name: Auto Format

# Stage 1 of 2 (producer). Runs with the default read-only token and never
# pushes or comments, so it is safe to format PR-authored code — including
# from forks. The companion "Auto Format — Apply" workflow (triggered by
# workflow_run) commits the result back with elevated permissions, isolated
# from PR-authored code.
on:
  pull_request:
    branches: [main]
    types: [opened, synchronize]

permissions:
  contents: read

jobs:
  format:
    name: Format
    # Skip the bot's own format commits to avoid a re-format loop.
    if: github.actor != 'emdashbot[bot]'
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          persist-credentials: false

      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
        with:
          node-version: 22

      - name: Run formatter
        run: npx oxfmt --ignore-path .gitignore

      - name: Compute patch
        id: patch
        run: |
          git add -A
          if git diff --staged --quiet; then
            echo "changed=false" >> "$GITHUB_OUTPUT"
            echo "Already formatted — nothing to apply."
          else
            echo "changed=true" >> "$GITHUB_OUTPUT"
            mkdir -p auto-format-out
            git diff --staged --binary > auto-format-out/format.patch
            echo "${{ github.event.pull_request.number }}" > auto-format-out/pr-number
            echo "Formatting changes detected — uploading patch for the Apply workflow."
          fi

      - name: Upload patch artifact
        if: steps.patch.outputs.changed == 'true'
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
        with:
          name: auto-format-patch
          path: auto-format-out/
          retention-days: 7
          if-no-files-found: error