code-review.yaml

name: AI Code Reviewer

on:
  issue_comment:
    types: [created]

permissions:
  contents: read
  pull-requests: write
  issues: write

jobs:
  gemini-code-review:
    runs-on: ubuntu-latest
    if: |
      github.event.issue.pull_request &&
      contains(github.event.comment.body, '/gemini-review')
    steps:
      - name: Checkout Repo
        uses: actions/checkout@v3

      - name: Set up Python
        uses: actions/setup-python@v4
        with:
          python-version: '3.10'

      - name: Install Google Gen AI SDK
        run: pip install google-generativeai

      - name: Run Gemini Code Review
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
          PR_NUMBER: ${{ github.event.issue.number }}
          REPO: ${{ github.repository }}
        run: |
          python -c "
          import os
          import subprocess
          import google.generativeai as genai

          # 1. Setup Gemini
          genai.configure(api_key=os.environ['GEMINI_API_KEY'])
          model = genai.GenerativeModel('gemini-1.5-flash')

          # 2. Get the PR Diff using GitHub CLI
          pr_num = os.environ['PR_NUMBER']
          repo = os.environ['REPO']
          print(f'Fetching diff for PR #{pr_num} in {repo}...')
          
          # Get the diff text
          diff_cmd = ['gh', 'pr', 'diff', pr_num, '--repo', repo]
          process = subprocess.run(diff_cmd, capture_output=True, text=True)
          diff_text = process.stdout

          if not diff_text:
              print('No diff found or error fetching diff.')
              exit(1)

          # Limit diff size to prevent token overflow (simple truncation)
          if len(diff_text) > 30000:
              diff_text = diff_text[:30000] + '\n...(truncated)...'

          # 3. Ask Gemini to review
          prompt = f'''
          You are an expert Senior Software Engineer. Review the following code diff.
          Focus on:
          1. Security vulnerabilities.
          2. Potential bugs.
          3. Performance improvements.
          4. Code cleanliness/Best practices.
          
          Be concise and constructive.

          Code Diff:
          {diff_text}
          '''
          
          print('Sending to Gemini...')
          response = model.generate_content(prompt)
          review_text = response.text

          # 4. Post the review as a comment
          print('Posting comment...')
          comment_cmd = ['gh', 'pr', 'comment', pr_num, '--repo', repo, '--body', review_text]
          subprocess.run(comment_cmd, check=True)
          print('Review posted!')
          "