Second$-$hand Vehicle System

A second$-$hand vehicle sales system will be developed to operate on web and mobile platforms. The primary purpose of this second$-$hand vehicle sales system is to store and manage detailed information about customers, vehicle models, sales listings, and vehicle owners. Vehicle owners who log into the system with their first name, last name, email address, and password will be able to perform operations such as entering a new vehicle listing, viewing, editing, deleting, and removing their existing listings. The vehicle owner will be able to enter and save sales listing details into the system, including the type of vehicle, production year, brand, model, fuel type, engine, transmission, mileage, sales price, and vehicle images. Additionally, the vehicle owner can add equipment to the vehicle, such as fog lights, foldable mirrors, parking sensors$,$ central locking, and sunroof. When the vehicle owner adds a new listing or makes any changes to the listing, the listing must be approved by the system administrators before it can be published. Once the system administrators approve the listing, it will be published. Published listings will be displayed as showcase listings for customers who want to buy vehicles. Customers will be able to examine the details of the vehicles they want to buy through showcase listings. Additionally, customers will be able to perform detailed searches using information such as the type of vehicle, production year, brand, model, fuel type, engine, transmission, mileage, and sales price. Through the developed system, customers will be able to compare the vehicle listings they are interested in$.$ Furthermore, customers will be able to access the contact information of vehicle owners, leave comments, and express their opinions about the vehicles they are interested in$.$ Apart from the operations that vehicle owners and customers can perform on the system, system administrators will be able to enter and update information such as new vehicle types, brands, models, and vehicle equipment through the system management panel.

Question: Draw a UML diagram containing the object$-$oriented infrastructure of the system $($objects$,$ relationships between objects, behaviors$)$ according to the scenario and code it considering SOLID design principles and the Singleton design pattern. You can think of behavior details as a prototype, meaning you do not have to write the full detailed content of the functions.