from typing import Optional, Type

from llama_index.legacy.download.module import (
    LLAMA_HUB_URL,
    MODULE_TYPE,
    download_llama_module,
    track_download,
)
from llama_index.legacy.llama_pack.base import BaseLlamaPack


def download_llama_pack(
    llama_pack_class: str,
    download_dir: str,
    llama_hub_url: str = LLAMA_HUB_URL,
    refresh_cache: bool = True,
    skip_load: bool = False,
) -> Optional[Type[BaseLlamaPack]]:
    """Download a single LlamaPack from Llama Hub.

    Args:
        llama_pack_class: The name of the LlamaPack class you want to download,
            such as `GmailOpenAIAgentPack`.
        refresh_cache: If true, the local cache will be skipped and the
            loader will be fetched directly from the remote repo.
        download_dir: Custom dirpath to download the pack into.

    Returns:
        A Loader.
    """
    pack_cls = download_llama_module(
        llama_pack_class,
        llama_hub_url=llama_hub_url,
        refresh_cache=refresh_cache,
        custom_path=download_dir,
        library_path="llama_packs/library.json",
        disable_library_cache=True,
        override_path=True,
        skip_load=skip_load,
    )
    track_download(llama_pack_class, MODULE_TYPE.LLAMAPACK)
    if pack_cls is None:
        return None

    if not issubclass(pack_cls, BaseLlamaPack):
        raise ValueError(f"Tool class {pack_cls} must be a subclass of BaseToolSpec.")
    return pack_cls