main.py

#####################################################################
# Script to get data from a P1 meter and push it to a database      #
# Built for HomeWizard WiFi P1 Meter                                #
#####################################################################
import os
import psycopg2
import urllib.request
from urllib.error import HTTPError
import json
import datetime
from datetime import timezone
import math
from decimal import Decimal

meterHost = os.environ.get("METER_HOST")
postgresHost = os.environ.get("POSTGRES_HOST")
postgresUser = os.environ.get("POSTGRES_USER")
postgresPass = os.environ.get("POSTGRES_PASS")
postgresName = os.environ.get("POSTGRES_NAME")

print("---- P1 Meter Reader ----")
print("Meter: {}".format(meterHost))
print("Database: {}@{}".format(postgresName, postgresHost))
print("User: {}".format(postgresUser))
print("-------------------------")

postgres = psycopg2.connect(
    host=postgresHost,
    user=postgresUser,
    password=postgresPass,
    database=postgresName
)

def getUtcTimestamp():
    dt = datetime.datetime.now(timezone.utc)
    utcTime = dt.replace(tzinfo=timezone.utc)
    return str(math.trunc(utcTime.timestamp()))

## Reads information from the API, returns an object with the information we need
def getMeterReading():
    print("> Getting readings...")

    response = None

    try:
        response = urllib.request.urlopen("http://{}/api/v1/data".format(meterHost))
    except HTTPError as e:
        print("! HTTP error: {}".format(e))
        exit(1)

    return json.loads(response.read())

def updateMetaData(meterReading):
    print("> Updating metadata...")

    cursor = postgres.cursor()
    cursor.execute(
        "update p1_meta SET meter_id=%s, meter_name=%s, wifi_ssid=%s, wifi_strength=%s, current_tariff=%s",
        (
            meterReading["unique_id"],
            meterReading["meter_model"],
            meterReading["wifi_ssid"],
            meterReading["wifi_strength"],
            meterReading["active_tariff"],
        )
    )

    postgres.commit()
    cursor.close()

def getActiveTariffs():
    cursor = postgres.cursor()
    cursor.execute("SELECT * FROM p1_tariff WHERE utc_active < {} ORDER BY utc_active DESC LIMIT 1".format(getUtcTimestamp()))

    result = cursor.fetchone()

    cursor.close()
    return result

def getLastEnergyReading():
    cursor = postgres.cursor()
    cursor.execute("SELECT * FROM p1_energy ORDER BY time_utc DESC LIMIT 1")

    result = cursor.fetchone()

    cursor.close()
    return result

def createEnergyReading(meterReading):
    print("> Processing energy reading...")

    lastReading = getLastEnergyReading()
    tariffClass = Decimal(meterReading["active_tariff"])
    totalKwh = Decimal(meterReading["total_power_import_kwh"])
    totalKwhTc1 = Decimal(meterReading["total_power_import_t1_kwh"])
    totalKwhTc2 = Decimal(meterReading["total_power_import_t2_kwh"])

    lastKwh = 0 if lastReading is None else lastReading[2]
    lastKwhTc1 = 0 if lastReading is None else lastReading[3]
    lastKwhTc2 = 0 if lastReading is None else lastReading[4]

    deltaKwh = totalKwh - lastKwh
    deltaKwhTc1 = totalKwhTc1 - lastKwhTc1
    deltaKwhTc2 = totalKwhTc2 - lastKwhTc2

    activeTariffs = getActiveTariffs()

    priceTotalTc1 = deltaKwhTc1 * activeTariffs[0]
    priceTotalTc2 = deltaKwhTc2 * activeTariffs[1]
    priceTotal = priceTotalTc1 + priceTotalTc2

    utcTs = getUtcTimestamp()

    activeWatt = Decimal(meterReading["active_power_w"])
    activeAmp = Decimal(meterReading["active_current_a"])

    cursor = postgres.cursor()
    cursor.execute(
        "INSERT INTO p1_energy "
        "(tariff_class, total_kwh, total_kwh_tc1, total_kwh_tc2, delta_kwh, delta_kwh_tc1, delta_kwh_tc2, price_total, price_total_tc1, price_total_tc2, time_utc, active_watt, active_amp)"
        "VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)",
        (tariffClass, totalKwh, totalKwhTc1, totalKwhTc2, deltaKwh, deltaKwhTc1, deltaKwhTc2, priceTotal, priceTotalTc1, priceTotalTc2, utcTs, activeWatt, activeAmp)
    )

    postgres.commit()
    cursor.close()

def getLastGasReading():
    cursor = postgres.cursor()
    cursor.execute("SELECT * FROM p1_gas ORDER BY time_utc DESC LIMIT 1")

    result = cursor.fetchone()

    cursor.close()
    return result

def createGasReading(meterReading):
    print("> Processing gas reading...")

    lastReading = getLastGasReading()

    lastM3 = 0 if lastReading is None else lastReading[1]

    totalM3 = Decimal(meterReading["total_gas_m3"])
    deltaM3 = totalM3 - lastM3

    activeTariffs = getActiveTariffs()

    priceTotal = deltaM3 * activeTariffs[2]

    utcTs = getUtcTimestamp()

    cursor = postgres.cursor()
    cursor.execute(
        "INSERT INTO p1_gas "
        "(total_m3, delta_m3, price_total, time_utc)"
        "VALUES (%s, %s, %s, %s)",
        (totalM3, deltaM3, priceTotal, utcTs)
    )

    postgres.commit()
    cursor.close()

meterReadings = getMeterReading()
updateMetaData(meterReadings)
createEnergyReading(meterReadings)
createGasReading(meterReadings)