#include <WiFi.h>
#include <HTTPClient.h>
#include <SPI.h>
#include <MFRC522.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <ESP32Servo.h>

// ============= PIN DEFINITIONS =============
#define SS_PIN    5
#define RST_PIN   26
#define GREEN_LED 2
#define RED_LED   4
#define BUZZER_PIN 15
#define BUTTON_PIN 14
#define SERVO_PIN 13

// ============= GLOBAL OBJECTS =============
MFRC522 rfid(SS_PIN, RST_PIN);
Adafruit_SSD1306 display(128, 64, &Wire, -1);
Servo gateServo;

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

// Timing variables
unsigned long ledOffTime = 0;
unsigned long buzzerOffTime = 0;
unsigned long servoReturnTime = 0;
bool isLedActive = false;
bool isBuzzerActive = false;
bool isServoMoving = false;
unsigned long lastButtonPress = 0;
bool isScanning = false;

// ============= SETUP =============
void setup() {
  Serial.begin(115200);
  Serial.println("\n\n=== ASTU PC Ownership Detector ===");
  
  // Initialize pins
  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(RED_LED, LOW);
  
  // Initialize OLED
  Wire.begin(21, 22);
  if(display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.println("ASTU Security");
    display.println("System Ready");
    display.display();
    Serial.println("OLED OK");
  } else {
    Serial.println("OLED Failed");
  }
  
  // Initialize RFID
  SPI.begin(18, 19, 23, 5);
  rfid.PCD_Init();
  Serial.println("RFID OK");
  
  // Initialize Servo
  gateServo.attach(SERVO_PIN);
  gateServo.write(0);
  Serial.println("Servo OK");
  
  // Connect WiFi
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, password);
  int attempts = 0;
  while (WiFi.status() != WL_CONNECTED && attempts < 20) {
    delay(500);
    Serial.print(".");
    attempts++;
  }
  
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nWiFi Connected!");
    display.clearDisplay();
    display.setCursor(0, 0);
    display.println("ASTU Security");
    display.println("WiFi Connected");
    display.println("Ready to Scan");
    display.display();
  } else {
    Serial.println("\nWiFi Failed!");
  }
  
  Serial.println("System Ready - Press Button to Scan");
}

// ============= DISPLAY FUNCTION =============
void updateDisplay(String line1, String line2, String line3) {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("=== ASTU SECURITY ===");
  display.println();
  display.println(line1);
  if (line2.length() > 0) display.println(line2);
  if (line3.length() > 0) display.println(line3);
  display.display();
}

// ============= LED and BUZZER FUNCTIONS =============
void startLed(int ledPin, int duration) {
  digitalWrite(ledPin, HIGH);
  if (ledPin == GREEN_LED) digitalWrite(RED_LED, LOW);
  else digitalWrite(GREEN_LED, LOW);
  ledOffTime = millis() + duration;
  isLedActive = true;
}

void updateLed() {
  if (isLedActive && millis() >= ledOffTime) {
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(RED_LED, LOW);
    isLedActive = false;
  }
}

void startBuzzer(int duration, bool isAlarm = false) {
  if (isAlarm) tone(BUZZER_PIN, 2500);
  else tone(BUZZER_PIN, 2000);
  buzzerOffTime = millis() + duration;
  isBuzzerActive = true;
}

void updateBuzzer() {
  if (isBuzzerActive && millis() >= buzzerOffTime) {
    noTone(BUZZER_PIN);
    isBuzzerActive = false;
  }
}

// ============= SERVO FUNCTION =============
void moveServoTemporarily(int angle, int delayMs) {
  gateServo.write(angle);
  servoReturnTime = millis() + delayMs;
  isServoMoving = true;
}

void updateServo() {
  if (isServoMoving && millis() >= servoReturnTime) {
    gateServo.write(0);
    isServoMoving = false;
  }
}

// ============= RFID SCAN FUNCTION =============
void scanRFID() {
  if (!rfid.PICC_IsNewCardPresent()) return;
  if (!rfid.PICC_ReadCardSerial()) return;
  
  String uid = "";
  for (byte i = 0; i < rfid.uid.size; i++) {
    if (rfid.uid.uidByte[i] < 0x10) uid += "0";
    uid += String(rfid.uid.uidByte[i], HEX);
  }
  uid.toUpperCase();
  
  Serial.print("RFID UID: ");
  Serial.println(uid);
  updateDisplay("RFID Detected", "UID: " + uid, "Verifying...");
  
  // FOR DEMO: Simulate server response
  // Remove this section and uncomment HTTP section for real server
  simulateServerResponse(uid);
  
  rfid.PICC_HaltA();
  rfid.PCD_StopCrypto1();
}

// ============= SIMULATED SERVER RESPONSE FOR TESTING =============
void simulateServerResponse(String uid) {
  // Demo: Authorize specific UIDs for testing
  // In Wokwi, you can set RFID cards to these values
  if (uid == "DEADBEEF" || uid == "12345678" || uid == "ASTU1234") {
    Serial.println("Authorized User Detected!");
    startLed(GREEN_LED, 2000);
    startBuzzer(500, false);
    moveServoTemporarily(90, 3000);
    updateDisplay("AUTHORIZED", "Welcome!", "Access Granted");
  } else {
    Serial.println("Unauthorized User Detected!");
    startLed(RED_LED, 2000);
    startBuzzer(2000, true);
    updateDisplay("UNAUTHORIZED", "ALERT!", "Access Denied");
  }
}

// ============= REAL HTTP FUNCTION (Uncomment to use with real server) =============
/*
void sendToServer(String uid) {
  if (WiFi.status() != WL_CONNECTED) {
    updateDisplay("Network Error", "No WiFi", "");
    return;
  }
  
  HTTPClient http;
  http.begin("http://host.docker.internal:5000/api/verify");
  http.addHeader("Content-Type", "application/json");
  
  String payload = "{\"rfid_uid\":\"" + uid + "\",\"device\":\"laptop\",\"location\":\"ASTU_GATE\"}";
  
  int httpCode = http.POST(payload);
  
  if (httpCode > 0) {
    String response = http.getString();
    Serial.println(response);
    
    if (response.indexOf("authorized") > 0 && response.indexOf("true") > 0) {
      startLed(GREEN_LED, 2000);
      startBuzzer(500, false);
      moveServoTemporarily(90, 3000);
      updateDisplay("AUTHORIZED", "Access Granted", "");
    } else {
      startLed(RED_LED, 2000);
      startBuzzer(2000, true);
      updateDisplay("UNAUTHORIZED", "Access Denied", "");
    }
  }
  
  http.end();
}
*/

// ============= MAIN LOOP =============
void loop() {
  updateLed();
  updateBuzzer();
  updateServo();
  
  // Check button press
  if (digitalRead(BUTTON_PIN) == LOW && !isScanning) {
    if (millis() - lastButtonPress > 200) {
      lastButtonPress = millis();
      isScanning = true;
      
      Serial.println("\nButton Pressed - Scanning...");
      updateDisplay("Scanning RFID", "Place tag near", "reader...");
      
      // Scan for 5 seconds
      unsigned long startTime = millis();
      bool found = false;
      
      while (millis() - startTime < 5000) {
        if (rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial()) {
          found = true;
          break;
        }
        updateLed();
        updateBuzzer();
        updateServo();
        delay(10);
      }
      
      if (found) {
        scanRFID();
      } else {
        Serial.println("No RFID Tag Found");
        updateDisplay("Timeout", "No Tag Found", "Press Button Again");
        startBuzzer(300, false);
      }
      
      isScanning = false;
    }
  }
  
  delay(10);
}