#include <ESP32Servo.h>
#include <WiFi.h>
#include <FireBase32.h>
#include <Firebase.h>

// Gate Ultrasonic Sensor Pins
const int gateTrig = 4; // Gate sensor Trig
const int gateEcho = 5; // Gate sensor Echo

// Parking Slot Ultrasonic Sensor Pins
const int slotPins[5][2] = { // Slot sensors (Trig, Echo)
  {18, 19}, {21, 22}, {23, 25}, {26, 27}, {32, 33}
};

// Servo Motor Pin for Gate
const int servoPin = 12;

// Firebase Configuration
#define FIREBASE_HOST "https://smart-parking-system-b0b1a-default-rtdb.firebaseio.com"
#define FIREBASE_AUTH "AIzaSyDu_vQoGLoiNFrwEtSYPbnhi_W724MqjPg"

// WiFi Credentials
#define WIFI_SSID "wokwi-GUEST"
#define WIFI_PASSWORD ""

// Constants
const int gateDistanceThreshold = 100; // Open gate if car is within 100 cm
const int slotDistanceThreshold = 10;  // Mark slot as FILLED if distance <= 10 cm

// Create Servo Object
Servo gateServo;

// Firebase Data Object
FirebaseData fbdo;

void setup() {
  Serial.begin(115200);

  // Initialize Gate Ultrasonic Sensor
  pinMode(gateTrig, OUTPUT);
  pinMode(gateEcho, INPUT);

  // Initialize Parking Slot Ultrasonic Sensors
  for (int i = 0; i < 5; i++) {
    pinMode(slotPins[i][0], OUTPUT); // Trig
    pinMode(slotPins[i][1], INPUT);  // Echo
  }

  // Initialize Servo Motor for Gate
  gateServo.attach(servoPin);
  gateServo.write(0); // Close gate initially

  // Connect to WiFi
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nConnected to WiFi");

  // Initialize Firebase
  Firebase.begin(FIREBASE_HOST, FIREBASE_AUTH);
  Firebase.reconnectWiFi(true);

  Serial.println("Firebase Initialized");
  Serial.println("System Ready");
}

void loop() {
  // Gate Control Logic
  int gateDistance = getDistance(gateTrig, gateEcho);

  Serial.print("Gate Sensor Distance: ");
  Serial.println(gateDistance);

  if (gateDistance > 0 && gateDistance <= gateDistanceThreshold) {
    openGate();          // Open gate
    delay(5000);         // Keep the gate open for 5 seconds
    closeGate();         // Close the gate
  } else {
    Serial.println("Gate Closed - No Car Detected within Threshold");
  }

  // Parking Slot Monitoring and Firebase Update
  for (int i = 0; i < 5; i++) {
    int slotDistance = getDistance(slotPins[i][0], slotPins[i][1]);
    bool isSlotFilled = (slotDistance > 0 && slotDistance <= slotDistanceThreshold);

    // Update slot status to Firebase
    String path = "/slots/slot" + String(i + 1); // Path: /slots/slot1, /slots/slot2, ...
    if (Firebase.setBool(fbdo, path, !isSlotFilled)) { // True = AVAILABLE, False = FILLED
      Serial.print("Slot ");
      Serial.print(i + 1);
      Serial.print(": ");
      Serial.println(isSlotFilled ? "FILLED" : "AVAILABLE");
    } else {
      Serial.print("Failed to update slot ");
      Serial.print(i + 1);
      Serial.print(" -> ");
      Serial.println(fbdo.errorReason());
    }
  }

  delay(1000); // Delay for 1 second before repeating
}

// Function to Measure Distance Using Ultrasonic Sensor
int getDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH, 20000); // Timeout after 20ms
  if (duration == 0) {
    return -1; // No response (object too far or not detected)
  }
  
  int distance = duration * 0.034 / 2; // Convert time to distance (cm)
  return distance;
}

// Function to Open the Gate
void openGate() {
  gateServo.write(90); // Rotate servo to open gate
  Serial.println("Gate Opened");
}

// Function to Close the Gate
void closeGate() {
  gateServo.write(0); // Rotate servo to close gate
  Serial.println("Gate Closed");
}