Congratulations—you've landed a job with TEnmo, whose product is an online payment service for transferring "TE bucks" between friends. However, they don't have a product yet. You've been tasked with writing a RESTful API server and command-line application.

You should attempt to complete all of the following required use cases.

1. [COMPLETE] As a user of the system, I need to be able to register myself with a username and password.
   1. A new registered user starts with an initial balance of 1,000 TE Bucks.
   2. The ability to register has been provided in your starter code.
2. [COMPLETE] As a user of the system, I need to be able to log in using my registered username and password.
   1. Logging in returns an Authentication Token. I need to include this token with all my subsequent interactions with the system outside of registering and logging in.
   2. The ability to log in has been provided in your starter code.
3. As an authenticated user of the system, I need to be able to see my Account Balance.
4. As an authenticated user of the system, I need to be able to send a transfer of a specific amount of TE Bucks to a registered user.
   1. I should be able to choose from a list of users to send TE Bucks to.
   2. A transfer includes the User IDs of the from and to users and the amount of TE Bucks.
   3. The receiver's account balance is increased by the amount of the transfer.
   4. The sender's account balance is decreased by the amount of the transfer.
   5. I can't send more TE Bucks than I have in my account.
   6. A Sending Transfer has an initial status of "approve."
5. As an authenticated user of the system, I need to be able to see transfers I have sent or received.
6. As an authenticated user of the system, I need to be able to retrieve the details of any transfer based upon the transfer ID.

If you complete all of the required use cases and are looking for additional challenge, complete as many of the following optional use cases as you can.

7. As an authenticated user of the system, I need to be able to request a transfer of a specific amount of TE Bucks from another registered user.
   1. I should be able to choose from a list of users to request TE Bucks from.
   2. A transfer includes the User IDs of the from and to users and the amount of TE Bucks.
   3. A Request Transfer has an initial status of "pending."
   4. No account balance changes until the request is approved.
   5. The transfer request should appear in both users' list of transfers (use case #5).
8. As an authenticated user of the system, I need to be able to see my "pending" transfers.
9. As an authenticated user of the system, I need to be able to either approve or reject a Request Transfer.
   1. I can't "approve" a given Request Transfer for more TE Bucks than I have in my account.
   2. The Request Transfer status is "approved" if I approve, or "rejected" if I reject the request.
   3. If the transfer is approved, the requester's account balance is increased by the amount of the request.
   4. If the transfer is approved, the requestee's account balance is decreased by the amount of the request.
   5. If the transfer is rejected, no account balance changes.

Your current account balance is: $9999.99

-------------------------------------------
Users
ID          Name
-------------------------------------------
313         Bernice
54          Larry
---------

Enter ID of user you are sending to (0 to cancel):
Enter amount:

-------------------------------------------
Transfers
ID          From/To                 Amount
-------------------------------------------
23          From: Bernice          $ 903.14
79          To:    Larry           $  12.55
---------
Please enter transfer ID to view details (0 to cancel): "

--------------------------------------------
Transfer Details
--------------------------------------------
 Id: 23
 From: Bernice
 To: Me Myselfandi
 Type: Send
 Status: Approved
 Amount: $903.14

-------------------------------------------
Users
ID          Name
-------------------------------------------
313         Bernice
54          Larry
---------

Enter ID of user you are requesting from (0 to cancel):
Enter amount:

-------------------------------------------
Pending Transfers
ID          To                     Amount
-------------------------------------------
88          Bernice                $ 142.56
147         Larry                  $  10.17
---------
Please enter transfer ID to approve/reject (0 to cancel): "

1: Approve
2: Reject
0: Don't approve or reject
---------
Please choose an option:

The users table stores the login information for users of the system.

The accounts table stores the accounts of users in the system.

The transfer_types table stores the types of transfers that are possible.

There are two types of transfers:

The transfer_statuses table stores the statuses of transfers that are possible.

There are three statuses of transfers:

The transfer table stores the transfers of TE bucks.

In the database folder, you'll find the database creation script tenmo.sql. Open this in SQL Server Management Studio and execute it.

The user registration and authentication functionality for the system has already been implemented. If you review the login code in Program.cs, you'll notice that after a successful authentication, the user is stored in UserService, which is a helper class to keep track of the logged in user and provide information about them.

There's also a method called UserService.GetToken() that returns the authorization token—meaning JWT—of the logged in user. When the use cases above refer to an "authenticated user", this means a request that includes the token.

Since both the client and server applications are included in the solution, you'll have to configure the solution to run both projects simultaneously. In Visual Studio, right-click the solution and select "properties." In the window that appears, select "Multiple startup projects" and set both "TenmoClient" and "TenmoServer" to have the action Start.