labels.yml

name: ci

on:
  pull_request_target:  # pull_request_target, NOT pull_request
    types: [opened, synchronize, reopened]

jobs:
  labels-by-language:
    runs-on: ubuntu-slim
    permissions:
      pull-requests: write  # So we can add labels to the pull request
    steps:  # Do NOT "uses: actions/checkout" here!
      - uses: actions/github-script@v9
        with:
          script: |
            const filenames = (await github.paginate(github.rest.pulls.listFiles, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number,
              per_page: 100,
            })).map(file => file.filename);
            console.log(filenames);

            const labels = new Set();
            for (const filename of filenames) {
              if (filename.endsWith('.lua')) labels.add('Scripting');
              else if (filename.endsWith('.py')) labels.add('Python');
            }
            console.log(labels);

            if (labels.size > 0) {
              github.rest.issues.addLabels({
                issue_number: context.issue.number,
                owner: context.repo.owner,
                repo: context.repo.repo,
                labels: Array.from(labels),
              })
            }