check_fast_forward.yml

name: Branch fast-forward-ness checker

on:
  pull_request:
    branches: [main, development, master]
  pull_request_review:
    branches: [main, development, master]
  pull_request_review_comment:
    branches: [main, development, master]

jobs:
  CHECK:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Fetching Main branch
        run: |
          if [ ! -z ${{ github.base_ref }} ]; then
            git fetch origin ${{ github.base_ref }} && \
            git tag "→-target-branch-←" origin/${{ github.base_ref }}
          else
            git fetch origin ${{ github.event.pull_request.base.ref }} && \
            git tag "→-target-branch-←" origin/${{ github.event.pull_request.base.ref }}
          fi
        shell: bash
      - name: Fetching Pull Request branch ${{ github.head_ref }}
        run: |
          if [ ! -z ${{ github.head_ref }} ]; then
            git fetch origin ${{ github.head_ref }} && \
            git tag "→-pull-request-branch-←" origin/${{ github.head_ref }}
          else
            git fetch origin ${{ github.event.pull_request.head.ref }} && \
            git tag "→-pull-request-branch-←" origin/${{ github.event.pull_request.head.ref }}
          fi
        shell: bash
      - name: Checking branch fast-forward-ness
        run: |
          if [ ! -z ${{ github.base_ref }} ]; then
            git merge-base origin/${{ github.base_ref }} origin/${{ github.head_ref }} --is-ancestor && \
            echo "Branch is ready for merging 👍" && exit 0 || \
            echo "Branch is not ready for merging yet. Check your tree to investigate 👇" && \
            git log --graph --abbrev-commit --decorate --simplify-by-decoration --all --format=format:'%C(bold blue)%h%C(reset) - %C(yellow)%aD%C(reset) %C(dim yellow)(%ar)%C(reset)%C(auto)%+d%n %<(80,trunc)' && exit 1
          else
            git merge-base origin/${{ github.event.pull_request.base.ref }} origin/${{ github.event.pull_request.head.ref }} --is-ancestor && \
            echo "Branch is ready for merging 👍" && exit 0 || \
            echo "Branch is not ready for merging yet. Check your tree to investigate 👇" && \
            git log --graph --abbrev-commit --decorate --simplify-by-decoration --all --format=format:'%C(bold blue)%h%C(reset) - %C(yellow)%aD%C(reset) %C(dim yellow)(%ar)%C(reset)%C(auto)%+d%n %<(80,trunc)' && exit 1
          fi
        shell: bash