name: Build and deploy Jekyll documentation site

on:
  push:
    branches:
      - master

env:
  RUBY_VERSION: 2.7

jobs:
  deploy_docs:
    if: "!contains(github.event.commits[0].message, '[ci skip]')"
    runs-on: 'ubuntu-latest'
    steps:
      - uses: actions/checkout@v2
      - uses: actions/setup-ruby@v1
        with:
          ruby-version: ${{ env.RUBY_VERSION }}
      - name: Setup cache for Bundler
        id: cache
        uses: actions/cache@v2.1.3
        with:
          path: vendor/bundle
          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}
          restore-keys: |
            ${{ runner.os }}-gems-
      - name: Set up dependencies
        run: |
          bundle install --path=vendor/bundle --jobs 4 --retry 3
          bundle clean
      - name: Clone target branch
        run: |
          REMOTE_BRANCH="${REMOTE_BRANCH:-gh-pages}"
          REMOTE_REPO="https://${GITHUB_ACTOR}:${{ secrets.GITHUB_TOKEN }}@github.com/${GITHUB_REPOSITORY}.git"

          echo "Publishing to ${GITHUB_REPOSITORY} on branch ${REMOTE_BRANCH}"
          rm -rf docs/_site/
          git clone --depth=1 --branch="${REMOTE_BRANCH}" --single-branch --no-checkout \
            "${REMOTE_REPO}" docs/_site/
      - name: Build site
        run: bundle exec jekyll build --source docs --destination docs/_site --verbose --trace
        env:
          # For jekyll-github-metadata
          JEKYLL_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      - name: Deploy to GitHub Pages
        run: |
          SOURCE_COMMIT="$(git log -1 --pretty="%an: %B" "$GITHUB_SHA")"
          pushd docs/_site &>/dev/null
          : > .nojekyll

          git add --all
          git -c user.name="${GITHUB_ACTOR}" -c user.email="${GITHUB_ACTOR}@users.noreply.github.com" \
            commit --quiet \
            --message "Deploy docs from ${GITHUB_SHA}" \
            --message "$SOURCE_COMMIT"
          git push

          popd &>/dev/null