#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <UniversalTelegramBot.h>
#include <ArduinoJson.h>

// --- WIFI CONNECTIONS (Wokwi uses this free virtual Wi-Fi) ---
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// --- TELEGRAM SETUP ---
#define BOT_TOKEN "7886923581:AAEJiCG5BnWdZQ5pHEC8QPsjLeHJly_Swtk"  // Paste your BotFather token here
#define CHAT_ID "1213332037"      // Paste your Chat ID here

WiFiClientSecure secured_client;
UniversalTelegramBot bot(BOT_TOKEN, secured_client);

// --- HARDWARE PINS ---
const int gasSensorPin = 34; // Potentiometer acting as MQ-6
const int fanRelayPin = 25;  // Relay / LED acting as Exhaust Fan
const int buzzerPin = 26;    // Buzzer

// --- VARIABLES ---
int gasLevel = 0;
int safetyThreshold = 2000; // ESP32 analog reads from 0 to 4095
bool isAlarmActive = false; // To prevent spamming Telegram messages

void setup() {
  Serial.begin(115200);
  
  pinMode(gasSensorPin, INPUT);
  pinMode(fanRelayPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);

  // Keep fan and buzzer OFF at start
  digitalWrite(fanRelayPin, LOW);
  digitalWrite(buzzerPin, LOW);

  // Connect to Wi-Fi
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi Connected!");

  // Required for Telegram API security
  secured_client.setCACert(TELEGRAM_CERTIFICATE_ROOT);

  // Send a startup message to your phone
  bot.sendMessage(CHAT_ID, "🟢 System Online: Gas Monitoring Active.", "");
}

void loop() {
  // Read the "gas" level from the potentiometer
  gasLevel = analogRead(gasSensorPin);
  Serial.print("Gas Level: ");
  Serial.println(gasLevel);

  // IF GAS EXCEEDS THRESHOLD
  if (gasLevel > safetyThreshold) {
    digitalWrite(fanRelayPin, HIGH); // Turn ON Exhaust Fan
    tone(buzzerPin, 1000);           // Turn ON Buzzer with a 1000Hz tone
    
    // Only send the Telegram message once per leak to avoid spam
    if (!isAlarmActive) {
      Serial.println("ALARM: Sending Telegram Message!");
      bot.sendMessage(CHAT_ID, "🚨 DANGER: High Gas Leak Detected! Exhaust Fan Activated automatically.", "");
      isAlarmActive = true;
    }
  } 
  
  // IF GAS RETURNS TO NORMAL
  else {
    digitalWrite(fanRelayPin, LOW); // Turn OFF Fan
    noTone(buzzerPin);              // Turn OFF Buzzer
    
    // Send a "safe" message once the room clears
    if (isAlarmActive) {
      Serial.println("SAFE: Sending Telegram Message!");
      bot.sendMessage(CHAT_ID, "✅ SAFE: Gas cleared. Exhaust Fan turned off.", "");
      isAlarmActive = false;
    }
  }

  delay(1000); // Check every 1 second
}