Scala Rule Engine 🚀

A high-performance rule engine for applying complex business rules to transaction data, written in pure functional Scala.

Key Features ✨

• Rule Composition: Combine multiple discount rules with custom logic
• Dynamic Evaluation: Rules evaluated at runtime based on transaction attributes
• Batch Processing: Efficiently process 1,000+ transactions
• Oracle Integration: JDBC-based data persistence
• Audit Logging: Detailed execution logs for every transaction
• Pure Functions: Immutable data structures and side-effect-free logic

Rule Catalog

Function Name	Description	Example Application
calculateExpiryDiscount	Calculates a discount based on how close the product is to expiration.	A product expiring in 29 days gets 1% off, expiring in 1 day gets 29% off.
categoryDiscount	Applies a discount for specific product types (cheese or wine).	"Cheddar Cheese" → 10% discount, "Red Wine" → 5% discount.
march23rdDiscount	Applies a special 50% discount for purchases on March 23rd.	Any item bought on 23rd March gets 50% off.
quantityDiscount	Applies a bulk discount based on how many units are bought.	Buying 12 units → 7% discount, buying 6 units → 5% discount.
channelDiscount	Applies a discount for app purchases based on quantity (rounded to 5).	Buying 7 units through app → 10% discount, 12 units → 15% discount.
cardDiscount	Applies a 5% discount for purchases made using Visa card.	Any product purchased with Visa → 5% discount.

Rule Composition Strategy: Applies the average of the top two eligible discounts per transaction.

Tech Stack 🛠️

• Language: Scala (Functional Programming)
• Build Tool: sbt
• Database: Oracle (JDBC)

Getting Started

Prerequisites

• Java 8+
• sbt 1.10.3
• scala 2.13.13
• Oracle Database (or Docker container)

Installation

git clone https://github.com/yourusername/scala_rule_engine.git
cd scala_rule_engine

Run the Project

1. Open a terminal in your project directory.
2. Execute:

   sbt run
   

Project Structure:

Project Directory Structure:
src/main/scala/code/
├── Main.scala               - Application entry point
├── models/
│   ├── TransactionModels.scala  
├── services/
│   ├── TransactionProcessing.scala 
│   ├── DatabaseService.scala    
│   ├── DiscountService.scala    
│   └── FileService.scala        
├── transformers/              
│   ├── TransformTransaction.scala  
└── utils/
    └── LoggerUtils.scala    

Database Schema

The application expects the following table:

CREATE TABLE discounted_transactions (
  timestamp TIMESTAMP,
  product_name VARCHAR2(100),
  expiry_date DATE,
  quantity NUMBER,
  unit_price NUMBER(10,2),
  channel VARCHAR2(20),
  payment_method VARCHAR2(20),
  discount NUMBER(5,2),
  final_price NUMBER(10,2)
);

Logging The application generates detailed logs in rules_engine.log:

2025-05-17T19:58:58.7708005 INFO Starting transaction processing application
2025-05-17T19:58:58.7746673 INFO Starting transaction processing
2025-05-17T19:58:59.6603174 INFO Database connection established
2025-05-17T19:58:59.6623348 INFO Reading transactions from D:\iti\Scala_rule_engine\src\main\scala\data\TRX1000.csv
2025-05-17T19:58:59.6925342 INFO Read 1000 transactions
``