name: Docker image build (Server)

on:
  workflow_dispatch:
    inputs:
      version:
        description: "Image version/tag to publish, for example v1.0.0-beta"
        required: false
        type: string
  push:
    tags: ["v*"]

permissions:
  contents: read
  packages: write
  attestations: write
  id-token: write

jobs:
  build:
    name: Build (${{ matrix.arch }})
    strategy:
      fail-fast: false
      matrix:
        include:
          - arch: amd64
            platform: linux/amd64
            runner: ubuntu-24.04
          - arch: arm64
            platform: linux/arm64
            runner: ubuntu-24.04-arm
    runs-on: ${{ matrix.runner }}
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-tags: true
          fetch-depth: 0
          persist-credentials: false

      - name: Set image metadata
        shell: bash
        env:
          INPUT_VERSION: ${{ github.event.inputs.version }}
        run: |
          POINTED_TAG="$(git tag --points-at HEAD --list 'v*' | sort -V | tail -n1)"
          INPUT_VERSION="${INPUT_VERSION//[[:space:]]/}"

          echo "IMAGE=ghcr.io/${GITHUB_REPOSITORY,,}" >> "$GITHUB_ENV"
          if [[ "${GITHUB_REF}" == refs/tags/* ]]; then
            VERSION="${GITHUB_REF_NAME}"
          elif [[ -n "$INPUT_VERSION" ]]; then
            VERSION="$INPUT_VERSION"
          elif [[ -n "$POINTED_TAG" ]]; then
            VERSION="$POINTED_TAG"
          else
            echo "workflow_dispatch requires an explicit version input when HEAD is not tagged" >&2
            exit 1
          fi

          echo "VERSION=$VERSION" >> "$GITHUB_ENV"

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v4

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

      - name: Build and push
        id: build
        uses: docker/build-push-action@v7
        with:
          context: .
          file: ./docker/Dockerfile
          platforms: ${{ matrix.platform }}
          outputs: type=image,name=${{ env.IMAGE }},push-by-digest=true,name-canonical=true,push=true
          build-args: |
            VERSION=${{ env.VERSION }}
          cache-from: type=gha,scope=docker-server-${{ matrix.arch }}
          cache-to: type=gha,mode=max,ignore-error=true,timeout=20m,scope=docker-server-${{ matrix.arch }}

      - name: Export digest
        shell: bash
        run: |
          mkdir -p /tmp/server-digests
          touch "/tmp/server-digests/${DIGEST#sha256:}"
        env:
          DIGEST: ${{ steps.build.outputs.digest }}

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

      - name: Generate artifact attestation
        uses: actions/attest-build-provenance@v3
        with:
          subject-name: ${{ env.IMAGE }}
          subject-digest: ${{ steps.build.outputs.digest }}
          push-to-registry: true

  merge:
    name: Merge multi-arch manifest
    runs-on: ubuntu-24.04
    needs: build
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-tags: true
          fetch-depth: 0
          persist-credentials: false

      - name: Set image metadata
        shell: bash
        env:
          INPUT_VERSION: ${{ github.event.inputs.version }}
        run: |
          POINTED_TAG="$(git tag --points-at HEAD --list 'v*' | sort -V | tail -n1)"
          INPUT_VERSION="${INPUT_VERSION//[[:space:]]/}"

          echo "IMAGE=ghcr.io/${GITHUB_REPOSITORY,,}" >> "$GITHUB_ENV"
          if [[ "${GITHUB_REF}" == refs/tags/* ]]; then
            VERSION="${GITHUB_REF_NAME}"
          elif [[ -n "$INPUT_VERSION" ]]; then
            VERSION="$INPUT_VERSION"
          elif [[ -n "$POINTED_TAG" ]]; then
            VERSION="$POINTED_TAG"
          else
            echo "workflow_dispatch requires an explicit version input when HEAD is not tagged" >&2
            exit 1
          fi

          echo "VERSION=$VERSION" >> "$GITHUB_ENV"

      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: /tmp/server-digests
          pattern: server-digests-*
          merge-multiple: true

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v4

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

      - name: Create and push manifest list
        working-directory: /tmp/server-digests
        shell: bash
        run: |
          shopt -s nullglob
          references=()
          for digest in *; do
            references+=("${IMAGE}@sha256:${digest}")
          done

          if [ ${#references[@]} -eq 0 ]; then
            echo "No digests found in /tmp/server-digests" >&2
            exit 1
          fi

          if [[ "${VERSION}" =~ (alpha|beta|rc) ]]; then
            FLOATING_TAG="beta"
          else
            FLOATING_TAG="latest"
          fi

          docker buildx imagetools create \
            -t "${IMAGE}:${VERSION}" \
            -t "${IMAGE}:${FLOATING_TAG}" \
            "${references[@]}"

      - name: Inspect image
        run: docker buildx imagetools inspect "${IMAGE}:${VERSION}"