import requests

def publish_to_pinnwand(content: str, expiry: str = "1day", lexer: str = "text", name: str = None, base_url: str = "https://bpa.st") -> str:
    """
    Uploads content to pinnwand pastebin and returns the link to the paste.
    
    Args:
    - content: The content of the paste.
    - expiry: Expiry time for the paste. Defaults to "1day".
    - lexer: The lexer to use for syntax highlighting. Defaults to "text".
    - name: Optional name for the file.
    - base_url: The base URL of the pinnwand instance. Defaults to "https://bpa.st".
    
    Returns:
    - The URL of the created paste.
    """
    
    # API endpoint for creating new pastes
    api_endpoint = f"{base_url}/api/v1/paste"
    
    # Create the payload
    payload = {
        "expiry": expiry,
        "files": [
            {
                "lexer": lexer,
                "content": content
            }
        ]
    }
    
    # Add the name field if provided
    if name:
        payload["files"][0]["name"] = name
    
    # Send the POST request to the API
    response = requests.post(api_endpoint, json=payload)
    
    # Check if the request was successful
    if response.status_code == 200:
        # Parse the response JSON
        response_data = response.json()
        paste_url = response_data.get("link")
        return paste_url
    else:
        raise Exception(f"Failed to upload to pinnwand, status code: {response.status_code}, message: {response.text}")