name: R builds

on:
  push:
    paths:
      - 'builder/**'
      - 'test/**'
      - 'Makefile'
      - '.github/workflows/test.yml'
  pull_request:
    paths:
      - 'builder/**'
      - 'test/**'
      - 'Makefile'
      - '.github/workflows/test.yml'
  workflow_dispatch:
    inputs:
      platforms:
        description: |
          Comma-separated list of platforms. Specify "all" to use all platforms (the default).
        required: false
        default: 'all'
        type: string
      r_versions:
        description: |
          Comma-separated list of R versions. Specify "last-N" to use the
          last N minor R versions, or "all" to use all minor R versions since R 3.1.
          Defaults to "last-5,devel".
        required: false
        default: 'last-5,devel'
        type: string

permissions:
  contents: read

jobs:
  setup-matrix:
    runs-on: ubuntu-latest
    outputs:
      platforms: ${{ steps.setup-matrix.outputs.platforms }}
      r_versions: ${{ steps.setup-matrix.outputs.r_versions }}
    steps:
    - uses: actions/checkout@v3

    - name: Set up matrix of platforms and R versions
      id: setup-matrix
      run: |
        platforms=$(python test/get_platforms.py ${{ github.event.inputs.platforms }})
        echo "platforms=$platforms" >> $GITHUB_OUTPUT
        r_versions=$(python test/get_r_versions.py ${{ github.event.inputs.r_versions }})
        echo "r_versions=$r_versions" >> $GITHUB_OUTPUT

  docker-images:
    needs: setup-matrix
    strategy:
      matrix:
        platform: ${{ fromJson(needs.setup-matrix.outputs.platforms) }}
    runs-on: ubuntu-latest
    name: Docker image (${{ matrix.platform }})
    steps:
      - uses: actions/checkout@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v2
        with:
          install: true

      # Enable Docker layer caching without having to push to a registry.
      # https://docs.docker.com/build/ci/github-actions/examples/#local-cache
      # This may eventually be migrated to the GitHub Actions cache backend,
      # which is still considered experimental.
      # https://github.com/moby/buildkit#github-actions-cache-experimental
      - name: Cache Docker layers
        uses: actions/cache@v3
        with:
          path: /tmp/.buildx-cache
          key: ${{ matrix.platform }}-buildx-${{ github.sha }}
          restore-keys: ${{ matrix.platform }}-buildx-

      # Use docker buildx instead of docker-compose here because cache exporting
      # does not seem to work as of docker-compose v2.6.0 and buildx v0.8.2, even
      # though it works with buildx individually.
      - name: Build image
        run: |
          docker buildx build -t r-builds:${{ matrix.platform }} \
            --file builder/Dockerfile.${{ matrix.platform }} \
            --cache-from "type=local,src=/tmp/.buildx-cache" \
            --cache-to "type=local,dest=/tmp/.buildx-cache-new,mode=max" \
            builder

      # Temporary workaround for unbounded GHA cache growth with the local cache mode.
      # https://github.com/docker/build-push-action/issues/252
      # https://github.com/moby/buildkit/issues/1896
      - name: Move cache
        run: |
          rm -rf /tmp/.buildx-cache
          mv /tmp/.buildx-cache-new /tmp/.buildx-cache

  test:
    needs: [setup-matrix, docker-images]
    strategy:
      fail-fast: false
      matrix:
        platform: ${{ fromJson(needs.setup-matrix.outputs.platforms) }}
        r_version: ${{ fromJson(needs.setup-matrix.outputs.r_versions) }}
    runs-on: ubuntu-latest
    name: ${{ matrix.platform }} (R ${{ matrix.r_version }})
    steps:
      - uses: actions/checkout@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v2
        with:
          install: true

      - name: Restore cached Docker layers
        uses: actions/cache@v3
        with:
          path: /tmp/.buildx-cache
          key: ${{ matrix.platform }}-buildx-${{ github.sha }}
          restore-keys: ${{ matrix.platform }}-buildx-

      - name: Load cached Docker image
        run: |
          docker buildx build -t r-builds:${{ matrix.platform }} \
            --file builder/Dockerfile.${{ matrix.platform }} \
            --cache-from "type=local,src=/tmp/.buildx-cache" \
            --load \
            builder

      - name: Build R
        run: |
          R_VERSION=${{ matrix.r_version }} make build-r-${{ matrix.platform }}

      - name: Test R
        run: |
          R_VERSION=${{ matrix.r_version }} make test-r-${{ matrix.platform }}