name: Poll React Sync

on:
  schedule:
    # GitHub runs cronjobs at most every 5 minutes.
    # Ideally we get 2 minutes or lower which is what we used to have with Vercel cronjobs.
    - cron: '*/5 * * * *'

concurrency:
  group: poll-react-sync
  cancel-in-progress: true

jobs:
  poll:
    runs-on: ubuntu-latest
    permissions:
      actions: write
    steps:
      # We're using react@experimental as a signal for a new React sync because
      # in facebook/react we publish experimental after canary. If we would just
      # look at canary, we might update before experimental is published.
      - name: Fetch latest react@experimental version
        id: current
        run: |
          CURRENT=$(npm --silent view --json react@experimental version | tr -d '"')
          if [ -z "$CURRENT" ]; then
            echo "Failed to resolve react@experimental version" >&2
            exit 1
          fi
          echo "version=$CURRENT" >> "$GITHUB_OUTPUT"
          echo "Current react@experimental: $CURRENT"

      - name: Check whether this version was already seen
        id: cache
        uses: actions/cache@v4
        with:
          # The key encodes the version. Cache hit = already processed; cache miss = new version.
          # The path just needs to exist so the post-step can save the cache entry on a miss.
          path: .cache/marker
          key: react-experimental-${{ steps.current.outputs.version }}

      - name: Mark version as seen
        if: steps.cache.outputs.cache-hit != 'true'
        run: |
          mkdir -p .cache
          printf '%s' '${{ steps.current.outputs.version }}' > .cache/marker

      - name: Resolve corresponding react@canary version
        id: canary
        if: steps.cache.outputs.cache-hit != 'true'
        run: |
          CANARY=$(npm --silent view --json react@canary version | tr -d '"')
          if [ -z "$CANARY" ]; then
            echo "Failed to resolve react@canary version" >&2
            exit 1
          fi
          echo "version=$CANARY" >> "$GITHUB_OUTPUT"
          echo "Current react@canary: $CANARY"

      - name: Dispatch update_react.yml
        if: steps.cache.outputs.cache-hit != 'true'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GH_REPO: ${{ github.repository }}
          EXPERIMENTAL: ${{ steps.current.outputs.version }}
          CANARY: ${{ steps.canary.outputs.version }}
        run: |
          echo "react@experimental changed to $EXPERIMENTAL. Dispatching update_react.yml with react@canary=$CANARY."
          gh workflow run update_react.yml --ref ${{ github.ref_name }} -f version="$CANARY"