🤖 AI Code Review Bot (Gemini)

A GitHub Action that automatically reviews pull requests using Google's Gemini AI API. This bot provides intelligent, constructive feedback on code changes to help improve code quality and catch potential issues early.

✨ Features

• Intelligent Code Review: Uses Google's Gemini 1.5 Flash model for comprehensive code analysis
• Smart File Filtering: Automatically excludes lock files, large files, and other non-reviewable content
• Detailed Feedback: Provides structured feedback covering code quality, security, performance, and best practices
• Rich Context: Includes PR title, description, and change statistics in the review
• Professional Formatting: Well-formatted comments with emojis and clear structure
• Error Handling: Robust error handling with detailed logging
• Configurable: Easy to customize and extend

🚀 Quick Start

1. Get a Gemini API Key

1. Go to Google AI Studio
2. Create a new API key
3. Copy the key for later use

2. Set up the GitHub Action

Create a .github/workflows/ai-review.yml file in your repository:

name: AI Code Review

on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  ai-review:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write
    steps:
      - name: AI Code Review
        uses: your-username/ai-code-review-bot@main
        with:
          gemini_api_key: ${{ secrets.GEMINI_API_KEY }}

3. Add the API Key as a Secret

1. Go to your repository's Settings → Secrets and variables → Actions
2. Click New repository secret
3. Name: GEMINI_API_KEY
4. Value: Your Gemini API key from step 1

📋 Usage

The action will automatically run on:

• New pull requests (opened)
• New commits to existing PRs (synchronize)
• Reopened pull requests (reopened)

Inputs

Input	Description	Required	Default
gemini_api_key	Your Gemini API key	No*	-

*Required if GEMINI_API_KEY environment variable is not set

Example Output

The bot will post a comment like this on your PR:

🤖 AI Code Review

📊 Review Summary:
- Files reviewed: 3/5
- Total changes: 45 lines
- Files excluded: 2 (large files, lock files, etc.)

## Overall Assessment
The changes look good overall with some minor improvements needed...

## Specific Issues
1. **Line 23**: Consider adding input validation...
2. **Line 45**: This function could benefit from error handling...

## Suggestions for Improvement
- Add JSDoc comments for better documentation
- Consider extracting the validation logic into a separate function
- Add unit tests for the new functionality

## Security Considerations
- No security issues detected
- Input sanitization looks appropriate

## Performance Implications
- The new caching mechanism should improve performance
- Consider memoization for expensive calculations

🔧 Configuration

File Filtering

The bot automatically excludes certain file types from review:

• Lock files: package-lock.json, yarn.lock, pnpm-lock.yaml
• Minified files: *.min.js, *.min.css
• Bundle files: *.bundle.js, *.bundle.css
• System files: .DS_Store, .log, .tmp, .temp
• Large files: Files larger than 50,000 characters

Customization

You can customize the bot by modifying the source code:

1. Review Prompt: Edit the createReviewPrompt function to change how the AI analyzes code
2. File Filtering: Modify EXCLUDED_FILE_PATTERNS to include/exclude different file types
3. File Size Limit: Change MAX_FILE_SIZE to adjust the maximum file size for review
4. AI Model: Switch to a different Gemini model by changing the API endpoint

🛠️ Development

Prerequisites

• Node.js 20+
• npm or yarn
• TypeScript

Setup

1. Clone the repository:

git clone https://github.com/your-username/ai-code-review-bot.git
cd ai-code-review-bot

2. Install dependencies:

npm install

3. Build the project:

npm run build

Scripts

• npm run build - Build the TypeScript code and bundle with ncc
• npm run build:watch - Build in watch mode for development
• npm run clean - Remove the dist directory

Project Structure

├── src/
│   └── index.ts          # Main action code
├── dist/                 # Built files (generated)
├── action.yml            # GitHub Action metadata
├── package.json          # Dependencies and scripts
├── tsconfig.json         # TypeScript configuration
└── README.md            # This file

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Make your changes
4. Build and test: npm run build
5. Commit your changes: git commit -m 'Add amazing feature'
6. Push to the branch: git push origin feature/amazing-feature
7. Open a Pull Request