Building Society Savings Account Interest Calculator

Introduction

This package calculates a Building Society's savings account applicable interest. The interest calculated is based on:

1. The balance of the account
2. The band the balance belongs to

The table below represents the different bands and their applicable interest rates:

| Range               | Interest Rate |
| ------------------- | ------------- |
| < $1,000            | 1%            |
| $1,000 - < $5,000   | 1.5%          |
| $5,000 - < $10,000  | 2%            |
| $10,000 - < $50,000 | 2.5%          |
| $50,000 +           | 3%            |

E.g. A balance of $1,001 would pay interest at 1.5% resulting in an interest rate of $15.02.

Code Structure

The package is structured using a thin DDD-inspired architecture as demostrated below:

|- pkg
    |- account
        |- domain.go # This represents our domain layer (Datastructures that drive the package e.g InterestRatingTable)
        |- interest_rate.go # This represents our usecase (business logice) layer i.e where our interest calculation logic lies
|- go.mod
|- go.sum
|- README.md
|- server.go # A thin `gorilla mux` server

How to Run the package

Prerequisiutes

You need to have the following before running the package:

- Go 1.21+
- Curl

Run the server

To run the server, open your terminal and run the following command(s):
```
$ go run server.go
|
```
The server run on http://localhost:8000 on your local machine
Using any application/tool of your choice, call the endpoint to calculate the interest by supplying your balance as a query parameter valus as illustrated below
```
$ curl http://localhost:8000/interest/{balance}
```

Calculate interest of any given balance

$ curl http://localhost:8000/interest/1000
{"interest":"$15"}

Run Tests

The package is covered by behaviour, table driven tests which can be run using the command:
```
$ go test ./...
```

To get the test coverage of the package, run the following command(s):

$ go test ./... -coverprofile=coverage.out
$ go tool cover -html=coverage.out

ageeknamedslickback / interest-rate