name: Update Stable Docs

on:
  release:
    types: [published]
  push:
    branches:
    - main

permissions:
  contents: write

jobs:
  update_stable_docs:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout repository
      uses: actions/checkout@v5
      with:
        fetch-depth: 0  # We need all commits to find docs/ changes
    - name: Set up Git user
      run: |
        git config user.name "Automated"
        git config user.email "actions@users.noreply.github.com"
    - name: Create stable branch if it does not yet exist
      run: |
        if ! git ls-remote --heads origin stable | grep -qE '\bstable\b'; then
          # Make sure we have all tags locally
          git fetch --tags --quiet

          # Latest tag that is just numbers and dots (optionally prefixed with 'v')
          # e.g., 0.65.2 or v0.65.2 — excludes 1.0a20, 1.0-rc1, etc.
          LATEST_RELEASE=$(
            git tag -l --sort=-v:refname \
            | grep -E '^v?[0-9]+(\.[0-9]+){1,3}$' \
            | head -n1
          )

          git checkout -b stable

          # If there are any stable releases, copy docs/ from the most recent
          if [ -n "$LATEST_RELEASE" ]; then
            rm -rf docs/
            git checkout "$LATEST_RELEASE" -- docs/ || true
          fi

          git commit -m "Populate docs/ from $LATEST_RELEASE" || echo "No changes"
          git push -u origin stable
        fi
    - name: Handle Release
      if: github.event_name == 'release' && !github.event.release.prerelease
      run: |
        git fetch --all
        git checkout stable
        git reset --hard ${GITHUB_REF#refs/tags/}
        git push origin stable --force
    - name: Handle Commit to Main
      if: contains(github.event.head_commit.message, '!stable-docs')
      run: |
        git fetch origin
        git checkout -b stable origin/stable
        # Get the list of modified files in docs/ from the current commit
        FILES=$(git diff-tree --no-commit-id --name-only -r ${{ github.sha }} -- docs/)
        # Check if the list of files is non-empty
        if [[ -n "$FILES" ]]; then
          # Checkout those files to the stable branch to over-write with their contents
          for FILE in $FILES; do
            git checkout ${{ github.sha }} -- $FILE
          done
          git add docs/
          git commit -m "Doc changes from ${{ github.sha }}"
          git push origin stable
        else
          echo "No changes to docs/ in this commit."
          exit 0
        fi