🛒 Simple E-Commerce Console App (Internship Task)

This is a Java-based console application that simulates a minimal e-commerce system.

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✅ Features

• Define products with:
  • Name, price, quantity
  • Optional expiry date
  • Optional weight for shipping
• Enforce validation rules via a rule-based system
• Calculate shipping cost based on product weight
• Print a full checkout invoice with itemized details

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📦 Product Types

• Product: Non-expirable, non-shippable
• ExpirableProduct: Has expiry date
• ShippableProduct: Has shipping weight
• ExpirableShippableProduct: Has both expiry and weight

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🧠 Business Rules

The system validates the following:

• Product name must not be empty
• Price must be positive
• Quantity must not be negative
• Expirable products must have a future expiry date
• Shippable products must have weight > 0
• Cart items cannot exceed available product quantity

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🛠 Technologies

• Java 23
• Object-Oriented Design
• Rule-based validation
• Factory pattern for product creation

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📁 Structure Overview

src/
└─ karim/
    ├─ models/
    ├─ rules/
    ├─ factories/
    ├─ services/user
    ├─ contracts/
    └─ Main.java

📌 Considerable notes

• Financial precision was considered by using BigDecimal for price calculations where needed.
• All rules are pluggable and reusable.
• Easily extendable for taxes, discounts, and more.

How to run application

# clone the repository
git clone https://github.com/yourusername/EcommerceSimulationSystem.git
cd EcommerceSimulationSystem