name: validate-pr

on:
  pull_request:
    types: [opened, edited, labeled, unlabeled]

jobs:
  check-area-label:
    runs-on: ubuntu-20.04
    steps:
      - name: Missing `area/` label
        if: contains(join(github.event.pull_request.labels.*.name, ','), 'impact/') && !contains(join(github.event.pull_request.labels.*.name, ','), 'area/')
        run: |
          echo "::error::Every PR with an 'impact/*' label should also have an 'area/*' label"
          exit 1
      - name: OK
        run: exit 0

  check-changelog:
    if: contains(join(github.event.pull_request.labels.*.name, ','), 'impact/')
    runs-on: ubuntu-20.04
    env:
      PR_BODY: |
        ${{ github.event.pull_request.body }}
    steps:
      - name: Check changelog description
        run: |
          # Extract the `markdown changelog` note code block
          block=$(echo -n "$PR_BODY" | tr -d '\r' | awk '/^```markdown changelog$/{flag=1;next}/^```$/{flag=0}flag')

          # Strip empty lines
          desc=$(echo "$block" |  awk NF)

          if [ -z "$desc" ]; then
            echo "::error::Changelog section is empty. Provide a description for the changelog."
            exit 1
          fi

          len=$(echo -n "$desc" | wc -c)
          if [[ $len -le 6 ]]; then
            echo "::error::Description looks too short: $desc"
            exit 1
          fi

          echo "This PR will be included in the release notes with the following note:"
          echo "$desc"

  check-pr-branch:
    runs-on: ubuntu-20.04
    env:
      PR_TITLE: ${{ github.event.pull_request.title }}
    steps:
      # Backports or PR that target a release branch directly should mention the target branch in the title, for example:
      # [X.Y backport] Some change that needs backporting to X.Y
      # [X.Y] Change directly targeting the X.Y branch
      - name: Get branch from PR title
        id: title_branch
        run: echo "$PR_TITLE" | sed -n 's/^\[\([0-9]*\.[0-9]*\)[^]]*\].*/branch=\1/p' >> $GITHUB_OUTPUT

      - name: Check release branch
        if: github.event.pull_request.base.ref != steps.title_branch.outputs.branch && !(github.event.pull_request.base.ref == 'master' && steps.title_branch.outputs.branch == '')
        run: echo "::error::PR title suggests targetting the ${{ steps.title_branch.outputs.branch }} branch, but is opened against ${{ github.event.pull_request.base.ref }}" && exit 1