demo.yml

name: Demo GIF

on:
  push:
    branches: [main]

permissions:
  contents: write

jobs:
  record:
    # Skip if the push was made by the CI bot to avoid loops.
    if: github.actor != 'github-actions[bot]'
    runs-on: ubuntu-latest
    steps:
      # Credentials intentionally persisted — needed for git push.
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          fetch-depth: 0
          persist-credentials: true

      - uses: actions/setup-go@7a3fe6cf4cb3a834922a1244abfce67bcef6a0c5 # v6.2.0
        with:
          go-version-file: go.mod

      - name: Build mdsmith
        run: go build -o mdsmith ./cmd/mdsmith

      - name: Cache VHS + ttyd binaries
        id: vhs-cache
        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
        with:
          path: |
            ~/vhs-bin
          key: vhs-0.10.0-ttyd-1.7.7-${{ runner.os }}-${{ runner.arch }}
      - name: Install VHS runtime dependencies
        run: |
          # Google Chrome is pre-installed on GitHub runners and
          # go-rod (used by VHS) finds it via launcher.LookPath().
          # Installing chromium via apt on Ubuntu 24.04 triggers a
          # slow snap install (~500 MB of dependencies), so we skip
          # it and only install ffmpeg.
          sudo apt-get update -qq
          sudo apt-get install -y -qq ffmpeg
          if [ -f ~/vhs-bin/ttyd ]; then
            sudo install ~/vhs-bin/ttyd /usr/local/bin/ttyd
          else
            curl -fsSL -o /tmp/ttyd \
              "https://github.com/tsl0922/ttyd/releases/download/1.7.7/ttyd.x86_64"
            sudo install /tmp/ttyd /usr/local/bin/ttyd
          fi
      - name: Install VHS
        run: |
          if [ -f ~/vhs-bin/vhs ]; then
            sudo install ~/vhs-bin/vhs /usr/local/bin/vhs
          else
            go install github.com/charmbracelet/vhs@v0.10.0
          fi
          echo "$(go env GOPATH)/bin" >> "$GITHUB_PATH"
      - name: Populate VHS cache
        if: steps.vhs-cache.outputs.cache-hit != 'true'
        run: |
          mkdir -p ~/vhs-bin
          cp /usr/local/bin/ttyd ~/vhs-bin/
          cp "$(go env GOPATH)/bin/vhs" ~/vhs-bin/ 2>/dev/null || cp /usr/local/bin/vhs ~/vhs-bin/ 2>/dev/null || true

      - name: Record demo in isolated directory
        run: |
          # Run VHS in a temp directory so demo.tape commands
          # cannot modify the repo working tree.
          iso="$(mktemp -d)"
          tar --exclude='.git' -cf - . | (cd "$iso" && tar -xf -)
          # No Output-path rewrite needed — VHS runs inside $iso,
          # so relative Output assets/demo.gif writes to $iso/assets/.
          (cd "$iso" && vhs demo.tape)
          cp "$iso/assets/demo.gif" /tmp/demo.gif
          rm -rf "$iso"

      - name: Push GIF to assets branch
        run: |
          # Create or update the orphan assets branch with only
          # the demo GIF. This avoids pushing to main entirely —
          # no branch protection bypass needed.
          git config user.name  "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"

          # Remove untracked build artifacts so branch switch succeeds.
          rm -f mdsmith

          # Check if assets branch exists on remote
          if git ls-remote --exit-code origin refs/heads/assets >/dev/null 2>&1; then
            git fetch origin assets
            git checkout assets
            git rm -rf --ignore-unmatch .
            git clean -fdx
          else
            git checkout --orphan assets
            git rm -rf --ignore-unmatch .
            git clean -fdx
          fi

          mkdir -p assets
          cp /tmp/demo.gif assets/demo.gif

          # Only push if the GIF actually changed
          git add assets/demo.gif
          if git diff --staged --quiet; then
            echo "assets/demo.gif unchanged — nothing to push"
          else
            git commit -m "chore: update demo GIF"
            git push -u origin assets
          fi