affected-pages.yml

name: Affected pages

on:
  deployment_status:

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

concurrency:
  group: affected-pages-${{ github.event.deployment.sha }}
  cancel-in-progress: true

jobs:
  affected-pages:
    if: |
      github.event.deployment_status.state == 'success' &&
      startsWith(github.event.deployment.environment, 'Preview') &&
      contains(github.event.deployment_status.target_url, 'vercel.app')
    runs-on: ubuntu-latest
    steps:
      - name: Find PR for this deployment
        id: pr
        uses: actions/github-script@v8
        env:
          DEPLOY_SHA: ${{ github.event.deployment.sha }}
        with:
          script: |
            const { data: prs } = await github.rest.repos.listPullRequestsAssociatedWithCommit({
              owner: context.repo.owner,
              repo: context.repo.repo,
              commit_sha: process.env.DEPLOY_SHA,
            });
            const pr = prs.find((p) => p.state === "open");
            if (!pr) {
              core.info("No open PR for this deployment; skipping.");
              return;
            }
            core.setOutput("number", pr.number);

      - name: Checkout repo at deploy SHA
        if: steps.pr.outputs.number
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.deployment.sha }}

      - name: Collect changed MDX files
        id: changed
        if: steps.pr.outputs.number
        uses: actions/github-script@v8
        env:
          PR_NUMBER: ${{ steps.pr.outputs.number }}
        with:
          script: |
            const pull_number = parseInt(process.env.PR_NUMBER, 10);
            const files = await github.paginate(github.rest.pulls.listFiles, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number,
            });
            const matching = files
              .filter((f) => f.status !== "removed")
              .map((f) => f.filename)
              .filter(
                (n) =>
                  (n.startsWith("src/content/") || n.startsWith("src/partials/")) &&
                  n.endsWith(".mdx"),
              );
            core.setOutput("any", matching.length > 0 ? "true" : "false");
            core.setOutput("files", matching.join("\n"));

      - name: Compute affected page URLs
        if: steps.pr.outputs.number
        env:
          CHANGED_FILES: ${{ steps.changed.outputs.files }}
          PREVIEW_URL: ${{ github.event.deployment_status.target_url }}
          BYPASS_SECRET: ${{ secrets.VERCEL_AUTOMATION_BYPASS_SECRET }}
        run: node scripts/affected-pages.mjs

      - name: Update PR description
        if: steps.pr.outputs.number
        uses: actions/github-script@v8
        env:
          BODY_PATH: pages-comment.md
          PR_NUMBER: ${{ steps.pr.outputs.number }}
        with:
          script: |
            const fs = require("fs");
            // Match any "## Affected pages" section: from the heading up to (but
            // not including) the next `## ` heading or end of body. The `\r?`
            // tolerates GitHub's CRLF line endings in PR bodies, and the `g`
            // flag lets us strip duplicate sections left behind by earlier runs
            // that hit the line-ending bug.
            const sectionRe = /## Affected pages[ \t]*\r?\n[\s\S]*?(?=\r?\n## |$)/g;

            const pull_number = parseInt(process.env.PR_NUMBER, 10);
            const { data: pr } = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number,
            });
            const original = pr.body || "";
            const content = fs.readFileSync(process.env.BODY_PATH, "utf8").trim();
            const block = `## Affected pages\n\n${content}\n`;

            // Strip every existing Affected pages section, then reinsert one
            // fresh copy in the canonical spot. This is idempotent and also
            // cleans up any duplicates accumulated by previous runs.
            const stripped = original
              .replace(sectionRe, "")
              .replace(/(\r?\n){3,}/g, "$1$1");

            let next;
            const heading = "## Related Issues";
            const idx = stripped.indexOf(heading);
            if (idx >= 0) {
              const before = stripped.slice(0, idx).trimEnd();
              const after  = stripped.slice(idx);
              next = `${before}\n\n${block}\n${after}`;
            } else {
              next = `${stripped.trim()}\n\n${block}`;
            }

            if (next !== original) {
              await github.rest.pulls.update({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number,
                body: next,
              });
              console.log("PR description updated.");
            } else {
              console.log("No change to PR description.");
            }