name: Pull request standards

on:
  pull_request_target: # zizmor: ignore[dangerous-triggers] -- safe: reads PR metadata from event payload only, no PR code checkout
    types:
      - opened
      - edited
      - reopened
      - ready_for_review
    branches:
      - dev

permissions: {}

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  check:
    name: Check pull request follows contribution standards
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write # To label and comment on pull requests
    steps:
      - name: Check pull request standards
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          script: |
            const pr = context.payload.pull_request;

            // Exempt bots (Copilot agent, dependabot), drafts, and maintainers.
            if (pr.user.type === "Bot") {
              core.info(`Skipping bot author: ${pr.user.login}`);
              return;
            }
            if (pr.draft) {
              core.info("Skipping draft pull request");
              return;
            }
            try {
              await github.rest.orgs.checkMembershipForUser({
                org: "home-assistant",
                username: pr.user.login,
              });
              core.info(`Skipping organization member: ${pr.user.login}`);
              return;
            } catch (error) {
              core.info(`${pr.user.login} is not an organization member, checking standards`);
            }

            const label = "Needs Template";
            const marker = "<!-- pr-standards-check -->";
            const { owner, repo } = context.repo;
            const issue_number = pr.number;

            const body = (pr.body || "").replace(/<!--[\s\S]*?-->/g, "");
            const normalized = body.toLowerCase();

            // Ignore 404s from mutations that race manual edits or cancelled runs.
            const ignoreMissing = async (fn) => {
              try {
                await fn();
              } catch (error) {
                if (error.status === 404) {
                  core.info("Target already removed, nothing to do");
                  return;
                }
                throw error;
              }
            };

            // Hide/restore our comment via GraphQL (REST cannot minimize).
            const setMinimized = async (subjectId, minimized) => {
              const mutation = minimized
                ? `mutation($id: ID!) {
                     minimizeComment(input: { subjectId: $id, classifier: RESOLVED }) {
                       clientMutationId
                     }
                   }`
                : `mutation($id: ID!) {
                     unminimizeComment(input: { subjectId: $id }) {
                       clientMutationId
                     }
                   }`;
              try {
                await github.graphql(mutation, { id: subjectId });
              } catch (error) {
                core.info(
                  `Could not ${minimized ? "minimize" : "restore"} comment: ${error.message}`
                );
              }
            };

            // Content of a "## <name>" section, or null when the heading is absent.
            const section = (name) => {
              const match = body.match(
                new RegExp(`##\\s${name}([\\s\\S]*?)(?=\\n##\\s|$)`, "i")
              );
              return match ? match[1] : null;
            };

            const problems = [];

            const requiredHeadings = [
              "## proposed change",
              "## type of change",
              "## checklist",
            ];
            if (requiredHeadings.some((h) => !normalized.includes(h))) {
              problems.push(
                "Use the pull request template without removing its sections."
              );
            }

            const typeOfChange = section("type of change");
            if (typeOfChange !== null) {
              const ticked = (typeOfChange.match(/-\s*\[[xX]\]/g) || []).length;
              if (ticked !== 1) {
                problems.push(
                  'Select exactly one option under "Type of change".'
                );
              }
            }

            const proposedChange = section("proposed change");
            if (proposedChange !== null && proposedChange.trim().length === 0) {
              problems.push('Describe your changes under "Proposed change".');
            }

            const isValid = problems.length === 0;

            const comments = await github.paginate(
              github.rest.issues.listComments,
              { owner, repo, issue_number, per_page: 100 }
            );
            const existing = comments.find((c) => c.body.includes(marker));
            const hasLabel = pr.labels.some((l) => l.name === label);

            if (isValid) {
              core.info("Pull request standards met");

              if (hasLabel) {
                await ignoreMissing(() =>
                  github.rest.issues.removeLabel({
                    owner, repo, issue_number, name: label,
                  })
                );
              }
              if (existing) {
                await setMinimized(existing.node_id, true);
              }
              return;
            }

            core.info(`Pull request standards not met:\n- ${problems.join("\n- ")}`);

            if (!hasLabel) {
              await github.rest.issues.addLabels({
                owner, repo, issue_number, labels: [label],
              });
            }

            const message =
              `${marker}\n` +
              `Hey @${pr.user.login}!\n\n` +
              `Thank you for your contribution! To help reviewers, please update ` +
              `this pull request to follow our pull request standards:\n\n` +
              problems.map((p) => `- ${p}`).join("\n") +
              `\n\n` +
              `Please complete the ` +
              `[PR template](https://github.com/home-assistant/frontend/blob/dev/.github/PULL_REQUEST_TEMPLATE.md?plain=1) ` +
              `and see the [developer docs](https://developers.home-assistant.io/docs/review-process) ` +
              `for more on creating a great pull request (see point 6).`;

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

            // Fail this check so it can block the PR from being merged
            core.setFailed(
              `Pull request standards not met:\n- ${problems.join("\n- ")}`
            );