Pack Optimizer

Overview

This application solves the pack size optimization problem using dynamic programming and backtracking.
It determines the optimal combination of packs to fulfill orders while minimizing both the total number of items and the number of packs used.

Demo

A live demo is available at retask.tural.pro
Watch video demo on YouTube

Problem Statement

When a customer orders a specific quantity of items, the system needs to determine the best combination of available pack sizes to fulfill the order according to these rules:

1. Only complete packs can be sent (no partial packs)
2. The total number of items must be minimized (must be ≥ order amount)
3. The number of packs must be minimized (for the chosen minimum total items)

See the pdf file for the details of task

Features

Core Functionality

• Dynamic Pack Size Management: Pack sizes are flexible and can be added or removed through API
• Optimal Solution Algorithm: Uses dynamic programming with backtracking to find the most efficient pack combination
• Interactive UI: User-friendly interface to interact with the API
• RESTful API: Clean API endpoints for all operations

Technical Features

• TLS Support: Secure communication over HTTPS
• Graceful Shutdown: The server stops accepting new requests while allowing in-flight requests to complete
• Panic Recovery: Middleware that catches panics and converts them to proper error responses
• Health Check Endpoint: Monitoring endpoint for system health
• Rate Limiting: Protection against excessive requests
• Dynamic CORS Settings: Configurable trusted origins via command-line flags
• Metrics Endpoint: Protected metrics endpoint accessible via localhost
• Database Migrations: Version-controlled database schema using migration files
• SQLite Database: Lightweight, portable database solution

Technology Stack

• Backend: Go 1.24+
• Database: SQLite with migration support
• Router: julienschmidt/httprouter
• Rate Limiting: golang.org/x/time/rate
• Structured Logging: log/slog
• Metrics: expvar

API Endpoints

Method	Endpoint	Description
GET	/	User interface
GET	/v1/healthcheck	Health check endpoint
GET	/v1/pack/calculate/:size	Calculate optimal pack combination for given order size
GET	/v1/pack/size	Get all available pack sizes
POST	/v1/pack/size	Add a new pack size
DELETE	/v1/pack/size/:size	Delete a pack size
GET	/debug/vars	Metrics endpoint (localhost only)

Getting Started

Prerequisites

• Go 1.24 or higher
• SQLite

Installation

1. Clone the repository

    git clone https://github.com/TuralAsgar/retask.git

2. Configure the environment:

   cp .envrc-example .envrc
   

3. Run database migrations:

   make db/migrations/up
   

4. Build and run the application:

   make run/api
   

Configuration

The application can be configured using the following command-line flags:

• port: API server port (default: 4004)
• env: Environment (development|staging|production)
• db-dsn: SQLite database path
• cors-trusted-origins: Trusted CORS origins (space separated)
• limiter-enabled: Enable rate limiter
• limiter-rps: Rate limiter maximum requests per second
• limiter-burst: Rate limiter maximum burst

Deployment

1. Cross-build the application

   make build/api

2. Deploy

   make production/deploy/api

Future Improvements

• Adding OpenAPI/Swagger documentation for the API
• Extracting code into more packages as the project grows
• Adding authentication and authorization
• Implementing CI/CD pipelines