name: Reusable Image Builder

on:
  workflow_call:
    inputs:
      dockerfile:
        required: true
        type: string
      build-json:
        required: true
        type: string
      build-args:
        required: false
        default: ""
        type: string

concurrency:
  group: ${{ github.workflow }}-${{ fromJSON(inputs.build-json).name }}-${{ fromJSON(inputs.build-json).version }}
  cancel-in-progress: false

jobs:
  build-image:
    name: Build ${{ fromJSON(inputs.build-json).name }} @ ${{ fromJSON(inputs.build-json).version }}
    runs-on: ubuntu-latest
    steps:
      -
        name: Login to Github Container Registry
        uses: docker/login-action@v1
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      -
        name: Determine if build needed
        id: build-skip-check
        run: |
          if ! docker manifest inspect ${{ fromJSON(inputs.build-json).image_tag }} &> /dev/null ; then
            echo "Building, no image exists with this version"
            echo ::set-output name=image-exists::false
          else
            echo "Not building, image exists with this version"
            echo ::set-output name=image-exists::true
          fi
      -
        name: Checkout
        uses: actions/checkout@v3
        if: ${{ steps.build-skip-check.outputs.image-exists == 'false' }}
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
        if: ${{ steps.build-skip-check.outputs.image-exists == 'false' }}
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
        if: ${{ steps.build-skip-check.outputs.image-exists == 'false' }}
      -
        name: Build ${{ fromJSON(inputs.build-json).name }}
        uses: docker/build-push-action@v2
        if: ${{ steps.build-skip-check.outputs.image-exists == 'false' }}
        with:
          context: .
          file: ${{ inputs.dockerfile }}
          tags: ${{ fromJSON(inputs.build-json).image_tag }}
          platforms: linux/amd64,linux/arm64,linux/arm/v7
          build-args: ${{ inputs.build-args }}
          push: true
          cache-from: type=gha
          cache-to: type=gha,mode=max