name: Reusable Docker Build Workflow

on:
  workflow_dispatch: # Prevents phantom runs on push, allows manual testing
  workflow_call:
    inputs:
      image_name:
        description: "Name of the Docker image (e.g. cua-ubuntu, cua-xfce)"
        required: true
        type: string
      context_dir:
        description: "Directory containing the Dockerfile relative to workspace root (e.g. libs/kasm, libs/xfce)"
        required: true
        type: string
      dockerfile_path:
        description: "Path to Dockerfile relative to context_dir (e.g. Dockerfile)"
        required: false
        type: string
        default: "Dockerfile"
      skip_arm64:
        description: "Skip arm64 build (for images that don't support arm64)"
        required: false
        type: boolean
        default: false

jobs:
  setup:
    runs-on: ubuntu-latest
    outputs:
      platforms: ${{ steps.set-platforms.outputs.platforms }}
    steps:
      - id: set-platforms
        run: |
          if [ "${{ inputs.skip_arm64 }}" == "true" ]; then
            echo 'platforms=["linux/amd64"]' >> $GITHUB_OUTPUT
          else
            echo 'platforms=["linux/amd64", "linux/arm64"]' >> $GITHUB_OUTPUT
          fi

  build:
    needs: setup
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        platform: ${{ fromJSON(needs.setup.outputs.platforms) }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Prepare platform tag
        id: platform
        run: |
          TAG=$(echo "${{ matrix.platform }}" | sed 's/\//-/g')
          echo "tag=${TAG}" >> $GITHUB_OUTPUT

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build Docker image
        uses: docker/build-push-action@v5
        with:
          context: ./${{ inputs.context_dir }}
          file: ./${{ inputs.context_dir }}/${{ inputs.dockerfile_path }}
          push: false
          platforms: ${{ matrix.platform }}

      - name: Verify build
        run: |
          echo "Successfully built ${{ inputs.image_name }} for ${{ matrix.platform }}"