#include <PubSubClient.h>
#include <WiFi.h>
#include <LiquidCrystal_I2C.h>
// WIFI config
const char* ssid = "Wokwi-GUEST";//wifi อาจจะไม่เสถียน
const char* password = "";
WiFiClient wifiClient;
// MQTT client config
const char* mqttServer = "broker.hivemq.com";
const int mqttPort = 1883;
const char* mqttUser = "";
const char* mqttPassword = "";
const char* topic_sub = "ITKPS/Lab/counter2";//ตัวรับ ใช้ช่องเดียวกัน ช่อง= connter
PubSubClient mqttClient(wifiClient);
// LCD config
LiquidCrystal_I2C lcd(0x27, 16, 2);


void initLCD() {
lcd.init();
lcd.backlight();
lcd.clear();
}
void displayLCD(int col, int row, String msg) {
lcd.clear();
lcd.setCursor(col,row);
lcd.print(msg);
}

//งานไหนก็ใช้ เปลี่ยนแค่ตัวข้างบน
void setup_wifi() {
// Start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println();
Serial.print("WiFi connected on ");
Serial.print("IP address: ");
Serial.print(WiFi.localIP());
Serial.print(" MAC address: ");
Serial.println(WiFi.macAddress());
}

void reconnectMQTT() {
// Loop until we're reconnected
char mqttinfo[80];
char clientId[100] = "\0";
snprintf (mqttinfo, 75, "Attempting MQTT connection at %s:%d(%s/%s)...", mqttServer, mqttPort, mqttUser, mqttPassword);
while (!mqttClient.connected()) {
Serial.println(mqttinfo);
sprintf(clientId, "ESP32Client-%04X", random(0xffff));
if (mqttClient.connect(clientId)) {
Serial.println("...MQTT Broker connected...");
mqttClient.subscribe(topic_sub); //เพิ่มใน if ถ้าเชื่อมสำเร็จ /ถ้ามีหลายอันเขียนเพิ่ม /เราเป็นทั้งรับทั้งส่งได้ 
} else {
Serial.print("failed, rc=");
Serial.print(mqttClient.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}

//มีเฉพาะฝังรับ ถ้ามีรับต้องใส่ /callback คือชื่อที่ใช้เรียก
void mqttCallback(char* topic, byte* payload, unsigned int length) {
char payloadMsg[128];//arry ของสตริง
Serial.print("Message arrived in topic: ");
Serial.print(topic);
Serial.print(" Message:");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
payloadMsg[i] = (char) payload[i];
}
payloadMsg[length] = '\0';//ตัวจบสตริง
Serial.println();
Serial.println("-----------------------");
doProcess(payloadMsg);
}
void doProcess(String rcvMsg) {
 displayLCD(6, 0, rcvMsg);
}



void setup() {
Serial.begin(115200);
initLCD();
setup_wifi();
// setup MQTT //set call black คือคีย์เวิร์ด เปลี่ยนไม่ได้
mqttClient.setServer(mqttServer, mqttPort);
mqttClient.setCallback(mqttCallback); // set the callback function
}
void loop() {
if (!mqttClient.connected()) {
reconnectMQTT();
}
mqttClient.loop();
delay(50);
}