version: 2
jobs:
  build:
    branches:
      ignore:
        - gh-pages
    docker:
      - image: circleci/python:3.6
    working_directory: ~/repo
    environment:
      - SOURCE_BRANCH: master
      - TARGET_BRANCH: gh-pages
    steps:
      - checkout
      - deploy:
          name: Deploy
          command: |
            if [ $CIRCLE_BRANCH == $SOURCE_BRANCH ]; then
              python -m venv venv
              source venv/bin/activate
              pip install -r requirements.txt

              git config --global user.email $GH_EMAIL
              git config --global user.name $GH_NAME

              git clone $CIRCLE_REPOSITORY_URL out

              cd out
              git checkout $TARGET_BRANCH || git checkout --orphan $TARGET_BRANCH
              git rm -rf .
              cd ..

              make publish

              cp -a output/. out/.

              mkdir -p out/.circleci && cp -a .circleci/. out/.circleci/.
              cp CNAME out/CNAME
              cd out

              git add -A
              git commit -m "Automated deployment to GitHub Pages: ${CIRCLE_SHA1}" --allow-empty

              git push origin $TARGET_BRANCH
            fi