#!/usr/bin/python3
#
# Listener to map MQTT channels into InfluxDB
#
# This MQTT client runs in the foreground, listening to the broker,
# then inserting the values into the InfluxDB. Should a failure occur,
# systemd will simply restart the script.
#

import os.path
import asyncio
import signal
import configparser
import importlib.util

import gmqtt

# Import our utilities.
_pathname = os.path.join(os.path.dirname(__file__), '../lib/util.py')
_spec = importlib.util.spec_from_file_location('util', _pathname)
util = importlib.util.module_from_spec(_spec)
_spec.loader.exec_module(util)

CONFIG_FNAME = '/etc/homesvr/bridge.conf'
SECTION_NAME = 'listener'


def parse_aqua_data(idb, payload):
    # format is: TEMP,HUMIDITY,DEWPOINT,CHIPID,KEY
    t, h, d, _, _ = payload.decode('utf-8').split(',')
    #print('T:%s, H:%s, D:%s' % (t, h, d))
    
    body = [{
              ### NOTE: 'sample' is local config-specific
              'measurement': 'sample',
              #'tags': { },
              'fields': {
                  'tempF': float(t),
                  'humidity': float(h),
                  'dewF': float(d),
                  }
              }]

    result = idb.write_points(body)
    #print('WROTE; result=', result)


### NOTE: this is specific to gstein's sensor data.
### TODO?? somehow make this stuff reasonably configurable
PARSERS = {  # TOPIC: PARSER_FUNC
    'aqua/data': parse_aqua_data,
    }


class Bridge(object):
    def __init__(self, idb):
        self.idb = idb

    def on_connect(self, client, flags, rc, properties):
        #print('Connected')

        subs = set()
        for k in PARSERS.keys():
            s, _ = k.rsplit('/', maxsplit=1)
            subs.add(s + '/#')

        for s in subs:
            #print('Subscribing to:', s)
            client.subscribe(s, qos=0)

    def on_message(self, client, topic, payload, qos, properties):
        f = PARSERS.get(topic)
        if f:
            f(self.idb, payload)
        else:
            print('UNKNOWN:', topic, payload)


def main():
    cfg = configparser.ConfigParser()
    cfg.read(CONFIG_FNAME)

    sect = cfg[SECTION_NAME]
    idb = util.prepare_influxdb(sect['influx'],
                                sect['i_user'], sect['i_pwd'],
                                sect['database'])

    client = gmqtt.Client(sect['client_name'])

    b = Bridge(idb)
    client.on_connect = b.on_connect
    client.on_message = b.on_message

    loop = asyncio.get_event_loop()
    loop.add_signal_handler(signal.SIGINT, loop.stop)
    loop.add_signal_handler(signal.SIGTERM, loop.stop)

    ### we know mosquitto is just v3.1.1
    loop.create_task(client.connect(sect['mqtt'],
                                    version=gmqtt.mqtt.constants.MQTTv311))

    loop.run_forever()

    # Graceful close.
    util.shutdown_mqtt(loop, client)
    loop.close()


if __name__ == '__main__':
    main()