$field` has the filter name
 * and is passed the `$value`, `$bookmark_id`, and `$context`, respectively.
 *
 * @since 2.3.0
 *
 * @param string $field       The bookmark field.
 * @param mixed  $value       The bookmark field value.
 * @param int    $bookmark_id Bookmark ID.
 * @param string $context     How to filter the field value. Accepts 'raw', 'edit', 'attribute',
 *                            'js', 'db', or 'display'
 * @return mixed The filtered value.
 */
function sanitize_bookmark_field( $field, $value, $bookmark_id, $context ) {
	switch ( $field ) {
	case 'link_id' : // ints
	case 'link_rating' :
		$value = (int) $value;
		break;
	case 'link_category' : // array( ints )
		$value = array_map('absint', (array) $value);
		// We return here so that the categories aren't filtered.
		// The 'link_category' filter is for the name of a link category, not an array of a link's link categories
		return $value;

	case 'link_visible' : // bool stored as Y|N
		$value = preg_replace('/[^YNyn]/', '', $value);
		break;
	case 'link_target' : // "enum"
		$targets = array('_top', '_blank');
		if ( ! in_array($value, $targets) )
			$value = '';
		break;
	}

	if ( 'raw' == $context )
		return $value;

	if ( 'edit' == $context ) {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "edit_{$field}", $value, $bookmark_id );

		if ( 'link_notes' == $field ) {
			$value = esc_html( $value ); // textarea_escaped
		} else {
			$value = esc_attr($value);
		}
	} elseif ( 'db' == $context ) {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "pre_{$field}", $value );
	} else {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "{$field}", $value, $bookmark_id, $context );

		if ( 'attribute' == $context ) {
			$value = esc_attr( $value );
		} elseif ( 'js' == $context ) {
			$value = esc_js( $value );
		}
	}

	return $value;
}

/**
 * Deletes the bookmark cache.
 *
 * @since 2.7.0
 *
 * @param int $bookmark_id Bookmark ID.
 */
function clean_bookmark_cache( $bookmark_id ) {
	wp_cache_delete( $bookmark_id, 'bookmark' );
	wp_cache_delete( 'get_bookmarks', 'bookmark' );
	clean_object_term_cache( $bookmark_id, 'link');
}