pr-triage.yml

name: PR Triage

on:
  pull_request:
    types: [opened, edited, synchronize, reopened, ready_for_review, converted_to_draft]

jobs:
  triage:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
      issues: write
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Triage PR
        uses: actions/github-script@v9
        with:
          script: |
            const pr = context.payload.pull_request;
            const title = pr.title;
            const author = pr.user.login;
            const isDraft = pr.draft || /\bwip\b/i.test(title) || title.toLowerCase().startsWith('draft');

            let labelsToAdd = [];
            let labelsToRemove = [];

            // 1. Handle Draft / WIP
            if (isDraft) {
              labelsToAdd.push('do-not-merge');
            } else {
              labelsToRemove.push('do-not-merge');
            }

            // 2. Title Linter & Priority Labeling
            const titleRegex = /^(fix|bug|security|feat|docs|style|refactor|perf|test|chore)(\(.+\))?:\s.+/i;
            const match = titleRegex.exec(title);
            let isValidTitle = false;
            let titlePrefix = "";

            if (match) {
              isValidTitle = true;
              titlePrefix = match[1].toLowerCase();
            }

            if (!isValidTitle) {
              const commentBody = `@${author} The PR title format is invalid. Please use the Conventional Commits format:\n\n\`<type>[optional scope]: <description>\`\n\nValid types are: \`fix\`, \`bug\`, \`security\`, \`feat\`, \`docs\`, \`style\`, \`refactor\`, \`perf\`, \`test\`, \`chore\`.\n\nExample: \`fix: resolve crash on startup\``;

              // Check if we already commented to avoid spamming
              const comments = await github.paginate(github.rest.issues.listComments, {
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: pr.number,
              });

              const hasCommented = comments.some(c => c.body.includes('The PR title format is invalid') && c.user.login === 'github-actions[bot]');

              if (!hasCommented) {
                await github.rest.issues.createComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: pr.number,
                  body: commentBody
                });
              }
              core.setFailed('Invalid PR title format.');
              return; // Stop execution if title is invalid
            } else {
              // Add priority based on prefix
              if (['fix', 'bug'].includes(titlePrefix)) {
                labelsToAdd.push('priority/high');
                labelsToRemove.push('priority/critical', 'priority/medium', 'priority/low');
              } else if (titlePrefix === 'security') {
                labelsToAdd.push('priority/critical');
                labelsToRemove.push('priority/high', 'priority/medium', 'priority/low');
              } else {
                labelsToAdd.push('priority/medium');
                labelsToRemove.push('priority/critical', 'priority/high', 'priority/low');
              }
            }

            // 3. Size Labeling
            const additions = pr.additions;
            const deletions = pr.deletions;
            const totalChanges = additions + deletions;

            let sizeLabel = '';
            if (totalChanges < 200) {
              sizeLabel = 'size/small';
              labelsToRemove.push('size/medium', 'size/large');
            } else if (totalChanges <= 700) {
              sizeLabel = 'size/medium';
              labelsToRemove.push('size/small', 'size/large');
            } else {
              sizeLabel = 'size/large';
              labelsToRemove.push('size/small', 'size/medium');
            }
            labelsToAdd.push(sizeLabel);

            // 4. Missing Tests Detection
            const files = await github.paginate(github.rest.pulls.listFiles, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: pr.number,
            });

            let sourceChanged = false;
            let testsChanged = false;

            for (const file of files) {
              const filename = file.filename.toLowerCase();
              if ((filename.endsWith('.c') || filename.endsWith('.h')) && !filename.includes('test')) {
                sourceChanged = true;
              }
              if (filename.includes('test') && (filename.endsWith('.c') || filename.endsWith('.h'))) {
                testsChanged = true;
              }
            }

            if (sourceChanged && !testsChanged) {
              labelsToAdd.push('needs-tests');
            } else {
              labelsToRemove.push('needs-tests');
            }

            // 5. Apply Labels
            if (labelsToAdd.length > 0) {
              // Remove duplicates
              labelsToAdd = [...new Set(labelsToAdd)];

              // Ensure labels exist before applying (optional, but good practice to avoid errors if label doesn't exist, though Github API usually auto-creates or we can ignore)
              try {
                await github.rest.issues.addLabels({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: pr.number,
                  labels: labelsToAdd
                });
              } catch (e) {
                console.log('Error adding labels:', e);
              }
            }

            // Remove old labels
            if (labelsToRemove.length > 0) {
              const currentLabels = pr.labels.map(l => l.name);
              for (const label of labelsToRemove) {
                if (currentLabels.includes(label)) {
                  try {
                    await github.rest.issues.removeLabel({
                      owner: context.repo.owner,
                      repo: context.repo.repo,
                      issue_number: pr.number,
                      name: label
                    });
                  } catch (e) {
                    console.log(`Could not remove label ${label}:`, e);
                  }
                }
              }
            }