#include <Arduino.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "DHT_Async.h"

#define DHT_SENSOR_TYPE DHT_TYPE_22
static const int DHT_SENSOR_PIN = 13;
DHT_Async dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE);

const uint8_t cols = 16;
const uint8_t rows = 2;
LiquidCrystal_I2C lcd0(0x27, cols, rows);
LiquidCrystal_I2C lcd1(0x28, cols, rows);

const uint8_t lightPin = 2;
const float GAMMA = 0.7;
const float RL10 = 50;

/*
 * Initialize the serial port.
 */
void setup() {
  Wire.begin();
  Serial.begin(115200);

  lcd0.begin(cols, rows);
  lcd0.backlight();

  lcd1.begin(cols, rows);
  lcd1.backlight();

  pinMode(lightPin, INPUT);
}


/*
 * Poll for a measurement, keeping the state machine alive.  Returns
 * true if a measurement is available.
 */
static bool measure_environment(float *temperature, float *humidity) {
  static unsigned long measurement_timestamp = millis();

  /* Measure once every four seconds. */
  if (millis() - measurement_timestamp > 1000ul) {
    if (dht_sensor.measure(temperature, humidity)) {
      measurement_timestamp = millis();
      return (true);
    }
  }

  return (false);
}


/*
 * Main program loop.
 */
void loop() {
  int analogValue = analogRead(lightPin);
  float voltage = analogValue / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  lcd1.setCursor(0, 0);
  lcd1.print(voltage, 1);
  lcd1.print("V");
  lcd1.setCursor(0,1);
  lcd1.print(lux);
  lcd1.print(" lux");


  float temperature;
  float humidity;

  /* Measure temperature and humidity.  If the functions returns
     true, then a measurement is available. */
  if (measure_environment(&temperature, &humidity)) {
    Serial.print("T = ");
    Serial.print(temperature, 1);
    Serial.print(" deg. C, H = ");
    Serial.print(humidity, 1);
    Serial.println("%");
  
    // print message
    lcd0.setCursor(0, 0);
    lcd0.print(temperature, 1);
    lcd0.print(" deg. C");
    lcd0.setCursor(0,1);
    lcd0.print(humidity, 1);
    lcd0.print("%");
  }

  delay(2000); 
  lcd1.clear();

}