from __future__ import print_function
import argparse
import torch
from PIL import Image
from torchvision.transforms import ToTensor

import numpy as np

class Test(ToTensor):
    def __call__(self, pic):
        """
        Args:
            pic (PIL.Image or numpy.ndarray): Image to be converted to tensor.
        Returns:
            Tensor: Converted image.
        """
        if isinstance(pic, np.ndarray):
            # handle numpy array
            img = torch.from_numpy(pic.transpose((2, 0, 1)))
            # backward compatibility
            return img.float().div(3700)

        if accimage is not None and isinstance(pic, accimage.Image):
            nppic = np.zeros([pic.channels, pic.height, pic.width], dtype=np.float32)
            pic.copyto(nppic)
            return torch.from_numpy(nppic)

        # handle PIL Image
        if pic.mode == 'I':
            img = torch.from_numpy(np.array(pic, np.int32, copy=False))
        elif pic.mode == 'I;16':
            img = torch.from_numpy(np.array(pic, np.int16, copy=False))
        else:
            img = torch.ByteTensor(torch.ByteStorage.from_buffer(pic.tobytes()))
        # PIL image mode: 1, L, P, I, F, RGB, YCbCr, RGBA, CMYK
        if pic.mode == 'YCbCr':
            nchannel = 3
        elif pic.mode == 'I;16':
            nchannel = 1
        else:
            nchannel = len(pic.mode)
        img = img.view(pic.size[1], pic.size[0], nchannel)
        # put it from HWC to CHW format
        # yikes, this transpose takes 80% of the loading time/CPU
        img = img.transpose(0, 1).transpose(0, 2).contiguous()
        if isinstance(img, torch.ByteTensor):
            return img.float().div(3700)
        else:
            return img
        
# Training settings
parser = argparse.ArgumentParser(description='PyTorch Super Res Example')
parser.add_argument('--input_image', type=str, required=True, help='input image to use')
parser.add_argument('--model', type=str, required=True, help='model file to use')
parser.add_argument('--output_filename', type=str, help='where to save the output image')
parser.add_argument('--cuda', action='store_true', help='use cuda')
opt = parser.parse_args()

print(opt)
img = Image.open(opt.input_image).convert('YCbCr')
y, cb, cr = img.split()

model = torch.load(opt.model)
img_to_tensor = Test()
input = img_to_tensor(y).view(1, -1, y.size[1], y.size[0])

if opt.cuda:
    model = model.cuda()
    input = input.cuda()

out = model(input)
out = out.cpu()
out_img_y = out[0].detach().numpy()
out_img_y *= 3700
out_img_y = out_img_y.clip(0, 3700)
out_img_y = Image.fromarray(np.uint8(out_img_y[0]), mode='L')

out_img_cb = cb.resize(out_img_y.size, Image.BICUBIC)
out_img_cr = cr.resize(out_img_y.size, Image.BICUBIC)
out_img = Image.merge('YCbCr', [out_img_y, out_img_cb, out_img_cr]).convert('RGB')

out_img.save(opt.output_filename)
print('output image saved to ', opt.output_filename)
