name: 'Get merged pull request labels'
shell: bash
description: 'Get the labels of the PR that was merged to create this push event'
inputs:
    token:
        description: 'GH token'
        required: true
outputs:
    labels:
        description: 'JSON array labels of the PR that was merged (if any)'
        value: ${{ steps.labels.outputs.labels }}
runs:
    using: 'composite'
    steps:
        - name: Get PR associated with the last commit
          id: pr-info
          uses: octokit/request-action@v2.x
          with:
              route: GET /repos/${{ github.repository }}/commits/${{ github.sha }}/pulls
          env:
              GITHUB_TOKEN: ${{ inputs.token }}

        - name: Extract PR number
          shell: bash
          if: steps.pr-info.outputs.data
          id: extract-pr
          continue-on-error: true
          run: |
              echo "PR_NUMBER=$(cat | jq -r '.[-1].number' <<EOF
                ${{ toJSON(fromJSON(steps.pr-info.outputs.data)) }}
              EOF
              )" >> $GITHUB_OUTPUT

        - name: Fetch PR Labels
          shell: bash
          id: labels
          run: |
              PR_NUMBER=${{ steps.extract-pr.outputs.PR_NUMBER }}
              if [ -z "${PR_NUMBER}" ] || [ "${PR_NUMBER}" = "null" ]; then
                echo labels="[]" >> $GITHUB_OUTPUT
                exit 0
              fi
              LABELS=$(curl \
                -H "Authorization: Bearer ${{ inputs.token }}" \
                -H "Accept: application/vnd.github.v3+json" \
                https://api.github.com/repos/${{ github.repository }}/issues/$PR_NUMBER/labels | jq -rc '[.[].name]')
              echo "Labels of PR #$PR_NUMBER: $LABELS"

              echo labels="$LABELS" >> $GITHUB_OUTPUT
          env:
              GITHUB_TOKEN: ${{ inputs.token }}