Requirements

Imagine we're building a system that allows users to compare products from different vendors based on various pricing strategies. This isn't just about displaying the cheapest option; we need to account for promotions, discounts, shipping costs, and potentially even user-specific pricing tiers. We aim to provide a flexible and extensible system where new pricing strategies and product attributes can be easily added without disrupting the existing codebase. Furthermore, the system should efficiently handle concurrent requests from multiple users comparing products simultaneously. We need to ensure data integrity and prevent race conditions during pricing calculations. The core challenge is to design a robust and maintainable system that adheres to SOLID principles and allows for future expansion of pricing models and product features. # Requirements ## Functional Requirements 1. **Product Definition:** The system must allow for the definition of products with attributes such as name, description, base price, and a list of applicable pricing rules. Each product has to have a unique identifier. 2. **Pricing Rule Definition:** The system must support various pricing rules, including: * **Discount Rules:** Percentage discounts, fixed amount discounts, and conditional discounts (e.g., "buy one get one free"). * **Shipping Cost Rules:** Fixed shipping costs, weight-based shipping costs, and free shipping options. * **Promotional Rules:** Rules that apply during specific time periods or based on user roles. * **Tax Rules:** Rules for calculating sales tax based on location. * **Volume Discounts:** Discounts based on the quantity of products purchased. 3. **Dynamic Pricing:** Pricing should be calculated dynamically based on the defined rules. The order of rule application should be configurable. 4. **Product Comparison:** The system should allow users to compare multiple products based on their calculated prices. This should include the ability to sort products by price and display price breakdowns (e.g., base price, discount, shipping cost, tax). 5. **Rule Prioritization:** Users should be able to define the order in which pricing rules are applied. This allows for complex pricing scenarios where the order of rule application affects the final price. 6. **Concurrency:** Multiple users should be able to request product comparisons concurrently without data corruption or race conditions. The pricing calculation process must be thread-safe. 7. **Audit Trail:** The system should maintain an audit trail of pricing calculations, including the rules that were applied and the resulting price adjustments. ## Non-Functional Requirements 1. **Extensibility:** The system should be easily extensible to support new product attributes, pricing rules, and discount types without requiring significant code changes. Favor composition over inheritance. 2. **Modularity:** The system should be designed with clear separation of concerns, allowing for independent development and testing of different modules. 3. **Testability:** The codebase should be designed to be easily testable, with clear interfaces and minimal dependencies between modules. Aim for high code coverage. 4. **Thread Safety:** The pricing calculation logic must be thread-safe to handle concurrent requests from multiple users. Utilize appropriate synchronization mechanisms (e.g., locks, atomic variables, immutable objects) to prevent race conditions. 5. **Performance:** The system should efficiently calculate prices for multiple products, even with a large number of pricing rules. Optimize data structures and algorithms to minimize processing time. 6. **Maintainability:** The codebase should be well-documented and easy to understand, making it easy to maintain and debug. 7. **SOLID Principles:** The design must adhere to the SOLID principles of object-oriented design. 8. **Configuration:** The pricing rule order and other system parameters should be configurable without requiring code changes (e.g., using a configuration file or database). ## Core Entities 1. **Product:** Represents a product with attributes like ID, name, description, and base price. 2. **PricingRule:** An abstract class or interface representing a pricing rule. Concrete implementations include DiscountRule, ShippingCostRule, PromotionalRule, and TaxRule. 3. **DiscountRule:** A specific type of pricing rule that applies a discount to the product price. 4. **ShippingCostRule:** A specific type of pricing rule that calculates shipping costs. 5. **PromotionalRule:** A specific type of pricing rule that applies a promotion. 6. **TaxRule:** A specific type of pricing rule that calculates taxes. 7. **PricingContext:** Holds the context for pricing calculations, including the product, user, and other relevant information. 8. **PricingEngine:** Orchestrates the pricing calculation process by applying the pricing rules in the specified order. 9. **RuleEngine:** An engine that manages rule executions and allows for customization.

Design pricing / product comparision system.

Requirements

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Functional Requirements

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Non-Functional Requirements

Core Entity Identification

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