# Documentation site.
#
# Two jobs with different jobs to do. On a pull request the site is *built* and
# nothing is published — a broken link or a page missing from the nav fails the
# check rather than shipping. On main it is published under a version, because
# readers are routinely running something other than the newest build and a
# single "latest" would describe a release they do not have.
name: Documentation

on:
  push:
    branches: [main]
    paths:
      - 'docs/**'
      - 'mkdocs.yml'
      - 'requirements-docs.txt'
      - '.github/workflows/docs.yml'
      - 'frontend/package.json'   # version stamp comes from here
  pull_request:
    paths:
      - 'docs/**'
      - 'mkdocs.yml'
      - 'requirements-docs.txt'
      - '.github/workflows/docs.yml'
  workflow_dispatch:

permissions:
  contents: write

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

jobs:
  build:
    name: Build (check only)
    if: github.event_name == 'pull_request'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-python@v6
        with:
          python-version: '3.12'
          cache: pip
      - run: pip install -r requirements-docs.txt
      # --strict turns warnings into errors, which is the point of running this
      # on a pull request at all: a link to a page that no longer exists should
      # fail here rather than 404 for a reader.
      - run: mkdocs build --strict

  deploy:
    name: Publish versioned site
    if: github.event_name != 'pull_request'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
        with:
          fetch-depth: 0        # mike needs history to update gh-pages
      - uses: actions/setup-python@v6
        with:
          python-version: '3.12'
          cache: pip
      - run: pip install -r requirements-docs.txt

      - name: Derive version from the shipped package
        id: v
        run: |
          # Documentation is versioned with the product, not separately, so the
          # site and the image a reader is running carry the same number.
          FULL=$(node -p "require('./frontend/package.json').version")
          SERIES=$(echo "$FULL" | sed -E 's/^([0-9]+\.[0-9]+).*/\1/')
          echo "full=$FULL"     >> "$GITHUB_OUTPUT"
          echo "series=$SERIES" >> "$GITHUB_OUTPUT"

      - name: Configure git for mike
        run: |
          git config user.name  "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

      # Aliased to "latest" so links stay stable while older series remain
      # readable at their own URLs.
      - name: Deploy
        run: |
          mike deploy --push --update-aliases \
            "${{ steps.v.outputs.series }}" latest \
            --title "${{ steps.v.outputs.series }} (${{ steps.v.outputs.full }})"
          mike set-default --push latest