Source code for easydel.utils.lazy_import

# Copyright 2025 The EasyDeL Author @erfanzar (Erfan Zare Chavoshi).
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import importlib
import os
import typing as tp
from itertools import chain
from types import ModuleType

BACKENDS_T = frozenset[str]
IMPORT_STRUCTURE_T = dict[BACKENDS_T, dict[str, set[str]]]


class LazyModule(ModuleType):
    # copy pasted from huggingface lazy module
    def __init__(
        self,
        name: str,
        module_file: str,
        import_structure: IMPORT_STRUCTURE_T,
        module_spec: importlib.machinery.ModuleSpec | None = None,
        extra_objects: dict[str, object] | None = None,
    ):
        super().__init__(name)

        self._object_missing_backend = {}
        if any(isinstance(key, frozenset) for key in import_structure.keys()):
            self._modules = set()
            self._class_to_module = {}
            self.__all__ = []

            _import_structure = {}

            for _backends, module in import_structure.items():
                self._modules = self._modules.union(set(module.keys()))

                for key, values in module.items():
                    for value in values:
                        self._class_to_module[value] = key
                    _import_structure.setdefault(key, []).extend(values)

                # Needed for autocompletion in an IDE
                self.__all__.extend(list(module.keys()) + list(chain(*module.values())))

            self.__file__ = module_file
            self.__spec__ = module_spec
            self.__path__ = [os.path.dirname(module_file)]
            self._objects = {} if extra_objects is None else extra_objects
            self._name = name
            self._import_structure = _import_structure

        # This can be removed once every exportable object has a `export()` export.
        else:
            self._modules = set(import_structure.keys())
            self._class_to_module = {}
            for key, values in import_structure.items():
                for value in values:
                    self._class_to_module[value] = key
            # Needed for autocompletion in an IDE
            self.__all__ = list(import_structure.keys()) + list(chain(*import_structure.values()))
            self.__file__ = module_file
            self.__spec__ = module_spec
            self.__path__ = [os.path.dirname(module_file)]
            self._objects = {} if extra_objects is None else extra_objects
            self._name = name
            self._import_structure = import_structure

    def __dir__(self):
        result = super().__dir__()
        for attr in self.__all__:
            if attr not in result:
                result.append(attr)
        return result

    def __getattr__(self, name: str) -> tp.Any:
        if name in self._objects:
            return self._objects[name]
        if name in self._object_missing_backend.keys():
            missing_backends = self._object_missing_backend[name]

            class Placeholder(metaclass=DummyObject):
                _backends = missing_backends

            Placeholder.__name__ = name
            Placeholder.__module__ = self.__spec__

            value = Placeholder
        elif name in self._class_to_module.keys():
            module = self._get_module(self._class_to_module[name])
            value = getattr(module, name)
        elif name in self._modules:
            value = self._get_module(name)
        else:
            raise AttributeError(f"module {self.__name__} has no attribute {name}")

        setattr(self, name, value)
        return value

    def _get_module(self, module_name: str):
        try:
            return importlib.import_module("." + module_name, self.__name__)
        except Exception as e:
            raise RuntimeError(
                f"Failed to import {self.__name__}.{module_name} because of the following error (look up to see its"
                f" traceback):\n{e}"
            ) from e

    def __reduce__(self):
        return (self.__class__, (self._name, self.__file__, self._import_structure))


class DummyObject(type):
    """
    Metaclass for the dummy objects. Any class inheriting from it will return the ImportError generated by
    `requires_backend` each time a user tries to access any method of that class.
    """

    def __getattribute__(cls, key):
        if key.startswith("_") and key != "_from_config":
            return super().__getattribute__(key)


def is_package_available(package_name: str) -> bool:
    """
    Checks if a package is available in the current Python environment.

    Args:
        package_name: The name of the package to check (e.g., "numpy").

    Returns:
        True if the package is available, False otherwise.
    """
    return importlib.util.find_spec(package_name.replace("-", "_")) is not None