Sync: adapt checkout endpoint for immediate full sync (#14158)

* fix checkout endpoint for immediate full sync[not verified]

* codeclimate

* update error message

* move callables to variables

* $this->

* we have the queue name already[not verified]

* don't block do_full_sync

json-endpoints/jetpack/class.jetpack-json-api-sync-endpoint.php

@@ -48,8 +48,8 @@ protected function validate_queue( $query ) {
 			return new WP_Error( 'invalid_queue', 'Queue name is required', 400 );
 		}
 
-		if ( ! in_array( $query, array( 'sync', 'full_sync' ) ) ) {
-			return new WP_Error( 'invalid_queue', 'Queue name should be sync or full_sync', 400 );
+		if ( ! in_array( $query, array( 'sync', 'full_sync', 'immediate' ) ) ) {
+			return new WP_Error( 'invalid_queue', 'Queue name should be sync, full_sync or immediate', 400 );
 		}
 		return $query;
 	}
@@ -191,6 +191,14 @@ protected function result() {
 
 		$number_of_items = absint( $args['number_of_items'] );
 
+		if ( 'immediate' === $queue_name ) {
+			return $this->immediate_full_sync_pull( $number_of_items );
+		}
+
+		return $this->queue_pull( $queue_name, $number_of_items, $args );
+	}
+
+	function queue_pull( $queue_name, $number_of_items, $args ){
 		$queue = new Queue( $queue_name );
 
 		if ( 0 === $queue->size() ) {
@@ -233,6 +241,36 @@ protected function result() {
 		);
 	}
 
+	public $items = [];
+
+	public function jetpack_sync_send_data_listener() {
+		foreach ( func_get_args()[0] as $key => $item ) {
+			$this->items[ $key ] = $item;
+		}
+	}
+
+	public function immediate_full_sync_pull( $number_of_items ) {
+		// try to give ourselves as much time as possible.
+		set_time_limit( 0 );
+
+		$original_send_data_cb = array( 'Automattic\Jetpack\Sync\Actions', 'send_data' );
+		$temp_send_data_cb     = array( $this, 'jetpack_sync_send_data_listener' );
+
+		Sender::get_instance()->set_enqueue_wait_time( 0 );
+		remove_filter( 'jetpack_sync_send_data', $original_send_data_cb );
+		add_filter( 'jetpack_sync_send_data', $temp_send_data_cb, 10, 6 );
+		Sender::get_instance()->do_full_sync();
+		remove_filter( 'jetpack_sync_send_data', $temp_send_data_cb );
+		add_filter( 'jetpack_sync_send_data', $original_send_data_cb, 10, 6 );
+
+		return array(
+			'items'          => $this->items,
+			'codec'          => Sender::get_instance()->get_codec()->name(),
+			'sent_timestamp' => time(),
+			'status'         => Actions::get_sync_status(),
+		);
+	}
+
 	protected function get_buffer( $queue, $number_of_items ) {
 		$start = time();
 		$max_duration = 5; // this will try to get the buffer