Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/wordpress-seo-premium/src/initializers/index-now-key.php

@@ -0,0 +1,123 @@
+<?php
+
+namespace Yoast\WP\SEO\Premium\Initializers;
+
+use Yoast\WP\SEO\Conditionals\No_Conditionals;
+use Yoast\WP\SEO\Helpers\Options_Helper;
+use Yoast\WP\SEO\Initializers\Initializer_Interface;
+
+/**
+ * Index_Now_Key class
+ */
+class Index_Now_Key implements Initializer_Interface {
+
+	use No_Conditionals;
+
+	/**
+	 * The options helper.
+	 *
+	 * @var Options_Helper
+	 */
+	private $options_helper;
+
+	/**
+	 * Holds the IndexNow key.
+	 *
+	 * @var string
+	 */
+	private $key;
+
+	/**
+	 * Index_Now_Key initializer constructor.
+	 *
+	 * @param Options_Helper $options_helper The option helper.
+	 */
+	public function __construct( Options_Helper $options_helper ) {
+		$this->options_helper = $options_helper;
+	}
+
+	/**
+	 * Initializes the integration.
+	 *
+	 * This is the place to register hooks and filters.
+	 *
+	 * @return void
+	 */
+	public function initialize() {
+		\add_action( 'init', [ $this, 'add_rewrite_rule' ], 1 );
+		\add_action( 'plugins_loaded', [ $this, 'load' ], 15 );
+	}
+
+	/**
+	 * Loads the integration.
+	 *
+	 * @return void
+	 */
+	public function load() {
+		if ( $this->options_helper->get( 'enable_index_now' ) === false ) {
+			return;
+		}
+
+		$this->key = $this->options_helper->get( 'index_now_key' );
+		if ( $this->key === '' ) {
+			$this->generate_key();
+		}
+		\add_action( 'wp', [ $this, 'output_key' ], 0 );
+	}
+
+	/**
+	 * Adds the rewrite rule for the IndexNow key txt file.
+	 *
+	 * @return void
+	 */
+	public function add_rewrite_rule() {
+		if ( $this->options_helper->get( 'enable_index_now' ) !== true ) {
+			return;
+		}
+		global $wp;
+
+		$wp->add_query_var( 'yoast_index_now_key' );
+		\add_rewrite_rule( '^yoast-index-now-([a-zA-Z0-9-]+)\.txt$', 'index.php?yoast_index_now_key=$matches[1]', 'top' );
+	}
+
+	/**
+	 * Outputs the key when it matches the key in the database.
+	 *
+	 * @return void
+	 */
+	public function output_key() {
+		$key_in_url = \get_query_var( 'yoast_index_now_key' );
+		if ( empty( $key_in_url ) ) {
+			return;
+		}
+
+		if ( $key_in_url === $this->key ) {
+			// Remove all headers.
+			\header_remove();
+			// Only send plain text header.
+			\header( 'Content-Type: text/plain;charset=UTF-8' );
+			echo \esc_html( $this->key );
+			die;
+		}
+
+		// Trying keys? Good luck.
+		global $wp_query;
+		$wp_query->set_404();
+	}
+
+	/**
+	 * Generates an IndexNow key.
+	 *
+	 * Adapted from wp_generate_password to include dash (-) and not be filtered.
+	 *
+	 * @return void
+	 */
+	private function generate_key() {
+		$chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-';
+
+		for ( $i = 0; $i < 100; $i++ ) {
+			$this->key .= \substr( $chars, \wp_rand( 0, ( \strlen( $chars ) - 1 ) ), 1 );
+		}
+		$this->options_helper->set( 'index_now_key', $this->key );
+	}
+}