deploy.yml

name: Deploy to GitHub Pages

on:
  push:
    branches: [main]
  workflow_dispatch:
  # SCHEDULED REBUILD — powers content scheduling. A static build freezes "now" at build
  # time, so a post with a future `pubDate` (src/lib/content.ts) or a video with a future
  # `publishedAt` (src/data/videos.ts) stays hidden until a build runs past that instant.
  # This cron re-runs the SAME build+deploy every 15 min so scheduled content reveals itself
  # AUTOMATICALLY — no manual step at publish time. Set the gate to your YouTube publish time
  # (or a few minutes after) and the site reveals the post + video together, after the video
  # is live. Caveat: GitHub cron is UTC and often runs several minutes LATE (never early), so
  # the gate guarantees "at or after" your time — exactly the "after YouTube" requirement.
  schedule:
    - cron: '*/15 * * * *'

permissions:
  contents: read
  pages: write
  id-token: write

# Serialize deploys: let an in-progress one FINISH, queue the next. Do NOT cancel —
# cancelling a Pages deploy mid-flight wedges the `github-pages` environment queue, and the
# next run then polls `deployment_queued` until it TIMES OUT (~10m). This bit us when a commit
# + its submodule-pointer bump landed minutes apart. GitHub's own Pages starter uses `false`.
concurrency:
  group: pages
  cancel-in-progress: false

jobs:
  build:
    runs-on: ubuntu-latest
    outputs:
      # Gate for the deploy job. 'true' on every push / manual run; on a SCHEDULED run only
      # when the freshly-built site actually differs from what's live (see the guard step).
      should_deploy: ${{ steps.guard.outputs.should_deploy }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Install, build, and upload
        uses: withastro/action@v4
        # withastro/action runs `npm ci && npm run build` (which also runs
        # `pagefind --site dist`) and uploads ./dist as the Pages artifact. It leaves
        # ./dist in the workspace, so the guard below can inspect the built sitemap.
      - name: Decide whether the scheduled build is worth deploying
        id: guard
        # The cron fires every 15 min, but a scheduled reveal only ever ADDS a page (a due
        # post's /post/<slug>/ + its video's /video/<slug>/). So on a cron run we build,
        # then compare THIS build's sitemap URL set to the LIVE one: identical => nothing is
        # due => skip the redeploy (keeps the Pages deployment history clean). Any push or
        # manual run always deploys. FAIL-OPEN: if the live sitemap can't be read (network,
        # first deploy, format change) we deploy — a missed reveal is worse than a no-op deploy.
        # Only reads our own sitemap as DATA (piped to grep); no untrusted input hits the shell.
        run: |
          if [ "${{ github.event_name }}" != "schedule" ]; then
            echo "Not a scheduled run — always deploy."
            echo "should_deploy=true" >> "$GITHUB_OUTPUT"
            exit 0
          fi
          built=$(grep -o '<loc>[^<]*</loc>' dist/sitemap-0.xml 2>/dev/null | sort -u)
          if [ -z "$built" ]; then
            echo "No built sitemap found — deploy to be safe."
            echo "should_deploy=true" >> "$GITHUB_OUTPUT"
            exit 0
          fi
          live=$(curl -sf --max-time 30 https://prostdev.com/sitemap-0.xml | grep -o '<loc>[^<]*</loc>' | sort -u)
          if [ -z "$live" ]; then
            echo "Could not read live sitemap — deploy to be safe."
            echo "should_deploy=true" >> "$GITHUB_OUTPUT"
            exit 0
          fi
          if [ "$built" = "$live" ]; then
            echo "Built site matches live — nothing due, skipping deploy."
            echo "should_deploy=false" >> "$GITHUB_OUTPUT"
          else
            echo "Built site differs from live — deploying."
            echo "should_deploy=true" >> "$GITHUB_OUTPUT"
          fi

  deploy:
    needs: build
    if: needs.build.outputs.should_deploy == 'true'
    runs-on: ubuntu-latest
    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}
    steps:
      - name: Deploy to GitHub Pages
        id: deployment
        uses: actions/deploy-pages@v4