name: docs

# Builds the mdBook site in docs/ and deploys it to GitHub Pages.
# One-time setup: repo Settings → Pages → Source = "GitHub Actions".
#
# Pull requests build the book but never deploy — so a broken book (or a
# chapter that {{#include}}s a file that moved) is a red PR check, not a
# post-merge surprise. results/** is a trigger because case-study chapters
# include evidence files from there.

on:
  push:
    branches: [main]
    paths:
      - "docs/**"
      - "results/**"
      - ".github/workflows/docs.yml"
  pull_request:
    paths:
      - "docs/**"
      - "results/**"
      - ".github/workflows/docs.yml"
  workflow_dispatch:

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

# Allow one concurrent deployment; don't cancel an in-progress prod deploy.
concurrency:
  group: pages-${{ github.event_name == 'pull_request' && github.ref || 'prod' }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

jobs:
  build:
    runs-on: ubuntu-latest
    env:
      MDBOOK_VERSION: "0.4.40"
    steps:
      - uses: actions/checkout@v4
      - name: Configure Pages
        if: github.event_name != 'pull_request'
        uses: actions/configure-pages@v5
      - name: Install mdBook
        run: |
          mkdir -p "$HOME/.local/bin"
          url="https://github.com/rust-lang/mdBook/releases/download/v${MDBOOK_VERSION}/mdbook-v${MDBOOK_VERSION}-x86_64-unknown-linux-gnu.tar.gz"
          curl -sSL "$url" | tar -xz -C "$HOME/.local/bin"
          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
      - name: Build
        run: mdbook build docs
      - name: Upload artifact
        if: github.event_name != 'pull_request'
        uses: actions/upload-pages-artifact@v3
        with:
          path: docs/book

  deploy:
    if: github.event_name != 'pull_request'
    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