A caf$$ is planning to develop a system to manage and calculate the total prices of different types of coffee. The caf$$ menu includes American coffee, espresso, cappuccino and Turkish coffee. The customer can order his$/$her favorite coffee type from the cashier who will use the system to input the order. The cashier, based on the order, can specify the size of the coffee $($small$,$ medium or large$).$ The prices of the coffee are as following:

American coffee price is $3\mathrm{.}5$ JD$.$ Espresso price is $1\mathrm{.}75$ JD$.$ Cappuccino price is $4\mathrm{.}25$ JD$.$ Turkish coffee price is $2\mathrm{.}5$ JD$.$

The customer can also have some additives on his$/$her cup of coffee. The additives with their prices include: Milk price is $1\mathrm{.}1$ JD$.$

Flavor price is $2\mathrm{.}1$ JD$.$

Diet price is Sweetener $2\mathrm{.}4$ JD$.$ Decaffeinated coffee price is $5\mathrm{.}5$ JD$.$ Foam price is $0\mathrm{.}3$ JD$.$

On the total price, $16\%$ tax will be added.

The customer can pay either in cash or by credit card. If cash, the cashier will confirm the payment by the system. If by credit card, the customer swipes the credit card, and the bank confirms the payment.

Customers of the caf$$ are interested in offers provided by the caf$.$ Accordingly, each customer can leave his$/$her mobile number to receive a message once an offer is available. In this case, the customer will enter the website of the caf$$ and register using his mobile number. Registration includes entering the first name, last name, email address, age and mobile number. However, email address and age are optional information as the customer can skip entering them. The other information is mandatory. The offer is of type string. An example of an offer is $$Buy One Get One Free$.$

In the future, the caf$$ is thinking of removing or adding some other types of coffee depending on the demand. The manager of the caf$$ can use the system to add or remove coffee types.

For the above scenario,

$1.$Draw a suitable Class diagram using appropriate SOLID principles and design patterns.

$2.$ For each used SOLID principle and design pattern, mention where you have used it and Justify your

design choice