#include <WiFi.h>
#include <PubSubClient.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <ESP32Servo.h>

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

// MQTT
const char* mqtt_server = "broker.hivemq.com";
const char* topic_pub = "smarthome/2330205030065/data";
const char* topic_sub = "smarthome/2330205030065/control";

WiFiClient espClient;
PubSubClient client(espClient);

// PIN
#define DHT_PIN 4
#define DHT_TYPE DHT22
#define LDR_PIN 34
#define PIR_PIN 27
#define MQ2_PIN 35
#define TRIG_PIN 18
#define ECHO_PIN 19
#define LED_PIN 26
#define RELAY_PIN 25
#define BUZZER_PIN 33
#define SERVO_PIN 13

// OBJECT
DHT dht(DHT_PIN, DHT_TYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo myServo;

// MODE
String mode = "AUTO";

// SENSOR VARIABLES
float temperature = 0, humidity = 0;
int lightValue = 0, motionValue = 0, gasValue = 0;
float distanceCM = 0;

// MOVING AVERAGE
#define N 5
float tempArr[N];
int indexMA = 0;

// TIMING
unsigned long lastMillis = 0;
const long interval = 3000;

// THRESHOLD
int lightThreshold = 2000;
int gasThreshold = 2000;

// ================= FUNCTIONS =================

// WIFI
void connectWiFi() {
  WiFi.begin(ssid, password);
  Serial.print("Connecting WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" Connected!");
}

// MQTT
void reconnectMQTT() {
  while (!client.connected()) {
    Serial.print("Connecting MQTT...");
    if (client.connect("ESP32Client-0065")) {
      Serial.println("Connected");
      client.subscribe(topic_sub);
    } else {
      Serial.println("Retry...");
      delay(2000);
    }
  }
}

// ULTRASONIC
float readDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  long duration = pulseIn(ECHO_PIN, HIGH, 30000);
  if (duration == 0) return -1;
  return duration * 0.034 / 2;
}

// MOVING AVERAGE
float movingAverage(float newVal) {
  tempArr[indexMA] = newVal;
  indexMA = (indexMA + 1) % N;

  float sum = 0;
  for (int i = 0; i < N; i++) sum += tempArr[i];

  return sum / N;
}

// SENSOR READ
void readSensors() {
  float t = dht.readTemperature();
  float h = dht.readHumidity();

  if (isnan(t) || isnan(h)) {
    Serial.println("DHT ERROR!");
    return;
  }

  temperature = movingAverage(t);
  humidity = h;
  lightValue = analogRead(LDR_PIN);
  motionValue = digitalRead(PIR_PIN);
  gasValue = analogRead(MQ2_PIN);
  distanceCM = readDistance();
}

// CONTROL SYSTEM
void controlSystem() {

  if (mode == "AUTO") {
    digitalWrite(LED_PIN, (lightValue > lightThreshold || motionValue) ? HIGH : LOW);
    digitalWrite(RELAY_PIN, (temperature > 28) ? HIGH : LOW);
    digitalWrite(BUZZER_PIN, (gasValue > gasThreshold) ? HIGH : LOW);

    myServo.write((distanceCM > 0 && distanceCM < 20) ? 90 : 0);
  }

  if (mode == "SECURITY") {
    if (motionValue == HIGH) {
      digitalWrite(BUZZER_PIN, HIGH);
      client.publish(topic_pub, "{\"alert\":\"motion\"}", true);
    } else {
      digitalWrite(BUZZER_PIN, LOW);
    }
  }
}

// MQTT CALLBACK
void callback(char* topic, byte* payload, unsigned int length) {
  String msg;
  for (int i = 0; i < length; i++) msg += (char)payload[i];

  msg.trim();
  Serial.println("CMD: " + msg);

  if (msg == "AUTO") mode = "AUTO";
  else if (msg == "MANUAL") mode = "MANUAL";
  else if (msg == "SECURITY") mode = "SECURITY";

  if (mode == "MANUAL") {
    if (msg == "LAMP_ON") digitalWrite(LED_PIN, HIGH);
    if (msg == "LAMP_OFF") digitalWrite(LED_PIN, LOW);
    if (msg == "AC_ON") digitalWrite(RELAY_PIN, HIGH);
    if (msg == "AC_OFF") digitalWrite(RELAY_PIN, LOW);
    if (msg == "BUZZER_ON") digitalWrite(BUZZER_PIN, HIGH);
    if (msg == "BUZZER_OFF") digitalWrite(BUZZER_PIN, LOW);
    if (msg == "DOOR_OPEN") myServo.write(90);
    if (msg == "DOOR_CLOSE") myServo.write(0);
  }
}

// PUBLISH
void publishData() {
  String payload = "{";
  payload += "\"temp\":" + String(temperature) + ",";
  payload += "\"hum\":" + String(humidity) + ",";
  payload += "\"light\":" + String(lightValue) + ",";
  payload += "\"motion\":" + String(motionValue) + ",";
  payload += "\"gas\":" + String(gasValue) + ",";
  payload += "\"distance\":" + String(distanceCM) + ",";
  payload += "\"mode\":\"" + mode + "\"}";
  
  client.publish(topic_pub, payload.c_str(), true);
  Serial.println(payload);
}

// LCD
void updateLCD() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("T:");
  lcd.print(temperature);
  lcd.print(" ");
  lcd.print(mode);

  lcd.setCursor(0, 1);
  lcd.print("L:");
  lcd.print(lightValue);
}

// ================= SETUP =================
void setup() {
  Serial.begin(115200);

  connectWiFi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  dht.begin();

  pinMode(PIR_PIN, INPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(LED_PIN, OUTPUT);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  myServo.attach(SERVO_PIN);

  lcd.init();
  lcd.backlight();
}

// ================= LOOP =================
void loop() {

  if (WiFi.status() != WL_CONNECTED) connectWiFi();
  if (!client.connected()) reconnectMQTT();

  client.loop();

  if (millis() - lastMillis > interval) {
    lastMillis = millis();

    readSensors();
    controlSystem();
    publishData();
    updateLCD();
  }
}