TEnmo - Online Payment Service

TEnmo is an online payment service designed to allow users to transfer "TE Bucks" between friends. This project involves creating a RESTful API server and a command-line application that supports various functionalities, such as registering users, logging in, viewing balances, and sending or requesting TE Bucks.

Table of Contents

• Use Cases
• Sample Screens
• Database Schema
• How to Set Up the Database

Use Cases

1. User Registration: Users can register with a username and password, starting with a balance of 1,000 TE Bucks.
2. User Login: Users can log in using their registered credentials and receive an authentication token for subsequent interactions.
3. View Account Balance: Authenticated users can view their current account balance.
4. Send TE Bucks: Authenticated users can send a specified amount of TE Bucks to another user.
   • Users cannot send TE Bucks to themselves.
   • Transfers include the IDs of the sender and receiver, and the amount.
   • The sender’s balance decreases, and the receiver’s balance increases.
   • Transfers cannot exceed the sender’s current balance or be zero/negative amounts.
5. View Transfers: Users can view all transfers they've sent or received.
6. Transfer Details: Users can view details of a specific transfer by its ID.
7. Request TE Bucks: Users can request a specified amount of TE Bucks from another user.
   • Users cannot request TE Bucks from themselves.
   • The request remains pending until approved or rejected.
8. View Pending Transfers: Users can view their pending transfer requests.
9. Approve or Reject Requests: Users can approve or reject pending transfer requests.
   • Approvals are contingent on sufficient balance.
   • Approved transfers adjust the balances of the requester and requestee; rejected transfers do not affect balances.

Sample Screens

View Current Balance

Your current account balance is: $9999.99

Send TE Bucks

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

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

View Transfers

-------------------------------------------
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

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

Request TE Bucks

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

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

Pending Requests

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

Approve or Reject Pending Transfer

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

Database Schema

Tables

• tenmo_user: Stores user login information.

Field	Description
user_id	Unique identifier of the user
username	String that identifies the name of the user; used as part of the login process
password_hash	Hashed version of the user's password
role	Name of the user's role

• account: Tracks users' TE Bucks balances.

Field	Description
account_id	Unique identifier of the account
user_id	Foreign key to the users table; identifies user who owns account
balance	The amount of TE bucks currently in the account

• transfer_type: Defines transfer types (Request or Send).

Field	Description
transfer_type_id	Unique identifier of the transfer type
transfer_type_desc	String description of the transfer type

transfer_type_id	transfer_type_desc	Purpose
1	Request	Identifies transfer where a user requests money from another user
2	Send	Identifies transfer where a user sends money to another user

• transfer_status: Defines statuses of transfers (Pending, Approved, Rejected).

Field	Description
transfer_status_id	Unique identifier of the transfer status
transfer_status_desc	String description of the transfer status

transfer_status_id	transfer_status_desc	Purpose
1	Pending	Identifies transfer that hasn't occurred yet and requires approval
2	Approved	Identifies transfer that has been approved and occurred
3	Rejected	Identifies transfer that wasn't approved

• transfer: Records details of TE Bucks transfers.

Field	Description
transfer_id	Unique identifier of the transfer
transfer_type_id	Foreign key to the transfer_types table; identifies type of transfer
transfer_status_id	Foreign key to the transfer_statuses table; identifies status of transfer
account_from	Foreign key to the accounts table; identifies the account that the funds are being taken from
account_to	Foreign key to the accounts table; identifies the account that the funds are going to
amount	Amount of the transfer

How to Set Up the Database

1. Create a new PostgreSQL database named tenmo.
2. Run the SQL script located at database/tenmo.sql to set up the required tables and constraints.