// Create an MQTT Connection
// TCP Connection
// import the WiFi and PubSubClient libraries
//The WiFi library allows ESP32 to establish connections with Wi-Fi networks
//The PubSubClient library enables ESP32 to connect to an MQTT broker for publishing messages and subscribing to topics.
#include <WiFi.h>
#include "PubSubClient.h"
// WiFi
char ssid[]="Wokwi-GUEST";
char pass[]="";
// MQTT Broker
const char *mqtt_broker = "broker.hivemq.com";//Public Broker
const char *mqtt_username = "taha.toplu";
const char *mqtt_password = "tahayunus123";
const int mqtt_port = 1883;
// App Protcol ---> Port 
const char *topic_publish = "emqx/esp32/S";//Topic ESP32 Pusblish
const char *topic_subsrcibe = "emqx/esp32/S";//Topic ESp32 Subs
WiFiClient espClient;//WIFI Opject
PubSubClient client(espClient);
void callback(char *topic, byte *payload, unsigned int length);
#define LED 2
const int redPin = 14;   
const int yellowPin = 12; 
const int greenPin = 13;  


bool ledState=false;
void setup(){
   // Setting LED pin as output
    pinMode(redPin, OUTPUT);
    pinMode(yellowPin, OUTPUT);    
    pinMode(greenPin, OUTPUT);
    digitalWrite(yellowPin, LOW);  // Turn off the LED initially
    digitalWrite(greenPin, LOW);  // Turn off the LED initially
    digitalWrite(redPin, LOW);  // Turn off the LED initially
    
    //Open a serial connection to display program results and establish a connection to the Wi-Fi network.
    // Set software serial baud to 115200;

    Serial.begin(115200);
    // Connecting to a Wi-Fi network
    WiFi.begin(ssid, pass);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.println("Connecting to WiFi..");
    }
        Serial.println("Connected to the Wi-Fi network");
    // Utilize PubSubClient to establish a connection with the MQTT broker.
    //connecting to a mqtt broker
    Serial.println("Before Connect MQTT");
    //Broker Configuration 
    client.setServer(mqtt_broker, mqtt_port);
    client.setCallback(callback);
   while (!client.connected()) {
        String client_id = "esp32-client-";
        client_id += String(WiFi.macAddress());
        //ESP32-ID -----> esp32-client-macaddress
        //variable.c_str()--->char [] , String
        Serial.printf("The client %s connects to the public MQTT broker\n", client_id.c_str());
        if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
            Serial.println("Public MQTT broker connected");
        } else {
            Serial.print("failed with state ");
            Serial.print(client.state());
            delay(2000);
        }
    }
    Serial.println("After Connect MQTT");
    client.publish(topic_publish, "Hi, I'm ESP32 ^^");
    client.subscribe(topic_subsrcibe);
}

void loop() {
    client.loop();
}



void callback(char *topic, byte *payload, unsigned int length) {
    Serial.print("Message arrived in topic: ");
    Serial.println(topic);
    Serial.print("Message:");
    String message;
    if(String(topic)=="emqx/esp32/S"){
        for (int i = 0; i < length; i++) {
            message += (char) payload[i];  // Convert *byte to string
        }
        Serial.print(message);
        if (message == "on" && !ledState) {
            digitalWrite(LED, HIGH);  // Turn on the LED
            ledState = true;
        }
        if (message == "off" && ledState) {
            digitalWrite(LED, LOW); // Turn off the LED
            ledState = false;
        }
    }

    Serial.println();
    Serial.println("-----------------------");

}