import gc

import torch


def value_map(inputs, min_in, max_in, min_out, max_out):
    return (inputs - min_in) * (max_out - min_out) / (max_in - min_in) + min_out


def flush(garbage_collect=True):
    torch.cuda.empty_cache()
    if garbage_collect:
        gc.collect()


def get_mean_std(tensor):
    if len(tensor.shape) == 3:
        tensor = tensor.unsqueeze(0)
    elif len(tensor.shape) != 4:
        raise Exception("Expected tensor of shape (batch_size, channels, width, height)")
    mean, variance = torch.mean(
        tensor, dim=[2, 3], keepdim=True
    ), torch.var(
        tensor, dim=[2, 3],
        keepdim=True
    )
    std = torch.sqrt(variance + 1e-5)
    return mean, std


def adain(content_features, style_features):
    # Assumes that the content and style features are of shape (batch_size, channels, width, height)

    dims = [2, 3]
    if len(content_features.shape) == 3:
        # content_features = content_features.unsqueeze(0)
        # style_features = style_features.unsqueeze(0)
        dims = [1]

    # Step 1: Calculate mean and variance of content features
    content_mean, content_var = torch.mean(content_features, dim=dims, keepdim=True), torch.var(content_features,
                                                                                                  dim=dims,
                                                                                                  keepdim=True)
    # Step 2: Calculate mean and variance of style features
    style_mean, style_var = torch.mean(style_features, dim=dims, keepdim=True), torch.var(style_features, dim=dims,
                                                                                            keepdim=True)

    # Step 3: Normalize content features
    content_std = torch.sqrt(content_var + 1e-5)
    normalized_content = (content_features - content_mean) / content_std

    # Step 4: Scale and shift normalized content with style's statistics
    style_std = torch.sqrt(style_var + 1e-5)
    stylized_content = normalized_content * style_std + style_mean

    return stylized_content