Student: Banu Miruna-Elena
Group: 321CA

Description:

The following program implements the functionality of the HTTP protocol via
a program that communicates with a REST API. It mimics the functionalities
of a web client that would usually be implemented using html, css or javascrpt.

Reason of JSON library choice:
    I have chosen the "nlohmann" library because I preferred working in C++
since it is more intuitive. Moreover, I have found that this library is
easier to use.
    The only way I could get it to work, however, is by following these steps
to install it (along with the inclusion of the needed header):
-> git clone https://github.com/nlohmann/json.git
-> cd json/
-> mkdir build
-> cd build/
-> cmake ..
-> sudo make install

Server IP:
    I have run locally the "dig" command on the given host to retreive the
IP address.

Functionalities:

-> Register: 
    This command sends a POST request to the server to register a pair of
credentials: username and password. It returns to stdout the response from
the server. Moreover, the case when there is already an ongoing session 
has been treated locally so that this case will not send any request further.

-> Login:
    This command sends a pair of credentials via a POST request to the server
so it can validate the authentification. It returns to stdout the response from
the server if successful or any possible error otherwise. Locally, the case when
there is already an ongoing session has been treated, printing an error to stdout.

-> Enter library:
    This command sends a GET request to the server so it allows the access to the
library of the current user. It returns the response of the server to the stdout
or any possible error. Locally, it has been checked if there is any ongoing
session.

-> Get Books:
    This command sends a GET request to the server to show the books in the library
of the current user. It returns the response of the server if successful, or an
error otherwise. Locally, the case of existing jwt token has been checked.

-> Get Book:
    This command sends a GET request to the server to get the details of a book
identified by a certain id. The response has been redirected to the stdout or 
an error otherwise. Locally, the cases treated were: if the id is not a valid
number or if there is a jwt token present.

-> Add Book:
    This command sends a POST request to the server to add another book and its
details to the library. The response from the server has been shown to stdout
or an error otherwise. Locally, the treated case were: the existence of a jwt
token.

-> Delete Book:
    This command sends a DELETE request to the server so it deletes the book
with the id from stdin. The response from the server is printed to stdout
or an error if failed. The locally treated cases are: check if the id is valid
or if there is not a jwt token.

-> Logout:
    This command sends a GET request to the server so it ends the current
session. The response from the server is printed to stdout or an error otherwise.
The locally treated error is: check the existence of an ongoing session.

-> Exit:
    Ends the execution of the program.

Another excepted case treated is if the the command from stdin is different
than those above-mentioned.