import torch
from torch.autograd import Variable

USE_CUDA = torch.cuda.is_available()
FLOAT = torch.cuda.FloatTensor if USE_CUDA else torch.FloatTensor


def to_numpy(var):
    return var.cpu().data.numpy() if USE_CUDA else var.data.numpy()


def to_tensor(ndarray, volatile=False, requires_grad=False, dtype=FLOAT):
    return Variable(
        torch.from_numpy(ndarray), volatile=volatile, requires_grad=requires_grad
    ).type(dtype)


def soft_update(target, source, tau):
    for target_param, param in zip(target.parameters(), source.parameters()):
        target_param.data.copy_(
            target_param.data * (1.0 - tau) + param.data * tau
        )


def hard_update(target, source):
    for target_param, param in zip(target.parameters(), source.parameters()):
        target_param.data.copy_(param.data)


activations = {
    "relu": torch.nn.ReLU,
    "elu": torch.nn.ELU,
    "leakyrelu": torch.nn.LeakyReLU,
    "selu": torch.nn.SELU,
    "sigmoid": torch.nn.Sigmoid,
    "tanh": torch.nn.Tanh
}