add_filter(

	'rest_authentication_errors',

	function ( $access ) {

		return new WP_Error(

			'rest_disabled',

			__( 'The WordPress REST API has been disabled.' ),

			array(

				'status' => rest_authorization_required_code(),

			)

		);

	}

);

/**

 * Disable all embeds in WordPress.

 */

add_action( 'init', function () {

	// Remove the REST API endpoint.

	remove_action( 'rest_api_init', 'wp_oembed_register_route' );

	// Turn off oEmbed auto discovery.

	add_filter( 'embed_oembed_discover', '__return_false' );

	// Don't filter oEmbed results.

	remove_filter( 'oembed_dataparse', 'wp_filter_oembed_result', 10 );

	// Remove oEmbed discovery links.

	remove_action( 'wp_head', 'wp_oembed_add_discovery_links' );

	// Remove oEmbed-specific JavaScript from the front-end and back-end.

	remove_action( 'wp_head', 'wp_oembed_add_host_js' );

	add_filter( 'tiny_mce_plugins', function ( $plugins ) {

		return array_diff( $plugins, array( 'wpembed' ) );

	} );

	// Remove all embeds rewrite rules.

	add_filter( 'rewrite_rules_array', function ( $rules ) {

		foreach ( $rules as $rule => $rewrite ) {

			if ( false !== strpos( $rewrite, 'embed=true' ) ) {

				unset( $rules[ $rule ] );

			}

		}

		return $rules;

	} );

	// Remove filter of the oEmbed result before any HTTP requests are made.

	remove_filter( 'pre_oembed_result', 'wp_filter_pre_oembed_result', 10 );

}, 9999 );