import os
import torch
import numpy as np
from glob import glob
from torch.utils.data import Dataset
import h5py
import itertools
from scipy import ndimage
import random
from torch.utils.data.sampler import Sampler
from skimage import transform as sk_trans
from scipy.ndimage import rotate, zoom

class BaseDataSets(Dataset):
    def __init__(self, base_dir=None, split='train', num=None, transform=None):
        self._base_dir = base_dir
        self.sample_list = []
        self.split = split
        self.transform = transform
        if self.split == 'train':
            with open(self._base_dir + '/train_slices.list', 'r') as f1:
                self.sample_list = f1.readlines()
            self.sample_list = [item.replace('\n', '') for item in self.sample_list]

        elif self.split == 'val':
            with open(self._base_dir + '/val.list', 'r') as f:
                self.sample_list = f.readlines()
            self.sample_list = [item.replace('\n', '') for item in self.sample_list]
        if num is not None and self.split == "train":
            self.sample_list = self.sample_list[:num]
        print("total {} samples".format(len(self.sample_list)))

    def __len__(self):
        return len(self.sample_list)

    def __getitem__(self, idx):
        case = self.sample_list[idx]
        if self.split == "train":
            h5f = h5py.File(self._base_dir + "/data/slices/{}.h5".format(case), 'r')
        else:
            h5f = h5py.File(self._base_dir + "/data/{}.h5".format(case), 'r')
        image = h5f['image'][:]
        label = h5f['label'][:]
        sample = {'image': image, 'label': label}
        if self.split == "train":
            sample = self.transform(sample)
        sample["idx"] = idx
        return sample

def random_rot_flip(image, label):
    k = np.random.randint(0, 4)
    image = np.rot90(image, k)
    label = np.rot90(label, k)
    axis = np.random.randint(0, 2)
    image = np.flip(image, axis=axis).copy()
    label = np.flip(label, axis=axis).copy()
    return image, label


def random_rotate(image, label):
    angle = np.random.randint(-20, 20)
    image = ndimage.rotate(image, angle, order=0, reshape=False)
    label = ndimage.rotate(label, angle, order=0, reshape=False)
    return image, label


class RandomGenerator(object):
    def __init__(self, output_size):
        self.output_size = output_size

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        # ind = random.randrange(0, img.shape[0])
        # image = img[ind, ...]
        # label = lab[ind, ...]
        if random.random() > 0.5:
            image, label = random_rot_flip(image, label)
        elif random.random() > 0.5:
            image, label = random_rotate(image, label)
        x, y = image.shape
        image = zoom(image, (self.output_size[0] / x, self.output_size[1] / y), order=0)
        label = zoom(label, (self.output_size[0] / x, self.output_size[1] / y), order=0)
        image = torch.from_numpy(image.astype(np.float32)).unsqueeze(0)
        label = torch.from_numpy(label.astype(np.uint8))
        sample = {'image': image, 'label': label}
        return sample


class LAHeart(Dataset):
    """ LA Dataset """
    def __init__(self, base_dir=None, split='train', num=None, transform=None):
        self._base_dir = base_dir
        self.transform = transform
        self.sample_list = []

        train_path = self._base_dir+'/train.list'
        test_path = self._base_dir+'/test.list'

        if split=='train':
            with open(train_path, 'r') as f:
                self.image_list = f.readlines()
        elif split == 'test':
            with open(test_path, 'r') as f:
                self.image_list = f.readlines()

        self.image_list = [item.replace('\n','') for item in self.image_list]
        if num is not None:
            self.image_list = self.image_list[:num]
        print("total {} samples".format(len(self.image_list)))

    def __len__(self):
        return len(self.image_list)

    def __getitem__(self, idx):
        image_name = self.image_list[idx]
        h5f = h5py.File(self._base_dir + "/2018LA_Seg_Training Set/" + image_name + "/mri_norm2.h5", 'r')
        # h5f = h5py.File(self._base_dir+"/"+image_name+"/mri_norm2.h5", 'r')
        image = h5f['image'][:]
        label = h5f['label'][:]
        sample = {'image': image, 'label': label}
        if self.transform:
            sample = self.transform(sample)

        return sample

class Resize(object):

    def __init__(self, output_size):
        self.output_size = output_size

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        (w, h, d) = image.shape
        label = label.astype(np.bool)
        image = sk_trans.resize(image, self.output_size, order = 1, mode = 'constant', cval = 0)
        label = sk_trans.resize(label, self.output_size, order = 0)
        assert(np.max(label) == 1 and np.min(label) == 0)
        assert(np.unique(label).shape[0] == 2)
        
        return {'image': image, 'label': label}
    
    
class CenterCrop(object):
    def __init__(self, output_size):
        self.output_size = output_size

    def __call__(self, sample):
        image, label = sample['image'], sample['label']

        # pad the sample if necessary
        if label.shape[0] <= self.output_size[0] or label.shape[1] <= self.output_size[1] or label.shape[2] <= \
                self.output_size[2]:
            pw = max((self.output_size[0] - label.shape[0]) // 2 + 3, 0)
            ph = max((self.output_size[1] - label.shape[1]) // 2 + 3, 0)
            pd = max((self.output_size[2] - label.shape[2]) // 2 + 3, 0)
            image = np.pad(image, [(pw, pw), (ph, ph), (pd, pd)], mode='constant', constant_values=0)
            label = np.pad(label, [(pw, pw), (ph, ph), (pd, pd)], mode='constant', constant_values=0)

        (w, h, d) = image.shape

        w1 = int(round((w - self.output_size[0]) / 2.))
        h1 = int(round((h - self.output_size[1]) / 2.))
        d1 = int(round((d - self.output_size[2]) / 2.))

        label = label[w1:w1 + self.output_size[0], h1:h1 + self.output_size[1], d1:d1 + self.output_size[2]]
        image = image[w1:w1 + self.output_size[0], h1:h1 + self.output_size[1], d1:d1 + self.output_size[2]]

        return {'image': image, 'label': label}


class RandomCrop(object):
    """
    Crop randomly the image in a sample
    Args:
    output_size (int): Desired output size
    """

    def __init__(self, output_size, with_sdf=False):
        self.output_size = output_size
        self.with_sdf = with_sdf

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        if self.with_sdf:
            sdf = sample['sdf']

        # pad the sample if necessary
        if label.shape[0] <= self.output_size[0] or label.shape[1] <= self.output_size[1] or label.shape[2] <= \
                self.output_size[2]:
            pw = max((self.output_size[0] - label.shape[0]) // 2 + 3, 0)
            ph = max((self.output_size[1] - label.shape[1]) // 2 + 3, 0)
            pd = max((self.output_size[2] - label.shape[2]) // 2 + 3, 0)
            image = np.pad(image, [(pw, pw), (ph, ph), (pd, pd)], mode='constant', constant_values=0)
            label = np.pad(label, [(pw, pw), (ph, ph), (pd, pd)], mode='constant', constant_values=0)
            if self.with_sdf:
                sdf = np.pad(sdf, [(pw, pw), (ph, ph), (pd, pd)], mode='constant', constant_values=0)

        (w, h, d) = image.shape

        w1 = np.random.randint(0, w - self.output_size[0])
        h1 = np.random.randint(0, h - self.output_size[1])
        d1 = np.random.randint(0, d - self.output_size[2])

        label = label[w1:w1 + self.output_size[0], h1:h1 + self.output_size[1], d1:d1 + self.output_size[2]]
        image = image[w1:w1 + self.output_size[0], h1:h1 + self.output_size[1], d1:d1 + self.output_size[2]]
        if self.with_sdf:
            sdf = sdf[w1:w1 + self.output_size[0], h1:h1 + self.output_size[1], d1:d1 + self.output_size[2]]
            return {'image': image, 'label': label, 'sdf': sdf}
        else:
            return {'image': image, 'label': label}


class RandomRotFlip(object):
    """
    Crop randomly flip the dataset in a sample
    Args:
    output_size (int): Desired output size
    """

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        image, label = random_rot_flip(image, label)

        return {'image': image, 'label': label}

class RandomRot(object):
    """
    Crop randomly flip the dataset in a sample
    Args:
    output_size (int): Desired output size
    """

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        image, label = random_rotate(image, label)

        return {'image': image, 'label': label}


class RandomNoise(object):
    def __init__(self, mu=0, sigma=0.1):
        self.mu = mu
        self.sigma = sigma

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        noise = np.clip(self.sigma * np.random.randn(image.shape[0], image.shape[1], image.shape[2]), -2*self.sigma, 2*self.sigma)
        noise = noise + self.mu
        image = image + noise
        return {'image': image, 'label': label}


class CreateOnehotLabel(object):
    def __init__(self, num_classes):
        self.num_classes = num_classes

    def __call__(self, sample):
        image, label = sample['image'], sample['label']
        onehot_label = np.zeros((self.num_classes, label.shape[0], label.shape[1], label.shape[2]), dtype=np.float32)
        for i in range(self.num_classes):
            onehot_label[i, :, :, :] = (label == i).astype(np.float32)
        return {'image': image, 'label': label,'onehot_label':onehot_label}


class ToTensor(object):
    """Convert ndarrays in sample to Tensors."""

    def __call__(self, sample):
        image = sample['image']
        image = image.reshape(1, image.shape[0], image.shape[1], image.shape[2]).astype(np.float32)
        if 'onehot_label' in sample:
            return {'image': torch.from_numpy(image), 'label': torch.from_numpy(sample['label']).long(),
                    'onehot_label': torch.from_numpy(sample['onehot_label']).long()}
        else:
            return {'image': torch.from_numpy(image), 'label': torch.from_numpy(sample['label']).long()}


class TwoStreamBatchSampler(Sampler):
    """Iterate two sets of indices

    An 'epoch' is one iteration through the primary indices.
    During the epoch, the secondary indices are iterated through
    as many times as needed.
    """
    def __init__(self, primary_indices, secondary_indices, batch_size, secondary_batch_size):
        self.primary_indices = primary_indices
        self.secondary_indices = secondary_indices
        self.secondary_batch_size = secondary_batch_size
        self.primary_batch_size = batch_size - secondary_batch_size

        assert len(self.primary_indices) >= self.primary_batch_size > 0
        assert len(self.secondary_indices) >= self.secondary_batch_size > 0

    def __iter__(self):
        primary_iter = iterate_once(self.primary_indices)
        secondary_iter = iterate_eternally(self.secondary_indices)
        return (
            primary_batch + secondary_batch
            for (primary_batch, secondary_batch)
            in zip(grouper(primary_iter, self.primary_batch_size),
                    grouper(secondary_iter, self.secondary_batch_size))
        )

    def __len__(self):
        return len(self.primary_indices) // self.primary_batch_size

def iterate_once(iterable):
    return np.random.permutation(iterable)


def iterate_eternally(indices):
    def infinite_shuffles():
        while True:
            yield np.random.permutation(indices)
    return itertools.chain.from_iterable(infinite_shuffles())


def grouper(iterable, n):
    "Collect data into fixed-length chunks or blocks"
    # grouper('ABCDEFG', 3) --> ABC DEF"
    args = [iter(iterable)] * n
    return zip(*args)
