name: Reusable Docs

on:
  workflow_call:
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
  cancel-in-progress: true

env:
  FORCE_COLOR: 1

jobs:
  build-doc:
    name: 'Docs'
    runs-on: ubuntu-latest
    timeout-minutes: 60
    env:
      branch_base: 'origin/${{ github.event.pull_request.base.ref }}'
      branch_pr: 'origin/${{ github.event.pull_request.head.ref }}'
      commits: ${{ github.event.pull_request.commits }}
      refspec_base: '+${{ github.event.pull_request.base.sha }}:remotes/origin/${{ github.event.pull_request.base.ref }}'
      refspec_pr: '+${{ github.event.pull_request.head.sha }}:remotes/origin/${{ github.event.pull_request.head.ref }}'
    steps:
    - name: 'Check out latest PR branch commit'
      uses: actions/checkout@v4
      with:
        persist-credentials: false
        ref: >-
          ${{
            github.event_name == 'pull_request'
            && github.event.pull_request.head.sha
            || ''
          }}
    # Adapted from https://github.com/actions/checkout/issues/520#issuecomment-1167205721
    - name: 'Fetch commits to get branch diff'
      if: github.event_name == 'pull_request'
      run: |
        # Fetch enough history to find a common ancestor commit (aka merge-base):
        git fetch origin "${refspec_pr}" --depth=$(( commits + 1 )) \
          --no-tags --prune --no-recurse-submodules

        # This should get the oldest commit in the local fetched history (which may not be the commit the PR branched from):
        COMMON_ANCESTOR=$( git rev-list --first-parent --max-parents=0 --max-count=1 "${branch_pr}" )
        DATE=$( git log --date=iso8601 --format=%cd "${COMMON_ANCESTOR}" )

        # Get all commits since that commit date from the base branch (eg: master or main):
        git fetch origin "${refspec_base}" --shallow-since="${DATE}" \
          --no-tags --prune --no-recurse-submodules
    - name: 'Set up Python'
      uses: actions/setup-python@v5
      with:
        python-version: '3'
        cache: 'pip'
        cache-dependency-path: 'Doc/requirements.txt'
    - name: 'Install build dependencies'
      run: make -C Doc/ venv

    # To annotate PRs with Sphinx nitpicks (missing references)
    - name: 'Build HTML documentation'
      continue-on-error: true
      run: |
        set -Eeuo pipefail
        # Build docs with the nit-picky option; write warnings to file
        make -C Doc/ PYTHON=../python SPHINXOPTS="--quiet --nitpicky --fail-on-warning --keep-going --warning-file sphinx-warnings.txt" html
    - name: 'Check warnings'
      if: github.event_name == 'pull_request'
      run: |
        python Doc/tools/check-warnings.py \
          --annotate-diff "${branch_base}" "${branch_pr}" \
          --fail-if-regression \
          --fail-if-improved \
          --fail-if-new-news-nit

  # Run "doctest" on HEAD as new syntax doesn't exist in the latest stable release
  doctest:
    name: 'Doctest'
    runs-on: ubuntu-24.04
    timeout-minutes: 60
    steps:
    - uses: actions/checkout@v4
      with:
        persist-credentials: false
    - uses: actions/cache@v4
      with:
        path: ~/.cache/pip
        key: ubuntu-doc-${{ hashFiles('Doc/requirements.txt') }}
        restore-keys: |
          ubuntu-doc-
    - name: 'Install Dependencies'
      run: sudo ./.github/workflows/posix-deps-apt.sh && sudo apt-get install wamerican
    - name: 'Configure CPython'
      run: ./configure --with-pydebug
    - name: 'Build CPython'
      run: make -j4
    - name: 'Install build dependencies'
      run: make -C Doc/ PYTHON=../python venv
    # Use "xvfb-run" since some doctest tests open GUI windows
    - name: 'Run documentation doctest'
      run: xvfb-run make -C Doc/ PYTHON=../python SPHINXERRORHANDLING="--fail-on-warning --keep-going" doctest
