import torch
import torch.utils.data as data
import os
import PIL
from .utils import download_file_from_google_drive, check_integrity


class CelebA(data.Dataset):
    """`Large-scale CelebFaces Attributes (CelebA) Dataset <http://mmlab.ie.cuhk.edu.hk/projects/CelebA.html>`_ Dataset.

    Args:
        root (string): Root directory where images are downloaded to.
        split (string): One of {'train', 'valid', 'test'}.
            Accordingly dataset is selected.
        target_type (string or list, optional): Type of target to use, ``attr``, ``identity``, ``bbox``,
            or ``landmarks``. Can also be a list to output a tuple with all specified target types.
            The targets represent:
                ``attr`` (np.array shape=(40,) dtype=int): binary (0, 1) labels for attributes
                ``identity`` (int): label for each person (data points with the same identity are the same person)
                ``bbox`` (np.array shape=(4,) dtype=int): bounding box (x, y, width, height)
                ``landmarks`` (np.array shape=(10,) dtype=int): landmark points (lefteye_x, lefteye_y, righteye_x,
                    righteye_y, nose_x, nose_y, leftmouth_x, leftmouth_y, rightmouth_x, rightmouth_y)
            Defaults to ``attr``.
        transform (callable, optional): A function/transform that  takes in an PIL image
            and returns a transformed version. E.g, ``transforms.ToTensor``
        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 = "celeba"
    # There currently does not appear to be a easy way to extract 7z in python (without introducing additional
    # dependencies). The "in-the-wild" (not aligned+cropped) images are only in 7z, so they are not available
    # right now.
    file_list = [
        # File ID                         MD5 Hash                            Filename
        ("0B7EVK8r0v71pZjFTYXZWM3FlRnM", "00d2c5bc6d35e252742224ab0c1e8fcb", "img_align_celeba.zip"),
        # ("0B7EVK8r0v71pbWNEUjJKdDQ3dGc", "b6cd7e93bc7a96c2dc33f819aa3ac651", "img_align_celeba_png.7z"),
        # ("0B7EVK8r0v71peklHb0pGdDl6R28", "b6cd7e93bc7a96c2dc33f819aa3ac651", "img_celeba.7z"),
        ("0B7EVK8r0v71pblRyaVFSWGxPY0U", "75e246fa4810816ffd6ee81facbd244c", "list_attr_celeba.txt"),
        ("1_ee_0u7vcNLOfNLegJRHmolfH5ICW-XS", "32bd1bd63d3c78cd57e08160ec5ed1e2", "identity_CelebA.txt"),
        ("0B7EVK8r0v71pbThiMVRxWXZ4dU0", "00566efa6fedff7a56946cd1c10f1c16", "list_bbox_celeba.txt"),
        ("0B7EVK8r0v71pd0FJY3Blby1HUTQ", "cc24ecafdb5b50baae59b03474781f8c", "list_landmarks_align_celeba.txt"),
        # ("0B7EVK8r0v71pTzJIdlJWdHczRlU", "063ee6ddb681f96bc9ca28c6febb9d1a", "list_landmarks_celeba.txt"),
        ("0B7EVK8r0v71pY0NSMzRuSXJEVkk", "d32c9cbf5e040fd4025c592c306e6668", "list_eval_partition.txt"),
    ]

    def __init__(self, root,
                 split="train",
                 target_type="attr",
                 transform=None, target_transform=None,
                 download=False):
        import pandas
        self.root = os.path.expanduser(root)
        self.split = split
        if isinstance(target_type, list):
            self.target_type = target_type
        else:
            self.target_type = [target_type]
        self.transform = transform
        self.target_transform = target_transform

        if download:
            self.download()

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

        self.transform = transform
        self.target_transform = target_transform

        if split.lower() == "train":
            split = 0
        elif split.lower() == "valid":
            split = 1
        elif split.lower() == "test":
            split = 2
        else:
            raise ValueError('Wrong split entered! Please use split="train" '
                             'or split="valid" or split="test"')

        with open(os.path.join(self.root, self.base_folder, "list_eval_partition.txt"), "r") as f:
            splits = pandas.read_csv(f, delim_whitespace=True, header=None, index_col=0)

        with open(os.path.join(self.root, self.base_folder, "identity_CelebA.txt"), "r") as f:
            self.identity = pandas.read_csv(f, delim_whitespace=True, header=None, index_col=0)

        with open(os.path.join(self.root, self.base_folder, "list_bbox_celeba.txt"), "r") as f:
            self.bbox = pandas.read_csv(f, delim_whitespace=True, header=1, index_col=0)

        with open(os.path.join(self.root, self.base_folder, "list_landmarks_align_celeba.txt"), "r") as f:
            self.landmarks_align = pandas.read_csv(f, delim_whitespace=True, header=1)

        with open(os.path.join(self.root, self.base_folder, "list_attr_celeba.txt"), "r") as f:
            self.attr = pandas.read_csv(f, delim_whitespace=True, header=1)

        mask = (splits[1] == split)
        self.filename = splits[mask].index.values
        self.identity = torch.as_tensor(self.identity[mask].values)
        self.bbox = torch.as_tensor(self.bbox[mask].values)
        self.landmarks_align = torch.as_tensor(self.landmarks_align[mask].values)
        self.attr = torch.as_tensor(self.attr[mask].values)
        self.attr = (self.attr + 1) // 2  # map from {-1, 1} to {0, 1}

    def _check_integrity(self):
        for (_, md5, filename) in self.file_list:
            fpath = os.path.join(self.root, self.base_folder, filename)
            _, ext = os.path.splitext(filename)
            # Allow original archive to be deleted (zip and 7z)
            # Only need the extracted images
            if ext not in [".zip", ".7z"] and not check_integrity(fpath, md5):
                return False

        # Should check a hash of the images
        return os.path.isdir(os.path.join(self.root, self.base_folder, "img_align_celeba"))

    def download(self):
        import zipfile

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

        for (file_id, md5, filename) in self.file_list:
            download_file_from_google_drive(file_id, os.path.join(self.root, self.base_folder), filename, md5)

        with zipfile.ZipFile(os.path.join(self.root, self.base_folder, "img_align_celeba.zip"), "r") as f:
            f.extractall(os.path.join(self.root, self.base_folder))

    def __getitem__(self, index):
        X = PIL.Image.open(os.path.join(self.root, self.base_folder, "img_align_celeba", self.filename[index]))

        target = []
        for t in self.target_type:
            if t == "attr":
                target.append(self.attr[index, :])
            elif t == "identity":
                target.append(self.identity[index, 0])
            elif t == "bbox":
                target.append(self.bbox[index, :])
            elif t == "landmarks":
                target.append(self.landmarks_align[index, :])
            else:
                raise ValueError("Target type \"{}\" is not recognized.".format(t))
        target = tuple(target) if len(target) > 1 else target[0]

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

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

        return X, target

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

    def __repr__(self):
        fmt_str = 'Dataset ' + self.__class__.__name__ + '\n'
        fmt_str += '    Number of datapoints: {}\n'.format(self.__len__())
        fmt_str += '    Target type: {}\n'.format(self.target_type)
        fmt_str += '    Split: {}\n'.format(self.split)
        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
