1. Functional Requirements

1 Allow users to search for available cars by location, date, and time, and view car details such as make, model, year, and features.

2 Users can book a car, select pick-up and drop-off locations, and make payments using a secure payment gateway.

3 The system should send a confirmation email or SMS to the user with the booking details and rental agreement.

4 Allow users to cancel or modify their bookings, and refund the appropriate amount based on the cancellation policy.

5 The system should notify the user and the rental agency about any changes to the booking, such as delays, cancellations, or extensions.

6 Provide an admin dashboard for the rental agency to add and manage cars, update rental rates, and view sales reports.

7 The system should ensure data privacy and security, and protect against fraud and unauthorized access.

2. Non-Functional Requirements

1 The system should be highly available and scalable to handle peak loads during weekends and holidays.

2 The system should be user-friendly, responsive, and accessible on different devices and platforms.

3 The system should have a fast and reliable search and booking engine, and provide real-time updates on car availability and pricing.

4 The system should have a robust and reliable payment gateway, and ensure secure and seamless transactions.

5 The system should comply with industry standards and regulations, and protect the user's personal and financial data.

3. Low level code

                      //Person class as a base class for User and Admin classes
class Person {
  constructor(firstName, lastName, email, phoneNo, address) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.email = email;
    this.phoneNo = phoneNo;
    this.address = address;
  }
}

//User class, which extends the Person class
class User extends Person {
  constructor(firstName, lastName, email, phoneNo, address, password) {
    // Call the parent class constructor with super()
    super(firstName, lastName, email, phoneNo, address);
    // Initialize the password and rentals array properties
    this.password = password;
    this.rentals = [];
  }

  //Method to search for available vehicles based on location and rental dates
  searchVehicles(location, startDate, endDate) {
    // search vehicles logic here
  }

  //Method to rent a vehicle and add a new rental to the rentals array
  rentVehicle(vehicle, startDate, endDate) {
    // rent vehicle logic here
    const rental = new Rental(this, vehicle, startDate, endDate, totalCost);
    this.rentals.push(rental);
    return rental;
  }

  //Method to view the user's rental history
  viewRentals() {
    // view rentals logic here
  }

  //Method to modify an existing rental by rental ID
  modifyRental(rentalId, newStartDate, newEndDate) {
    // modify rental logic here
     const rental = this.rentals.find((r) => r.id === rentalId);
    if (rental) {
      rental.modifyRental(newStartDate, newEndDate);
    }
  }

  //Method to cancel an existing rental by rental ID
  cancelRental(rentalId) {
    // cancel rental logic here
    const rentalIndex = this.rentals.findIndex((r) => r.id === rentalId);
    if (rentalIndex !== -1) {
      this.rentals.splice(rentalIndex, 1);
    }
  }

  //Method to make a payment for a rental or other expense
  makePayment(paymentInfo) {
    // make payment logic here
  }
  
  //Method to submit the return date of a rental by rental ID
  submitVehicleReturnDate(rentalId, returnDate) {
    const rental = this.rentals.find((r) => r.id === rentalId);
    if (rental) {
      rental.submitVehicleReturnDate(returnDate);
    }
  }
}

//Admin class, which also extends the Person class
class Admin extends Person {
  constructor(firstName, lastName, email, phoneNo, address, password) {
    // Call the parent class constructor with super()
    super(firstName, lastName, email, phoneNo, address);
    // Initialize the password property
    this.password = password;
  }

  //Method to manage vehicles (e.g. add, delete, update)
  manageVehicles() {
    // manage vehicles logic here
  }

  //Method to manage rentals (e.g. approve, deny, modify)
  manageRentals() {
    // manage rentals logic here
  }

  //Method to view all rentals (for all users)
  viewRentals() {
    // view rentals logic here
  }

  //Method to cancel an existing rental by rental ID
  cancelRental(rentalId) {
    // cancel rental logic here
  }
}





class Vehicle {
  constructor(make, model, year, type, capacity, pricePerDay, location, color, brand) {
    this.make = make;
    this.model = model;
    this.year = year;
    this.type = type;
    this.capacity = capacity;
    this.pricePerDay = pricePerDay;
    this.location = location;
    this.color = colorl
    this.brand = brand;
  }
}

class Rental {
  constructor(user, vehicle, startDate, endDate, totalCost) {
    this.user = user;
    this.vehicle = vehicle;
    this.startDate = startDate;
    this.endDate = endDate;
    this.totalCost = totalCost;
    this.status = "Booked";
  }

  modifyRental(newStartDate, newEndDate) {
    // modify rental logic here
  }

  cancelRental() {
    // cancel rental logic here
  }
  
   submitVehicleReturnDate(returnDate) {
    this.returnDate = returnDate;
    if (this.returnDate > this.endDate) {
      // raise alert if the car is returned late
      console.log("Late return alert!");
    }
  }
}

class Payment {
  constructor(cardholderName, cardNumber, expiryDate, cvv) {
    this.cardholderName = cardholderName;
    this.cardNumber = cardNumber;
    this.expiryDate = expiryDate;
    this.cvv = cvv;
  }

  makePayment(amount) {
    // make payment logic here
  }
}

4. Database