import pathlib
from typing import Any, Dict, List, Tuple, Union

import torch
from torchdata.datapipes.iter import CSVParser, IterDataPipe, Mapper
from torchvision.prototype.datapoints import Image, OneHotLabel
from torchvision.prototype.datasets.utils import Dataset, HttpResource, OnlineResource
from torchvision.prototype.datasets.utils._internal import hint_sharding, hint_shuffling

from .._api import register_dataset, register_info

NAME = "semeion"


@register_info(NAME)
def _info() -> Dict[str, Any]:
    return dict(categories=[str(i) for i in range(10)])


@register_dataset(NAME)
class SEMEION(Dataset):
    """Semeion dataset
    homepage="https://archive.ics.uci.edu/ml/datasets/Semeion+Handwritten+Digit",
    """

    def __init__(self, root: Union[str, pathlib.Path], *, skip_integrity_check: bool = False) -> None:

        self._categories = _info()["categories"]
        super().__init__(root, skip_integrity_check=skip_integrity_check)

    def _resources(self) -> List[OnlineResource]:
        data = HttpResource(
            "http://archive.ics.uci.edu/ml/machine-learning-databases/semeion/semeion.data",
            sha256="f43228ae3da5ea6a3c95069d53450b86166770e3b719dcc333182128fe08d4b1",
        )
        return [data]

    def _prepare_sample(self, data: Tuple[str, ...]) -> Dict[str, Any]:
        image_data, label_data = data[:256], data[256:-1]

        return dict(
            image=Image(torch.tensor([float(pixel) for pixel in image_data], dtype=torch.float).reshape(16, 16)),
            label=OneHotLabel([int(label) for label in label_data], categories=self._categories),
        )

    def _datapipe(self, resource_dps: List[IterDataPipe]) -> IterDataPipe[Dict[str, Any]]:
        dp = resource_dps[0]
        dp = CSVParser(dp, delimiter=" ")
        dp = hint_shuffling(dp)
        dp = hint_sharding(dp)
        return Mapper(dp, self._prepare_sample)

    def __len__(self) -> int:
        return 1_593
