Add support for notification streams

[robbinjanssen]

Both WD5 and WD4 have support for notification streams. Basically this is a HTTP GET call that is kept-alive and keeps receiving JSON updates about thermostats.

1. Where do we put this code, ojmicroline.py is currently responsible for data-fetching, however since both WD4 and WD5 are pretty different (1 call vs 3 calls), im not sure where to put it. @adamjernst any suggestions?
2. Then we need to figure out what HA requires for these push updates. I think we need to implement something like registration for listeners and callbacks to those listeners?

For WD5 this is a POC:

async def get_stream_connection(
    self, 
    session_id: str,
    session: ClientSession
) -> Any:
    async with async_timeout.timeout(30):
        # Negotiate
        url = URL.build(
            scheme="https", 
            host=self.host, 
            path="/ocd5notification/negotiate",
            query={"clientProtocol": "1.3"}
        )
        
        response = await session.request(method="GET", url=url, ssl=True)
        response.raise_for_status()

        data = json.loads(await response.text());
        connectionId = data['ConnectionId']
        connectionToken = data['ConnectionToken']
    
        # Start
        url = URL.build(
            scheme="https", 
            host=self.host, 
            path="/ocd5notification/send",
            query={
                "transport": "serverSentEvents",
                "connectionToken": connectionToken,
                "connectionId": connectionId,
            },
        )

        response = await session.request(
            method="POST",
            url=url, 
            headers={"Content-Type": "application/x-www-form-urlencoded"}, 
            data=f"data={session_id}",
            ssl=True
        )
        response.raise_for_status()

        # Connect to stream
        url = URL.build(
            scheme="https", 
            host=self.host, 
            path="/ocd5notification/connect",
            query={
                "transport": "serverSentEvents",
                "connectionToken": connectionToken,
                "connectionId": connectionId,
            },
        )

        response = await session.request(method="GET", url=url, headers={"Accept":"text/event-stream"}, ssl=True)
        response.raise_for_status()

        async for line in response.content:
            data = line.decode('ascii').strip()
            if (data == ""):
                continue

            data = data[6:]
            if data != 'initialized':
                data = json.loads(data)
            
            if "M" not in data:
                continue
            
            for event in data["M"]:
                print(json.dumps(event, indent=2))

[adamjernst]

Where do we put this code

I'm not sure but my first impulse is to add a method to the OJMicrolineAPI protocol, but keep most of the actual code in the respective WD5 and WG4 classes (which live in separate files). Use shared helper methods for any similar functionality.

i.e. keep ojmicroline.py pretty dumb and simple, and all the loop/keepalive management/etc in the wd5/wg4 classes, especially since the two models are so different

[adamjernst]

I think we need to implement something like registration for listeners and callbacks to those listeners?

Good question. I am not sure what the most Pythonic way to represent this is with asyncio. I guess check out some HA integrations that do similar push stuff and copy their approach?

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