name: Publish to GitHub Container Registry

on:
  push:
    # Publish `v*` tags as releases.
    tags:
    - v*
  pull_request:

env:
  IMAGE_NAME: hugo-extended

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Build image
      run: docker build . --file Dockerfile

  # Push image to GitHub Container Registry
  push:
    runs-on: ubuntu-latest
    if: github.event_name == 'push'
    needs: build
    steps:
    - uses: actions/checkout@v2
    - name: Build image
      run: docker build . --file Dockerfile --tag $IMAGE_NAME
    - name: Login to GitHub Container Registry
      run: echo "${{ secrets.GHCR_PAT }}" | docker login ghcr.io -u ${{ github.actor }} --password-stdin
    - name: Push image to GitHub
      run: |
        IMAGE_ID=ghcr.io/${{ github.repository_owner }}/$IMAGE_NAME

        # Change all uppercase to lowercase
        IMAGE_ID=$(echo $IMAGE_ID | tr '[A-Z]' '[a-z]')

        # Strip git ref prefix from version
        VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')

        # Strip "v" prefix from tag name
        [[ "${{ github.ref }}" == "refs/tags/"* ]] && VERSION=$(echo $VERSION | sed -e 's/^v//')

        echo IMAGE_ID=$IMAGE_ID
        echo VERSION=$VERSION

        # Push image with both version tag and `latest` tag
        docker tag $IMAGE_NAME $IMAGE_ID:$VERSION
        docker tag $IMAGE_NAME $IMAGE_ID:latest
        docker push $IMAGE_ID:$VERSION
        docker push $IMAGE_ID:latest