pr-validator.yml

name: PR Validator

on:
  pull_request:
    types: [opened, edited, reopened, synchronize]

permissions:
  pull-requests: write
  issues: write
  contents: read

jobs:
  validate-pr:
    name: validate-pr
    runs-on: ubuntu-latest

    steps:
      - name: Validate PR and enforce contribution rules
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const pr = context.payload.pull_request;
            const title   = pr.title;
            const body    = pr.body || "";
            const headRef = pr.head.ref;
            const baseRef = pr.base.ref;
            const author  = pr.user.login;
            const prNumber = pr.number;
            const owner   = context.repo.owner;
            const repo    = context.repo.repo;

            const failures = [];

            // ── Check 1: PR title format ─────────────────────────────────────────
            const titleRegex = /^(feat|fix|docs|chore|refactor|test|style|perf)\((app|backend|ml-worker|repo)\): .{10,}$/;
            if (!titleRegex.test(title)) {
              failures.push(
                `**Invalid PR title:** \`${title}\` — must follow \`type(scope): description\` format where type is one of \`feat|fix|docs|chore|refactor|test|style|perf\`, scope is one of \`app|backend|ml-worker|repo\`, and description is at least 10 characters.`
              );
            }

            // ── Check 2: PR body sections ────────────────────────────────────────
            const hasWhatChanged = /##\s*what changed/i.test(body);
            const hasWhy         = /##\s*why/i.test(body);
            const hasHowToTest   = /##\s*how to test/i.test(body);
            if (!body.trim() || !hasWhatChanged || !hasWhy || !hasHowToTest) {
              failures.push(
                `**Missing PR description sections:** Your PR body must include all three headings: \`## What changed\`, \`## Why\`, and \`## How to test\`. Add them and fill them in.`
              );
            }

            // ── Check 3: Linked issue ────────────────────────────────────────────
            const issueRegex = /(?:closes|fixes|resolves|relates to|ref)\s+#\d+/i;
            if (!issueRegex.test(body)) {
              failures.push(
                `**No linked issue:** Reference the issue this PR addresses using \`closes #N\`, \`fixes #N\`, or \`relates to #N\`. Open an issue first if one doesn't exist.`
              );
            }

            // ── Check 4: Target branch ───────────────────────────────────────────
            if (baseRef !== "main") {
              failures.push(
                `**Wrong target branch:** This PR targets \`${baseRef}\` but all PRs must target \`main\`.`
              );
            }

            // ── Check 5: Branch name ─────────────────────────────────────────────
            const branchRegex = /^(feat|fix|docs|chore|refactor|test|style|perf)\/(app|backend|ml-worker|repo|shared)\/[a-z0-9-]+$/;
            if (!branchRegex.test(headRef)) {
              failures.push(
                `**Invalid branch name:** \`${headRef}\` — must follow \`type/scope/short-description\` e.g. \`feat/app/timetable-progress\`.`
              );
            }

            // ── Helper: safe label operations ───────────────────────────────────
            async function addLabel(name) {
              try {
                await github.rest.issues.addLabels({
                  owner, repo, issue_number: prNumber,
                  labels: [name],
                });
              } catch (e) {
                // Label may not exist in the repo yet — skip silently
                core.warning(`Could not add label "${name}": ${e.message}`);
              }
            }

            async function removeLabel(name) {
              try {
                await github.rest.issues.removeLabel({
                  owner, repo, issue_number: prNumber,
                  name,
                });
              } catch (e) {
                // Label not present — ignore 404
              }
            }

            // ── All checks passed ────────────────────────────────────────────────
            if (failures.length === 0) {
              await addLabel("ready-for-review");
              await removeLabel("invalid-pr");
              console.log("✅ PR passed all validation checks.");
              return;
            }

            // ── Checks failed — build comment ────────────────────────────────────
            const bulletList = failures.map(f => `- ${f}`).join("\n");
            const comment = `## ❌ PR Validation Failed

Hi @${author}, this PR was automatically closed because it does not follow Sentri's contribution guidelines. Please read [CONTRIBUTING.md](../blob/main/CONTRIBUTING.md) before re-submitting.

### Issues found:

${bulletList}

### How to fix and reopen
1. Fix all issues listed above
2. Push your changes or edit the PR title/description
3. Reopen the PR — validation will run again automatically

---
_This check is automated. If you believe this is a mistake, ping a maintainer._`;

            // Post comment
            await github.rest.issues.createComment({
              owner, repo,
              issue_number: prNumber,
              body: comment,
            });

            // Apply / remove labels
            await addLabel("invalid-pr");
            await removeLabel("ready-for-review");

            // Close the PR
            await github.rest.pulls.update({
              owner, repo,
              pull_number: prNumber,
              state: "closed",
            });

            // Fail the job so the status check is red
            core.setFailed(`PR validation failed with ${failures.length} issue(s).`);