name: Comment on pull request
on:
    workflow_run:
        workflows: ['Publish (PR)']
        types: [completed]
jobs:
    pr_comment:
        if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
        runs-on: ubuntu-latest
        steps:
            - uses: actions/github-script@v6
              with:
                  # This snippet is public-domain, taken from
                  # https://github.com/oprypin/nightly.link/blob/master/.github/workflows/pr-comment.yml
                  script: |
                      async function upsertComment(owner, repo, issue_number, purpose, body) {
                        const {data: comments} = await github.rest.issues.listComments(
                          {owner, repo, issue_number});
                        const marker = `<!-- bot: ${purpose} -->`;
                        body = marker + "\n" + body;
                        const existing = comments.filter((c) => c.body.includes(marker));
                        if (existing.length > 0) {
                          const last = existing[existing.length - 1];
                          core.info(`Updating comment ${last.id}`);
                          await github.rest.issues.updateComment({
                            owner, repo,
                            body,
                            comment_id: last.id,
                          });
                        } else {
                          core.info(`Creating a comment in issue / PR #${issue_number}`);
                          await github.rest.issues.createComment({issue_number, body, owner, repo});
                        }
                      }
                      const {owner, repo} = context.repo;
                      const run_id = ${{github.event.workflow_run.id}};
                      const pull_requests = ${{ toJSON(github.event.workflow_run.pull_requests) }};
                      if (!pull_requests.length) {
                        return core.error("This workflow doesn't match any pull requests!");
                      }
                      const artifacts = await github.paginate(
                        github.rest.actions.listWorkflowRunArtifacts, {owner, repo, run_id});
                      if (!artifacts.length) {
                        return core.error(`No artifacts found`);
                      }
                      let body = `Download the artifacts for this pull request:\n`;
                      for (const art of artifacts) {
                        body += `\n* [${art.name}.zip](https://nightly.link/${owner}/${repo}/actions/artifacts/${art.id}.zip)`;
                      }
                      core.info("Review thread message body:", body);
                      for (const pr of pull_requests) {
                        await upsertComment(owner, repo, pr.number,
                          "nightly-link", body);
                      }