Lit - A Lightweight Version Control System

Lit is a simple, Git-inspired version control system built in JavaScript. It provides basic version control functionality through a command-line interface, implementing core Git concepts like staging, committing, and viewing history.

Features

• Repository Management: Initialize new repositories with lit init
• Staging Area: Add files to staging with lit add <file>
• Commits: Create commits with descriptive messages
• History: View commit history and changes with lit log
• Diff Viewing: See changes between commits with lit show <commit-hash>
• Content Addressing: Files and commits are stored using SHA-1 hashes

Prerequisites

• Node.js (version 14 or higher)
• npm (comes with Node.js)

Installation

Option 1: Install Globally (Recommended)

1. Clone the repository:

git clone <repository-url>
cd lit-vcs

2. Install dependencies:

npm install

3. Install the lit command globally:

npm install -g .

Now you can use lit from anywhere in your system!

Option 2: Development Setup

1. Clone and install dependencies:

git clone <repository-url>
cd lit-vcs
npm install

2. Create a symlink for development:

npm link

3. Make the script executable:

chmod +x main.mjs

Usage

Initialize a Repository

lit init

Creates a new .lit repository in the current directory. This sets up the internal structure needed for version control.

Add Files to Staging Area

lit add <filename>

Adds the specified file to the staging area. The file content is hashed and stored in the objects directory.

Example:

lit add main.js
lit add README.md

Commit Changes

lit commit "Your commit message here"

Creates a commit with all files currently in the staging area. The staging area is cleared after a successful commit.

Example:

lit commit "Add initial project setup"
lit commit "Fix bug in file handling"

View Commit History

lit log

Displays a chronological history of all commits, showing commit hashes, timestamps, and messages.

Show Commit Diff

lit show <commit-hash>

Shows the differences introduced in the specified commit, displaying added lines in green and removed lines in red.

Example:

lit show abc123def456

Project Structure

When you initialize a repository, Lit creates the following structure:

.lit/
├── objects/     # Stores file content and commit objects (SHA-1 hashed)
├── HEAD         # Points to the current commit hash
└── index        # Tracks staged files (JSON format)

How It Works

Lit implements a simplified version of Git's internal model:

1. Content Addressing: All file content is hashed using SHA-1 and stored in the objects/ directory
2. Staging Area: The index file tracks which files are staged for the next commit
3. Commits: Each commit contains metadata (timestamp, message, parent) and references to file hashes
4. History: Commits form a linked list, with each commit pointing to its parent
5. HEAD: The HEAD file always points to the latest commit

Example Workflow

# Initialize a new repository
lit init

# Add some files
lit add main.js
lit add package.json

# Make your first commit
lit commit "Initial project setup"

# Make some changes to files, then add and commit again
lit add main.js
lit commit "Add new feature"

# View your commit history
lit log

# See what changed in the last commit
lit show <latest-commit-hash>

Development

Project Structure

lit-vcs/
├── main.mjs          # Main CLI application
├── package.json      # Project configuration and dependencies
└── README.md         # This file

Dependencies

• commander: Command-line interface framework
• chalk: Terminal color formatting
• diff: Text diffing functionality

Running Tests

Currently, the project doesn't have automated tests, but you can test functionality manually using the commands above.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

License

This project is licensed under the ISC License.

Acknowledgments

This project is inspired by Git and serves as a learning tool to understand version control system internals.