name: Build Docker

permissions:
  contents: read    # needed to checkout repo
  packages: write    # needed for interacting with GHCR

on:
  push:
    branches:
      - master
  pull_request:
    branches:
      - master
    paths:
      - '.github/workflows/docker-release.yml'
      - '.dockerignore'
      - 'Dockerfile'
      - 'docker-compose.yml'
      - 'docker-compose.yml.windows'
  release:
    types:
      - released    # publishing of stable releases

# Cancel earlier, unfinished runs of this workflow on the same branch (unless on release)
concurrency:
  group: "${{ github.workflow }} @ ${{ github.ref_name }}"
  cancel-in-progress: ${{ github.event_name != 'release' }}

env:
  GHCR_IMAGE: ghcr.io/cockatrice/servatrice
  OCI_DESCRIPTION: Server for Cockatrice, a cross-platform virtual tabletop for multiplayer card games
  OCI_TITLE: Servatrice
  OCI_URL: https://cockatrice.github.io/

jobs:
  # Create one platform-specific image and publish its OCI image manifest per matrix job
  build:
    name: "Servatrice (${{ matrix.label }})"
    if: github.repository_owner == 'Cockatrice'
    runs-on: ${{ matrix.runner }}

    strategy:
      fail-fast: false
      matrix:
        include:
          - label: x86
            platform: linux/amd64
            runner: ubuntu-latest    # https://github.com/actions/runner-images

          - label: arm
            platform: linux/arm64
            runner: ubuntu-24.04-arm    # https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2404-Arm64-Readme.md, replace with "ubuntu-latest-arm" once available

    env:
      CACHE_SCOPE: servatrice-${{ matrix.label }}

    steps:
      - name: "Checkout"
        uses: actions/checkout@v7

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

      - name: "Login to GitHub Container Registry (GHCR)"
        if: github.event_name == 'release' && github.event.release.prerelease == false
        id: login
        uses: docker/login-action@v4
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ github.token }}

      # Don't push for non-release triggers
      - name: "Build image"
        if: steps.login.outcome != 'success'
        uses: docker/build-push-action@v7
        with:
          cache-from: type=gha,scope=${{ env.CACHE_SCOPE }}
          cache-to: ${{ case(github.ref == 'refs/heads/master', format('type=gha,mode=max,scope={0}', env.CACHE_SCOPE), '') }}
          context: .
          platforms: ${{ matrix.platform }}
          push: false

      # Add OCI labels and push single-platform image by digest (without tags)
      - name: "Build image and push by digest"
        if: steps.login.outcome == 'success'
        id: build
        uses: docker/build-push-action@v7
        with:
          cache-from: type=gha,scope=${{ env.CACHE_SCOPE }}
          cache-to: type=gha,mode=max,scope=${{ env.CACHE_SCOPE }}
          context: .
          labels: |
            org.opencontainers.image.description=${{ env.OCI_DESCRIPTION }}
            org.opencontainers.image.title=${{ env.OCI_TITLE }}
            org.opencontainers.image.url=${{ env.OCI_URL }}
          outputs: type=image,name=${{ env.GHCR_IMAGE }},name-canonical=true,push=true,push-by-digest=true
          platforms: ${{ matrix.platform }}
          provenance: mode=max    # Do not pass secrets as build arguments with this option
          sbom: true

      - name: "Export digest"
        if: steps.login.outcome == 'success'
        env:
          DIGEST: ${{ steps.build.outputs.digest }}
        run: |
          mkdir -p "$RUNNER_TEMP/digests"
          touch "$RUNNER_TEMP/digests/${DIGEST#sha256:}"

      - name: "Upload digest"
        if: steps.login.outcome == 'success'
        uses: actions/upload-artifact@v7
        with:
          archive: false
          if-no-files-found: error
          name: digest-${{ matrix.label }}
          path: ${{ runner.temp }}/digests/*
          retention-days: 1


  # Create an OCI image index from the platform-specific image manifests
  index:
    name: "Publish multi-platform Servatrice image"
    if: github.repository_owner == 'Cockatrice' && github.event_name == 'release' && github.event.release.prerelease == false
    needs: build
    runs-on: ubuntu-slim    # https://github.com/actions/runner-images/blob/main/images/ubuntu-slim/ubuntu-slim-Readme.md

    steps:
      - name: "Download digests"
        uses: actions/download-artifact@v7
        with:
          path: ${{ runner.temp }}/digests
          pattern: digest-*
          merge-multiple: true

      - name: "Login to GitHub Container Registry (GHCR)"
        uses: docker/login-action@v4
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ github.token }}

      - name: "Docker metadata"
        id: metadata
        uses: docker/metadata-action@v6
        with:
          images: ${{ env.GHCR_IMAGE }}
          flavor: |
            latest=auto
          tags: |
            type=ref,event=tag    # if semver, also: type=semver,pattern={{version}} / {{major}}.{{minor}}

      # Add OCI annotations to image index and publish tags
      - name: "Create image index"
        env:
          DOCKER_TAGS: ${{ steps.metadata.outputs.tags }}
        working-directory: ${{ runner.temp }}/digests
        run: |
          TAG_ARGS=()
          while IFS= read -r tag; do
            TAG_ARGS+=(--tag "$tag")
          done <<< "$DOCKER_TAGS"

          DIGEST_ARGS=()
          for digest in *; do
            DIGEST_ARGS+=("$GHCR_IMAGE@sha256:$digest")
          done

          docker buildx imagetools create \
            --prefer-index=true \
            --annotation "index:org.opencontainers.image.description=$OCI_DESCRIPTION" \
            --annotation "index:org.opencontainers.image.title=$OCI_TITLE" \
            --annotation "index:org.opencontainers.image.url=$OCI_URL" \
            "${TAG_ARGS[@]}" \
            "${DIGEST_ARGS[@]}"

      - name: "Inspect images"
        env:
          GITHUB_TAG: ${{ github.ref_name }}
        run: |
          docker buildx imagetools inspect "$GHCR_IMAGE:latest"
          docker buildx imagetools inspect "$GHCR_IMAGE:$GITHUB_TAG"