pr-label-inheritance.yml

name: PR Label Inheritance

on:
  pull_request_target:
    types: [opened, edited, reopened]

permissions:
  issues: read
  pull-requests: write

jobs:
  inherit-labels:
    runs-on: ubuntu-latest
    steps:
      - name: Inherit Labels from Linked Issues
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const prNumber = context.issue.number;
            const prBody = context.payload.pull_request.body || '';
            const prCreatedAt =
              new Date(context.payload.pull_request.created_at);

            console.log(`Processing PR #${prNumber}`);
            console.log(`PR created at: ${prCreatedAt}`);

            // Extract issue numbers from PR body
            // Matches patterns like:
            // Fixes #123, Closes #456, Resolves #789, etc.
            const issuePattern =
              /(?:close[sd]?|fix(?:e[sd])?|resolve[sd]?)\s+#(\d+)/gi;
            const matches = [...prBody.matchAll(issuePattern)];
            const issueNumbers = matches.map(match => parseInt(match[1]));

            const foundIssues = issueNumbers.join(', ') || 'none';
            console.log(`Found linked issues: ${foundIssues}`);

            // Collect all labels to add
            const labelsToAdd = new Set();

            // Fetch labels from linked issues
            for (const issueNumber of issueNumbers) {
              try {
                const issue = await github.rest.issues.get({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: issueNumber
                });

                const issueLabels = issue.data.labels.map(label =>
                  typeof label === 'string' ? label : label.name
                );

                const labelsList = issueLabels.join(', ') || 'none';
                console.log(`Issue #${issueNumber} has labels: ${labelsList}`);

                issueLabels.forEach(label => labelsToAdd.add(label));
              } catch (error) {
                console.log(`Could not fetch issue #${issueNumber}: ${error.message}`);
              }
            }

            // Add hacktoberfest-accepted label for PRs in October
            const month = prCreatedAt.getMonth(); // 0-indexed (9 = Oct)
            if (month === 9) { // October
              labelsToAdd.add('hacktoberfest-accepted');
              console.log('PR in October - adding hacktoberfest-accepted');
            }

            // Get current PR labels
            const pr = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: prNumber
            });

            const currentLabels = new Set(
              pr.data.labels.map(label =>
                typeof label === 'string' ? label : label.name
              )
            );

            // Filter out labels that are already on the PR
            const newLabels = [...labelsToAdd].filter(
              label => !currentLabels.has(label)
            );

            if (newLabels.length > 0) {
              console.log(`Adding labels to PR: ${newLabels.join(', ')}`);

              await github.rest.issues.addLabels({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: prNumber,
                labels: newLabels
              });

              console.log('Labels added successfully!');
            } else {
              console.log('No new labels to add');
            }