bookform.java ( anti book multi multi )

 private void canSubmitBooking(String userId, String hotelId, String fullName, String checkInDate, String checkOutDate,
                                  int adults, int children, String contactNumber, String email, String roomPreference,
                                  String yourGcashName, String yourGcashNumber, String referenceNumber) {

        DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference();

        DatabaseReference userBookingsRef = databaseReference.child("booking_info");
        userBookingsRef.orderByChild("userId").equalTo(userId).addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                boolean canSubmit = true;
                for (DataSnapshot bookingSnapshot : dataSnapshot.getChildren()) {
                    String existingCheckInDate = bookingSnapshot.child("checkInDate").getValue(String.class);
                    String existingCheckOutDate = bookingSnapshot.child("checkOutDate").getValue(String.class);

                    SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
                    Date currentDate = new Date();
                    Date existingCheckIn = null;
                    Date existingCheckOut = null;

                    try {
                        existingCheckIn = sdf.parse(existingCheckInDate);
                        existingCheckOut = sdf.parse(existingCheckOutDate);
                    } catch (ParseException e) {
                        e.printStackTrace();
                    }
                    if (existingCheckIn != null && existingCheckOut != null) {
                        // Check if the new booking completely falls outside the range of existing booking
                        if (!(existingCheckOut.before(existingCheckIn) && existingCheckIn.before(existingCheckOut) ||
                                existingCheckIn.after(existingCheckOut) && existingCheckIn.after(existingCheckIn))) {
                            canSubmit = false;
                            break;
                        }
                    }

                    if (existingCheckOut != null && currentDate.before(existingCheckOut)) {
                        canSubmit = false;
                        break;
                    }
                }

                if (canSubmit) {
                    saveBooking(userId, hotelId, fullName, checkInDate, checkOutDate, adults, children, contactNumber, email, roomPreference, yourGcashName, yourGcashNumber, referenceNumber, timestamp);
                } else {
                    Toast.makeText(BookForm.this, "You cannot submit a new booking until your current booking has ended.", Toast.LENGTH_SHORT).show();
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Log.e("BookForm", "Database error: " + databaseError.getMessage());
            }
        });
    }