MyGit

MyGit is a simple implementation of a version control system inspired by Git. This project aims to provide a basic understanding of how Git works under the hood by implementing core functionalities such as initializing a repository, managing objects, committing changes, and cloning repositories.

Features

• Initialize a Repository: Create a new Git repository with the necessary directory structure.
• Manage Git Objects: Read, write, and hash Git objects (blobs, trees, commits).
• Commit Changes: Create commit objects with associated metadata.
• Clone Repositories: Clone a remote Git repository and check out files.
• Checkout Commits: Restore files from a specific commit.

Installation

To install MyGit, clone the repository and build the application:

git clone <repository-url>
cd mygit
go build -o mygit ./cmd/mygit

Usage

After building the application, you can use it from the command line:

./mygit <command> [<args>...]

Commands

• init: Initializes a new Git repository.
• cat-file -p <hash>: Displays the content of a Git object.
• hash-object -w <file>: Computes the hash of a file and optionally writes it as a Git object.
• ls-tree --name-only <tree_hash>: Lists the files in a tree object.
• write-tree: Writes the current directory structure as a tree object.
• commit-tree <tree_sha> -p <parent_sha> -m <message>: Creates a new commit object.
• clone <repo-url> <dir>: Clones a remote repository into the specified directory.

Project Structure

codecrafters-git-go/
├── cmd/
│   └── mygit/
│       └── main.go           # Main entry point and CLI handling
├── internal/
│   ├── objects/              # Git object operations
│   │   └── objects.go        # Read/write objects, tree operations, commits
│   ├── pack/                 # Pack file handling
│   │   └── pack.go           # Pack file parsing and unpacking
│   ├── protocol/             # Git Smart HTTP protocol
│   │   └── git_http.go       # HTTP communication, refs discovery
│   └── clone/                # Clone orchestration
│       └── clone.go          # High-level clone workflow
└── go.mod                    # Go module definition

Module Overview

1. internal/objects - Git Object Operations

• Purpose: Handle all Git object types (blobs, trees, commits, tags)
• Key Functions:
  • ReadObject() / WriteObject() - Core object I/O
  • HashObject() - Object hashing and storage
  • CatFile() - Display object contents
  • LsTree() / ParseTree() - Tree operations
  • WriteTree() - Create tree objects from filesystem
  • CommitTree() - Create commit objects
  • CheckoutTree() - Extract tree to working directory

2. internal/protocol - Git Smart HTTP Protocol

• Purpose: Handle Git's Smart HTTP transfer protocol
• Key Functions:
  • DiscoverRefs() - Query repository references
  • NegotiatePackfile() - Request and receive pack data
  • FindDefaultRef() - Determine default branch
• Types: GitRef - Represents Git references

3. internal/pack - Pack File Operations

• Purpose: Parse and unpack Git pack files
• Key Functions:
  • UnpackPackfile() - Main pack file processing
  • parsePackObject() - Individual object parsing
  • Delta object handling (basic framework)
• Types: PackObject - Represents pack file objects

4. internal/clone - Clone Orchestration

• Purpose: Coordinate the complete clone workflow
• Key Functions:
  • Clone() - Main clone function
  • initializeGitRepo() - Set up repository structure
  • updateRefs() - Configure branches and refs
  • checkoutWorkingTree() - Extract files to working directory

5. cmd/mygit - Main Entry Point

• Purpose: CLI interface and command routing
• Features:
  • Command-line argument parsing
  • Error handling and user feedback
  • Integration of all internal packages

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any improvements or bug fixes.

License

This project is licensed under the MIT License. See the LICENSE file for details.