---
name: Star History

on:
  schedule:
    - cron: "0 0 * * *"  # daily, 00:00 UTC
  workflow_dispatch:

permissions:
  contents: write

concurrency:
  # Only one chart regeneration per branch at a time; a newer run on the same
  # branch cancels an in-flight one so overlapping runs never conflict on
  # note/star_history.svg during rebase. Scoped by ref so a manual run on
  # another branch can't cancel the daily master update.
  group: star-history-${{ github.ref }}
  cancel-in-progress: true

jobs:
  render:
    name: Regenerate star history chart
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v7
        with:
          # Full history so the chart commit can rebase onto a moved master.
          fetch-depth: 0

      - name: Set up Python
        uses: actions/setup-python@v7
        with:
          python-version: "3.x"
          cache: pip
          cache-dependency-path: .github/scripts/star_history.py

      - name: Install matplotlib
        run: pip install matplotlib

      - name: Render chart
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: python .github/scripts/star_history.py

      - name: Commit if changed
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          if git diff --quiet -- note/star_history.svg; then
            echo "No changes to the chart."
            exit 0
          fi
          git add note/star_history.svg
          git commit -m "docs: regenerate star history chart"
          # Rebase and retry so a concurrent push to master doesn't lose the chart.
          for attempt in 1 2 3 4 5; do
            if [ "$attempt" -gt 1 ]; then
              # Guard the rebase: a transient fetch error or conflict must not
              # abort the fail-fast shell before the remaining attempts run.
              if ! git pull --rebase origin "$GITHUB_REF_NAME"; then
                echo "rebase failed (attempt ${attempt}); aborting and retrying"
                git rebase --abort || true
                continue
              fi
            fi
            if git push origin HEAD:"$GITHUB_REF_NAME"; then
              exit 0
            fi
            echo "push rejected (attempt ${attempt}); will rebase and retry"
          done
          echo "::error::could not push star history chart after retries"
          exit 1