#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DHT.h>

// --- CONFIGURATION ---
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// Pin Definitions
#define DHTPIN 15     
#define DHTTYPE DHT22   
#define RELAY_PIN 4
#define DUST_POT_PIN 34  // Simulating PMS5003
#define GAS_POT_PIN 35   // Simulating MQ-135

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  
  // Initialize Pins
  pinMode(RELAY_PIN, OUTPUT);
  // ESP32 Analog pins are input by default
  
  dht.begin();

  // Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  
  // Show Boot Screen
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(25, 20);
  display.println("AirGuard Pro");
  display.setCursor(30, 35);
  display.println("Initializing...");
  display.display();
  delay(2000);
}

void loop() {
  // --- 1. READ SENSORS ---
  // ESP32 ADC is 12-bit (0-4095)
  int dustRaw = analogRead(DUST_POT_PIN);
  int gasRaw = analogRead(GAS_POT_PIN);
  
  // Map raw voltage to realistic sensor values
  // Dust: 0 to 500 ug/m3
  int dustValue = map(dustRaw, 0, 4095, 0, 500); 
  // Gas: 0 to 1000 PPM
  int gasValue = map(gasRaw, 0, 4095, 0, 1000);  
  
  float t = dht.readTemperature();
  float h = dht.readHumidity();

  // --- 2. LOGIC CONTROL ---
  // Thresholds: Dust > 50 OR Gas > 400
  bool isUnsafe = (dustValue > 50 || gasValue > 400);

  if (isUnsafe) {
    digitalWrite(RELAY_PIN, HIGH); // Turn Relay ON
  } else {
    digitalWrite(RELAY_PIN, LOW);  // Turn Relay OFF
  }

  // --- 3. DISPLAY OUTPUT ---
  display.clearDisplay();
  
  // Header
  display.setCursor(0,0);
  if(isUnsafe) display.print("STATUS: ALERT!");
  else display.print("STATUS: NORMAL");

  // Data
  display.setCursor(0, 15);
  display.print("PM2.5: "); display.print(dustValue); display.print(" ug");
  
  display.setCursor(0, 25);
  display.print("Gas:   "); display.print(gasValue); display.print(" PPM");
  
  display.setCursor(0, 35);
  display.print("Temp:  "); display.print(t, 1); display.print(" C");
  
  // Fan Status at bottom
  display.setCursor(0, 52);
  display.print("FAN: ");
  if(digitalRead(RELAY_PIN)) display.print("ON [Active]");
  else display.print("OFF");
  
  display.display();
  delay(500); // Refresh rate
}