name: Merged Blocking Pull Request Automation

on:
  pull_request_target:
    types:
      - closed
  workflow_dispatch:
    inputs:
      pr_id:
        description: Local Pull Request number to work on
        required: true
        type: number

jobs:
  update-blocked-status:
    name: Update Blocked Status
    runs-on: ubuntu-latest

    # a pr that was a `blocking:<id>` label was merged.
    # find the open pr's it was blocked by and trigger a refresh of their state
    if: ${{ github.event_name == 'workflow_dispatch' || github.event.pull_request.merged == true && contains(github.event.pull_request.labels.*.name, 'blocking') }}

    steps:
      - name: Generate token
        id: generate-token
        uses: actions/create-github-app-token@v2
        with:
          app-id: ${{ vars.PULL_REQUEST_APP_ID }}
          private-key: ${{ secrets.PULL_REQUEST_APP_PRIVATE_KEY }}

      - name: Gather Dependent PRs
        id: gather_deps
        env:
          GH_TOKEN: ${{ steps.generate-token.outputs.token }}
          PR_NUMBER: ${{ inputs.pr_id || github.event.pull_request.number }}
        run: |
          blocked_prs=$(
          gh -R ${{ github.repository }} pr list --label 'blocked' --json 'number,body' \
            | jq -c --argjson pr "$PR_NUMBER" '
                reduce ( .[] | select(
                  .body |  
                    scan("(?:blocked (?:by|on)|stacked on):? #([0-9]+)") |
                    map(tonumber) |
                    any(.[]; . == $pr)
                )) as $i ([]; . + [$i])
              '
          )
          {
            echo "deps=$blocked_prs"
            echo "numdeps=$(jq -r '. | length' <<< "$blocked_prs")" 
          }  >> "$GITHUB_OUTPUT"

      - name: Trigger Blocked PR Workflows for Dependants
        if: fromJSON(steps.gather_deps.outputs.numdeps) > 0
        env:
          GH_TOKEN: ${{ steps.generate-token.outputs.token }}
          DEPS: ${{ steps.gather_deps.outputs.deps }}
        run: |
          while read -r pr ; do
            gh -R ${{ github.repository }} workflow run 'blocked-prs.yml' -r "${{ github.ref_name }}" -f pr_id="$pr"
          done < <(jq -c '.[].number' <<< "$DEPS")