name: Check pull request template

# Runs on pull_request_target so the token can comment, label, and close pull
# requests that come from forks. Only the base branch is checked out, and the
# script reads nothing but the pull request body, so the head commit never runs.
on:
  pull_request_target:
    types: [opened, edited, reopened]

permissions:
  pull-requests: write

jobs:
  template:
    if: >-
      github.event.pull_request.user.login != 'wsvincent' &&
      github.event.pull_request.user.login != 'jefftriplett' &&
      github.event.pull_request.user.login != 'dependabot[bot]'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          ref: ${{ github.event.repository.default_branch }}
          sparse-checkout: .github/scripts

      - uses: actions/github-script@v7
        with:
          script: |
            const { checkTemplate } = require("./.github/scripts/check-pr-template.js");
            const pr = context.payload.pull_request;
            const { owner, repo } = context.repo;
            const issue_number = pr.number;
            const LABEL = "needs-template";
            const MARKER = "<!-- pr-template-check -->";
            const { missing, company } = checkTemplate(pr.body);

            const { data: comments } = await github.rest.issues.listComments({ owner, repo, issue_number, per_page: 100 });
            const existing = comments.find((c) => c.body && c.body.includes(MARKER));

            async function say(body) {
              body = `${MARKER}\n${body}`;
              if (existing) {
                await github.rest.issues.updateComment({ owner, repo, comment_id: existing.id, body });
              } else {
                await github.rest.issues.createComment({ owner, repo, issue_number, body });
              }
            }

            if (missing.length) {
              const list = missing.map((m) => `- ${m}`).join("\n");
              await say(
                `Thanks for the submission! This pull request does not fill out the ` +
                `[pull request template](https://github.com/${owner}/${repo}/blob/main/.github/pull_request_template.md), ` +
                `so it was closed automatically.\n\nMissing:\n${list}\n\n` +
                `Edit the pull request description to add the missing items. ` +
                `The check runs again on every edit and reopens the pull request when the template is complete.`
              );
              await github.rest.issues.addLabels({ owner, repo, issue_number, labels: [LABEL] });
              if (pr.state === "open") {
                await github.rest.pulls.update({ owner, repo, pull_number: issue_number, state: "closed" });
              }
              return;
            }

            const hadLabel = pr.labels.some((l) => l.name === LABEL);
            if (hadLabel) {
              await github.rest.issues.removeLabel({ owner, repo, issue_number, name: LABEL }).catch(() => {});
              if (pr.state === "closed" && !pr.merged_at) {
                await github.rest.pulls.update({ owner, repo, pull_number: issue_number, state: "open" });
              }
            }

            let note = "The pull request template is complete. Thanks! A maintainer will review it.";
            if (company) {
              note +=
                `\n\nThis submission is on behalf of a company. Please read the ` +
                `[commercial products and services](https://github.com/${owner}/${repo}/blob/main/contributing.md#commercial-products-and-services) ` +
                `section of the contribution guidelines.`;
            }
            if (existing || company) await say(note);