Trigger first step in an individual event handler

tfw/components/frontend/__init__.py

@@ -1,4 +1,5 @@
 from .console_logs_handler import ConsoleLogsHandler
 from .frontend_proxy_handler import FrontendProxyHandler
+from .frontend_ready_handler import FrontendReadyHandler
 from .message_queue_handler import MessageQueueHandler
 from .message_sender import MessageSender

tfw/components/frontend/frontend_ready_handler.py

@@ -0,0 +1,39 @@
+import logging
+
+from tfw.internals.crypto import KeyManager, sign_message
+
+LOG = logging.getLogger(__name__)
+
+
+class FrontendReadyHandler:
+    keys = ['frontend.ready', 'fsm.update']
+
+    def __init__(self, initial_trigger):
+        self.connector = None
+        self._auth_key = KeyManager().auth_key
+        self.initial_trigger = initial_trigger
+
+        self.commands = {
+            'frontend.ready': self.handle_ready,
+            'fsm.update': self.handle_update
+        }
+
+    def handle_event(self, message, _):
+        try:
+            self.commands[message['key']]()
+        except KeyError:
+            LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
+
+    def handle_ready(self):
+        trigger = {
+            'key': 'fsm.step',
+            'trigger': self.initial_trigger
+        }
+        sign_message(self._auth_key, trigger)
+        self.connector.send_message(trigger)
+
+    def handle_update(self):
+        self.stop()
+
+    def stop(self):
+        pass