name: "[PR Management] Add Backport Label"

on:
  pull_request_target:
    types: [opened, reopened]
    branches: [main]

permissions:
  pull-requests: write

jobs:
  add-backport-label:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          ref: ${{ github.base_ref }}

      - name: Fetch release branches and PR labels
        id: fetch_info
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          set -euo pipefail

          repo="${{ github.repository }}"
          pr_number=${{ github.event.pull_request.number }}

          release_branches=$(gh api "repos/${repo}/branches" --paginate --jq '.[].name' | grep -E '^release-harvester-v[0-9]+\.[0-9]+$' || true)

          if [[ -z "$release_branches" ]]; then
            echo "should_label=false" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          latest_branch=$(echo "$release_branches" | sort -Vr | head -n1)
          version="${latest_branch#release-harvester-v}"
          release_tag="v${version}.0"

          tags=$(gh api "repos/${repo}/releases" --paginate --jq '.[].tag_name')
          if echo "$tags" | grep -Fxq "$release_tag"; then
            echo "should_label=false" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          label="require backport/v${version}"
          echo "should_label=true" >> "$GITHUB_OUTPUT"
          echo "backport_label=$label" >> "$GITHUB_OUTPUT"

          pr_labels=$(gh pr view "$pr_number" --repo "$repo" --json labels --jq '.labels[].name' || echo "")
          pr_labels_csv=$(echo "$pr_labels" | tr '\n' ',' | sed 's/,$//')
          echo "pr_labels=$pr_labels_csv" >> "$GITHUB_OUTPUT"

      - name: Add backport label if needed
        if: steps.fetch_info.outputs.should_label == 'true' && !contains(steps.fetch_info.outputs.pr_labels, steps.fetch_info.outputs.backport_label)
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          echo "Adding label: ${{ steps.fetch_info.outputs.backport_label }}"
          gh pr edit ${{ github.event.pull_request.number }} \
            --repo ${{ github.repository }} \
            --add-label "${{ steps.fetch_info.outputs.backport_label }}"