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"],
)

temperature = Gauge(
    "temperature_celsius", "The current temperature", labelnames=["location"]
)


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.message_callback_add("sensors/temperature/#", handle_temperature)

    client.subscribe("sensors/people_now_present")
    client.subscribe("space/status")
    client.subscribe("space/member_count")
    client.subscribe("availability/+")
    client.subscribe("availability/shutdown/+")
    client.subscribe("sensors/temperature/#")


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 handle_temperature(client, userdata, msg):
    t = msg.topic.split("/")
    location = "-".join(t[2:])
    temperature.labels(location).set(float(msg.payload))


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()