.github/workflows/update_changelog.yml

name: Update Changelog.md

on:
  pull_request_target:
    types:
      - closed

jobs:
  update-changelog:
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest

    steps:

      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.base.ref }}
          fetch-depth: 0
          # Prevent later git operations from reusing the same authentication
          persist-credentials: false

      - name: Extract and update Changelog
        id: modify-changelog
        shell: python
        run: |
          import re
          if "${{ github.event.pull_request.user.login }}" == "dependabot[bot]":
              changelog = "  - **Description:** ${{ github.event.pull_request.title }}\n  - **Products impact:** Dev Dependency upgrade\n  - **Addresses:** -\n  - **Components:** -\n  - **Breaking:** -\n  - **Impacts a11y:** -\n  - **Guidance:** -"
          else:
              description = """${{ github.event.pull_request.body }}"""
              capture = re.compile("<!-- \[DO NOT REMOVE-USED BY GH ACTION\] CHANGELOG START -->(\n|.)+?(?=- \*\*Description)(?P<body>(\n|.)+?(?=<!-- \[DO NOT REMOVE-USED BY GH ACTION\] CHANGELOG END -->))")
              match = capture.search(description)
              changelog = match.groupdict()["body"].strip()

          final_changelog = "<!-- [DO NOT REMOVE-USED BY GH ACTION] PASTE CHANGELOG -->\n\n"

          pr_number = "${{ github.event.pull_request.number }}"
          pr_link = "[#{}]".format(pr_number)
          pr_link_ref = pr_link + ": ${{ github.event.pull_request.html_url }}"

          for changeline in changelog.splitlines():
              changeline = changeline.strip()
              if not changeline:
                  continue

              if changeline.startswith("- **Description:**"):
                  final_changelog += "\n" + "- " + pr_link + "\n"

              final_changelog += "  " + changeline + "\n"

              if changeline.startswith("- **Guidance:**"):
                  final_changelog += "\n" + pr_link_ref + "\n"

          with open("CHANGELOG.md", "r") as f:
              current_changelog = f.read()

          new_changelog = current_changelog.replace("<!-- [DO NOT REMOVE-USED BY GH ACTION] PASTE CHANGELOG -->", final_changelog, 1)

          with open("CHANGELOG.md", "w") as f:
              f.write(new_changelog)
      - uses: tibdex/github-app-token@v2
        id: generate-token
        with:
          app_id: ${{ secrets.LE_BOT_APP_ID }}
          private_key: ${{ secrets.LE_BOT_PRIVATE_KEY }}
      - name: Commit updated CHANGELOG.md
        run: |
          git config --local user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git config --local user.name "github-actions[bot]"
          git add CHANGELOG.md
          git commit -m "Update CHANGELOG.md for PR #${{ github.event.pull_request.number }}"
      - name: Push changes
        uses: ad-m/github-push-action@v0.8.0
        with:
          github_token: ${{ steps.generate-token.outputs.token }}
          branch: ${{ github.event.pull_request.base.ref }}