#!/usr/bin/python
import smbus
import time

# Define some constants from the datasheet
DEVICE = 0x23  # Default device I2C address
POWER_DOWN = 0x00  # No active state
POWER_ON = 0x01  # Power on
RESET = 0x07  # Reset data register value

# Start measurement at 4lx resolution. Time typically 16ms.
CONTINUOUS_LOW_RES_MODE = 0x13
# Start measurement at 1lx resolution. Time typically 120ms
CONTINUOUS_HIGH_RES_MODE_1 = 0x10
# Start measurement at 0.5lx resolution. Time typically 120ms
CONTINUOUS_HIGH_RES_MODE_2 = 0x11
# Start measurement at 1lx resolution. Time typically 120ms
# Device is automatically set to Power Down after measurement.
ONE_TIME_HIGH_RES_MODE_1 = 0x20
# Start measurement at 0.5lx resolution. Time typically 120ms
# Device is automatically set to Power Down after measurement.
ONE_TIME_HIGH_RES_MODE_2 = 0x21
# Start measurement at 1lx resolution. Time typically 120ms
# Device is automatically set to Power Down after measurement.
ONE_TIME_LOW_RES_MODE = 0x23

# bus = smbus.SMBus(0) # Rev 1 Pi uses 0
bus = smbus.SMBus(1)  # Rev 2 Pi uses 1


def convertToNumber(data):
    # Simple function to convert 2 bytes of data
    # into a decimal number
    return ((data[1] + (256 * data[0])) / 1.2)


def readLight(addr=DEVICE):
    data = bus.read_i2c_block_data(addr, ONE_TIME_HIGH_RES_MODE_1)
    return convertToNumber(data)


def main():

    # while True:
    print("%.2f" % readLight())
    # time.sleep(1)


if __name__ == "__main__":
    main()
