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config/custom_components/pyscript/event.py

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+"""Handles event firing and notification."""
+
+import logging
+
+from .const import LOGGER_PATH
+
+_LOGGER = logging.getLogger(LOGGER_PATH + ".event")
+
+
+class Event:
+    """Define event functions."""
+
+    #
+    # Global hass instance
+    #
+    hass = None
+
+    #
+    # notify message queues by event type
+    #
+    notify = {}
+    notify_remove = {}
+
+    def __init__(self):
+        """Warn on Event instantiation."""
+        _LOGGER.error("Event class is not meant to be instantiated")
+
+    @classmethod
+    def init(cls, hass):
+        """Initialize Event."""
+
+        cls.hass = hass
+
+    @classmethod
+    async def event_listener(cls, event):
+        """Listen callback for given event which updates any notifications."""
+
+        func_args = {
+            "trigger_type": "event",
+            "event_type": event.event_type,
+            "context": event.context,
+        }
+        func_args.update(event.data)
+        await cls.update(event.event_type, func_args)
+
+    @classmethod
+    def notify_add(cls, event_type, queue):
+        """Register to notify for events of given type to be sent to queue."""
+
+        if event_type not in cls.notify:
+            cls.notify[event_type] = set()
+            _LOGGER.debug("event.notify_add(%s) -> adding event listener", event_type)
+            cls.notify_remove[event_type] = cls.hass.bus.async_listen(event_type, cls.event_listener)
+        cls.notify[event_type].add(queue)
+
+    @classmethod
+    def notify_del(cls, event_type, queue):
+        """Unregister to notify for events of given type for given queue."""
+
+        if event_type not in cls.notify or queue not in cls.notify[event_type]:
+            return
+        cls.notify[event_type].discard(queue)
+        if len(cls.notify[event_type]) == 0:
+            cls.notify_remove[event_type]()
+            _LOGGER.debug("event.notify_del(%s) -> removing event listener", event_type)
+            del cls.notify[event_type]
+            del cls.notify_remove[event_type]
+
+    @classmethod
+    async def update(cls, event_type, func_args):
+        """Deliver all notifications for an event of the given type."""
+
+        _LOGGER.debug("event.update(%s, %s)", event_type, func_args)
+        if event_type in cls.notify:
+            for queue in cls.notify[event_type]:
+                await queue.put(["event", func_args.copy()])