#include <LiquidCrystal.h>

const byte pinRS = 8;
const byte pinE = 9;
const byte pinDB4 = 10;
const byte pinDB5 = 11;
const byte pinDB6 = 12;
const byte pinDB7 = 13;

const byte pinBttMode = 4;
const byte pinLedGreen = 6;
const byte pinLedRed = 7;

const byte pinGasSensor = 2;
const byte pinTempSensor = 1;
const byte pinLightSensor = 0;

LiquidCrystal lcd(pinRS, pinE, pinDB4, pinDB5, pinDB6, pinDB7);

float stepADC = 0.0048828125;
int gas = 0;
float temp = 0;
int light = 0;
int bttMode = 0;

int gasLimit = 750;
int tempHigh = 40;
int tempLow = 10;
int lightLimit = 350;

void setup()
{
  lcd.begin(16, 2);
  Serial.begin(9600);

  pinMode(pinLedGreen, OUTPUT);
  pinMode(pinLedRed, OUTPUT);
  pinMode(pinBttMode, INPUT);
}

void loop()
{
  light = analogRead(pinLightSensor);
  temp = (analogRead(pinTempSensor) * stepADC - 0.5) * 100;
  gas = analogRead(pinGasSensor);

  if ((light > lightLimit) && (temp > tempLow) && (temp < tempHigh) && (gas < gasLimit))
  {
    digitalWrite(pinLedGreen, HIGH);
    digitalWrite(pinLedRed, LOW);
  }
  else
  {
    digitalWrite(pinLedGreen, LOW);
    digitalWrite(pinLedRed, HIGH);
  }

  if (digitalRead(pinBttMode) == HIGH)
  {
    bttMode++;
    delay(200);
    if (bttMode > 2) bttMode = 0;
  }

  lcd.clear();
  switch (bttMode)
  {
    case 0:
      lcd.print("Light level: ");
      lcd.setCursor(2, 1);
      lcd.print(light);
      break;
    case 1:
      lcd.print("Temp level: ");
      lcd.setCursor(2, 1);
      lcd.print(temp);
      break;
    case 2:
      lcd.print("Gas level: ");
      lcd.setCursor(2, 1);
      lcd.print(gas);
      break;
  }

  Serial.print(gas); Serial.print(" ");
  Serial.print(temp); Serial.print(" ");
  Serial.print(light); Serial.println("");

  delay(500);
}