#!/usr/bin/env python

from prometheus_client import start_http_server, Gauge
from yoctopuce.yocto_api import YAPI, YRefParam
from yoctopuce.yocto_temperature import YTemperature
import sys

HTTP_PORT = 9400
INTERVAL = 5000
YOCTO_SENSOR_TEMPERATURE = Gauge(
        'yocto_sensor_temperature',
        'Yocto-Temperature sensor temperature value in Celcius'
        )

if __name__ == '__main__':
    # Setup the API to use local USB devices
    errmsg = YRefParam()
    if YAPI.RegisterHub("usb", errmsg) != YAPI.SUCCESS:
        sys.exit("Could not initialize USB: " + errmsg.value)

    # Use first YoctoTemerature sensor found.
    sensor = YTemperature.FirstTemperature()
    if sensor is None:
        sys.exit('Did not find any YoctoTemerature sensor.')
    elif sensor.isOnline():
        print("YoctoTemerature sensor is ONLINE.")
    else:
        sys.exit("I found a sensor but it seems unavailable for some reason. Exiting.")

    # Serve metrics over HTTP.
    print("Starting prometheus-yoctotemp-exporter on port",
            "{}...".format(HTTP_PORT), end='')
    start_http_server(HTTP_PORT, addr='::')
    print(" OK.")

    while sensor.isOnline():
        YOCTO_SENSOR_TEMPERATURE.set(sensor.get_currentValue())
        YAPI.Sleep(INTERVAL)

    sys.stderr.write("YoctoTemperature sensor disappeared for some reason.")

    # Cleanup.
    YAPI.FreeAPI()
    sys.exit("Cleaned up - Now exiting.")