#! /usr/bin/env python3
import asyncio
import uuid
import aioserial
import aiomqtt
import pyubx2

BAUD = 115200


class SerialMQTTHandler:
    def __init__(
        self,
        handler_id: str,
        serial_port: str,
        mqtt_host: str = "127.0.0.1",
        mqtt_port: int = 1883,
    ):
        self.handler_id = handler_id
        self.serial_port = serial_port
        self.mqtt_host = mqtt_host
        self.mqtt_port = mqtt_port

        # Serial
        self.ser = aioserial.AioSerial(
            port=serial_port,
            baudrate=BAUD,
            timeout=0.05,  # 50 ms
        )

        # MQTT client
        self.client_id = f"{handler_id}-{uuid.uuid4()}"
        self.mqtt_client = aiomqtt.Client(
            mqtt_host, port=mqtt_port, identifier=self.client_id
        )

        # Topic base
        self.topic_base = f"asset/{handler_id}"

    async def parse_serial(self):
        buffer = bytearray()

        class StreamWrapper:
            def read(inner_self, n=1):
                if not buffer:
                    raise BlockingIOError
                out = buffer[:n]
                del buffer[:n]
                return bytes(out)

        ubr = pyubx2.UBXReader(StreamWrapper(), parsing=True)

        while True:
            chunk = await self.ser.read_async(200)
            if chunk:
                buffer.extend(chunk)

                try:
                    while True:
                        raw, parsed = ubr.read()
                        if raw is None:
                            break
                        yield raw, parsed
                except (pyubx2.UBXStreamError, BlockingIOError, Exception):
                    pass
            else:
                await asyncio.sleep(0)

    async def serial_reader_task(self):
        async for raw, parsed in self.parse_serial():
            if isinstance(parsed, pyubx2.UBXMessage):
                for name, value in vars(parsed).items():
                    if name.startswith("_"):
                        continue
                    topic = f"{self.topic_base}/{parsed.identity}/{name}"
                    await self.mqtt_client.publish(topic, value, qos=1, retain=True)
            else:
                print(parsed)

            await self.mqtt_client.publish(f"{self.topic_base}/raw", raw)
            await self.mqtt_client.publish(f"{self.topic_base}/parsed", str(parsed))

    async def mqtt_command_writer_task(self):
        command_topic = f"{self.topic_base}/command"
        async for message in self.mqtt_client.messages:
            topic = str(message.topic)
            if topic == command_topic:
                await self.ser.write_async(message.payload)

    async def run(self):
        command_topic = f"{self.topic_base}/command"
        interval = 5

        while True:
            try:
                async with self.mqtt_client as client:
                    await client.subscribe(command_topic)

                    await asyncio.gather(
                        self.serial_reader_task(),
                        self.mqtt_command_writer_task(),
                    )

            except aiomqtt.MqttError as e:
                print(
                    f"[{self.handler_id}] MQTT connection error: {e}. Reconnecting in {interval}s..."
                )
                await asyncio.sleep(interval)


if __name__ == "__main__":

    async def main():
        handler = SerialMQTTHandler("example-gps", "/tmp/ttyV0")
        await handler.run()

    asyncio.run(main())