#!/usr/bin/python3

import bme680
import time

################## main ###################

print("""Estimate indoor air quality

Runs the sensor for a burn-in period, then uses a
combination of relative humidity and gas resistance
to estimate indoor air quality as a percentage.

Press Ctrl+C to exit

""")

### bme680

ADDR_1 = 0x77
ADDR_2 = 0x66

try:
    #sensor = bme680.BME680(bme680.I2C_ADDR_PRIMARY)
    #print('sensor found at: ', bme680.I2C_ADDR_PRIMARY)
    sensor = bme680.BME680(ADDR_1)
    print('sensor found at: ', ADDR_1)
except IOError:
    #sensor = bme680.BME680(bme680.I2C_ADDR_SECONDARY)
    #print('sensor found at: ', bme680.I2C_ADDR_SECONDARY)
    sensor = bme680.BME680(ADDR_2)
    print('sensor found at: ', ADDR_2)

# These oversampling settings can be tweaked to
# change the balance between accuracy and noise in
# the data.

sensor.set_humidity_oversample(bme680.OS_2X)
sensor.set_pressure_oversample(bme680.OS_4X)
sensor.set_temperature_oversample(bme680.OS_8X)
sensor.set_filter(bme680.FILTER_SIZE_3)
sensor.set_gas_status(bme680.ENABLE_GAS_MEAS)

sensor.set_gas_heater_temperature(320)
sensor.set_gas_heater_duration(150)
sensor.select_gas_heater_profile(0)

# start_time and curr_time ensure that the
# burn_in_time (in seconds) is kept track of.

start_time = time.time()
curr_time = time.time()
burn_in_time = 1  # burn_in_time (in seconds) is kept track of.

burn_in_data = []

try:
    # Collect gas resistance burn-in values, then use the average
    # of the last 50 values to set the upper limit for calculating
    # gas_baseline.
    print("Collecting gas resistance burn-in data for 5 mins\n")
    while curr_time - start_time < burn_in_time:
        curr_time = time.time()
        if sensor.get_sensor_data() and sensor.data.heat_stable:
            gas = sensor.data.gas_resistance
            burn_in_data.append(gas)
            print("Gas: {0} Ohms".format(gas))
            time.sleep(1)

    gas_baseline = sum(burn_in_data[-50:]) / 50.0

    # Set the humidity baseline to 40%, an optimal indoor humidity.
    hum_baseline = 40.0

    # This sets the balance between humidity and gas reading in the
    # calculation of air_quality_score (25:75, humidity:gas)
    hum_weighting = 0.25

    print("Gas baseline: {0} Ohms, humidity baseline: {1:.2f} %RH\n".format(gas_baseline, hum_baseline))

    while True:
        if sensor.get_sensor_data() and sensor.data.heat_stable:
            gas = sensor.data.gas_resistance
            gas_offset = gas_baseline - gas

            hum = sensor.data.humidity
            hum_offset = hum - hum_baseline

            tCels = sensor.data.temperature
            print('temp {}'.format(tCels))

            # Calculate hum_score as the distance from the hum_baseline.
            if hum_offset > 0:
                hum_score = (100 - hum_baseline - hum_offset) / (100 - hum_baseline) * (hum_weighting * 100)

            else:
                hum_score = (hum_baseline + hum_offset) / hum_baseline * (hum_weighting * 100)

            # Calculate gas_score as the distance from the gas_baseline.
            if gas_offset > 0:
                gas_score = (gas / gas_baseline) * (100 - (hum_weighting * 100))

            else:
                gas_score = 100 - (hum_weighting * 100)

            # Calculate air_quality_score.
            air_quality_score = hum_score + gas_score

            humidity = str(round(hum, 2))
            temperature = str(round(tCels, 2))
            pressure = str(round(sensor.data.pressure, 2))
            air_qual = str(round(air_quality_score, 2))

            print("Gas: {0:.2f} Ohms, t: {0:.2f}, humidity: {1:.2f} %RH,air quality: {2:.2f}".format(gas, tCels, hum, air_quality_score))

except KeyboardInterrupt:
    pass