name: Documentation

on:
  push:
    branches: [master]
    tags: ['[0-9]*.[0-9]*.[0-9]*']
  pull_request:
  workflow_dispatch:

concurrency:
  group: pages-${{ github.ref }}
  cancel-in-progress: true

jobs:
  build:
    name: Build Sphinx Documentation
    runs-on: ubuntu-26.04
    defaults:
      run:
        shell: bash -e -o pipefail {0}
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: '3.15'
          cache: 'pip'
          cache-dependency-path: docs/requirements.txt

      - name: Install dependencies
        run: pip install -r docs/requirements.txt

      - name: Build stable release documentation (default)
        run: |
          STABLE_TAG=$(git tag --list '[0-9]*.[0-9]*.[0-9]*' --sort=-v:refname | grep -E '^[0-9]+\.[0-9]+\.[0-9]+$' | head -n1)
          mkdir -p "${RUNNER_TEMP}/stable-src"
          git archive "${STABLE_TAG}" | tar -x -C "${RUNNER_TEMP}/stable-src"
          cp docs/source/conf.py docs/source/CNAME "${RUNNER_TEMP}/stable-src/docs/source/"
          rm -rf "${RUNNER_TEMP}/stable-src/docs/source/_templates"
          cp -r docs/source/_templates "${RUNNER_TEMP}/stable-src/docs/source/_templates"
          sphinx-build -D nitpicky=0 \
            -A ceres_doc_variant=stable \
            -A "stable_version=${STABLE_TAG}" \
            -D "html_theme_options.source_branch=${STABLE_TAG}" \
            -b html "${RUNNER_TEMP}/stable-src/docs/source" _site

      - name: Build development (HEAD) documentation
        run: |
          STABLE_TAG=$(git tag --list '[0-9]*.[0-9]*.[0-9]*' --sort=-v:refname | grep -E '^[0-9]+\.[0-9]+\.[0-9]+$' | head -n1)
          sphinx-build -W -n \
            -A ceres_doc_variant=dev \
            -A "stable_version=${STABLE_TAG}" \
            -b html docs/source _site/dev

      - name: Upload Pages artifact
        if: github.event_name != 'pull_request' && (github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/'))
        uses: actions/upload-pages-artifact@v3
        with:
          path: _site

  deploy:
    name: Deploy to GitHub Pages
    if: github.event_name != 'pull_request' && (github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/'))
    needs: build
    runs-on: ubuntu-26.04
    permissions:
      pages: write
      id-token: write
    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}
    steps:
      - name: Deploy to GitHub Pages
        id: deployment
        uses: actions/deploy-pages@v4