"""

Part of the bsie module.
A copy of the license is provided with the project.
Author: Matthias Baumgartner, 2022
"""
# standard imports
import importlib
import typing

# inner-module imports
from . import errors

# exports
__all__: typing.Sequence[str] = (
    'safe_load',
    'unpack_qualified_name',
    )


## code ##

def safe_load(module_name: str, class_name: str):
    """Get a class from a module. Raise BuilderError if anything goes wrong."""
    try:
        # load the module
        module = importlib.import_module(module_name)
    except Exception as err:
        # cannot import module
        raise errors.LoaderError(f'cannot load module {module_name}') from err

    try:
        # get the class from the module
        cls = getattr(module, class_name)
    except Exception as err:
        # cannot find the class
        raise errors.LoaderError(f'cannot load class {class_name} from module {module_name}') from err

    return cls


def unpack_qualified_name(name):
    """Split a name into its module and class component (dot-separated)."""
    if not isinstance(name, str):
        raise TypeError(name)
    if '.' not in name:
        raise ValueError('name must be a qualified class name.')
    module_name, class_name = name[:name.rfind('.')], name[name.rfind('.')+1:]
    if module_name == '':
        raise ValueError('name must be a qualified class name.')
    return module_name, class_name


## EOF ##