name: 'Get Commit Message'
description: 'Gets commit message for both push and pull_request events and sets XAHAU_GA_COMMIT_MSG env var'

inputs:
  event-name:
    description: 'The event name (push or pull_request)'
    required: true
  head-commit-message:
    description: 'The head commit message (for push events)'
    required: false
    default: ''
  pr-head-sha:
    description: 'The PR head SHA (for pull_request events)'
    required: false
    default: ''

runs:
  using: 'composite'
  steps:
    - name: Get commit message and set environment variable
      shell: python
      env:
        GH_TOKEN: ${{ github.token }}
      run: |
        import json
        import os
        import secrets
        import urllib.request

        event_name = "${{ inputs.event-name }}"
        pr_head_sha = "${{ inputs.pr-head-sha }}"
        repository = "${{ github.repository }}"

        print("==========================================")
        print("Setting XAHAU_GA_COMMIT_MSG environment variable")
        print("==========================================")
        print(f"Event: {event_name}")

        if event_name == 'push':
            # For push events, use the input directly
            message = """${{ inputs.head-commit-message }}"""
            print("Source: workflow input (github.event.head_commit.message)")
        elif event_name == 'pull_request' and pr_head_sha:
            # For PR events, fetch via GitHub API
            print(f"Source: GitHub API (fetching commit {pr_head_sha})")
            try:
                url = f"https://api.github.com/repos/{repository}/commits/{pr_head_sha}"
                req = urllib.request.Request(url, headers={
                    "Accept": "application/vnd.github.v3+json",
                    "Authorization": f"Bearer {os.environ.get('GH_TOKEN', '')}"
                })
                with urllib.request.urlopen(req) as response:
                    data = json.load(response)
                    message = data["commit"]["message"]
            except Exception as e:
                print(f"Failed to fetch commit message: {e}")
                message = ""
        else:
            message = ""
            print(f"Warning: Unknown event type: {event_name}")

        print(f"Commit message (first 100 chars): {message[:100]}")

        # Write to GITHUB_ENV using heredoc with random delimiter (prevents injection attacks)
        # See: https://securitylab.github.com/resources/github-actions-untrusted-input/
        delimiter = f"EOF_{secrets.token_hex(16)}"

        with open(os.environ['GITHUB_ENV'], 'a') as f:
            f.write(f'XAHAU_GA_COMMIT_MSG<<{delimiter}\n')
            f.write(message)
            f.write(f'\n{delimiter}\n')

        print(f"✓ XAHAU_GA_COMMIT_MSG set (available to all subsequent steps)")
        print("==========================================")