ESP32 Web Server Setup for OTP Input

#include <WiFi.h>
#include <ESPAsyncWebServer.h>
#include <HTTPClient.h>

const char* ssid = "Your_SSID";             // Replace with your WiFi SSID
const char* password = "Your_PASSWORD";     // Replace with your WiFi Password
const char* otp = "123456";                 // Temporary hardcoded OTP, replace with generated OTP

AsyncWebServer server(80);                  // Start a web server on port 80

const int relayPin = 5;                     // Relay connected to GPIO 5
bool doorUnlocked = false;

void setup() {
  Serial.begin(115200);
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW);              // Ensure door is locked by default

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  // Web server to enter OTP
  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    String html = "<html><body><h2>Enter OTP to Unlock Door</h2><form action='/verify' method='POST'><input type='text' name='otp' placeholder='Enter OTP'><input type='submit' value='Submit'></form></body></html>";
    request->send(200, "text/html", html);
  });

  // OTP verification and door control
  server.on("/verify", HTTP_POST, [](AsyncWebServerRequest *request){
    if (request->hasParam("otp", true)) {
      String inputOTP = request->getParam("otp", true)->value();
      if (inputOTP == otp) {
        digitalWrite(relayPin, HIGH);          // Unlock door
        delay(5000);                           // Keep unlocked for 5 seconds
        digitalWrite(relayPin, LOW);           // Lock door again
        request->send(200, "text/html", "Door Unlocked! Welcome.");
        doorUnlocked = true;
      } else {
        request->send(200, "text/html", "Invalid OTP. Try again.");
      }
    }
  });

  server.begin();
}

void loop() {
  // The main loop remains empty as the web server handles requests
}