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wp-content/plugins/jetpack-boost/app/lib/critical-css/class-generator.php

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+<?php
+
+namespace Automattic\Jetpack_Boost\Lib\Critical_CSS;
+
+use Automattic\Jetpack_Boost\Modules\Optimizations\Critical_CSS\CSS_Proxy;
+
+class Generator {
+
+	const GENERATE_QUERY_ACTION = 'jb-generate-critical-css';
+
+	public static function init() {
+		$generator = new static();
+		if ( static::is_generating_critical_css() ) {
+			add_action( 'wp_head', array( $generator, 'display_generate_meta' ), 0 );
+			$generator->force_logged_out_render();
+		}
+	}
+
+	/**
+	 * Force the current page to render as viewed by a logged out user. Useful when generating
+	 * Critical CSS.
+	 */
+	private function force_logged_out_render() {
+		$current_user_id = get_current_user_id();
+
+		if ( 0 !== $current_user_id ) {
+			// Force current user to 0 to ensure page is rendered as a non-logged-in user.
+			wp_set_current_user( 0 );
+
+			// Turn off display of admin bar.
+			add_filter( 'show_admin_bar', '__return_false', PHP_INT_MAX );
+		}
+	}
+
+	/**
+	 * Return true if page is loaded to generate critical CSS
+	 *
+	 * phpcs:disable WordPress.Security.NonceVerification.Recommended
+	 */
+	public static function is_generating_critical_css() {
+		return isset( $_GET[ self::GENERATE_QUERY_ACTION ] );
+	}
+
+	/**
+	 * Get a Critical CSS status block, adding in local generation nonces (if applicable).
+	 * i.e.: Call this method to supply enough Critical CSS status to kick off local generation,
+	 * such as in response to a request-generate API call or during page initialization.
+	 */
+	public function get_generation_metadata() {
+		$status = array();
+
+		// Add a user-bound nonce to use when proxying CSS for Critical CSS generation.
+		$status['proxy_nonce'] = wp_create_nonce( CSS_Proxy::NONCE_ACTION );
+
+		return $status;
+	}
+
+	/**
+	 * Renders a <meta> tag used to verify this is a valid page to generate Critical CSS with.
+	 */
+	public function display_generate_meta() {
+		?>
+		<meta name="<?php echo esc_attr( self::GENERATE_QUERY_ACTION ); ?>" content="true"/>
+		<?php
+	}
+}