name: Publish Docker Image

on:
   push:
      branches:
         - master
         - multi-runner-docker
      tags:
         - v**
   workflow_dispatch:

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

jobs:
   gen-versions:
      name: Generate tags
      runs-on: ubuntu-24.04
      outputs:
         DOCKER_IMAGE_TAG_JSON: ${{ steps.variables.outputs.DOCKER_IMAGE_TAG_JSON }}
         DOCKER_IMAGE_TAG: ${{ steps.variables.outputs.DOCKER_IMAGE_TAG }}
      steps:
         -  name: Setup variables
            id: variables
            run: |
               # docker/build-push-action supports comma separated tags
               DOCKER_IMAGE_TAG_BASE="$REGISTRY/$IMAGE"
               DOCKER_IMAGE_TAG_JSON="$(
               ( # Every line echoed inside of these parenthesis will result in a version
                  echo dev
                  GH_REF="${{ github.ref }}"
                  # if this is a versioned release, github.ref will start with 'refs/tags/v'
                  # cut off 'refs/tags/v'
                  if [[ $GH_REF == "refs/tags/v"* ]]; then
                     VERSION=$(echo $GH_REF | cut -c 12-)
                     echo latest
                     echo $VERSION
                  fi
               ) | sed -e 's|.*|'"$DOCKER_IMAGE_TAG_BASE"':\0|' | jq -R -s -c 'split("\n") | map(select (. != "" ))')"

               echo "DOCKER_IMAGE_TAG_JSON=$DOCKER_IMAGE_TAG_JSON" >> "$GITHUB_OUTPUT"
               echo "DOCKER_IMAGE_TAG=$(echo "$DOCKER_IMAGE_TAG_JSON" | jq -r 'join(",")')" >> "$GITHUB_OUTPUT"

   publish-base:
      name: Publish ${{ matrix.arch }} image
      strategy:
         matrix:
            include:
               -  arch: arm64
                  os: ubuntu-24.04-arm
               -  arch: amd64
                  os: ubuntu-24.04

      runs-on: ${{ matrix.os }}
      needs:
         - gen-versions
      env:
         ARCH: ${{matrix.arch}}
      permissions:
         packages: write
      steps:
         -  name: Check out the repo
            uses: actions/checkout@v4

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

         -  name: Enhance tags
            id: variables
            run: |
               echo "DOCKER_IMAGE_TAG=$(echo "$TAG" | jq -r 'map(. + "-${{ matrix.arch }}") | join(",")')" >>"$GITHUB_OUTPUT"
            env:
               TAG: ${{ needs.gen-versions.outputs.DOCKER_IMAGE_TAG_JSON }}
         -  name: Set up Docker Buildx # Even if we don't directly invoke buildx it should set up github action caches, which is nice
            uses: docker/setup-buildx-action@v3
         -  name: Build and push Docker Image
            uses: docker/build-push-action@v6
            id: upload-docker-image
            with:
               context: .
               push: true
               tags: ${{ steps.variables.outputs.DOCKER_IMAGE_TAG }}
               cache-from: type=gha
               cache-to: type=gha,mode=max
         -  name: Write digest
            run: |
               digest="${{ steps.upload-docker-image.outputs.digest }}"
               mkdir -p digests
               touch "digests/${digest#sha256:}"

         -  name: Upload docker image digest
            uses: actions/upload-artifact@v4
            with:
               if-no-files-found: error
               name: digests-${{ matrix.arch }}
               path: digests/*

   publish-multiarch:
      name: Publish multi-arch image
      needs:
         - publish-base
         - gen-versions
      runs-on: ubuntu-24.04
      permissions:
         packages: write
      steps:
         -  name: Download digests
            uses: actions/download-artifact@v4
            with:
               path: digests
               pattern: digests-*
               merge-multiple: true

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


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

         -  name: Create manifest list
            run: |
               cd digests
               docker buildx imagetools create \
                  `# A -t {tag} for each tag in DOCKER_IMAGE_TAGS` \
                  $(echo '${{ needs.gen-versions.outputs.DOCKER_IMAGE_TAG }}'| tr ',' '\n' | sed -e 's|.*|-t \0|') \
                  `# Then a reference for each of the arches. This uses the fact that printf repeats its format string if it has too many arguments.` \
                  $(printf '${{env.REGISTRY}}/${{ env.IMAGE }}@sha256:%s ' *)