Building a PR Complexity Score Bot with OpenAI and GitHub Webhooks

1function canAccessFeature(user) {
2  if (!user) {
3    return false;                  // Decision 1
4  }
5  if (user.role === "admin") {     // Decision 2
6    return true;
7  } else {
8    if (user.subscription) {       // Decision 3
9      if (user.subscription.active) {     // Decision 4
10        if (user.permissions.includes("feature_access")) { // Decision 5
11          return true;
12        }
13      }
14    }
15  }
16  return false;
17}

1function canAccessFeature(user) {
2  if (!user) return false;
3  if (user.role === "admin") return true;
4  if (!user.subscription?.active) return false;
5  return user.permissions.includes("feature_access");
6}

1mkdir github - pr - complexity - bot
2cd github - pr - complexity - bot
3npm init - y
4npm install @octokit/rest openai dotenv express

1const express = require('express');
2const { Octokit } = require('@octokit/rest');
3const { computePRComplexityScore, calculateCyclomaticComplexity } = require('../utils/complexity');
4
5const router = express.Router();
6const octokit = new Octokit({ auth: process.env.GITHUB_TOKEN });
7
8router.post('/webhook', async (req, res) => {
9  try {
10    const { pull_request, repository, action } = req.body;
11
12    if (!pull_request || !['opened', 'ready_for_review'].includes(action)) {
13      return res.status(400).send('Not a relevant PR event');
14    }
15
16    const owner = repository.owner.login;
17    const repo = repository.name;
18    const prNumber = pull_request.number;
19
20    // Fetch PR Files and Changes
21    const { data: files } = await octokit.pulls.listFiles({ owner, repo, pull_number: prNumber });
22    const totalFilesChanged = files.length;
23    const totalLinesAdded = files.reduce((sum, file) => sum + (file.additions || 0), 0);
24    const totalLinesRemoved = files.reduce((sum, file) => sum + (file.deletions || 0), 0);
25
26    // Compute Cyclomatic Complexity
27    const fileDiffs = files.map(f => f.patch || '').join('\n');
28    const cyclomaticComplexity = calculateCyclomaticComplexity(fileDiffs);
29
30    // Compute PR Complexity Score
31    const prComplexity = computePRComplexityScore({
32      filesChanged: totalFilesChanged,
33      linesAdded: totalLinesAdded,
34      linesRemoved: totalLinesRemoved,
35      cyclomaticComplexity
36    });
37
38    // Post a Comment on the PR
39    const complexityComment = `
40📊 **PR Complexity Score: ${prComplexity}/10**
41- 📝 **Files Changed:** ${totalFilesChanged}
42- ➕ **Lines Added:** ${totalLinesAdded}
43- ➖ **Lines Removed:** ${totalLinesRemoved}
44- 🔄 **Cyclomatic Complexity:** ${cyclomaticComplexity}
45
46🚀 **What This Means:**
47${prComplexity < 4 ? '🟢 Low complexity—should be easy to review ✅' : prComplexity < 7 ? '🟡 Moderate complexity—review carefully! 🧐' : '🔴 High complexity—consider breaking this into smaller PRs! ⚠️'}
48`;
49
50    await octokit.issues.createComment({ owner, repo, issue_number: prNumber, body: complexityComment });
51
52    res.status(200).send('PR Complexity Score added');
53  } catch (error) {
54    console.error(error);
55    res.status(500).send('Something went wrong');
56  }
57});
58
59module.exports = router;

1function computePRComplexityScore({ filesChanged, linesAdded, linesRemoved, cyclomaticComplexity }) {
2  const weightFiles = 2;
3  const weightLines = 1;
4  const weightComplexity = 3;
5
6  const scoreFiles = Math.min((filesChanged / 10) * weightFiles, 10);
7  const scoreLines = Math.min(((linesAdded + linesRemoved) / 500) * weightLines, 10);
8  const scoreComplexity = Math.min((cyclomaticComplexity / 10) * weightComplexity, 10);
9
10  return Math.min((scoreFiles + scoreLines + scoreComplexity) / (weightFiles + weightLines + weightComplexity) * 10, 10).toFixed(1);
11}
12
13function calculateCyclomaticComplexity(code) {
14  const controlStructures = /(\bif\b|\belse if\b|\bfor\b|\bwhile\b|\bswitch\b|\bcase\b)/g;
15  return (code.match(controlStructures) || []).length + 1;
16}
17
18module.exports = { computePRComplexityScore, calculateCyclomaticComplexity };