#include <WiFi.h>
#include <ThingSpeak.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h>
#include <DHT.h>

// ThingSpeak settings
long myChannelNumber = 2658258;
const char *myWriteAPIKey = "3LMZX4SBTK8U87NP";
char ssid[] = "Wokwi-GUEST";
char pass[] = "";
WiFiClient client;

// Pin definitions
#define DHTPIN 15      // Pin for DHT22
#define DHTTYPE DHT22  // DHT 22 (AM2302)
DHT dht(DHTPIN, DHTTYPE);

#define POT_PIN 34     // Pin for potentiometer (simulated gas sensor)
#define LED_PIN 2      // Pin for LED
#define BUZZER_PIN 5   // Pin for buzzer

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

// Thresholds
float gasThreshold = 300.0;      // Gas threshold in ppm
float temperatureThreshold = 50.0; // Temperature threshold in °C

int statusCode;

void setup() {
  // Initialize serial communication
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  ThingSpeak.begin(client);

  // Initialize DHT22
  dht.begin();

  // Initialize OLED display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("OLED allocation failed"));
    while (true);
  }
  display.clearDisplay();

  // Set up the LED and Buzzer pins
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(POT_PIN, INPUT);

  Serial.println("System started");
}

void loop() {
  // WiFi connection handling
  if (WiFi.status() != WL_CONNECTED) {
    Serial.print("Attempting to connect");
    while (WiFi.status() != WL_CONNECTED) {
      WiFi.begin(ssid, pass);
      Serial.print(".");
      delay(5000);
    }
    Serial.println("\nConnected");
  }

  // Read temperature and humidity from DHT22
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  // Check if readings are valid
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Read potentiometer value to simulate gas levels (0-4095 mapped to 0-1000 ppm)
  int gasValue = analogRead(POT_PIN);
  float gasPPM = map(gasValue, 0, 4095, 0, 1000); // Simulated gas sensor range

  // Display readings on OLED
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  display.println("CBRN Defense System");
  display.print("Temp: "); display.print(temperature); display.println(" C");
  display.print("Humidity: "); display.print(humidity); display.println(" %");
  display.print("Gas: "); display.print(gasPPM); display.println(" ppm");
  display.display();

  // Check for dangerous conditions
  if (gasPPM > gasThreshold || temperature > temperatureThreshold) {
    // Danger detected
    digitalWrite(LED_PIN, HIGH);   // Turn on LED
    tone(BUZZER_PIN, 1000);        // Activate buzzer
    Serial.println("Danger! Gas or Temp alert!");
  } else {
    // Safe conditions
    digitalWrite(LED_PIN, LOW);    // Turn off LED
    noTone(BUZZER_PIN);            // Deactivate buzzer
  }

  // Send data to ThingSpeak
  ThingSpeak.setField(1, temperature);
  ThingSpeak.setField(2, humidity);
  ThingSpeak.setField(3, gasPPM);
  statusCode = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

  if (statusCode == 200) { // Successful writing code
    Serial.println("Channel update successful.");
  } else {
    Serial.println("Problem writing data. HTTP error code: " + String(statusCode));
  }

  delay(2000); // Delay before next reading
}