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

// 🛠️ Pin Definitions
#define DHTPIN         26
#define DHTTYPE        DHT22
#define BUTTON_PIN     14
#define LED_PIN        19
#define ALARM_PIN      33

// 📡 WiFi & MQTT Configuration
const char* ssid             = "Wokwi-GUEST";
const char* password         = "";
const char* mqtt_server      = "broker.hivemq.com";

// 📦 MQTT Topics
const char* mqtt_topic_pub    = "MS1/NG/sensor";
const char* mqtt_topic_time   = "MS1/NG/time";
const char* mqtt_topic_sub    = "MS1/NG/led";
const char* mqtt_topic_status = "MS1/PDD/status";
const char* mqtt_topic_alarm  = "MS1/NG/alarm";

// 📚 Global Variables
WiFiClient espClient;
PubSubClient client(espClient);
DHT dht(DHTPIN, DHTTYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);

bool ledState = false;
bool alarmSent = false;
unsigned long lastMsg = 0;
unsigned long lastButtonPress = 0;
const unsigned long debounceDelay = 200;
char msg[100];

// 🌐 Connect to WiFi
void setup_wifi() {
  Serial.println("Connecting to WiFi...");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
  }
  Serial.println("\nWiFi connected successfully!");
}

// 🔄 MQTT Callback (LCD print removed)
void callback(char* topic, byte* payload, unsigned int length) {
  payload[length] = 0;
  String command = String((char*)payload);
  command.trim();
  command.toUpperCase();

  Serial.print("Received MQTT message: ");
  Serial.println(command);

  if (command == "ON") {
    digitalWrite(LED_PIN, HIGH);
    ledState = true;
  } else if (command == "OFF") {
    digitalWrite(LED_PIN, LOW);
    ledState = false;
  }
}

// 🔌 MQTT Reconnection
void reconnect() {
  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    if (client.connect("ESP32ClientDevice", NULL, NULL,
                       mqtt_topic_status, 0, true, "offline")) {
      Serial.println("MQTT connected successfully");
      client.publish(mqtt_topic_status, "online", true);
      client.subscribe(mqtt_topic_sub);
    } else {
      Serial.print("MQTT connection failed, status=");
      Serial.println(client.state());
      delay(2000);
    }
  }
}

// 🕒 Time Sync
void syncTime() {
  Serial.println("Syncing time...");
  configTime(8 * 3600, 0, "pool.ntp.org");
  struct tm timeinfo;
  while (!getLocalTime(&timeinfo)) {
    Serial.println("Waiting for time sync...");
    delay(1000);
  }
  Serial.println("Time synchronized");
}

// 🚀 Setup
void setup() {
  Serial.begin(115200);
  Serial.println("Starting setup()...");

  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
  pinMode(ALARM_PIN, INPUT_PULLUP);

  lcd.init();
  lcd.backlight();
  lcd.clear();

  dht.begin();
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  syncTime();
  Serial.println("setup() complete, entering loop()");
}

// 🔁 Loop
void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  unsigned long now = millis();

  // 📤 Sensor publish every 5 seconds
  if (now - lastMsg > 5000) {
    lastMsg = now;

    float h = dht.readHumidity();
    float t = dht.readTemperature();
    if (isnan(h) || isnan(t)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
    }

    struct tm timeinfo;
    getLocalTime(&timeinfo);
    char timeStr[30];
    strftime(timeStr, sizeof(timeStr), "%H:%M:%S", &timeinfo);

    snprintf(msg, sizeof(msg), "{\"TEMPERATURE\": %.1f, \"HUMIDITY\": %.1f}", t, h);
    client.publish(mqtt_topic_pub, msg);
    client.publish(mqtt_topic_time, timeStr);

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.printf("T:%.1fC H:%.1f%%", t, h);
    lcd.setCursor(0, 1);
    lcd.print(timeStr);
  }

  // 🔘 LED toggle via button
  if (digitalRead(BUTTON_PIN) == LOW && now - lastButtonPress > debounceDelay) {
    lastButtonPress = now;
    ledState = !ledState;
    digitalWrite(LED_PIN, ledState);
    Serial.printf("Button pressed, LED: %s\n", ledState ? "ON" : "OFF");
  }

  // 📨 Serial message forwarding
  if (Serial.available() > 0) {
    String inputMessage = Serial.readStringUntil('\n');
    inputMessage.trim();
    if (inputMessage.length() > 0) {
      client.publish(mqtt_topic_pub, inputMessage.c_str());
      Serial.print("Published to MQTT: ");
      Serial.println(inputMessage);

      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Sent to MQTT:");
      lcd.setCursor(0, 1);
      lcd.print(inputMessage);
    }
  }

  // 🚨 Alarm placeholder (ready to implement)
  // if (digitalRead(ALARM_PIN) == LOW && !alarmSent) { ... }
}