#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include  <Adafruit_SSD1306.h>
#include <Fonts/FreeSansBoldOblique9pt7b.h>
#include  <DHT.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define  SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET     -1  // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH,  SCREEN_HEIGHT, &Wire, OLED_RESET);

#define sensor    A0 
#define DHTPIN  2          // Digital pin 2
#define DHTTYPE DHT22     // DHT 22*/

#define buzzer 9 //buzzer to arduino pin 9

#define red_pin 6
#define blue_pin 8
#define green_pin 7

int gasLevel  = 0;         //int variable for gas level
String quality =""; 

DHT dht(DHTPIN,  DHTTYPE);

void sendSensor()
{
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  if (isnan(h) || isnan(t)) {
  Serial.println("Failed  to read from DHT sensor!");
    return;
  }
  display.setTextColor(WHITE);
  display.setTextSize(1);
  display.setFont();

  display.setCursor(1,55);
  display.print("  ");
  display.print(t);
  display.print(" C   ");
  display.print(h);
  display.print("%   ");
}

void air_sensor()
{
  gasLevel = analogRead(sensor);
  Serial.println(gasLevel);
  if(gasLevel<181){
    quality = "  GOOD!";
    digitalWrite(red_pin, LOW);
    digitalWrite(green_pin, HIGH);
    digitalWrite(blue_pin, LOW);

  }
  else if (gasLevel >181 && gasLevel<225){
    digitalWrite(red_pin, HIGH);
    digitalWrite(green_pin, HIGH);
    digitalWrite(blue_pin, LOW);
    quality =  "  Poor!";
  }
  else if (gasLevel >225 && gasLevel<340){
    digitalWrite(red_pin, HIGH);
    digitalWrite(green_pin, HIGH);
    digitalWrite(blue_pin, LOW);
    quality  = "Very bad!";
  }
    else if (gasLevel > 340){
    quality  = "  Toxic";
    tone(buzzer, 1000); // Send 1KHz sound signal...
    delay(500);        // ...for 1 sec
    noTone(buzzer);     // Stop sound...
    delay(500);

    digitalWrite(red_pin, HIGH);
    digitalWrite(green_pin, LOW);
    digitalWrite(blue_pin, LOW);
  }
  
  display.setTextColor(WHITE);
  display.setTextSize(1);  
  display.setCursor(2,5);
  display.setFont();
  display.print(" Air Quality:");
  display.setTextSize(1);
  display.setCursor(20,26);
  //display.setFont(&FreeSansBoldOblique9pt7b);
  display.print(quality);
}

void setup() {
  Serial.begin(9600);
  pinMode(sensor,INPUT);
  pinMode(buzzer, OUTPUT);

  pinMode(red_pin, OUTPUT);
  pinMode(blue_pin, OUTPUT);
  pinMode(green_pin, OUTPUT);
  dht.begin();
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3c)) { // Address  0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
}
  display.clearDisplay();
}

void loop() {
display.clearDisplay();
air_sensor();
//sendSensor();
display.setFont();
display.setTextColor(WHITE);
  display.setTextSize(1);  
  display.setCursor(1,45);
  display.setFont();
  display.print("   Temp:    Rel. H:   ");
  sendSensor();
display.display();
delay(100); 
}