name: Build Branch Image

on:
  push:
    branches:
      - dev
      - staging
      - unstable

# Cancel an in-flight build for a branch if a new push arrives before it finishes — avoids wasting runner minutes racing two builds of the same branch.
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

permissions:
  contents: read
  packages: write

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

jobs:
  build:
    strategy:
      fail-fast: false
      matrix:
        include:
          - platform: linux/amd64
            runs-on: ubuntu-26.04
          - platform: linux/arm64
            runs-on: ubuntu-26.04-arm
    runs-on: ${{ matrix.runs-on }}
    timeout-minutes: 45
    steps:
      - name: Checkout
        uses: actions/checkout@v4

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

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

      - name: Prepare platform tag
        id: platform
        run: |
          platform=${{ matrix.platform }}
          echo "pair=${platform//\//-}" >> "$GITHUB_OUTPUT"

      - name: Build and push (${{ matrix.platform }})
        id: build
        uses: docker/build-push-action@v6
        with:
          context: .
          platforms: ${{ matrix.platform }}
          provenance: false
          sbom: false
          outputs: type=image,name=${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=true
          cache-from: type=gha,scope=${{ github.ref_name }}-${{ steps.platform.outputs.pair }}
          cache-to: type=gha,mode=max,scope=${{ github.ref_name }}-${{ steps.platform.outputs.pair }}

      - name: Export digest
        run: |
          mkdir -p /tmp/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "/tmp/digests/${digest#sha256:}"

      - name: Upload digest
        uses: actions/upload-artifact@v4
        with:
          name: digests-${{ steps.platform.outputs.pair }}
          path: /tmp/digests/*
          if-no-files-found: error
          retention-days: 1

  merge:
    needs: build
    runs-on: ubuntu-latest
    timeout-minutes: 15
    steps:
      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: /tmp/digests
          pattern: digests-*
          merge-multiple: true

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

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

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.IMAGE_NAME }}
          tags: |
            type=raw,value=${{ github.ref_name == 'dev' && 'latest' || github.ref_name }}
            type=sha,format=short,prefix=${{ github.ref_name == 'dev' && 'latest' || github.ref_name }}-

      - name: Create manifest list and push
        working-directory: /tmp/digests
        run: |
          docker buildx imagetools create \
            $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
            $(printf '${{ env.IMAGE_NAME }}@sha256:%s ' *)
        env:
          DOCKER_METADATA_OUTPUT_JSON: ${{ steps.meta.outputs.json }}

      - name: Inspect image
        run: |
          docker buildx imagetools inspect ${{ env.IMAGE_NAME }}:${{ steps.meta.outputs.version }}