import argparse
import os
import sys
import re
import json
import traceback
from PIL import Image

import torch
from torchvision import transforms

from azureml.core.model import Model

style_model = None


class TransformerNet(torch.nn.Module):
    def __init__(self):
        super(TransformerNet, self).__init__()
        # Initial convolution layers
        self.conv1 = ConvLayer(3, 32, kernel_size=9, stride=1)
        self.in1 = torch.nn.InstanceNorm2d(32, affine=True)
        self.conv2 = ConvLayer(32, 64, kernel_size=3, stride=2)
        self.in2 = torch.nn.InstanceNorm2d(64, affine=True)
        self.conv3 = ConvLayer(64, 128, kernel_size=3, stride=2)
        self.in3 = torch.nn.InstanceNorm2d(128, affine=True)
        # Residual layers
        self.res1 = ResidualBlock(128)
        self.res2 = ResidualBlock(128)
        self.res3 = ResidualBlock(128)
        self.res4 = ResidualBlock(128)
        self.res5 = ResidualBlock(128)
        # Upsampling Layers
        self.deconv1 = UpsampleConvLayer(128, 64, kernel_size=3, stride=1, upsample=2)
        self.in4 = torch.nn.InstanceNorm2d(64, affine=True)
        self.deconv2 = UpsampleConvLayer(64, 32, kernel_size=3, stride=1, upsample=2)
        self.in5 = torch.nn.InstanceNorm2d(32, affine=True)
        self.deconv3 = ConvLayer(32, 3, kernel_size=9, stride=1)
        # Non-linearities
        self.relu = torch.nn.ReLU()

    def forward(self, X):
        y = self.relu(self.in1(self.conv1(X)))
        y = self.relu(self.in2(self.conv2(y)))
        y = self.relu(self.in3(self.conv3(y)))
        y = self.res1(y)
        y = self.res2(y)
        y = self.res3(y)
        y = self.res4(y)
        y = self.res5(y)
        y = self.relu(self.in4(self.deconv1(y)))
        y = self.relu(self.in5(self.deconv2(y)))
        y = self.deconv3(y)
        return y


class ConvLayer(torch.nn.Module):
    def __init__(self, in_channels, out_channels, kernel_size, stride):
        super(ConvLayer, self).__init__()
        reflection_padding = kernel_size // 2
        self.reflection_pad = torch.nn.ReflectionPad2d(reflection_padding)
        self.conv2d = torch.nn.Conv2d(in_channels, out_channels, kernel_size, stride)

    def forward(self, x):
        out = self.reflection_pad(x)
        out = self.conv2d(out)
        return out


class ResidualBlock(torch.nn.Module):
    """ResidualBlock
    introduced in: https://arxiv.org/abs/1512.03385
    recommended architecture: http://torch.ch/blog/2016/02/04/resnets.html
    """

    def __init__(self, channels):
        super(ResidualBlock, self).__init__()
        self.conv1 = ConvLayer(channels, channels, kernel_size=3, stride=1)
        self.in1 = torch.nn.InstanceNorm2d(channels, affine=True)
        self.conv2 = ConvLayer(channels, channels, kernel_size=3, stride=1)
        self.in2 = torch.nn.InstanceNorm2d(channels, affine=True)
        self.relu = torch.nn.ReLU()

    def forward(self, x):
        residual = x
        out = self.relu(self.in1(self.conv1(x)))
        out = self.in2(self.conv2(out))
        out = out + residual
        return out


class UpsampleConvLayer(torch.nn.Module):
    """UpsampleConvLayer
    Upsamples the input and then does a convolution. This method gives better results
    compared to ConvTranspose2d.
    ref: http://distill.pub/2016/deconv-checkerboard/
    """

    def __init__(self, in_channels, out_channels, kernel_size, stride, upsample=None):
        super(UpsampleConvLayer, self).__init__()
        self.upsample = upsample
        if upsample:
            self.upsample_layer = torch.nn.Upsample(mode='nearest', scale_factor=upsample)
        reflection_padding = kernel_size // 2
        self.reflection_pad = torch.nn.ReflectionPad2d(reflection_padding)
        self.conv2d = torch.nn.Conv2d(in_channels, out_channels, kernel_size, stride)

    def forward(self, x):
        x_in = x
        if self.upsample:
            x_in = self.upsample_layer(x_in)
        out = self.reflection_pad(x_in)
        out = self.conv2d(out)
        return out


def load_image(filename):
    img = Image.open(filename)
    return img


def save_image(filename, data):
    img = data.clone().clamp(0, 255).numpy()
    img = img.transpose(1, 2, 0).astype("uint8")
    img = Image.fromarray(img)
    img.save(filename)


def init():
    global output_path, args
    global style_model, device
    output_path = os.environ['AZUREML_BI_OUTPUT_PATH']
    print(f'output path: {output_path}')
    print(f'Cuda available? {torch.cuda.is_available()}')

    arg_parser = argparse.ArgumentParser(description="parser for fast-neural-style")
    arg_parser.add_argument("--style", type=str, help="style name")
    args, unknown_args = arg_parser.parse_known_args()
    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
    with torch.no_grad():
        style_model = TransformerNet()
        model_path = Model.get_model_path(args.style)
        state_dict = torch.load(os.path.join(model_path))
        # remove saved deprecated running_* keys in InstanceNorm from the checkpoint
        for k in list(state_dict.keys()):
            if re.search(r'in\d+\.running_(mean|var)$', k):
                del state_dict[k]
        style_model.load_state_dict(state_dict)
        style_model.to(device)
    print(f'Model loaded successfully. Path: {model_path}')


def run(mini_batch):

    result = []
    for image_file_path in mini_batch:
        img = load_image(image_file_path)

        with torch.no_grad():
            content_transform = transforms.Compose([
                transforms.ToTensor(),
                transforms.Lambda(lambda x: x.mul(255))
            ])
            content_image = content_transform(img)
            content_image = content_image.unsqueeze(0).to(device)

            output = style_model(content_image).cpu()
            output_file_path = os.path.join(output_path, os.path.basename(image_file_path))
            save_image(output_file_path, output[0])
            result.append(output_file_path)

    return result