from pathlib import Path
from typing import Any, Dict, Iterator, List, Tuple

import datasets


_DESCRIPTION = (
    "書籍『大規模言語モデル入門』で使用する JSNLI のデータセットです。"
    "JSNLI Version 1.1 のデータセットのうち、フィルタリング後の訓練セット (train_w_filtering) と検証セット (dev) を使用しています。"
)
_HOMEPAGE = "https://nlp.ist.i.kyoto-u.ac.jp/?日本語SNLI(JSNLI)データセット"
_LICENSE = "CC BY-SA 4.0"

_URL = "https://nlp.ist.i.kyoto-u.ac.jp/DLcounter/lime.cgi?down=https://nlp.ist.i.kyoto-u.ac.jp/nl-resource/JSNLI/jsnli_1.1.zip&name=JSNLI.zip"


class JSNLI(datasets.GeneratorBasedBuilder):
    VERSION = datasets.Version("1.0.0")

    def _info(self) -> datasets.DatasetInfo:
        features = datasets.Features({
            "premise": datasets.Value("string"),
            "hypothesis": datasets.Value("string"),
            "label": datasets.Value("string"),
        })
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            homepage=_HOMEPAGE,
            license=_LICENSE,
            features=features,
        )

    def _split_generators(self, dl_manager: datasets.DownloadManager) -> List[datasets.SplitGenerator]:
        base_filepath = dl_manager.download_and_extract(_URL)
        train_filepath = Path(base_filepath) / "jsnli_1.1" / "train_w_filtering.tsv"
        dev_filepath = Path(base_filepath) / "jsnli_1.1" / "dev.tsv"

        split_generators = [
            datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"filepath": train_filepath}),
            datasets.SplitGenerator(name=datasets.Split.VALIDATION, gen_kwargs={"filepath": dev_filepath}),
        ]
        return split_generators

    def _generate_examples(self, filepath: str) -> Iterator[Tuple[int, Dict[str, Any]]]:
        with open(filepath, encoding="utf-8") as f:
            for i, line in enumerate(f):
                label, premise, hypothesis = line.rstrip("\n").split("\t")
                example = {
                    "premise": premise,
                    "hypothesis": hypothesis,
                    "label": label,
                }
                yield i, example