runclangformat.yml

name: Run ClangFormat

on:
  issue_comment: # GitHub PRs are considered the same type of thing as issues.
    types: [ created ]

jobs:
  reformat:
    name: ClangFormat
    # If we are a pull_request, we have the trigger comment, and the person
    # requesting is the one who made the PR, then we run.
    if: >-
      github.event.issue.pull_request != ''
      && github.event.comment.body == 'Do: Reformat'
      && github.event.comment.user.id == github.event.issue.user.id
    # We must run on a ubuntu, as we use unix-only commands
    runs-on: ubuntu-latest

    steps:
      # Add an emote reaction to acknowledge the request.
      # For long-running tasks, this is helpful.
      # For just clang-format, it may not be needed, but it's still nice.
      - name: Acknowledge
        uses: peter-evans/create-or-update-comment@v1.4.1
        with:
          comment-id: ${{ github.event.comment.id }}
          reactions: rocket # (Launch)

      - uses: actions/checkout@v2
        with:
          # We need the entire history so that we can rebase many commits.
          fetch-depth: 0

      - name: Checkout PR
        uses: dawidd6/action-checkout-pr@v1
        with:
          pr: ${{ github.event.issue.number }}

      - name: Get clang-format
        run: sudo apt-get install clang-format-9

      - name: Clang format each commit in place
        run: |
          # Git requires user email and name to do commits.
          # As we are only amending each commit, these shouldn't end up in the
          # history.
          # Set user email to the email of the last commit:
          git config --local user.email "$(git log -n 1 --pretty=format:'%ae')"
          git config --local user.name 'GitHub Action'

          # Rebases every commit since when this PR branched off of master.
          # The sed command tells git that we want to edit the code for each commit.
          GIT_EDITOR="sed -iE 's/^pick/edit/g'" git rebase -i $(git merge-base master HEAD)

          # Abort on error
          set -e
          echo '>>> Beginning Rebasing...'

          # While a rebase is ongoing, `git status` contains the text "rebase".
          while [[ -n $(git status | grep rebase) ]]; do
            # Run clang-format
            find . -name '*.hpp' -o -name '*.cpp' | xargs -L1 clang-format-9 -style=file -i --verbose

            # Add all changes and update the commit
            echo '>>> Rewriting commit...'
            git add -A
            git commit --amend --no-edit

            echo '>>> Continuing Rebasing...'
            git rebase --continue
          done
          echo '>>> Finished Rebasing!'

      - name: Push
        run: git push --force -v