generate_pdfs.yml

name: Generate PDFs

# Triggered by:
#   - push to master that changes lecture markdown files
#   - manual dispatch (regenerates PDFs for ALL lecture files)
on:
  push:
    branches:
      - master
    paths:
      - '[0-9][0-9]_*.md'
  workflow_dispatch:

concurrency:
  group: pdf-generation
  cancel-in-progress: false

permissions:
  contents: write

jobs:
  # -------------------------------------------------------------------------
  # Job 1 – build PDFs and publish GitHub Releases
  # -------------------------------------------------------------------------
  generate_pdfs:
    name: Generate PDFs and create releases
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 2
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Detect changed lecture files (push) or select all (dispatch)
        id: changes
        run: |
          if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
            # Regenerate PDFs for every numbered lecture file
            files=$(ls [0-9][0-9]_*.md 2>/dev/null | tr '\n' ' ')
          else
            files=$(git diff --name-only HEAD^ HEAD \
                    | grep -E '^[0-9]{2}_.*\.md$' || true)
            files="${files//$'\n'/ }"
          fi
          echo "changed_files=${files}" >> "$GITHUB_OUTPUT"
          echo "Files to process: ${files}"

      # -----------------------------------------------------------------------
      # Validate that every changed file has a version tag and auto-increment
      # the patch component when the corresponding release tag already exists.
      #
      # Logic:
      #   1. Extract version from the <!-- ... --> frontmatter.
      #      → Fail hard if the tag is absent.
      #   2. Compute the release tag (same algorithm as the PDF step below).
      #      → If the release tag already exists on GitHub, the user forgot to
      #        bump the version.  We increment the patch component in the file.
      #   3. Commit & push any modified files with "[skip ci]" so the PDF step
      #      reads the correct (bumped) version from the working tree.
      # -----------------------------------------------------------------------
      - name: Check versions and auto-increment patch if tag already exists
        if: steps.changes.outputs.changed_files != ''
        run: |
          set -euo pipefail

          git config user.name  "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

          bumped_files=""
          error_files=""

          for file in ${{ steps.changes.outputs.changed_files }}; do
            [ -f "$file" ] || continue

            filename=$(basename "$file" .md)

            # ── 1. Require a version tag ───────────────────────────────────
            version=$(grep -oP '(?m)^version:\s*\K[\d.]+' "$file" | head -1 || true)
            if [ -z "$version" ]; then
              echo "ERROR: $file has no 'version:' tag in its frontmatter." >&2
              error_files="$error_files $file"
              continue
            fi

            # ── 2. Compute safe release tag ───────────────────────────────
            safe_tag=$(echo "$filename" \
              | tr '[:upper:]' '[:lower:]' \
              | sed -e 's/ä/ae/g' -e 's/ö/oe/g' -e 's/ü/ue/g' -e 's/ß/ss/g' \
                    -e 's/Ä/ae/g' -e 's/Ö/oe/g' -e 's/Ü/ue/g' \
                    -e 's/[^a-z0-9_-]//g')
            release_tag="${safe_tag}_v${version}"

            # ── 3. Auto-increment patch if release tag already exists ─────
            if gh release view "$release_tag" > /dev/null 2>&1; then
              echo "Tag '$release_tag' already exists for $file – auto-incrementing patch."

              # Increment last numeric component: e.g. 1.0.10 → 1.0.11
              new_version=$(echo "$version" | awk -F. '{$NF = $NF + 1; print}' OFS='.')

              # Replace the version line inside the HTML comment frontmatter.
              # The sed pattern handles optional spaces around the colon.
              sed -i -E "s/^(version:[[:space:]]*)[0-9]+(\.[0-9]+)*/\1${new_version}/" "$file"

              echo "  $file: $version → $new_version"
              bumped_files="$bumped_files $file"
            else
              echo "Tag '$release_tag' is new – no version bump needed for $file."
            fi
          done

          # ── Fail if any file was missing a version tag ───────────────────
          if [ -n "$error_files" ]; then
            echo ""
            echo "The following files are missing a 'version:' tag:" >&2
            for f in $error_files; do echo "  $f" >&2; done
            echo "Please add 'version: X.Y.Z' to the HTML comment frontmatter." >&2
            exit 1
          fi

          # ── Commit & push version bumps ───────────────────────────────────
          if [ -n "$bumped_files" ]; then
            git add $bumped_files
            git commit -m "ci: auto-increment patch version for changed courses [skip ci]"
            git pull --rebase origin master || true
            git push
            echo "Version bumps pushed to master."
          fi
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Set up Node.js
        if: steps.changes.outputs.changed_files != ''
        uses: actions/setup-node@v4
        with:
          node-version: '22'

      - name: Install LiaScript exporter
        if: steps.changes.outputs.changed_files != ''
        run: npm install -g @liascript/exporter

      - name: Generate PDFs and publish GitHub Releases
        if: steps.changes.outputs.changed_files != ''
        run: |
          set -euo pipefail
          mkdir -p /tmp/pdf_build

          for file in ${{ steps.changes.outputs.changed_files }}; do
            [ -f "$file" ] || continue

            filename=$(basename "$file" .md)

            # Safe tag: lowercase, transliterate umlauts, remove non-ASCII
            safe_tag=$(echo "$filename" \
              | tr '[:upper:]' '[:lower:]' \
              | sed -e 's/ä/ae/g' -e 's/ö/oe/g' -e 's/ü/ue/g' -e 's/ß/ss/g' \
                    -e 's/Ä/ae/g' -e 's/Ö/oe/g' -e 's/Ü/ue/g' \
                    -e 's/[^a-z0-9_-]//g')

            # Re-read version from the file (may have been bumped in the
            # previous step; the version tag is guaranteed to exist by now).
            version=$(grep -oP '(?m)^version:\s*\K[\d.]+' "$file" | head -1)

            asset_name="${filename}_v${version}_Documentation"
            release_tag="${safe_tag}_v${version}"

            echo "==> $file  (tag: $release_tag)"

            # Generate PDF
            liaex \
              --input "$file" \
              --format pdf \
              --output "/tmp/pdf_build/${asset_name}" \
              --pdf-timeout 60000

            pdf_path="/tmp/pdf_build/${asset_name}.pdf"

            if [ ! -f "$pdf_path" ]; then
              echo "ERROR: PDF not created for $file" >&2
              exit 1
            fi

            # The version-check step guarantees the tag is new at this point.
            gh release create "$release_tag" \
              --title "PDF – ${filename} (v${version})" \
              --notes "Automated PDF export for \`${file}\` – version ${version}" \
              "$pdf_path"
          done
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}