name: Cloudflare Pages PR Preview — Deploy
description: >-
  Deploys a pre-built static HTML directory to Cloudflare Pages under a per-PR
  branch alias, injects noindex headers/meta tags, and posts/updates a sticky
  PR comment with the preview URLs.

inputs:
  directory:
    description: Path to the built static HTML directory (e.g. blog/public)
    required: true
  project-name:
    description: Cloudflare Pages project name (must already exist in the CF dashboard)
    required: true
  api-token:
    description: Cloudflare API token with Pages:Edit permission on the project
    required: true
  account-id:
    description: Cloudflare account ID
    required: true
  branch:
    description: Cloudflare Pages branch alias for this deployment
    required: false
    default: pr-${{ github.event.pull_request.number }}
  inject-noindex:
    description: >-
      Whether to inject X-Robots-Tag headers (via _headers file) and a
      <meta name="robots"> tag into all HTML pages to prevent search engine
      indexing of the preview. Set to 'false' to skip.
    required: false
    default: 'true'
  comment-marker:
    description: HTML comment marker used to identify and update the sticky PR comment
    required: false
    default: '<!-- cf-pages-preview -->'
  comment-title:
    description: Heading shown in the sticky PR comment
    required: false
    default: 'Preview Deployed'
  github-token:
    description: GitHub token for posting/updating the PR comment
    required: false
    default: ${{ github.token }}
  pr-number:
    description: >-
      PR number to comment on. Only needed on triggers where
      context.payload.pull_request is unavailable (e.g. workflow_dispatch).
      Defaults to the event payload's PR number.
    required: false
    default: ${{ github.event.pull_request.number }}
  commit-sha:
    description: >-
      Commit SHA shown in the sticky comment. Useful when the checked-out
      ref differs from github.sha (e.g. building a pinned head SHA on
      workflow_dispatch). Defaults to github.sha.
    required: false
    default: ${{ github.sha }}

outputs:
  deployment-url:
    description: URL of the specific deployment (changes per push)
    value: ${{ steps.deploy.outputs.deployment-url }}
  alias-url:
    description: Stable branch-alias URL (same across pushes to this PR)
    value: ${{ steps.deploy.outputs.pages-deployment-alias-url }}

runs:
  using: composite
  steps:
    # Prevent preview deployments from being indexed by search engines.
    # Cloudflare Pages serves _headers as HTTP headers for matching paths.
    # X-Robots-Tag covers all content types (HTML, RSS, sitemaps, etc.)
    - name: Add noindex headers
      if: inputs.inject-noindex == 'true'
      shell: bash
      env:
        DIR: ${{ inputs.directory }}
      run: |
        cat > "${DIR}/_headers" <<'EOF'
        /*
          X-Robots-Tag: noindex, nofollow, noarchive, nosnippet
        EOF

    # Also inject a <meta> tag into every HTML page as belt-and-suspenders
    # in case the site is later served from somewhere that ignores _headers.
    - name: Inject noindex meta tag
      if: inputs.inject-noindex == 'true'
      shell: bash
      env:
        DIR: ${{ inputs.directory }}
      run: |
        find "${DIR}" -name '*.html' -print0 | \
          xargs -0 -r sed -i 's|<head>|<head><meta name="robots" content="noindex, nofollow, noarchive, nosnippet">|'

    - name: Deploy to Cloudflare Pages
      id: deploy
      uses: cloudflare/wrangler-action@v3
      with:
        apiToken: ${{ inputs.api-token }}
        accountId: ${{ inputs.account-id }}
        command: pages deploy ${{ inputs.directory }} --project-name=${{ inputs.project-name }} --branch=${{ inputs.branch }}

    - name: Comment with preview URL
      uses: actions/github-script@v8
      env:
        DEPLOY_URL: ${{ steps.deploy.outputs.deployment-url }}
        ALIAS_URL: ${{ steps.deploy.outputs.pages-deployment-alias-url }}
        COMMENT_MARKER: ${{ inputs.comment-marker }}
        COMMENT_TITLE: ${{ inputs.comment-title }}
        INJECT_NOINDEX: ${{ inputs.inject-noindex }}
        PR_NUMBER: ${{ inputs.pr-number }}
        COMMIT_SHA: ${{ inputs.commit-sha }}
      with:
        github-token: ${{ inputs.github-token }}
        script: |
          const { owner, repo } = context.repo;
          const prNumber = Number(process.env.PR_NUMBER);
          if (!prNumber) {
            core.info('No PR number available — skipping comment.');
            return;
          }
          const deployUrl = process.env.DEPLOY_URL;
          const aliasUrl = process.env.ALIAS_URL || deployUrl;
          const marker = process.env.COMMENT_MARKER;
          const title = process.env.COMMENT_TITLE;
          const noindex = process.env.INJECT_NOINDEX === 'true';

          const noindexNote = noindex
            ? ' All pages served with `noindex, nofollow` — search engines will not crawl this preview.'
            : '';

          const body = `${marker}
          ## ${title}

          | | |
          |---|---|
          | **Preview (stable)** | ${aliasUrl} |
          | **This commit** | ${deployUrl} |
          | **Commit** | \`${process.env.COMMIT_SHA.slice(0, 7)}\` |

          _Includes drafts and future-dated posts.${noindexNote}_`;

          const { data: comments } = await github.rest.issues.listComments({
            owner, repo, issue_number: prNumber
          });
          const existing = comments.find(c =>
            c.user.type === 'Bot' && c.body.includes(marker)
          );

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