Supermarket Discount Engine

A Flutter-based demo project simulating a discount engine for a supermarket, built as a solution to code_test_01.

This app calculates the total purchase amount for a customer by applying the correct order of discounts and tax, following business rules and object-oriented programming principles.

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Specifications

• Fixed discounts are applied before percentage discounts
• Product discounts are applied before overall discounts
• An 11% VAT is applied to every purchase
• All discounts are applied before tax

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Requirements Implemented

• ✅ All classes are defined using OOP principles:
  • Inheritance
  • Encapsulation
  • Abstraction
  • Polymorphism
• ✅ Mock methods serve as API calls for:
  • Customers
  • Items
  • Orders
  • Discounts
• ✅ A central logic calculates the total cost of purchase for a given list of items and a customer ID
• ✅ UI includes a button to simulate an order and display the total after applying discounts and VAT

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Features

• Product-level discounts (FixedDiscount, PercentageDiscount)
• Overall-level discounts (OverallDiscount) based on customer loyalty
• 11% VAT is calculated after all discounts