Discount Service

1. Technologies used

• Maven 3.0
• Java 1.8

2. To Run this project locally

1. $ git clone https://github.com/nilabhsagar/discountservice
2. $ cd /home/sagar/discountservice
3. $ mvn install
4. $ cd target
5. $ java -jar discountapp.jar /home/sagar/input.txt

• Note: in the above /home/sagar/input.txt is the path to sample input file

3. To import this project into Eclipse IDE

• $ mvn eclipse:eclipse
• Import into Eclipse via existing projects into workspace option. Done.

About the Problem

A small system that calculates the discounts on all the applicable items a customer has bought.

There are several categories of products. In fact, categories have subcategories which themselves can have subcategories. Below is a diagram. Casuals is a subcategory of Trousers, which by itself is a subcategory of Men's wear. Some categories have discounts.

        Men's wear                 Women's wear (50% off)
        |- Shirts                      |- Dresses
        |- Trousers                    |- Footwear
           |- Casuals (30% off)
        |- Jeans   (20% off)

Each product belongs to a brand which by themselves are running discounts. Below is a table that lists them: Brands Discounts:

Wrangler        10%
Arrow           20%
Vero Moda       60%
UCB             None
Adidas          5%
Provogue        20%

This way, a product can have three types of discounts applicable:

1. Discount on the brand
2. Discount on the category
3. Discount on the ancestor category (e.g. Footwear doesn't have a discount, but it's parent category Women's wear has 50% off). It is worth noting, that it is an ancestor: not just a direct parent, anyone in the lineage.

The discount that is applied is the greatest of the above three. For example, if the customer buys a Jeans of Wrangler Brand, the discounts are:

1. Discount on brand: 10%
2. Discount on category (Jeans): 20%
3. Discount on parents (Trousers, Men's wear): None So, the discount that is applied 20%.

The shop inventory is given in CSV form as standard input and also customer options as comma separated Id's after a newline. In the example below, 1,2,3,4 are the customer choices.

Sample Input file:

5
1, Arrow,Shirts,800
2, Vero Moda,Dresses,1400
3, Provogue,Footwear,1800
4, Wrangler,Jeans,2200
5, UCB,Shirts,1500
 
2
1,2,3,4
1,5

Expected output:

3860 
2140

About the Design

Its a basic code where the initial category and brand details are loaded using Json document, which is added in the resource folder. These can certainly be extended to database.

All the responsibilities like loading categories, brands, building the discount path upfront as one time activity, calculating the discount for a given cart items are kept in a separate methods. These methods can easily be extended to separate class or to a separate service layer when the need arises.