name: docker

on:
  push:
    branches: [main]
    tags: ["v*"]
  pull_request:
  workflow_dispatch:

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

concurrency:
  group: docker-${{ github.ref }}
  cancel-in-progress: true

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - uses: actions/checkout@v4

      # QEMU lets one runner produce the arm64 image alongside amd64.
      - uses: docker/setup-qemu-action@v3
      - uses: docker/setup-buildx-action@v3

      # Pull requests build but never publish: forks must not be able to push.
      - name: Log in to ${{ env.REGISTRY }}
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Derive tags and labels
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}
            type=semver,pattern={{major}}
            type=ref,event=branch
            type=ref,event=pr
            type=sha,format=short
            type=raw,value=latest,enable={{is_default_branch}}

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          platforms: linux/amd64,linux/arm64
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          build-args: |
            VERSION=${{ steps.meta.outputs.version }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Summary
        if: github.event_name != 'pull_request'
        run: |
          {
            echo "### Published"
            echo
            echo '```'
            echo "${{ steps.meta.outputs.tags }}"
            echo '```'
          } >> "$GITHUB_STEP_SUMMARY"