release-prepare.yml

name: 'Release: Prepare PR'

on:
  push:
    branches: [ develop ]

env:
  GITHUB_USERNAME: jarvus-bot
  GITHUB_TOKEN: ${{ secrets.BOT_GITHUB_TOKEN }}
  RELEASE_BRANCH: master

jobs:
  release-prepare:
    runs-on: ubuntu-latest
    steps:

    - uses: actions/checkout@v2
      with:
        fetch-depth: 0

    # - uses: mxschmitt/action-tmate@v3

    - name: Create/update pull request
      run: |
        # get latest release tag
        latest_release=$(git describe --tags --abbrev=0 "origin/${RELEASE_BRANCH}")
        latest_release_bumped=$(echo $latest_release | awk -F. -v OFS=. '{$NF++;print}')


        # create or update PR
        pr_body="$(cat <<EOF
        Release: ${latest_release_bumped}

        ## Improvements

        ## Technical

        EOF
        )"

        pr_number=$(hub pr list -h develop -f '%I')

        if [ -n "${pr_number}" ]; then
          echo "Updating PR #${pr_number}"
          existing_comment_id=$(hub api "/repos/${GITHUB_REPOSITORY}/issues/${pr_number}/comments" | jq ".[] | select(.user.login==\"${GITHUB_USERNAME}\") | .id")
        else
          echo "Opening PR"
          hub pull-request -b "${RELEASE_BRANCH}" -h develop -F <(echo "${pr_body}") > /tmp/pr.json
          pr_number=$(hub pr list -h develop -f '%I')
          echo "Opened PR #${pr_number}"
        fi


        # build changelog
        commits=$(
          git log \
            --first-parent \
            --reverse \
            --format="%H" \
            "origin/${RELEASE_BRANCH}..develop"
        )

        changelog=()

        while read -r commit; do
          subject="$(git show -s --format=%s "${commit}")"
          line=""

          if [[ "${subject}" =~ Merge\ pull\ request\ \#([0-9]+) ]]; then
            line="$(hub pr show -f '%t [%i] @%au' "${BASH_REMATCH[1]}" || true)"
          fi

          if [ -z "${line}" ]; then
            author="$(hub api "/repos/${GITHUB_REPOSITORY}/commits/${commit}" -H Accept:application/vnd.github.v3+json | jq -r '.author.login')"
            if [ -n "${author}" ]; then
              author="@${author}"
            else
              author="$(git show -s --format=%ae "${commit}")"
            fi

            line="${subject} ${author}"
          fi

          # move ticket number prefix into to existing square brackets at end
          line="$(echo "${line}" | perl -pe 's/^([A-Z]+-[0-9]+):?\s*(.*?)\s*\[([^]]+)\]\s*(\S+)$/\2 [\3, \1] \4/')"

          # move ticket number prefix into to new square brackets at end
          line="$(echo "${line}" | perl -pe 's/^([A-Z]+-[0-9]+):?\s*(.*?)\s*(\S+)$/\2 [\1] \3/')"

          # combine doubled square brackets at the end
          line="$(echo "${line}" | perl -pe 's/^\s*(.*?)\s*\[([A-Z]+-[0-9]+)\]\s*\[([^]]+)\]\s*(\S+)$/\1 [\3, \2] \4/')"

          changelog+=("- ${line}")
        done <<< "${commits}"


        # create or update comment
        comment_body="$(cat <<EOF
        ## Changelog

        \`\`\`markdown
        $(IFS=$'\n'; echo "${changelog[*]}")
        \`\`\`
        EOF
        )"

        if [ -n "${existing_comment_id}" ]; then
          echo "Updating comment #${existing_comment_id}"
          hub api "/repos/${GITHUB_REPOSITORY}/issues/comments/${existing_comment_id}" -f body="${comment_body}"
        else
          echo "Creating comment"
          hub api "/repos/${GITHUB_REPOSITORY}/issues/${pr_number}/comments" -f body="${comment_body}"
        fi