#include <WiFi.h>
#include <HTTPClient.h>
#include <DHT.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <LiquidCrystal_I2C.h>
#include <PubSubClient.h> 

// ---------------- PIN DEFINITIONS ----------------
#define DHTPIN 4          
#define DHTTYPE DHT22
#define GAS_PIN 34
#define BUZZER 19
#define RELAY 15          
#define LED_RED 18
#define LED_YELLOW 5
#define LED_GREEN 23
#define BUTTON_PIN 13

// ---------------- THRESHOLDS ----------------
const int GAS_SAFE_MAX     = 1500;
const int GAS_WARNING_MAX  = 2500;
const float TEMP_WARNING   = 35.0;
const float TEMP_UNSAFE    = 50.0;
const float HUM_WARNING    = 70.0;
const float HUM_UNSAFE     = 85.0;

// ---------------- WIFI ----------------
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// ---------------- FIREBASE & TELEGRAM ----------------
const char* firebaseURL = "https://smart-air-quality-system-97e90-default-rtdb.firebaseio.com/device_1.json";
const char* BOT_TOKEN = "8342604590:AAHd8syzDi7qS-PTyd8LTp120-nhcHYKg6k";
const char* CHAT_ID   = "1761625405";

// ---------------- THINGSBOARD ----------------
const char* TB_SERVER = "thingsboard.cloud";
const int   TB_PORT   = 1883;
const char* TB_TOKEN  = "eoC2r1jb5HSRgaEwoapL";

// ---------------- OBJECTS ----------------
WiFiClient espClient;
PubSubClient tbClient(espClient);
DHT dht(DHTPIN, DHTTYPE);
Adafruit_SSD1306 oled(128, 64, &Wire, -1);
LiquidCrystal_I2C lcd(0x27, 20, 4);

// ---------------- STATES ----------------
enum SystemState { SAFE, WARNING, UNSAFE };
SystemState currentState = SAFE;
SystemState lastState    = SAFE;
bool buzzerSilenced = false;

// ---------------- GAS SMOOTHING ----------------
#define GAS_WINDOW_SIZE 5
int gasBuffer[GAS_WINDOW_SIZE];
int gasIndex = 0;
bool gasBufferFilled = false;

int getSmoothedGas(int newGas) {
  gasBuffer[gasIndex++] = newGas;
  if (gasIndex >= GAS_WINDOW_SIZE) { gasIndex = 0; gasBufferFilled = true; }
  int sum = 0;
  int count = gasBufferFilled ? GAS_WINDOW_SIZE : gasIndex;
  for (int i = 0; i < count; i++) sum += gasBuffer[i];
  return sum / count;
}

// ---------------- LOGIC ----------------
SystemState evaluateAirQuality(float t, float h, int g) {
  if (g >= GAS_WARNING_MAX || t >= TEMP_UNSAFE || h >= HUM_UNSAFE) return UNSAFE;
  if (g >= GAS_SAFE_MAX || t >= TEMP_WARNING || h >= HUM_WARNING) return WARNING;
  return SAFE;
}

void applyState(SystemState s, float t, float h, int g) {
  bool fanOn = (s != SAFE);
  digitalWrite(RELAY, fanOn ? HIGH : LOW);
  
  if (s != UNSAFE) {
    buzzerSilenced = false;
    noTone(BUZZER);
    if (s == SAFE) { digitalWrite(LED_GREEN, HIGH); digitalWrite(LED_YELLOW, LOW); digitalWrite(LED_RED, LOW); }
    else { digitalWrite(LED_GREEN, LOW); digitalWrite(LED_YELLOW, HIGH); digitalWrite(LED_RED, LOW); }
  } else {
    digitalWrite(LED_GREEN, LOW); digitalWrite(LED_YELLOW, LOW); digitalWrite(LED_RED, HIGH);
    
    if (!buzzerSilenced) {
      bool isTotalUnsafe = (g >= GAS_WARNING_MAX && (t >= TEMP_UNSAFE || h >= HUM_UNSAFE));
      bool isGasOnly = (g >= GAS_WARNING_MAX);

      // Continuous sound for Total Danger or Gas Leak
      if (isTotalUnsafe || isGasOnly) {
        tone(BUZZER, 1000);
      } 
      // 3-second interval for Temp/Hum only
      else {
        static unsigned long lastToggle = 0;
        static bool bState = false;
        if (millis() - lastToggle >= 3000) {
          bState = !bState;
          if (bState) tone(BUZZER, 1000); else noTone(BUZZER);
          lastToggle = millis();
        }
      }
    }
  }
}

// ---------------- EXTERNAL SERVICES ----------------
void sendTelegramAlert(String msg) {
  if (WiFi.status() != WL_CONNECTED) return;
  HTTPClient http;
  String url = "https://api.telegram.org/bot" + String(BOT_TOKEN) + "/sendMessage?chat_id=" + String(CHAT_ID) + "&text=" + msg;
  http.begin(url); http.GET(); http.end();
}

void sendToFirebase(float t, float h, int g, bool fanOn) {
  if (WiFi.status() != WL_CONNECTED) return;
  HTTPClient http;
  http.begin(firebaseURL);
  http.addHeader("Content-Type", "application/json");
  String airQ = (currentState == SAFE) ? "SAFE" : (currentState == WARNING) ? "WARNING" : "UNSAFE";
  String payload = "{\"sensors\":{\"temp\":" + String(t,1) + ",\"hum\":" + String(h,1) + ",\"gas\":" + String(g) + "},";
  payload += "\"status\":{\"air_quality\":\"" + airQ + "\",\"fan\":\"" + String(fanOn ? "ON" : "OFF") + "\"}}";
  http.PUT(payload); http.end();
}

void sendToThingsBoard(float t, float h, int g, bool fanOn) {
  if (!tbClient.connected()) return;
  String stateStr = (currentState == SAFE) ? "SAFE" : (currentState == WARNING) ? "WARNING" : "UNSAFE";
  String payload = "{\"temperature\":" + String(t,1) + ",\"humidity\":" + String(h,1) + ",\"gas\":" + String(g) + ",\"fan\":\"" + String(fanOn ? "ON" : "OFF") + "\",\"air_quality\":\"" + stateStr + "\"}";
  tbClient.publish("v1/devices/me/telemetry", payload.c_str());
}

// ---------------- OLED & LCD COMPLEX UPDATES ----------------
void updateDisplays(float t, float h, int g, bool fanOn) {
  lcd.clear();
  oled.clearDisplay();
  oled.setTextSize(1);
  oled.setTextColor(SSD1306_WHITE);

  // OLED Standard Readings
  oled.setCursor(0,0);  oled.print("T: "); oled.print(t,1); oled.print(" C");
  oled.setCursor(0,13); oled.print("H: "); oled.print(h,1); oled.print(" %");
  oled.setCursor(0,26); oled.print("G: "); oled.print(g); oled.print(" PPM");
  oled.setCursor(0,39); oled.print("F: "); oled.print(fanOn ? "ON" : "OFF");
  oled.setCursor(0,54); oled.print(currentState == SAFE ? "STATUS: SAFE" : currentState == WARNING ? "STATUS: WARN" : "STATUS: DANGER");

  // LCD Complex Logic
  lcd.setCursor(0, 0);
  if (currentState == SAFE) {
    lcd.print("Status: SAFE");
  } else if (currentState == WARNING) {
    lcd.print("Status: WARNING");
  } else {
    if (g >= GAS_WARNING_MAX && (t >= TEMP_UNSAFE || h >= HUM_UNSAFE)) {
      lcd.print("Unsafe Air Quality"); lcd.setCursor(0,1); lcd.print("Please evacuate!");
    } else if (g >= GAS_WARNING_MAX) {
      lcd.print("GAS UNSAFE,Please"); lcd.setCursor(0,1); lcd.print("leave the house!");
    } else if (t >= TEMP_UNSAFE && h >= HUM_UNSAFE) {
      lcd.print("!!! WARNING !!!"); lcd.setCursor(0,1); lcd.print("HIGH Temp & Hum");
    } else if (t >= TEMP_UNSAFE) {
      lcd.print("!!! WARNING !!!"); lcd.setCursor(0,1); lcd.print("HIGH Temperature");
    } else if (h >= HUM_UNSAFE) {
      lcd.print("!!! WARNING !!!"); lcd.setCursor(0,1); lcd.print("HIGH Humidity");
    }
  }
  oled.display();
}

// ---------------- SETUP & LOOP ----------------
void setup() {
  Serial.begin(115200);
  Serial.println("--- IoT System Booting ---");
  WiFi.begin(ssid, password);
  unsigned long startT = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - startT < 8000) delay(500);
  tbClient.setServer(TB_SERVER, TB_PORT);
  pinMode(BUZZER, OUTPUT); pinMode(RELAY, OUTPUT); pinMode(LED_RED, OUTPUT);
  pinMode(LED_YELLOW, OUTPUT); pinMode(LED_GREEN, OUTPUT); pinMode(BUTTON_PIN, INPUT_PULLUP);
  dht.begin(); oled.begin(SSD1306_SWITCHCAPVCC, 0x3C); lcd.init(); lcd.backlight();
}

void loop() {
  if (!tbClient.connected() && WiFi.status() == WL_CONNECTED) tbClient.connect("IoTDevice", TB_TOKEN, NULL);
  tbClient.loop();

  float t = dht.readTemperature(); float h = dht.readHumidity();
  int g = getSmoothedGas(analogRead(GAS_PIN));

  currentState = evaluateAirQuality(t, h, g);
  bool fanOn = (currentState != SAFE);
  
  applyState(currentState, t, h, g);
  updateDisplays(t, h, g, fanOn);
  sendToFirebase(t, h, g, fanOn);
  sendToThingsBoard(t, h, g, fanOn);

  // Telegram Specific Messages
  if (currentState == UNSAFE && lastState != UNSAFE) {
    String tMsg = "";
    if (g >= GAS_WARNING_MAX && (t >= TEMP_UNSAFE || h >= HUM_UNSAFE)) tMsg = "Unsafe Air Quality detected Please evacuate immediately";
    else if (g >= GAS_WARNING_MAX) tMsg = "GAS UNSAFE, Please leave the house or fix the leak immediately";
    else if (t >= TEMP_UNSAFE && h >= HUM_UNSAFE) tMsg = "!!! WARNING !!! HIGH Temperature and Humidity detected";
    else if (t >= TEMP_UNSAFE) tMsg = "!!! WARNING !!! HIGH Temperature";
    else if (h >= HUM_UNSAFE) tMsg = "!!! WARNING !!! HIGH Humidity";
    sendTelegramAlert(tMsg);
  }

  // Serial Monitor Output
  // Serial Monitor Output with Humidity added
  Serial.print("T: "); Serial.print(t, 1);
  Serial.print(" | H: "); Serial.print(h, 1); // Added Humidity here
  Serial.print(" | G: "); Serial.print(g);
  Serial.print(" | Fan: "); Serial.print(fanOn ? "ON" : "OFF");
  Serial.print(" | Status: ");
  Serial.println(currentState == SAFE ? "SAFE" : currentState == WARNING ? "WARN" : "DANGER");
  

  lastState = currentState;
  delay(2000);
}