from __future__ import print_function
from PIL import Image
import os
import os.path
import numpy as np
import sys
if sys.version_info[0] == 2:
    import cPickle as pickle
else:
    import pickle

import torch.utils.data as data
#from torch.utils import download_url, check_integrity

import pdb

class CIFAR10(data.Dataset):
    """`CIFAR10 <https://www.cs.toronto.edu/~kriz/cifar.html>`_ Dataset.
    Args:
        root (string): Root directory of dataset where directory
            ``cifar-10-batches-py`` exists or will be saved to if download is set to True.
        train (bool, optional): If True, creates dataset from training set, otherwise
            creates from test set.
        transform (callable, optional): A function/transform that takes in an PIL image
            and returns a transformed version. E.g, ``transforms.RandomCrop``
        target_transform (callable, optional): A function/transform that takes in the
            target and transforms it.
        download (bool, optional): If true, downloads the dataset from the internet and
            puts it in root directory. If dataset is already downloaded, it is not
            downloaded again.
    """
    base_folder = 'cifar-10-batches-py'
    url = "https://www.cs.toronto.edu/~kriz/cifar-10-python.tar.gz"
    filename = "cifar-10-python.tar.gz"
    tgz_md5 = 'c58f30108f718f92721af3b95e74349a'
    train_list = [
        ['data_batch_1', 'c99cafc152244af753f735de768cd75f'],
        ['data_batch_2', 'd4bba439e000b95fd0a9bffe97cbabec'],
        ['data_batch_3', '54ebc095f3ab1f0389bbae665268c751'],
        ['data_batch_4', '634d18415352ddfa80567beed471001a'],
        ['data_batch_5', '482c414d41f54cd18b22e5b47cb7c3cb'],
    ]

    test_list = [
        ['test_batch', '40351d587109b95175f43aff81a1287e'],
    ]
    meta = {
        'filename': 'batches.meta',
        'key': 'label_names',
        'md5': '5ff9c542aee3614f3951f8cda6e48888',
    }

    def __init__(self, root, train=True,
                 transform=None, target_transform=None,
                 download=False, index=None,num_instance_per_class=0):
        self.root = os.path.expanduser(root)
        self.transform = transform
        self.target_transform = target_transform
        self.train = train  # training set or test set

        # if download:
        #     self.download()

        # if not self._check_integrity():
        #     raise RuntimeError('Dataset not found or corrupted.' +
        #                        ' You can use download=True to download it')

        if self.train:
            downloaded_list = self.train_list
        else:
            downloaded_list = self.test_list

        self.data = []
        self.targets = []

        # now load the picked numpy arrays
        for file_name, checksum in downloaded_list:
            file_path = os.path.join(self.root, self.base_folder, file_name)
            with open(file_path, 'rb') as f:
                if sys.version_info[0] == 2:
                    entry = pickle.load(f)
                else:
                    entry = pickle.load(f, encoding='latin1')
                self.data.append(entry['data'])
                if 'labels' in entry:
                    self.targets.extend(entry['labels'])
                else:
                    self.targets.extend(entry['fine_labels'])

        self.data = np.vstack(self.data).reshape(-1, 3, 32, 32)
        self.data = self.data.transpose((0, 2, 3, 1))  # convert to HWC
        #self.data = self.data/255.
        #pdb.set_trace()
        self.targets = np.asarray(self.targets)
        #index_sort = np.argsort(self.targets)
        # Sort label and corresponding data from 0-9
        #self.data = self.data[index_sort]
        #self.targets=np.asarray(sorted(self.targets))

        self.targets = target_transform[self.targets] 

        if num_instance_per_class==0:
            self.data,self.targets = self.RandomPercentage(self.data,self.targets,index)
        else:
            self.data,self.targets = self.RandomExempalers(self.data,self.targets,index,num_instance_per_class)


        self._load_meta()

    def RandomPercentage(self, data,targets,index):
        data_tmp = []
        targets_tmp = []
        for i in index:
            ind_cl = np.where(i == targets)[0]
            if data_tmp==[]:
                data_tmp = data[ind_cl]
                targets_tmp = targets[ind_cl]
            else:
                data_tmp = np.vstack((data_tmp,data[ind_cl]))
                targets_tmp = np.hstack((targets_tmp,targets[ind_cl]))

        return data_tmp,targets_tmp
    def RandomExempalers(self, data,targets,index,num):
        data_tmp = []
        targets_tmp = []
        for i in index:
            ind_cl = np.where(i == targets)[0][:num]
            if data_tmp==[]:
                data_tmp = data[ind_cl]
                targets_tmp = targets[ind_cl]
            else:
                data_tmp = np.vstack((data_tmp,data[ind_cl]))
                targets_tmp = np.hstack((targets_tmp,targets[ind_cl]))
                
        return data_tmp,targets_tmp
    def _load_meta(self):
        path = os.path.join(self.root, self.base_folder, self.meta['filename'])
        # if not check_integrity(path, self.meta['md5']):
        #     raise RuntimeError('Dataset metadata file not found or corrupted.' +
        #                        ' You can use download=True to download it')
        with open(path, 'rb') as infile:
            if sys.version_info[0] == 2:
                data = pickle.load(infile)
            else:
                data = pickle.load(infile, encoding='latin1')
            self.classes = data[self.meta['key']]
        self.class_to_idx = {_class: i for i, _class in enumerate(self.classes)}

    def __getitem__(self, index):
        """
        Args:
            index (int): Index
        Returns:
            tuple: (image, target) where target is index of the target class.
        """
        img, target = self.data[index], self.targets[index]

        # doing this so that it is consistent with all other datasets
        # to return a PIL Image
        img = Image.fromarray(img)

        if self.transform is not None:
            img = self.transform(img)

        # if self.target_transform is not None:
        #     target = self.target_transform(target)

        return img, target

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

    # def _check_integrity(self):
    #     root = self.root
    #     for fentry in (self.train_list + self.test_list):
    #         filename, md5 = fentry[0], fentry[1]
    #         fpath = os.path.join(root, self.base_folder, filename)
    #         if not check_integrity(fpath, md5):
    #             return False
    #     return True

    # def download(self):
    #     import tarfile

    #     # if self._check_integrity():
    #     #     print('Files already downloaded and verified')
    #     #     return

    #     download_url(self.url, self.root, self.filename, self.tgz_md5)

    #     # extract file
    #     with tarfile.open(os.path.join(self.root, self.filename), "r:gz") as tar:
    #         tar.extractall(path=self.root)

    def __repr__(self):
        fmt_str = 'Dataset ' + self.__class__.__name__ + '\n'
        fmt_str += '    Number of datapoints: {}\n'.format(self.__len__())
        tmp = 'train' if self.train is True else 'test'
        fmt_str += '    Split: {}\n'.format(tmp)
        fmt_str += '    Root Location: {}\n'.format(self.root)
        tmp = '    Transforms (if any): '
        fmt_str += '{0}{1}\n'.format(tmp, self.transform.__repr__().replace('\n', '\n' + ' ' * len(tmp)))
        tmp = '    Target Transforms (if any): '
        fmt_str += '{0}{1}'.format(tmp, self.target_transform.__repr__().replace('\n', '\n' + ' ' * len(tmp)))
        return fmt_str

class CIFAR100(CIFAR10):
    """`CIFAR100 <https://www.cs.toronto.edu/~kriz/cifar.html>`_ Dataset.
    This is a subclass of the `CIFAR10` Dataset.
    """
    base_folder = 'cifar-100-python'
    url = "https://www.cs.toronto.edu/~kriz/cifar-100-python.tar.gz"
    filename = "cifar-100-python.tar.gz"
    tgz_md5 = 'eb9058c3a382ffc7106e4002c42a8d85'
    train_list = [
        ['train', '16019d7e3df5f24257cddd939b257f8d'],
    ]

    test_list = [
        ['test', 'f0ef6b0ae62326f3e7ffdfab6717acfc'],
    ]
    meta = {
        'filename': 'meta',
        'key': 'fine_label_names',
        'md5': '7973b15100ade9c7d40fb424638fde48',
    }