#include <WiFi.h>

const char* ssid = "XXXX"; //don't forget to add your own ssid
const char* password = "XXXXX"; //don't forget to add your own password
const char* host = "XXX"; //don't forget to add the ESP slave IP

const int buttonPin = XX; //don't forget to add your own button pin

void setup() {
  Serial.begin(115200);
  pinMode(buttonPin, INPUT_PULLUP);
  connectToWiFi();
}

void loop() {
  if (digitalRead(buttonPin) == LOW) {
    sendCommandToSlave("TOGGLE_LED");
    delay(500); // Delay to avoid button "rebound"
  }
}

void connectToWiFi() {
  Serial.print("Connection to WiFi");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to WiFi !");
}

void sendCommandToSlave(String command) {
  WiFiClient client;
  if (!client.connect(host, 80)) {
    Serial.println("Fail to connect to the server");
    return;
  }
  client.print(command);
  delay(10);
  client.stop();
}