# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
#
# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
import collections
import copy
import inspect
from collections.abc import MutableMapping, MutableSequence
from inspect import FullArgSpec
from typing import Callable, Dict, Iterable, List, Optional, Sequence, Union

from .. import get_logger
from ..module import Module
from ..tensor import Tensor

logger = get_logger(__name__)


def replace_container_with_module_container(container):
    has_module = False
    module_container = None
    if isinstance(container, Dict):
        m_dic = copy.copy(container)
        for key, value in container.items():
            if isinstance(value, Module):
                has_module = True
            elif isinstance(value, (List, Dict)):
                (
                    _has_module,
                    _module_container,
                ) = replace_container_with_module_container(value)
                m_dic[key] = _module_container
                if _has_module:
                    has_module = True
        if not all(isinstance(v, Module) for v in m_dic.values()):
            return has_module, None
        else:
            return has_module, _ModuleDict(m_dic)
    elif isinstance(container, List):
        m_list = copy.copy(container)
        for ind, value in enumerate(container):
            if isinstance(value, Module):
                has_module = True
            elif isinstance(value, (List, Dict)):
                (
                    _has_module,
                    _module_container,
                ) = replace_container_with_module_container(value)
                m_list[ind] = _module_container
                if _has_module:
                    has_module = True
        if not all(isinstance(v, Module) for v in m_list):
            return has_module, None
        else:
            return has_module, _ModuleList(m_list)
    return has_module, module_container


def _convert_kwargs_to_args(
    argspecs: Union[Callable, FullArgSpec], args, kwargs, is_bounded=False
):
    # is_bounded = True when func is a method and provided args don't include 'self'
    arg_specs = (
        inspect.getfullargspec(argspecs) if isinstance(argspecs, Callable) else argspecs
    )
    func_name = argspecs.__qualname__ if isinstance(argspecs, Callable) else "function"
    assert isinstance(arg_specs, FullArgSpec)
    arg_specs_args = arg_specs.args
    arg_specs_defaults = arg_specs.defaults if arg_specs.defaults else []
    arg_specs_kwonlyargs = arg_specs.kwonlyargs
    arg_specs_kwonlydefaults = (
        arg_specs.kwonlydefaults if arg_specs.kwonlydefaults else dict()
    )
    if is_bounded:
        arg_specs_args = arg_specs.args[1:]
    new_args = []
    new_kwargs = {}
    new_args.extend(args)
    if set(arg_specs_args[0 : len(new_args)]) & set(kwargs.keys()):
        repeated_arg_name = set(arg_specs_args[0 : len(new_args)]) & set(kwargs.keys())
        raise TypeError(
            "{} got multiple values for argument {}".format(
                func_name, ", ".join(repeated_arg_name)
            )
        )
    if len(new_args) < len(arg_specs_args):
        for ind in range(len(new_args), len(arg_specs_args)):
            arg_name = arg_specs_args[ind]
            if arg_name in kwargs:
                new_args.append(kwargs[arg_name])
            else:
                index = ind - len(arg_specs_args) + len(arg_specs_defaults)
                if index >= len(arg_specs_defaults) or index < 0:
                    raise TypeError(
                        "{} missing required positional arguments: {}".format(
                            func_name, arg_name
                        )
                    )
                new_args.append(arg_specs_defaults[index])

    for kwarg_name in arg_specs_kwonlyargs:
        if kwarg_name in kwargs:
            new_kwargs[kwarg_name] = kwargs[kwarg_name]
        else:
            if kwarg_name not in arg_specs_kwonlydefaults:
                raise TypeError(
                    "{} missing required keyword-only argument: {}".format(
                        func_name, kwarg_name
                    )
                )
            new_kwargs[kwarg_name] = arg_specs_kwonlydefaults[kwarg_name]
    for k, v in kwargs.items():
        if k not in arg_specs_args and k not in arg_specs_kwonlyargs:
            if arg_specs.varkw is None:
                raise TypeError(
                    "{} got an unexpected keyword argument {}".format(func_name, k)
                )
            new_kwargs[k] = v
    return tuple(new_args), new_kwargs


def _check_obj_attr(obj):
    # check if all the attributes of a obj is serializable
    from .pytree import tree_flatten
    from .pytree import SUPPORTED_LEAF_CLS, SUPPORTED_LEAF_TYPE, TreeDef
    from .expr import Expr
    from .traced_module import TracedModule, InternalGraph, NameSpace

    def _check_leaf_type(leaf):
        leaf_type = leaf if isinstance(leaf, type) else type(leaf)
        traced_module_types = [Expr, TreeDef, TracedModule, InternalGraph, NameSpace]
        return (
            issubclass(leaf_type, tuple(SUPPORTED_LEAF_CLS + traced_module_types))
            or leaf_type in SUPPORTED_LEAF_TYPE
        )

    for _, v in obj.items():
        leafs, _ = tree_flatten(v, is_leaf=lambda _: True)
        for leaf in leafs:
            assert _check_leaf_type(leaf), (
                "Type {} is not supported in TracedModule serialization by default. "
                "If you want to save this object to file, please call tm.register_supported_type({}) "
                "before saving.".format(
                    leaf if isinstance(leaf, type) else type(leaf), type(leaf).__name__
                )
            )


def _check_builtin_module_attr(mod):
    from .pytree import _is_leaf as _check_leaf_type
    from .pytree import tree_flatten

    # check if all the attributes of a builtin module is serializable
    is_non_serializable_module = lambda m: isinstance(
        m, Module
    ) and not _check_builtin_module_attr(m)
    for k, v in mod.__dict__.items():
        if k == "_m_dump_modulestate":
            continue
        if is_non_serializable_module(v):
            return False
        elif not isinstance(v, Module):
            leafs, _ = tree_flatten(v, is_leaf=lambda _: True)
            for leaf in leafs:
                if not _check_leaf_type(leaf) or is_non_serializable_module(leaf):
                    logger.warn(
                        "Type {} is not supported by traced module".format(
                            leaf if isinstance(leaf, type) else type(leaf)
                        )
                    )
                    return False
    return True


class _ModuleList(Module, MutableSequence):
    r"""A List-like container.

    Using a ``ModuleList``, one can visit, add, delete and modify submodules
    just like an ordinary python list.
    """

    def __init__(self, modules: Optional[Iterable[Module]] = None):
        super().__init__()
        self._size = 0
        if modules is None:
            return
        for mod in modules:
            self.append(mod)

    @classmethod
    def _ikey(cls, idx):
        return "{}".format(idx)

    def _check_idx(self, idx):
        L = len(self)
        if idx < 0:
            idx = L + idx
        if idx < 0 or idx >= L:
            raise IndexError("list index out of range")
        return idx

    def __getitem__(self, idx: int):
        if isinstance(idx, slice):
            idx = range(self._size)[idx]
        if not isinstance(idx, Sequence):
            idx = [
                idx,
            ]
        rst = []
        for i in idx:
            i = self._check_idx(i)
            key = self._ikey(i)
            try:
                rst.append(getattr(self, key))
            except AttributeError:
                raise IndexError("list index out of range")
        return rst if len(rst) > 1 else rst[0]

    def __setattr__(self, key, value):
        # clear mod name to avoid warning in Module's setattr
        if isinstance(value, Module):
            value._short_name = None
        super().__setattr__(key, value)

    def __setitem__(self, idx: int, mod: Module):
        if not isinstance(mod, Module):
            raise ValueError("invalid sub-module")
        idx = self._check_idx(idx)
        setattr(self, self._ikey(idx), mod)

    def __delitem__(self, idx):
        idx = self._check_idx(idx)
        L = len(self)
        for orig_idx in range(idx + 1, L):
            new_idx = orig_idx - 1
            self[new_idx] = self[orig_idx]
        delattr(self, self._ikey(L - 1))
        self._size -= 1

    def __len__(self):
        return self._size

    def insert(self, idx, mod: Module):
        assert isinstance(mod, Module)
        L = len(self)
        if idx < 0:
            idx = L - idx
        # clip idx to (0, L)
        if idx > L:
            idx = L
        elif idx < 0:
            idx = 0

        for new_idx in range(L, idx, -1):
            orig_idx = new_idx - 1
            key = self._ikey(new_idx)
            setattr(self, key, self[orig_idx])

        key = self._ikey(idx)
        setattr(self, key, mod)
        self._size += 1

    def forward(self):
        raise RuntimeError("ModuleList is not callable")


class _ModuleDict(Module, MutableMapping):
    r"""A Dict-like container.

    Using a ``ModuleDict``, one can visit, add, delete and modify submodules
    just like an ordinary python dict.
    """

    def __init__(self, modules: Optional[Dict[str, Module]] = None):
        super().__init__()
        self._module_keys = []
        if modules is not None:
            self.update(modules)

    def __delitem__(self, key):
        delattr(self, key)
        assert key in self._module_keys
        self._module_keys.remove(key)

    def __getitem__(self, key):
        return getattr(self, key)

    def __setattr__(self, key, value):
        # clear mod name to avoid warning in Module's setattr
        if isinstance(value, Module):
            value._short_name = None
        super().__setattr__(key, value)

    def __setitem__(self, key, value):
        if not isinstance(value, Module):
            raise ValueError("invalid sub-module")
        setattr(self, key, value)
        if key not in self._module_keys:
            self._module_keys.append(key)

    def __iter__(self):
        return iter(self.keys())

    def __len__(self):
        return len(self._module_keys)

    def items(self):
        return [(key, getattr(self, key)) for key in self._module_keys]

    def values(self):
        return [getattr(self, key) for key in self._module_keys]

    def keys(self):
        return self._module_keys

    def forward(self):
        raise RuntimeError("ModuleList is not callable")


def assign_attr(obj: Union[Module, Tensor], module: Module, target: str):
    *prefix, name = target.split(".")
    for item in prefix:
        module = getattr(module, item)
        if not isinstance(module, Module):
            raise AttributeError("`{}` is not an Module".format(item))
    setattr(module, name, obj)


def get_subattr(module: Module, target: str):
    # todo : remove this import
    from .node import ModuleNode

    if target == "":
        return module
    *prefix, name = target.split(".")
    for item in prefix:
        module = getattr(module, item)
        if not isinstance(module, (Module, ModuleNode)):
            raise AttributeError("`{}` is not an Module".format(item))
    return getattr(module, name)