'''This module handles task-dependent operations (A) and noises (n) to simulate a measurement y=Ax+n.'''

from abc import ABC, abstractmethod
from functools import partial

from torch.nn import functional as F
from torchvision import torch

from src.flair.utils.blur_util import Blurkernel
from src.flair.utils.img_util import fft2d
import numpy as np
from src.flair.utils.resizer import Resizer
from src.flair.utils.utils_sisr import pre_calculate_FK, pre_calculate_nonuniform
from torch.fft import fft2, ifft2


from src.flair.motionblur.motionblur import Kernel

# =================
# Operation classes
# =================

__OPERATOR__ = {}
_GAMMA_FACTOR = 2.2

def register_operator(name: str):
    def wrapper(cls):
        if __OPERATOR__.get(name, None):
            raise NameError(f"Name {name} is already registered!")
        __OPERATOR__[name] = cls
        return cls
    return wrapper


def get_operator(name: str, **kwargs):
    if __OPERATOR__.get(name, None) is None:
        raise NameError(f"Name {name} is not defined.")
    return __OPERATOR__[name](**kwargs)


class LinearOperator(ABC):
    @abstractmethod
    def forward(self, data, **kwargs):
        # calculate A * X
        pass

    @abstractmethod
    def noisy_forward(self, data, **kwargs):
        # calculate A * X + n
        pass

    @abstractmethod
    def transpose(self, data, **kwargs):
        # calculate A^T * X
        pass

    def ortho_project(self, data, **kwargs):
        # calculate (I - A^T * A)X
        return data - self.transpose(self.forward(data, **kwargs), **kwargs)

    def project(self, data, measurement, **kwargs):
        # calculate (I - A^T * A)Y - AX
        return self.ortho_project(measurement, **kwargs) - self.forward(data, **kwargs)


@register_operator(name='noise')
class DenoiseOperator(LinearOperator):
    def __init__(self, device):
        self.device = device

    def forward(self, data):
        return data

    def noisy_forward(self, data):
        return data

    def transpose(self, data):
        return data

    def ortho_project(self, data):
        return data

    def project(self, data):
        return data


@register_operator(name='sr_bicubic')
class SuperResolutionOperator(LinearOperator):
    def __init__(self,
                 in_shape,
                 scale_factor,
                 noise,
                 noise_scale,
                 device):
        self.device = device
        self.up_sample = partial(F.interpolate, scale_factor=scale_factor)
        self.down_sample = Resizer(in_shape, 1/scale_factor).to(device)
        self.noise = get_noise(name=noise, scale=noise_scale)

    def A(self, data, **kwargs):
        return self.forward(data, **kwargs)

    def forward(self, data, **kwargs):
        return self.down_sample(data)

    def noisy_forward(self, data, **kwargs):
        return self.noise.forward(self.down_sample(data))

    def transpose(self, data, **kwargs):
        return self.up_sample(data)

    def project(self, data, measurement, **kwargs):
        return data - self.transpose(self.forward(data)) + self.transpose(measurement)

@register_operator(name='deblur_motion')
class MotionBlurOperator(LinearOperator):
    def __init__(self,
                 kernel_size,
                 intensity,
                 device):
        self.device = device
        self.kernel_size = kernel_size
        self.conv = Blurkernel(blur_type='motion',
                               kernel_size=kernel_size,
                               std=intensity,
                               device=device).to(device)  # should we keep this device term?

        self.kernel_size =kernel_size
        self.intensity = intensity
        self.kernel = Kernel(size=(kernel_size, kernel_size), intensity=intensity)
        kernel = torch.tensor(self.kernel.kernelMatrix, dtype=torch.float32)
        self.conv.update_weights(kernel)

    def forward(self, data, **kwargs):
        # A^T * A
        return self.conv(data)

    def noisy_forward(self, data, **kwargs):
        pass

    def transpose(self, data, **kwargs):
        return data

    def change_kernel(self):
        self.kernel = Kernel(size=(self.kernel_size, self.kernel_size), intensity=self.intensity)
        kernel = torch.tensor(self.kernel.kernelMatrix, dtype=torch.float32)
        self.conv.update_weights(kernel)

    def get_kernel(self):
        kernel = self.kernel.kernelMatrix.type(torch.float32).to(self.device)
        return kernel.view(1, 1, self.kernel_size, self.kernel_size)

    def A(self, data):
        return self.forward(data)

    def At(self, data):
        return self.transpose(data)

@register_operator(name='deblur_gauss')
class GaussialBlurOperator(LinearOperator):
    def __init__(self,
                 kernel_size,
                 intensity,
                 device):
        self.device = device
        self.kernel_size = kernel_size
        self.conv = Blurkernel(blur_type='gaussian',
                               kernel_size=kernel_size,
                               std=intensity,
                               device=device).to(device)
        self.kernel = self.conv.get_kernel()
        self.conv.update_weights(self.kernel.type(torch.float32))

    def forward(self, data, **kwargs):
        return self.conv(data)

    def noisy_forward(self, data, **kwargs):
        pass

    def transpose(self, data, **kwargs):
        return data

    def get_kernel(self):
        return self.kernel.view(1, 1, self.kernel_size, self.kernel_size)

    def apply_kernel(self, data, kernel):
        self.conv.update_weights(kernel.type(torch.float32))
        return self.conv(data)

    def A(self, data):
        return self.forward(data)

    def At(self, data):
        return self.transpose(data)

@register_operator(name='inpainting')
class InpaintingOperator(LinearOperator):
    '''This operator get pre-defined mask and return masked image.'''
    def __init__(self,
                 noise,
                 noise_scale,
                 device):
        self.device = device
        self.noise = get_noise(name=noise, scale=noise_scale)

    def forward(self, data, **kwargs):
        try:
            return data * kwargs.get('mask', None).to(self.device)
        except:
            raise ValueError("Require mask")

    def noisy_forward(self, data, **kwargs):
        return self.noise.forward(self.forward(data, **kwargs))

    def transpose(self, data, **kwargs):
        return data

    def ortho_project(self, data, **kwargs):
        return data - self.forward(data, **kwargs)

# Operator for BlindDPS.
@register_operator(name='blind_blur')
class BlindBlurOperator(LinearOperator):
    def __init__(self, device, **kwargs) -> None:
        self.device = device

    def forward(self, data, kernel, **kwargs):
        return self.apply_kernel(data, kernel)

    def transpose(self, data, **kwargs):
        return data

    def apply_kernel(self, data, kernel):
        #TODO: faster way to apply conv?:W

        b_img = torch.zeros_like(data).to(self.device)
        for i in range(3):
            b_img[:, i, :, :] = F.conv2d(data[:, i:i+1, :, :], kernel, padding='same')
        return b_img


class NonLinearOperator(ABC):
    @abstractmethod
    def forward(self, data, **kwargs):
        pass

    @abstractmethod
    def noisy_forward(self, data, **kwargs):
        pass

    def project(self, data, measurement, **kwargs):
        return data + measurement - self.forward(data)

@register_operator(name='phase_retrieval')
class PhaseRetrievalOperator(NonLinearOperator):
    def __init__(self,
                 oversample,
                 noise,
                 noise_scale,
                 device):
        self.pad = int((oversample / 8.0) * 256)
        self.device = device
        self.noise = get_noise(name=noise, scale=noise_scale)

    def forward(self, data, **kwargs):
        padded = F.pad(data, (self.pad, self.pad, self.pad, self.pad))
        amplitude = fft2d(padded).abs()
        return amplitude

    def noisy_forard(self, data, **kwargs):
        return self.noise.forward(self.forward(data, **kwargs))

@register_operator(name='nonuniform_blur')
class NonuniformBlurOperator(LinearOperator):
    def __init__(self, in_shape, kernel_size, device,
                 kernels=None, masks=None):
        self.device = device
        self.kernel_size = kernel_size
        self.in_shape = in_shape

        # TODO: generalize
        if kernels is None and masks is None:
            self.kernels = np.load('./functions/nonuniform/kernels/000001.npy')
            self.masks = np.load('./functions/nonuniform/masks/000001.npy')
            self.kernels = torch.tensor(self.kernels).to(device)
            self.masks = torch.tensor(self.masks).to(device)

    # approximate in image space
    def forward_img(self, data):
        K = self.kernel_size
        data = F.pad(data, (K//2, K//2, K//2, K//2), mode="reflect")
        kernels = self.kernels.transpose(0, 1)
        data_rgb_batch = data.transpose(0, 1)
        conv_rgb_batch = F.conv2d(data_rgb_batch, kernels)
        y_rgb_batch = conv_rgb_batch * self.masks
        y_rgb_batch = torch.sum(y_rgb_batch, dim=1, keepdim=True)
        y = y_rgb_batch.transpose(0, 1)
        return y

    # NOTE: Only using this operator will make the problem nonlinear (gamma-correction)
    def forward_nonlinear(self, data, flatten=False, noiseless=False):
        # 1. Usual nonuniform blurring degradataion pipeline
        kernels = self.kernels.transpose(0, 1)
        FK, FKC = pre_calculate_FK(kernels)
        y = ifft2(FK * fft2(data)).real
        y = y.transpose(0, 1)
        y_rgb_batch = self.masks * y
        y_rgb_batch = torch.sum(y_rgb_batch, dim=1, keepdim=True)
        y = y_rgb_batch.transpose(0, 1)
        F2KM, FKFMy = pre_calculate_nonuniform(data, y, FK, FKC, self.masks)
        self.pre_calculated = (FK, FKC, F2KM, FKFMy)
        # 2. Gamma-correction
        y = (y + 1) / 2
        y = y ** (1 / _GAMMA_FACTOR)
        y = (y - 0.5) / 0.5
        return y

    def noisy_forward(self, data, **kwargs):
        return self.noise.forward(self.forward(data))

    # exact in Fourier
    def forward(self, data, flatten=False, noiseless=False):
        # [1, 25, 33, 33] -> [25, 1, 33, 33]
        kernels = self.kernels.transpose(0, 1)
        # [25, 1, 512, 512]
        FK, FKC = pre_calculate_FK(kernels)
        # [25, 3, 512, 512]
        y = ifft2(FK * fft2(data)).real
        # [3, 25, 512, 512]
        y = y.transpose(0, 1)
        y_rgb_batch = self.masks * y
        # [3, 1, 512, 512]
        y_rgb_batch = torch.sum(y_rgb_batch, dim=1, keepdim=True)
        # [1, 3, 512, 512]
        y = y_rgb_batch.transpose(0, 1)
        F2KM, FKFMy = pre_calculate_nonuniform(data, y, FK, FKC, self.masks)
        self.pre_calculated = (FK, FKC, F2KM, FKFMy)
        return y

    def transpose(self, y, flatten=False):
        kernels = self.kernels.transpose(0, 1)
        FK, FKC = pre_calculate_FK(kernels)
        # 1. braodcast and multiply
        # [3, 1, 512, 512]
        y_rgb_batch = y.transpose(0, 1)
        # [3, 25, 512, 512]
        y_rgb_batch = y_rgb_batch.repeat(1, 25, 1, 1)
        y = self.masks * y_rgb_batch
        # 2. transpose of convolution in Fourier
        # [25, 3, 512, 512]
        y = y.transpose(0, 1)
        ATy_broadcast = ifft2(FKC * fft2(y)).real
        # [1, 3, 512, 512]
        ATy = torch.sum(ATy_broadcast, dim=0, keepdim=True)
        return ATy

    def A(self, data):
        return self.forward(data)

    def At(self, data):
        return self.transpose(data)

# =============
# Noise classes
# =============


__NOISE__ = {}

def register_noise(name: str):
    def wrapper(cls):
        if __NOISE__.get(name, None):
            raise NameError(f"Name {name} is already defined!")
        __NOISE__[name] = cls
        return cls
    return wrapper

def get_noise(name: str, **kwargs):
    if __NOISE__.get(name, None) is None:
        raise NameError(f"Name {name} is not defined.")
    noiser = __NOISE__[name](**kwargs)
    noiser.__name__ = name
    return noiser

class Noise(ABC):
    def __call__(self, data):
        return self.forward(data)

    @abstractmethod
    def forward(self, data):
        pass

@register_noise(name='clean')
class Clean(Noise):
    def __init__(self, **kwargs):
        pass

    def forward(self, data):
        return data

@register_noise(name='gaussian')
class GaussianNoise(Noise):
    def __init__(self, scale):
        self.scale = scale

    def forward(self, data):
        return data + torch.randn_like(data, device=data.device) * self.scale


@register_noise(name='poisson')
class PoissonNoise(Noise):
    def __init__(self, scale):
        self.scale = scale

    def forward(self, data):
        '''
        Follow skimage.util.random_noise.
        '''

        # version 3 (stack-overflow)
        import numpy as np
        data = (data + 1.0) / 2.0
        data = data.clamp(0, 1)
        device = data.device
        data = data.detach().cpu()
        data = torch.from_numpy(np.random.poisson(data * 255.0 * self.scale) / 255.0 / self.scale)
        data = data * 2.0 - 1.0
        data = data.clamp(-1, 1)
        return data.to(device)