update-submodules.yml

name: Update Submodules

on:
  schedule:
    # Run at 2:00 AM UTC every day
    - cron: '0 2 * * *'
  workflow_dispatch:  # Allow manual trigger

jobs:
  update-submodules:
    runs-on: ubuntu-latest
    permissions:
      contents: write
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
        with:
          # Fetch all history for all branches and tags
          fetch-depth: 0
          # Get submodules
          submodules: 'recursive'

      - name: Set up Git
        run: |
          git config --global user.name 'Read the Docs Bot'
          git config --global user.email 'rtd-bot@shader-slang.com'

      - name: Get default branch
        id: default_branch
        run: |
          DEFAULT_BRANCH=$(git remote show origin | grep 'HEAD branch' | cut -d' ' -f5)
          echo "name=$DEFAULT_BRANCH" >> $GITHUB_OUTPUT

      - name: Checkout default branch
        run: |
          git checkout ${{ steps.default_branch.outputs.name }}

      - name: Update submodules
        run: |
          git submodule update --remote --recursive
      
      - name: Check if submodules changed
        id: check_changes
        run: |
          git add -A
          
          # Check if the index differs from HEAD
          # git diff --cached --quiet exits 0 if no diff, 1 if diff
          if ! git diff --cached --quiet; then
            echo "Changes detected in submodule references."
            echo "changes=true" >> $GITHUB_OUTPUT
          else
            echo "No changes detected in submodule references."
            echo "changes=false" >> $GITHUB_OUTPUT
            # If no changes, reset the index in case unrelated changes were staged
            git reset HEAD --quiet
          fi

      - name: Commit and push changes
        if: steps.check_changes.outputs.changes == 'true'
        run: |
          git commit -m "Auto-update submodules"
          git push origin ${{ steps.default_branch.outputs.name }}