name: Deploy Docs to GitHub Pages

on:
  push:
    branches:
      - main
      - dev
    paths:
      - 'docs/**'
      - 'mkdocs.yml'
      - '.github/workflows/docs.yml'
  workflow_dispatch:

permissions:
  contents: read
  pages: write
  id-token: write

concurrency:
  group: "pages"
  cancel-in-progress: false

jobs:
  build:
    name: Build Documentation
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0  # Für git-dates Plugin

      - name: Setup Python
        uses: actions/setup-python@v5
        with:
          python-version: '3.x'

      - name: Cache pip packages
        uses: actions/cache@v4
        with:
          key: mkdocs-material-${{ runner.os }}-${{ hashFiles('requirements-docs.txt') }}
          path: ~/.cache/pip
          restore-keys: |
            mkdocs-material-${{ runner.os }}-

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

      - name: Build MkDocs site (main -> /, dev -> /dev)
        env:
          REF_NAME: ${{ github.ref_name }}
          SHA: ${{ github.sha }}
        run: |
          set -euo pipefail

          # Ensure both refs are available locally.
          git fetch origin main dev

          MAIN_REF="origin/main"
          DEV_REF="origin/dev"
          if [ "${REF_NAME}" = "main" ]; then
            MAIN_REF="${SHA}"
          fi
          if [ "${REF_NAME}" = "dev" ]; then
            DEV_REF="${SHA}"
          fi

          # Build each branch in its own worktree and merge into one Pages artifact:
          # - main docs at site/
          # - dev docs at site/dev/
          rm -rf .worktrees site
          mkdir -p .worktrees
          git worktree add --detach .worktrees/main "${MAIN_REF}"
          git worktree add --detach .worktrees/dev "${DEV_REF}"

          mkdocs build --strict --verbose \
            --config-file .worktrees/main/mkdocs.yml \
            --site-dir site

          mkdocs build --strict --verbose \
            --config-file .worktrees/dev/mkdocs.yml \
            --site-dir site/dev

      - name: Upload Pages artifact
        uses: actions/upload-pages-artifact@v3
        with:
          path: site/

  deploy:
    name: Deploy to GitHub Pages
    needs: build
    runs-on: ubuntu-latest
    environment:
      name: github-pages
      url: ${{ steps.deployment.outputs.page_url }}
    steps:
      - name: Deploy to GitHub Pages
        id: deployment
        uses: actions/deploy-pages@v4