####
# Rules to calculate outside light lux.
# Rules are taken from Domoticz LUA script at https://www.domoticz.com/wiki/Real-time_solar_data_without_any_hardware_sensor_:_azimuth,_Altitude,_Lux_sensor...
# Authors: S bastien Joly, Neutrino, Jmleglise
#
# Adapted to openHab rule by mherwege
# Adapted further to work with astro and synop bindings by William
# Adapted to jython by William
#
# For this script to work you need astro and synop. See the "Config section"
####

from org.slf4j import LoggerFactory
from core.triggers import when
from core.rules import rule
from datetime import date
from datetime import datetime
import math
from decimal import Decimal

## Config section
config_debugSolar=True
config_useArbitraryTwilight=True
config_SunElevation="LocalSun_Position_Elevation"
config_SunTotalRadiation="LocalSun_Radiation_TotalRadiation"
config_SynopOcta="SynopMessage_Octa"
config_LuxItem="Lux"
config_WeightedLuxItem="WeightedLux"
##

@rule("CurrentVirtualLux", description="VirtualLux calculator", tags=["Example", "virtualLux"])
@when("Item "+config_SunElevation+" received update")
@when("Item "+config_SunTotalRadiation+" received update")
@when("Item "+config_SynopOcta+" received update")
def CurrentVirtualLux(event):
    if config_debugSolar: CurrentVirtualLux.log.info("%s received update" % event.itemName)

# Fetch data from configured OH items
    try: #Octa is sometimes not updated correctly, let's try to handle it and print a warning
        data_octa=unicode(ir.getItem(config_SynopOcta).getState())
    except Exception as e:
        CurrentVirtualLux.log.warning("Error fetching Octa from OH, using 0 as Octa. error: %s" % e)
        data_octa=0
        pass
    data_SunElev=unicode(ir.getItem(config_SunElevation).getState())
    data_SunRadTotal=unicode(ir.getItem(config_SunTotalRadiation).getState())

    if config_debugSolar: CurrentVirtualLux.log.info("synop cloudcoverage: %s SunElev: %s SunRadTotal: %s" % (data_octa, data_SunElev, data_SunRadTotal) )

# mangle data to help python make it Decimal() (split on space to remove the extra data from str eg. centigrade charecter and hPa)
    decimal_data_SunElev=Decimal(data_SunElev.split()[0])
    decimal_data_SunRadTotal=Decimal(data_SunRadTotal.split()[0])
    decimal_data_octa=Decimal(data_octa.split()[0])
    if config_debugSolar: CurrentVirtualLux.log.info("synop cloudcoverage: %s SunElev: %s SunRadTotal: %s" % (decimal_data_octa, decimal_data_SunElev, decimal_data_SunRadTotal) )

# Calculate cloud coverage from octa
    float_cloudCoverage = float(1 - 0.75 * math.pow(float(decimal_data_octa)/8.0, 3.4))
    if config_debugSolar: CurrentVirtualLux.log.info("cloudcoverage value: %s" % (float_cloudCoverage))

# Arbitrary twilight calculations (below 3 degrees calculations astro reports 0.0 for SunRadTotalArbitrary).
# W/m^2 equal 800 Lux     (the theoretical value is 4.74 but more accurate result with 6.32...)
# In my situation I need the Lux to go all the way down to 0 (some automatic lights)
    arbitraryTwilightLux = 6.32
    decimal_data_SunRadTotalArbitrary=Decimal(arbitraryTwilightLux - (1.0 - float(decimal_data_SunElev))/8.0 * arbitraryTwilightLux)

    if config_useArbitraryTwilight and decimal_data_SunRadTotal < 1.0:
        decimal_data_SunRadTotal=decimal_data_SunRadTotalArbitrary
    if config_debugSolar: CurrentVirtualLux.log.info("decimal_data_SunRadTotalArbitrary: %s" % (decimal_data_SunRadTotalArbitrary))

# Radiation in Lux. 1 Lux = 0.0079 W/m   *
    decimal_vLux = float(decimal_data_SunRadTotal) / 0.0079
    decimal_vLuxArbitrary=Decimal(decimal_data_SunRadTotalArbitrary / Decimal(0.0079))

# radiation of the Sun with the cloud layer
    decimal_vWeightedLux = float(decimal_vLux * float_cloudCoverage)
    decimal_vWeightedLuxArbitrary=Decimal(decimal_vLuxArbitrary * Decimal(float_cloudCoverage))

# If values are negative set them to 0
    if decimal_vLux < 0.0: decimal_vLux=0
    if decimal_vWeightedLux < 0.0: decimal_vWeightedLux=0
    if decimal_vLuxArbitrary < 0.0: decimal_vLuxArbitrary=0
    if decimal_vWeightedLuxArbitrary < 0.0: decimal_vWeightedLuxArbitrary=0

# print values to log, we did some stuff
    CurrentVirtualLux.log.info("Lux: %s WeightedLux: %s" % (decimal_vLux, decimal_vWeightedLux))
    if config_debugSolar: CurrentVirtualLux.log.info("ArbitraryTwilight:%s Lux: %s WeightedLux: %s" % (config_useArbitraryTwilight, decimal_vLuxArbitrary, decimal_vWeightedLuxArbitrary))

# postUpdate OH items (use arbitrary twilight calculations if it is enabled)
    events.postUpdate(ir.getItem(config_LuxItem), float(decimal_vLux))
    events.postUpdate(ir.getItem(config_WeightedLuxItem), float(decimal_vWeightedLux))