web server - Wokwi ESP32, STM32, Arduino Simulator

#include <WiFi.h>

// Server running on port 80
WiFiServer server(80);

// Variables for storing HTTP request and output state
String header;
String outputState = "off";

// Timing variables for client timeout
unsigned long currentTime = millis();
unsigned long previousTime = 0;
const long timeoutTime = 2000;

void setup() {
  // Initialize Serial Monitor
  Serial.begin(9600);

  // Set GPIO 2 as output
  pinMode(2, OUTPUT);

  // Connect to WiFi
  WiFi.begin("soc2019", "socka2019");
  while (WiFi.status() != WL_CONNECTED) {
    delay(250);
    Serial.print(".");
  }

  // Print connection details
  Serial.println("\nWiFi úspešne pripojená!");
  Serial.print("IP adresa: ");
  Serial.println(WiFi.localIP());

  // Start the server
  server.begin();
}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (client) {
    Serial.println("Nový klient");
    currentTime = millis();
    previousTime = currentTime;

    // String to store the request line
    String currentLine = "";

    while (client.connected() && (currentTime - previousTime <= timeoutTime)) {
      currentTime = millis();

      // Check if data is available to read
      if (client.available()) {
        char c = client.read();
        Serial.write(c); // Print received characters
        header += c;

        // If a newline is received
        if (c == '\n') {
          // If the current line is empty, the request is complete
          if (currentLine.length() == 0) {
            // Send HTTP response
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println("");

            // Handle GPIO on/off requests
            if (header.indexOf("GET /2/on") >= 0) {
              Serial.println("GPIO 2 ON");
              outputState = "on";
              digitalWrite(2, HIGH);
            } else if (header.indexOf("GET /2/off") >= 0) {
              Serial.println("GPIO 2 OFF");
              outputState = "off";
              digitalWrite(2, LOW);
            }

            // Send the HTML webpage
            client.println("<!DOCTYPE html><html>");
            client.println("<head><title>ESP32 Web Server</title>");
            client.println("<style>");
            client.println("body { font-family: Arial; text-align: center; margin: 20px; }");
            client.println(".button { padding: 10px 20px; text-decoration: none; color: white; border-radius: 5px; }");
            client.println(".button-on { background-color: green; }");
            client.println(".button-off { background-color: red; }");
            client.println("</style></head>");
            client.println("<body>");
            client.println("<h1>ESP32 Web Server</h1>");
            client.println("<p>GPIO 2 - State: <strong>" + outputState + "</strong></p>");

            if (outputState == "off") {
              client.println("<p><a href=\"/2/on\" class=\"button button-on\">ON</a></p>");
            } else {
              client.println("<p><a href=\"/2/off\" class=\"button button-off\">OFF</a></p>");
            }

            client.println("</body></html>");
            client.println("");
            break;
          } else {
            currentLine = ""; // Clear the current line
          }
        } else if (c != '\r') {
          currentLine += c; // Add character to the current line
        }
      }
    }

    // Clear the header and stop the client
    header = "";
    client.stop();
    Serial.println("Klient je odpojený.");
    Serial.println("");
  }
}