Implemented synchronization with webhook responses.

When a client triggers a `WebhookEvent` by calling a configured webhook
over `/hook/<hook_name>`, the server will now wait for the configured
`@hook` function to complete and it will return the returned response
back to the client.

This makes webhooks much more powerful, as they can be used to proxy
HTTP calls or other services, and in general return something to the
client instead of just executing actions.

platypush/backend/http/app/routes/hook.py

@@ -1,9 +1,11 @@
 import json
 
-from flask import Blueprint, abort, request, Response
+from flask import Blueprint, abort, request
+from flask.wrappers import Response
 
 from platypush.backend.http.app import template_folder
 from platypush.backend.http.app.utils import logger, send_message
+from platypush.config import Config
 from platypush.message.event.http.hook import WebhookEvent
 
 
@@ -15,8 +17,10 @@ __routes__ = [
 ]
 
 
-@hook.route('/hook/<hook_name>', methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS'])
-def _hook(hook_name):
+@hook.route(
+    '/hook/<hook_name>', methods=['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS']
+)
+def hook_route(hook_name):
     """Endpoint for custom webhooks"""
 
     event_args = {
@@ -28,20 +32,36 @@ def _hook(hook_name):
     }
 
     if event_args['data']:
-        # noinspection PyBroadException
         try:
             event_args['data'] = json.loads(event_args['data'])
         except Exception as e:
-            logger().warning('Not a valid JSON string: {}: {}'.format(event_args['data'], str(e)))
+            logger().warning(
+                'Not a valid JSON string: %s: %s', event_args['data'], str(e)
+            )
 
     event = WebhookEvent(**event_args)
+    matching_hooks = [
+        hook
+        for hook in Config.get_event_hooks().values()
+        if hook.condition.type == WebhookEvent
+        and hook.condition.args.get('hook') == hook_name
+        and request.method.lower()
+        == hook.condition.args.get('method', request.method).lower()
+    ]
 
     try:
         send_message(event)
-        return Response(json.dumps({'status': 'ok', **event_args}), mimetype='application/json')
+
+        # If there are matching hooks, wait for their completion before returning
+        if matching_hooks:
+            return event.wait_response(timeout=60)
+
+        return Response(
+            json.dumps({'status': 'ok', **event_args}), mimetype='application/json'
+        )
     except Exception as e:
         logger().exception(e)
-        logger().error('Error while dispatching webhook event {}: {}'.format(event, str(e)))
+        logger().error('Error while dispatching webhook event %s: %s', event, str(e))
         abort(500, str(e))
 
 

platypush/event/hook.py

@@ -18,7 +18,7 @@ def parse(msg):
     """Builds a dict given another dictionary or
     a JSON UTF-8 encoded string/bytearray"""
 
-    if isinstance(msg, bytes) or isinstance(msg, bytearray):
+    if isinstance(msg, (bytes, bytearray)):
         msg = msg.decode('utf-8')
     if isinstance(msg, str):
         try:
@@ -30,7 +30,7 @@ def parse(msg):
     return msg
 
 
-class EventCondition(object):
+class EventCondition:
     """Event hook condition class"""
 
     def __init__(self, type=Event.__class__, priority=None, **kwargs):
@@ -64,8 +64,7 @@ class EventCondition(object):
             rule = parse(rule)
 
         assert isinstance(rule, dict), f'Not a valid rule: {rule}'
-        type = get_event_class_by_type(
-            rule.pop('type') if 'type' in rule else 'Event')
+        type = get_event_class_by_type(rule.pop('type') if 'type' in rule else 'Event')
 
         args = {}
         for (key, value) in rule.items():
@@ -99,7 +98,7 @@ class EventAction(Request):
         return super().build(action)
 
 
-class EventHook(object):
+class EventHook:
     """Event hook class. It consists of one conditions and
     one or multiple actions to be executed"""
 
@@ -163,7 +162,9 @@ class EventHook(object):
 
         if result.is_match:
             logger.info('Running hook {} triggered by an event'.format(self.name))
-            threading.Thread(target=_thread_func, name='Event-' + self.name, args=(result,)).start()
+            threading.Thread(
+                target=_thread_func, name='Event-' + self.name, args=(result,)
+            ).start()
 
 
 def hook(event_type=Event, **condition):
@@ -172,8 +173,14 @@ def hook(event_type=Event, **condition):
         f.condition = EventCondition(type=event_type, **condition)
 
         @wraps(f)
-        def wrapped(*args, **kwargs):
-            return exec_wrapper(f, *args, **kwargs)
+        def wrapped(event, *args, **kwargs):
+            from platypush.message.event.http.hook import WebhookEvent
+
+            response = exec_wrapper(f, event, *args, **kwargs)
+            if isinstance(event, WebhookEvent):
+                event.send_response(response)
+
+            return response
 
         return wrapped
 

platypush/message/event/http/hook.py

@@ -1,11 +1,26 @@
+import json
+import uuid
+
 from platypush.message.event import Event
+from platypush.utils import get_redis
+
 
 class WebhookEvent(Event):
     """
     Event triggered when a custom webhook is called.
     """
 
-    def __init__(self, *argv, hook, method, data=None, args=None, headers=None, **kwargs):
+    def __init__(
+        self,
+        *argv,
+        hook,
+        method,
+        data=None,
+        args=None,
+        headers=None,
+        response=None,
+        **kwargs,
+    ):
         """
         :param hook: Name of the invoked web hook, from http://host:port/hook/<hook>
         :type hook: str
@@ -21,10 +36,35 @@ class WebhookEvent(Event):
 
         :param headers: Request headers
         :type args: dict
-        """
 
-        super().__init__(hook=hook, method=method, data=data, args=args or {},
-                         headers=headers or {}, *argv, **kwargs)
+        :param response: Response returned by the hook.
+        :type args: dict | list | str
+        """
+        # This queue is used to synchronize with the hook and wait for its completion
+        kwargs['response_queue'] = kwargs.get(
+            'response_queue', f'platypush/webhook/{str(uuid.uuid1())}'
+        )
+
+        super().__init__(
+            *argv,
+            hook=hook,
+            method=method,
+            data=data,
+            args=args or {},
+            headers=headers or {},
+            response=response,
+            **kwargs,
+        )
+
+    def send_response(self, response):
+        output = response.output
+        if isinstance(output, (dict, list)):
+            output = json.dumps(output)
+
+        get_redis().rpush(self.args['response_queue'], output)
+
+    def wait_response(self, timeout=None):
+        return get_redis().blpop(self.args['response_queue'], timeout=timeout)[1]
 
 
 # vim:sw=4:ts=4:et: