import json
import time

import paho.mqtt.client as mqtt

from prometheus_client import start_http_server, Gauge

CONFIG = json.load(open('/etc/mqtt2prometheus.json', mode='r', encoding='utf-8'))

people_now_present = Gauge('people_now_present', 'People currently present in the space')

space_state = Gauge('space_state', 'The current space state')
space_lastchange = Gauge('space_lastchange', 'The lastchange timestamp of the current space state')

member_count = Gauge('member_count', 'The current count of members', labelnames=['name'])

availability = Gauge('availability', 'The availability status of different MQTT clients', labelnames=['clientname'])


def on_connect(client, userdata, flags, rc):
    client.publish('availability/mqtt2prometheus', 'online', 2, True)

    client.message_callback_add('sensors/people_now_present', handle_people_now_present)
    client.message_callback_add('space/status', handle_space_status)
    client.message_callback_add('space/member_count', handle_member_count)
    client.message_callback_add('availability/#', handle_availability)

    client.subscribe('sensors/people_now_present')
    client.subscribe('space/status')
    client.subscribe('space/member_count')
    client.subscribe('availability/+')
    client.subscribe('availability/shutdown/+')


def handle_people_now_present(client, userdata, msg):
    people_now_present.set(json.loads(msg.payload))


def handle_space_status(client, userdata, msg):
    state = json.loads(msg.payload)
    space_state.set(int(state['open']))
    space_lastchange.set(state['lastchange'])


def handle_member_count(client, userdata, msg):
    count = json.loads(msg.payload)
    member_count.labels(count['name']).set(count['value'])


def handle_availability(client, userdata, msg):
    t = msg.topic.split('/')
    if len(t) == 2:
        c = t[-1]
    else:
        c = '_'.join(t[1:])
    v = 1 if msg.payload == b'online' else 0
    availability.labels(c).set(v)


def main():

    client = mqtt.Client('mqtt2prometheus')
    client.on_connect = on_connect
    client.username_pw_set(CONFIG['mqtt']['username'], CONFIG['mqtt']['password'])
    client.will_set('availability/mqtt2prometheus', 'offline', 2, True)

    client.connect(CONFIG['mqtt']['host'])
    client.loop_start()
    start_http_server(CONFIG['prometheus']['port'])
    while True:
        time.sleep(1)


if __name__ == '__main__':
    main()