name: C++ reference

# Builds the upstream SMLib/SM_API reference libraries with harness/cpp/build.sh and
# publishes them as the GitHub Release cpp-ref-<key> (asset
# solidcore-cpp-ref-<key>-linux-x86_64.tar.zst plus .sha256), which scripts/fetch-cpp.sh
# downloads in CI and on contributors' machines instead of compiling SMLib (about a
# minute on a 16-vCPU runner plus tool installs, much longer on a laptop).
# <key> comes from scripts/cpp-ref-key.sh: the pinned upstream commit
# (scripts/upstream-pin.env, the single source of truth for the pin) plus a hash of
# harness/cpp/{CMakeLists.txt,build.sh,stubs/**,patches/**}. Shims are compiled by
# solidcore-ffi, so editing them never needs a new release. Until a new key is published,
# CI falls back to building from source (and caches that build).
on:
  push:
    branches: [main]
    paths:
      - 'harness/cpp/**'
      - '!harness/cpp/shim/**'
      - 'scripts/cpp-ref-key.sh'
      - 'scripts/upstream-pin.env'
      - 'scripts/package-cpp-ref.sh'
      - '.github/workflows/cpp-reference.yml'
  workflow_dispatch:
    inputs:
      force:
        description: Rebuild and replace the asset even if the release already has it
        type: boolean
        default: false

# Only this workflow may write: it creates the release and uploads its assets.
permissions:
  contents: write

concurrency:
  group: cpp-reference-${{ github.ref }}
  cancel-in-progress: false

jobs:
  publish:
    # Ubuntu 24.04 (glibc 2.39, GCC 13): the image every CI job runs on, and the
    # compatibility floor scripts/fetch-cpp.sh documents and checks.
    runs-on: blacksmith-16vcpu-ubuntu-2404
    env:
      GH_TOKEN: ${{ github.token }}
    steps:
      - uses: actions/checkout@v4

      - name: Compute key
        id: key
        run: |
          echo "SOLIDCORE_CPP_DIR=$RUNNER_TEMP/cpp" >> "$GITHUB_ENV"
          grep -E '^UPSTREAM_(REPO|VERSION|COMMIT)=' scripts/upstream-pin.env >> "$GITHUB_ENV"
          key="$(scripts/cpp-ref-key.sh)"
          echo "key=$key" >> "$GITHUB_OUTPUT"
          echo "tag=cpp-ref-$key" >> "$GITHUB_OUTPUT"
          echo "name=solidcore-cpp-ref-$key-linux-x86_64.tar.zst" >> "$GITHUB_OUTPUT"
          echo "key: $key"

      - name: Skip when already published
        id: have
        run: |
          url="https://github.com/${{ github.repository }}/releases/download/${{ steps.key.outputs.tag }}/${{ steps.key.outputs.name }}.sha256"
          if [ "${{ inputs.force }}" != "true" ] && curl -fsSLI "$url" >/dev/null 2>&1; then
            echo "skip=true" >> "$GITHUB_OUTPUT"
            echo "Already published: $url"
          else
            echo "skip=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Clone upstream at pinned commit
        if: steps.have.outputs.skip != 'true'
        run: |
          git init upstream
          git -C upstream remote add origin "$UPSTREAM_REPO"
          git -C upstream fetch --depth 1 origin "$UPSTREAM_COMMIT" \
            || git -C upstream fetch origin
          git -C upstream checkout --detach "$UPSTREAM_COMMIT"

      - name: Install C++ build tools
        if: steps.have.outputs.skip != 'true'
        run: sudo apt-get update && sudo apt-get install -y ninja-build cmake g++ zstd

      - name: Build C++ reference
        if: steps.have.outputs.skip != 'true'
        run: harness/cpp/build.sh --no-tests --jobs "$(nproc)"

      - name: Package
        if: steps.have.outputs.skip != 'true'
        run: scripts/package-cpp-ref.sh "$SOLIDCORE_CPP_DIR" "$RUNNER_TEMP/dist"

      - name: Publish release
        if: steps.have.outputs.skip != 'true'
        env:
          TAG: ${{ steps.key.outputs.tag }}
          NAME: ${{ steps.key.outputs.name }}
        run: |
          if ! gh release view "$TAG" -R "$GITHUB_REPOSITORY" >/dev/null 2>&1; then
            gh release create "$TAG" -R "$GITHUB_REPOSITORY" --target "$GITHUB_SHA" \
              --prerelease --title "C++ reference $TAG" \
              --notes "Prebuilt SMLib/SM_API reference libraries (Apache-2.0, upstream commit $UPSTREAM_COMMIT) for solidcore's difftest, built by harness/cpp/build.sh on Ubuntu 24.04 x86_64 from $GITHUB_SHA. Download with scripts/fetch-cpp.sh."
          fi
          gh release upload "$TAG" -R "$GITHUB_REPOSITORY" --clobber \
            "$RUNNER_TEMP/dist/$NAME" "$RUNNER_TEMP/dist/$NAME.sha256"
          echo "https://github.com/$GITHUB_REPOSITORY/releases/tag/$TAG" >> "$GITHUB_STEP_SUMMARY"