"""Universal Text Classification Dataset (UTCD)"""


import os
import json
from os.path import join as os_join
from typing import List

import datasets


_DESCRIPTION = """
UTCD is a compilation of 18 classification datasets spanning 3 categories of Sentiment, 
Intent/Dialogue and Topic classification. UTCD focuses on the task of zero-shot text classification where the 
candidate labels are descriptive of the text being classified. UTCD consists of ~ 6M/800K train/test examples. 
"""

# TODO: citation

_URL = "https://github.com/ChrisIsKing/zero-shot-text-classification/tree/master"
_URL_ZIP = "https://huggingface.co/datasets/claritylab/UTCD/raw/main/datasets.zip"

_VERSION = datasets.Version('0.0.1')


class UtcdConfig(datasets.BuilderConfig):
    """BuilderConfig for SuperGLUE."""

    def __init__(self, domain: str, normalize_aspect: bool = False, **kwargs):
        """BuilderConfig for UTCD.
        Args:
          domain: `string`, dataset domain, one of [`in`, `out`].
          normalize_aspect: `bool`, if True, an aspect-normalized version of the dataset is returned.
          **kwargs: keyword arguments forwarded to super.
        """
        # Version history:
        # 0.0.1: Initial version.
        super(UtcdConfig, self).__init__(version=_VERSION, **kwargs)
        assert domain in ['in', 'out']
        self.domain = domain
        self.normalize_aspect = normalize_aspect

    def to_dir_name(self):
        """
        :return: directory name for the dataset files for this config stored on hub
        """
        domain_str = 'in-domain' if self.domain == 'in' else 'out-of-domain'
        prefix = 'aspect-normalized-' if self.normalize_aspect else ''
        return f'{prefix}{domain_str}'


with open(os_join(os.path.dirname(__file__), '_utcd_info.json')) as f:
    _config = json.load(f)
_split2hf_split = dict(train=datasets.Split.TRAIN, eval=datasets.Split.VALIDATION, test=datasets.Split.TEST)


class Utcd(datasets.GeneratorBasedBuilder):
    """UTCD: Universal Text Classification Dataset. Version 0.0."""

    VERSION = _VERSION

    BUILDER_CONFIGS = [
        UtcdConfig(
            name='in-domain',
            description='All in-domain datasets.',
            domain='in',
            normalize_aspect=False
        ),
        UtcdConfig(
            name='aspect-normalized-in-domain',
            description='Aspect-normalized version of all in-domain datasets.',
            domain='in',
            normalize_aspect=True
        ),
        UtcdConfig(
            name='out-of-domain',
            description='All out-of-domain datasets.',
            domain='out',
            normalize_aspect=False
        ),
        UtcdConfig(
            name='aspect-normalized-out-of-domain',
            description='Aspect-normalized version of all out-of-domain datasets.',
            domain='out',
            normalize_aspect=True
        )
    ]
    DEFAULT_CONFIG_NAME = 'in-domain'

    def _get_dataset_names(self):
        return [dnm for dnm, d_dset in _config.items() if d_dset['domain'] == self.config.domain]

    def _info(self):
        dnms = self._get_dataset_names()
        labels = [_config[dnm]['splits'][split]['labels'] for dnm in dnms for split in ['train', 'test']]

        labels = sorted(set().union(*labels))  # drop duplicate labels across datasets
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                text=datasets.Value(dtype='string'),
                labels=datasets.Sequence(feature=datasets.ClassLabel(names=labels), length=-1),  # for multi-label
                dataset_name=datasets.ClassLabel(names=dnms)
            ),
            homepage=_URL
            # TODO: citation
        )

    def _split_generators(self, dl_manager: datasets.DownloadManager) -> List[datasets.SplitGenerator]:
        # for aspect-normalized versions of the dataset, we include a validation set
        splits = ['train', 'eval', 'test'] if self.config.normalize_aspect else ['train', 'test']
        dnms = self._get_dataset_names()
        dir_nm = self.config.to_dir_name()
        # TODO: update root dataset naming version & dataset split naming

        base_path = dl_manager.download_and_extract('datasets.zip')
        split2paths = {s: [os_join(base_path, f'{dir_nm}_split', dnm, f'{s}.json') for dnm in dnms] for s in splits}
        # order of dataset file paths will be deterministic for deterministic dataset name ordering
        return [
            datasets.SplitGenerator(name=_split2hf_split[s], gen_kwargs=dict(filepath=split2paths[s])) for s in splits
        ]

    def _generate_examples(self, filepath: List[str]):
        id_ = 0
        for path in filepath:  # each file for one split of one dataset
            dnm = path.split(os.sep)[-2]
            with open(path, encoding='utf-8') as fl:
                dset = json.load(fl)
                for txt, labels in dset.items():
                    yield id_, dict(text=txt, labels=labels, dataset_name=dnm)
                    id_ += 1