name: Docker CI

on:
  pull_request:
    branches:
      - main

env:
  IMAGE_NAME: jcreek23/open-network-diagram

jobs:
  docker:
    runs-on: ubuntu-latest
    permissions:
      contents: read

    steps:
      - name: Checkout
        uses: actions/checkout@v6

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

      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: docker.io/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=pr
            type=sha,prefix=sha-

      - name: Build (PR validation only)
        uses: docker/build-push-action@v7
        with:
          context: .
          file: Dockerfile
          push: false
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max