import importlib
import pkgutil
from pathlib import Path
from types import ModuleType

from fastapi import FastAPI, APIRouter


def auto_include_routers(app: FastAPI, package: ModuleType, full_path: bool = False):
    """
    Automatically discover and include FastAPI routers from a given package.

    :param FastAPI app: FastAPI application.
    :param ModuleType package: Imported package.
    :param bool full_path: If True, prefix is built from full path. If False, prefix is only the last filename.
    """

    package_path = Path(package.__file__).parent
    base_pkg_name = package.__name__.replace("_", "-")

    for _, name, _ in pkgutil.walk_packages(package.__path__, package.__name__ + "."):
        module = importlib.import_module(name)

        # Try to get `router` from the module
        router = getattr(module, "router", None)
        if not isinstance(router, APIRouter):
            continue

        # Build API prefix
        file_path = Path(module.__file__)
        relative_path = file_path.relative_to(package_path)

        parts: list[str] = list(relative_path.parts)

        # Remove "routers" folder(s) from prefix parts
        parts = [p for p in parts if p != "routers"]

        # Drop extension from filename
        parts[-1] = parts[-1].replace(".py", "")

        if full_path:
            # Use full path
            prefix_parts = [p.replace("_", "-") for p in parts if p != "__init__"]
            prefix_parts.insert(0, base_pkg_name)
        else:
            # Only use last file name
            prefix_parts = [parts[-1].replace("_", "-")]

        prefix = "/" + "/".join(prefix_parts)

        app.include_router(router, prefix=prefix)