/*
  uses library PubSubClient.h - A simple client for MQTT.
  https://github.com/knolleary/pubsubclient
  Based on example presented below 
  https://github.com/knolleary/pubsubclient/blob/master/examples/mqtt_esp8266/mqtt_esp8266.ino
*/
#include <WiFi.h>
#include <PubSubClient.h>

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

// MQTT
const char* mqtt_server = "mqtt.eclipseprojects.io";  // Change if using a different broker
const int mqtt_port = 1883;  
const char* SUBTOPIC_BUTTON = "esp32-BIP/BUTTON";
const char* SUBTOPIC_LED = "esp32-BIP/LED";

// Initialize Wi-Fi and MQTT client
WiFiClient espClient;
PubSubClient client(espClient);

// BUTTON
const int BUTTON_PIN = 14;
const int LED_PIN = 26;
int old_button = -1;

void setup_wifi() {
  delay(10);
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password, 6);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}


// Callback function when an MQTT message is received
void callback(char *topic, byte *payload, unsigned int length) {
  Serial.print("Receive Topic: ");
  Serial.println(topic);

  payload[length] = '\0';
  char *str = (char *) payload;
  Serial.print("Payload: ");
  Serial.println(str);
}

// Function to connect to MQTT broker
void reconnect() {
  while (!client.connected()) {
    Serial.println("Attempting MQTT connection...");
    String clientId = "esp32-sol-clientId-";
    clientId += String(random(0xffff), HEX);
    if (client.connect(clientId.c_str())) {
      Serial.println("Connected");
      client.subscribe(SUBTOPIC_LED);
    } else {
      delay(5000);
    }
  }
}

// -------------------------
// FUNCTION TO CHECK IF BUTTON WAS PRESSED
// -------------------------
void buttonState(int old) {
  int button_State = digitalRead(BUTTON_PIN);
  if (button_State == 1 && old != button_State) {
    Serial.println("Button pressed");
    client.publish(SUBTOPIC_BUTTON, String(button_State).c_str(), 2);
    delay(250);
  }
  old_button = button_State;
  if(old_button>=1)
    digitalWrite(26, HIGH); 
  else
    digitalWrite(26, LOW);
}

// -------------------------
// INITIAL PART OF THE CODE
// -------------------------
void setup() {
  // SERIAL INIT
  Serial.begin(115200);
  randomSeed(micros());

  // BUTTON INIT
  pinMode(BUTTON_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  
  // WI-FI INIT
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

// -------------------------
// PART OF CODE RUNNING IN THE LOOP
// -------------------------
void loop() {
  if (!client.connected()) {
    reconnect();
  }
  buttonState(old_button);
  client.loop();
  delay(500);
}