import math
import inspect
from typing import Callable

from colossalai.utils import get_current_device
from torch import dtype, nn

from ... import init as init
from ..parallel_1d import *
from ..parallel_2d import *
from ..parallel_2p5d import *
from ..parallel_3d import *
from ..utils import get_tensor_parallel_mode
from ..vanilla import *
from ._utils import ColossalaiModule

_parallel_linear = {'1d': Linear1D, '2d': Linear2D, '2.5d': Linear2p5D, '3d': Linear3D}

_parallel_classifier = {
    None: VanillaClassifier,
    '1d': Classifier1D,
    '2d': Classifier2D,
    '2.5d': Classifier2p5D,
    '3d': Classifier3D
}

_vocab_parallel_classifier = {
    '1d': VocabParallelClassifier1D,
    '2d': VocabParallelClassifier2D,
    '2.5d': VocabParallelClassifier2p5D,
    '3d': VocabParallelClassifier3D
}


class Linear(ColossalaiModule):
    """Linear layer of colossalai.

    Args:
        in_features (int): size of each input sample.
        out_features (int): size of each output sample.
        bias (bool, optional): If set to ``False``, the layer will not learn an additive bias, defaults to ``True``.
        dtype (:class:`torch.dtype`, optional): The dtype of parameters, defaults to None.
        weight_initializer (:class:`typing.Callable`, optional):
            The initializer of weight, defaults to kaiming uniform initializer.
        bias_initializer (:class:`typing.Callable`, optional):
            The initializer of bias, defaults to xavier uniform initializer.

    Note: ``kwargs`` would contain different parameters when you use different parallelisms.

    The ``kwargs`` should contain parameters below:
    ::

        Linear1D:
            gather_output: bool (optional, default to be false)
            skip_bias_add: bool (optional, default to be false)
        Linear2D:
            skip_bias_add: bool (optional, default to be false)
        Linear2p5D:
            skip_bias_add: bool (optional, default to be false)
        Linear3D:
            None

    More details about ``initializer`` please refer to
    `init <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/nn/init.py>`_.
    """

    def __init__(self,
                 in_features: int,
                 out_features: int,
                 bias: bool = True,
                 dtype: dtype = None,
                 weight_initializer: Callable = init.kaiming_uniform_(a=math.sqrt(5)),
                 bias_initializer: Callable = init.xavier_uniform_(a=1, scale=1),
                 **kwargs) -> None:
        tensor_parallel = get_tensor_parallel_mode()
        if tensor_parallel is None:
            layer = nn.Linear(in_features, out_features, bias=bias).to(dtype).to(get_current_device())
            weight_initializer(layer.weight, fan_in=in_features, fan_out=out_features)
            if layer.bias is not None:
                bias_initializer(layer.bias, fan_in=in_features)
        else:
            linear_cls = _parallel_linear[tensor_parallel]
            gather_output = kwargs.pop('gather_output', None)
            if 'gather_output' in inspect.signature(
                    linear_cls.__init__).parameters.keys():    # gather_out arg is available
                kwargs['gather_output'] = gather_output
            layer = linear_cls(
                in_features,
                out_features,
                bias=bias,
                dtype=dtype,
                weight_initializer=weight_initializer,
                bias_initializer=bias_initializer,
                **kwargs,
            )
        super().__init__(layer)


class Classifier(ColossalaiModule):
    """Classifier layer of colossalai.

    Args:
        in_features (int): size of each input sample.
        num_classes (int): number of classes.
        weight (:class:`torch.nn.Parameter`, optional): weight of the classifier, defaults to None.
        bias (bool, optional): If set to ``False``, the layer will not learn an additive bias, defaults to ``True``.
        dtype (:class:`torch.dtype`, optional): The dtype of parameters, defaults to None.
        weight_initializer (:class:`typing.Callable`, optional):
            The initializer of weight, defaults to kaiming uniform initializer.
        bias_initializer (:class:`typing.Callable`, optional):
            The initializer of bias, defaults to xavier uniform initializer.

    More details about ``initializer`` please refer to
    `init <https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/nn/init.py>`_.
    """

    def __init__(self,
                 in_features: int,
                 num_classes: int,
                 weight: nn.Parameter = None,
                 bias: bool = True,
                 dtype: dtype = None,
                 weight_initializer: Callable = init.kaiming_uniform_(a=math.sqrt(5)),
                 bias_initializer: Callable = init.xavier_uniform_(a=1, scale=1),
                 vocab_parallel_limit: int = 2048) -> None:
        tensor_parallel = get_tensor_parallel_mode()
        if num_classes <= vocab_parallel_limit or tensor_parallel is None:
            layer = _parallel_classifier[tensor_parallel](
                in_features,
                num_classes,
                weight=weight,
                bias=bias,
                dtype=dtype,
                weight_initializer=weight_initializer,
                bias_initializer=bias_initializer,
            )
        else:
            layer = _vocab_parallel_classifier[tensor_parallel](
                in_features,
                num_classes,
                weight=weight,
                bias=bias,
                dtype=dtype,
                weight_initializer=weight_initializer,
                bias_initializer=bias_initializer,
            )
        super().__init__(layer)
