name: Generate Documentation

on:
  push:
    branches:
      - 'root'
      - '!documentation'
    paths:
      - '.github/workflows/documentation.yml'
      - 'vst.h'
      - 'vst.hpp'
      - 'Doxyfile'

jobs:
  docs:
    name: "Generate Documentation"
    runs-on: ubuntu-latest
    steps:    
    - name: "Set up Git"
      shell: bash
      run: |
        git config --global user.name 'GitHub Actions'
        git config --global user.email 'xaymar@users.noreply.github.com'
        git config --global pull.ff only
        git config --global pull.rebase true

    - name: "Clone"
      uses: actions/checkout@v3
      with:
        submodules: 'recursive'
        fetch-depth: 0

    - name: "Clone Documentation Cache"
      id: doc_cache
      continue-on-error: true
      uses: actions/checkout@v3      
      with:      
        ref: 'documentation'
        path: 'build/docs/html'
        submodules: 'recursive'
        fetch-depth: 0

    - name: "Initialize Documentation Cache"
      if: steps.doc_cache.outcome == 'failure'
      shell: bash
      run: |
        mkdir -p build/docs/html
        pushd build/docs/html
        git init
        git switch --orphan documentation
        git remote remove origin
        git remote add -t documentation origin ${{ github.repositoryUrl }}
        popd

    - name: "Install Prerequisites"
      shell: bash
      run: |
        sudo apt-get install -y clang-19 clang-tools-19 doxygen graphviz 

    - name: "Generate Documentation"
      shell: bash
      run: |
        doxygen Doxyfile

    - name: "Update Documentation"
      shell: bash
      run: |
        pushd build/docs/html
        git add .
        git --no-pager diff --patch --minimal HEAD -- || true
        git update-index --refresh
        if ! git diff-index --quiet HEAD -- &> /dev/null; then
          git commit -a -m "${{ github.sha }}"

          # Only push from master branch.
          if [[ "${{ github.ref }}" == "refs/heads/root" ]]; then
            git push --set-upstream origin documentation
            echo "Documentation has been updated!"
          else
            git log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit
          fi
        else
          echo "Documentation is still up to date."
        fi
        popd