Domoticz_LWRF_EnergyMon

import socket
import time
import datetime
import urllib2
import re
import json
import math
import sys

sys.stdout = open("/home/pi/energy.log", "w")

global totalWattsSoFar, lastEnergyUpdate, lastEnergyUpdateDateTime, domoticz_url, ip, userVarIdx, deviceIdx

ip = "192.168.0.99:8080"
userVarIdx = "2"
deviceIdx = "8"

# to start off with, grab the running energy total, and the last update date from domoticz
while True:
    try:
        # the virtual energy device has the running total stored as '1234 kWh'
        domoticz_url = "http://" + ip + "/json.htm?type=devices&rid=" + deviceIdx
        json_data = urllib2.urlopen(domoticz_url).read()
        json_dict = json.loads(json_data)
        totalWattsString = json_dict["result"][0]["Data"]
        print "Total Watts String: " + totalWattsString
        totalWattsSoFar = float(totalWattsString[0:len(totalWattsString) - 4]) * 1000

        # the last update date is stored in a user variable in the form of seconds since epoch
        domoticz_url = "http://" + ip + "/json.htm?type=command&param=getuservariable&idx=" + userVarIdx
        json_data = urllib2.urlopen(domoticz_url).read()
        json_dict = json.loads(json_data)
        lastEnergyUpdateString = json_dict["result"][0]["Value"]
        lastEnergyUpdate = float(lastEnergyUpdateString)
        lastEnergyUpdateDateTime = datetime.datetime.utcfromtimestamp(lastEnergyUpdate)
        print "Total Watts: " + str(totalWattsSoFar) + ", Time since last update: " + str(lastEnergyUpdateDateTime)
        break
    except:
        time.sleep(10) # in case of domoticz downtime, just wait and try again

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('0.0.0.0', 9761))
epoch = datetime.datetime.utcfromtimestamp(0)

# infinite loop
while True:
    # wait for an energy update
    data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
    #print "received message:", data
    if "todUse" in data:
        try:
            # calculate the time in seconds since the last update
            currentDateTime = datetime.datetime.now()
            elapsedTimeSinceEpoch = currentDateTime - epoch
            elapsedSecondsSinceEpoch = elapsedTimeSinceEpoch.total_seconds()
            elapsedTimeSinceLastUpdate = currentDateTime - lastEnergyUpdateDateTime
            elapsedSecondsSinceLastUpdate = elapsedTimeSinceLastUpdate.total_seconds()
            print "Seconds since last update: " + str(elapsedSecondsSinceLastUpdate)

            # extract the current usage
            json_dict = json.loads(data[2:])
            currentWatts = json_dict["cUse"]
            #currWatts = math.ceil(json_dict["cUse"] / 0.8) # test without adjustment to start off with
            #todayWatts = math.ceil(json_dict["todUse"] / 0.8) # this figure is unreliable and unsuitable for the domoticz counter anyway

            # calculate the additional watts used since last reading and add this to the total
            additionalWatts = (elapsedSecondsSinceLastUpdate / 3600 * currentWatts) if lastEnergyUpdate > 0 else 0
            totalWattsSoFar += additionalWatts

            # output the reading to the os log
            timeStamp = str(currentDateTime.hour).zfill(2) + ":" + str(currentDateTime.minute).zfill(2) + ":" + str(currentDateTime.second).zfill(2)
            print timeStamp + ", Curr Watts: " + str(currentWatts) + ", Add Watts: " + str(additionalWatts) + ", Tot Watts: " + str(totalWattsSoFar)

            # send the new readings
            domoticz_url = "http://" + ip + "/json.htm?type=command&param=udevice&idx=" + deviceIdx + "&nvalue=0&svalue="+str(currentWatts)+";"+str(totalWattsSoFar)
            urllib2.urlopen(domoticz_url)

            # update the local vars ready for next reading
            lastEnergyUpdate = elapsedSecondsSinceEpoch
            lastEnergyUpdateDateTime = datetime.datetime.utcfromtimestamp(lastEnergyUpdate)

            # update the domoticz user variable with the last update date (only used on restart of script)
            domoticz_url = "http://" + ip + "/json.htm?type=command&param=updateuservariable&idx=" + userVarIdx + "&vname=lastEnergyUpdate&vtype=1&vvalue="+str(lastEnergyUpdate)
            urllib2.urlopen(domoticz_url).read()

            time.sleep(10)
        except:
            time.sleep(10)