prek/.github/workflows/pr-comment.yml

# This workflow comments on a PR with the results of the `cargo bloat check` performed in the performance workflow.
# This is a workaround for the limitations imposed by GitHub Actions on workflows triggered by pull requests from forked repositories.

# The restrictions apply to the pull_request event triggered by a fork opening a pull request in the upstream repository.
# - Events from forks cannot access secrets, except for the default GITHUB_TOKEN.
# - The GITHUB_TOKEN has read-only access when an event is triggered by a forked repository.
#
# These restrictions mean that during a pull_request event triggered by a forked repository,
# actions have no write access to GitHub resources and will fail on any attempt.
name: PR comment
on:
  workflow_run: # zizmor: ignore[dangerous-triggers]
    workflows: [Performance]
    types: [completed]
  workflow_dispatch:
    inputs:
      workflow_run_id:
        description: The CI workflow that triggers the workflow run
        required: true

permissions: {}

jobs:
  bloat-comment:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
    steps:
      - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7.0.0
        with:
          name: bloat-check-results
          path: /tmp/bloat-check/
          github-token: ${{ secrets.GITHUB_TOKEN }}
          run-id: ${{ github.event.workflow_run.id ||  github.event.inputs.workflow_run_id }}

      - name: Comment bloat check on PR
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
        with:
          script: |
            const fs = require('node:fs');
            const marker = '<!-- prek-bloat-check -->';
            const comparison = await fs.promises.readFile('/tmp/bloat-check/bloat-comparison.txt', 'utf8');
            const body = `${marker}\n${comparison}`;

            const { repo, owner } = context.repo;
            const prNumber = await fs.promises.readFile('/tmp/bloat-check/pr-number.txt', 'utf8').then(Number);

            const comments = await github.paginate(github.rest.issues.listComments, {
              owner,
              repo,
              issue_number: prNumber,
              per_page: 100,
            });

            const existing = comments.find((comment) => comment.body?.includes(marker));

            if (existing) {
              await github.rest.issues.updateComment({
                owner,
                repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner,
                repo,
                issue_number: prNumber,
                body,
              });
            }