import torch
from colossalai.tensor.op_wrapper import colo_op_impl
from colossalai.tensor import ColoTensor


@colo_op_impl(torch.mean)
def colo_mean(types, args=(), kwargs=None, pg=None):
    input_t = args[0]
    if isinstance(input_t, ColoTensor):
        input_t = input_t.torch_tensor()
    return ColoTensor.init_from_torch_tensor(torch.mean(input_t))


def register_elementwise_op(op):

    @colo_op_impl(op)
    def elementwise_op(types, args=(), kwargs=None, pg=None):
        """
        Handles ``__torch_function__`` dispatch for the elementwise op such
        as ``torch.nn.functional.gelu`` or ``torch.nn.functional.relu``.
        This method computes on either a normal tensor or a sharded tensor.
        """
        input_tensor = args[0]
        # Validate types
        if not isinstance(input_tensor, ColoTensor):
            raise TypeError("input needs to be a ColoTensor")
        return ColoTensor.init_from_torch_tensor(op(input_tensor.torch_tensor()))


register_elementwise_op(torch.nn.functional.gelu)
register_elementwise_op(torch.nn.functional.relu)