from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np
from skimage.measure import compare_ssim
import torch
from torch.autograd import Variable

from lpips import dist_model

class PerceptualLoss(torch.nn.Module):
    def __init__(self, model='net-lin', net='alex', colorspace='rgb', spatial=False, use_gpu=True, gpu_ids=[0]): # VGG using our perceptually-learned weights (LPIPS metric)
    # def __init__(self, model='net', net='vgg', use_gpu=True): # "default" way of using VGG as a perceptual loss
        super(PerceptualLoss, self).__init__()
        print('Setting up Perceptual loss...')
        self.use_gpu = use_gpu
        self.spatial = spatial
        self.gpu_ids = gpu_ids
        self.model = dist_model.DistModel()
        self.model.initialize(model=model, net=net, use_gpu=use_gpu, colorspace=colorspace, spatial=self.spatial, gpu_ids=gpu_ids)
        print('...[%s] initialized'%self.model.name())
        print('...Done')

    def forward(self, pred, target, normalize=False):
        """
        Pred and target are Variables.
        If normalize is True, assumes the images are between [0,1] and then scales them between [-1,+1]
        If normalize is False, assumes the images are already between [-1,+1]

        Inputs pred and target are Nx3xHxW
        Output pytorch Variable N long
        """

        if normalize:
            target = 2 * target  - 1
            pred = 2 * pred  - 1

        return self.model.forward(target, pred)

def normalize_tensor(in_feat,eps=1e-10):
    norm_factor = torch.sqrt(torch.sum(in_feat**2,dim=1,keepdim=True))
    return in_feat/(norm_factor+eps)

def l2(p0, p1, range=255.):
    return .5*np.mean((p0 / range - p1 / range)**2)

def psnr(p0, p1, peak=255.):
    return 10*np.log10(peak**2/np.mean((1.*p0-1.*p1)**2))

def dssim(p0, p1, range=255.):
    return (1 - compare_ssim(p0, p1, data_range=range, multichannel=True)) / 2.

def rgb2lab(in_img,mean_cent=False):
    from skimage import color
    img_lab = color.rgb2lab(in_img)
    if(mean_cent):
        img_lab[:,:,0] = img_lab[:,:,0]-50
    return img_lab

def tensor2np(tensor_obj):
    # change dimension of a tensor object into a numpy array
    return tensor_obj[0].cpu().float().numpy().transpose((1,2,0))

def np2tensor(np_obj):
     # change dimenion of np array into tensor array
    return torch.Tensor(np_obj[:, :, :, np.newaxis].transpose((3, 2, 0, 1)))

def tensor2tensorlab(image_tensor,to_norm=True,mc_only=False):
    # image tensor to lab tensor
    from skimage import color

    img = tensor2im(image_tensor)
    img_lab = color.rgb2lab(img)
    if(mc_only):
        img_lab[:,:,0] = img_lab[:,:,0]-50
    if(to_norm and not mc_only):
        img_lab[:,:,0] = img_lab[:,:,0]-50
        img_lab = img_lab/100.

    return np2tensor(img_lab)

def tensorlab2tensor(lab_tensor,return_inbnd=False):
    from skimage import color
    import warnings
    warnings.filterwarnings("ignore")

    lab = tensor2np(lab_tensor)*100.
    lab[:,:,0] = lab[:,:,0]+50

    rgb_back = 255.*np.clip(color.lab2rgb(lab.astype('float')),0,1)
    if(return_inbnd):
        # convert back to lab, see if we match
        lab_back = color.rgb2lab(rgb_back.astype('uint8'))
        mask = 1.*np.isclose(lab_back,lab,atol=2.)
        mask = np2tensor(np.prod(mask,axis=2)[:,:,np.newaxis])
        return (im2tensor(rgb_back),mask)
    else:
        return im2tensor(rgb_back)

def rgb2lab(input):
    from skimage import color
    return color.rgb2lab(input / 255.)

def tensor2im(image_tensor, imtype=np.uint8, cent=1., factor=255./2.):
    image_numpy = image_tensor[0].cpu().float().numpy()
    image_numpy = (np.transpose(image_numpy, (1, 2, 0)) + cent) * factor
    return image_numpy.astype(imtype)

def im2tensor(image, imtype=np.uint8, cent=1., factor=255./2.):
    return torch.Tensor((image / factor - cent)
                        [:, :, :, np.newaxis].transpose((3, 2, 0, 1)))

def tensor2vec(vector_tensor):
    return vector_tensor.data.cpu().numpy()[:, :, 0, 0]

def voc_ap(rec, prec, use_07_metric=False):
    """ ap = voc_ap(rec, prec, [use_07_metric])
    Compute VOC AP given precision and recall.
    If use_07_metric is true, uses the
    VOC 07 11 point method (default:False).
    """
    if use_07_metric:
        # 11 point metric
        ap = 0.
        for t in np.arange(0., 1.1, 0.1):
            if np.sum(rec >= t) == 0:
                p = 0
            else:
                p = np.max(prec[rec >= t])
            ap = ap + p / 11.
    else:
        # correct AP calculation
        # first append sentinel values at the end
        mrec = np.concatenate(([0.], rec, [1.]))
        mpre = np.concatenate(([0.], prec, [0.]))

        # compute the precision envelope
        for i in range(mpre.size - 1, 0, -1):
            mpre[i - 1] = np.maximum(mpre[i - 1], mpre[i])

        # to calculate area under PR curve, look for points
        # where X axis (recall) changes value
        i = np.where(mrec[1:] != mrec[:-1])[0]

        # and sum (\Delta recall) * prec
        ap = np.sum((mrec[i + 1] - mrec[i]) * mpre[i + 1])
    return ap

def tensor2im(image_tensor, imtype=np.uint8, cent=1., factor=255./2.):
# def tensor2im(image_tensor, imtype=np.uint8, cent=1., factor=1.):
    image_numpy = image_tensor[0].cpu().float().numpy()
    image_numpy = (np.transpose(image_numpy, (1, 2, 0)) + cent) * factor
    return image_numpy.astype(imtype)

def im2tensor(image, imtype=np.uint8, cent=1., factor=255./2.):
# def im2tensor(image, imtype=np.uint8, cent=1., factor=1.):
    return torch.Tensor((image / factor - cent)
                        [:, :, :, np.newaxis].transpose((3, 2, 0, 1)))