#include <WiFi.h>
#include "PubSubClient.h"
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4); 

const char * MQTTServer = "broker.emqx.io";
const char * MQTT_Topic = "MQTT_LCD";
String stMessage ;
int scrollPosition = 0;
const char * MQTT_ID = "";
int Port = 1883;
WiFiClient espClient;
PubSubClient client(espClient);
void WIFIConnect() {
  Serial.println("Connecting to SSID: Wokwi-GUEST");
  WiFi.begin("Wokwi-GUEST", "");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("WiFi connected");
  Serial.print(", IP address: ");
  Serial.println(WiFi.localIP());
}

void MQTT_Reconnect() {
  while (!client.connected()) {
    if (client.connect(MQTT_ID)) {
      Serial.print("MQTT Topic: ");
      Serial.print(MQTT_Topic);
      Serial.print(" connected");
      client.subscribe(MQTT_Topic);
      Serial.println("");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.println(topic);
  Serial.print("Message: ");
  String stMessage ="";

  for (int i = 0; i < length; i++) {
    Serial.print((char)message[i]);
    stMessage += (char)message[i];
  }
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(stMessage);
  scrollText();
  delay(1000);
}

void setup() {
  Serial.begin(115200);
  WIFIConnect();
  lcd.init();
  lcd.backlight();
  client.setServer(MQTTServer, Port);
  client.setCallback(callback);
}

void loop() {
  delay(10);
  if (!client.connected()) {
    MQTT_Reconnect();
  }
  client.loop();
}
 
void scrollText(){
  String displayText;
        if (stMessage.length() > 20) {
            // Cuộn văn bản từ phải sang trái
            displayText = stMessage.substring(scrollPosition, scrollPosition + 20);
            scrollPosition++;
            if (scrollPosition > stMessage.length()) {
                scrollPosition = 0; // Quay lại từ đầu
            }
        } else {
            displayText = stMessage;
        }
        lcd.print(displayText);
    }