name: milestone

# A pull request without a milestone gets the one of its branch: base integration/X.Y-batch-N -> X.Y; head release/X.Y[.Z]... into main -> X.Y[.Z]. Other pull requests
# to main keep the patch milestone that is set by hand. pull_request_target, so the token can write on a fork too: nothing of the pull request is checked out or run, and
# the branch names reach the shell through the environment only. A failure is a warning, never a red check.
on:
  pull_request_target:
    types: [opened, reopened]

permissions:
  pull-requests: write

jobs:
  milestone:
    runs-on: ubuntu-24.04
    timeout-minutes: 2
    if: github.event.pull_request.milestone == null
    steps:
      - name: Set the milestone
        env:
          GH_TOKEN: ${{ github.token }}
          GH_REPO: ${{ github.repository }}
          PR: ${{ github.event.pull_request.number }}
          BASE: ${{ github.event.pull_request.base.ref }}
          HEAD: ${{ github.event.pull_request.head.ref }}
        run: |
          ms=
          if [[ $BASE =~ ^integration/([0-9]+\.[0-9]+)-batch-[0-9]+$ ]]; then ms=${BASH_REMATCH[1]}
          elif [[ $BASE == main && $HEAD =~ ^release/([0-9]+\.[0-9]+(\.[0-9]+)?) ]]; then ms=${BASH_REMATCH[1]}; fi
          [[ -z $ms ]] || gh pr edit "$PR" --milestone "$ms" || echo "::warning::could not set the milestone $ms on #$PR"