name: Build and publish image

on:
  push:
    branches: [ main ]
    tags: [ 'v*' ]

# Only one build per ref at a time; cancel superseded main builds.
concurrency:
  group: build-${{ github.ref }}
  cancel-in-progress: ${{ github.ref == 'refs/heads/main' }}

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write  # Required to push to GHCR

    steps:
      - name: Checkout code
        uses: actions/checkout@v5

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

      - name: Log in to GitHub Container Registry
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract image metadata (tags, labels)
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ghcr.io/${{ github.repository }}
          tags: |
            type=edge,branch=main
            type=sha,prefix=sha-,format=short,enable={{is_default_branch}}
            type=semver,pattern=v{{version}}
            type=semver,pattern=v{{major}}.{{minor}}
          flavor: |
            latest=auto

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          platforms: linux/amd64
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max