labels-verify.yml

name: "Verify PR labels"

on:
  pull_request:
    types:
      - opened
      - reopened
      - synchronize
      - ready_for_review
      - labeled
      - unlabeled
      - edited

permissions:
  contents: read
  pull-requests: read
  issues: read

jobs:
  triage:
    name: Require exactly one pr label
    runs-on: ubuntu-latest
    steps:
      - name: Validate release notes label
        env:
          GH_TOKEN: ${{ github.token }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        shell: bash
        run: |
          labels="$(gh api "repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/labels" --jq '.[].name')"
          pr_labels="$(printf '%s\n' "${labels}" | grep '^pr:' || true)"

          if [ -z "${pr_labels}" ]; then
            count=0
          else
            count="$(printf '%s\n' "${pr_labels}" | wc -l | tr -d ' ')"
          fi

          if [ "${count}" -eq 1 ]; then
            echo "Found PR release-note label: ${pr_labels}"
            exit 0
          fi

          {
            echo "Pull requests must have exactly one label with the pr: prefix."
            echo "Found ${count} pr: labels."
            if [ "${count}" -gt 0 ]; then
              printf 'Matching labels:\n'
              printf '%s\n' "${pr_labels}" | sed 's/^/- /'
            fi
            echo
            echo "Available labels on this PR:"
            if [ -n "${labels}" ]; then
              printf '%s\n' "${labels}" | sed 's/^/- /'
            else
              echo "- <none>"
            fi
          } >> "${GITHUB_STEP_SUMMARY}"

          echo "::error title=Invalid pr: label count::Pull requests must have exactly one label with the pr: prefix. Found ${count}."
          exit 1