import os
from typing import List

import datasets

logger = datasets.logging.get_logger(__name__)

_DESCRIPTION = """"""
_LICENSE = """GNU GPL v3.0"""
_CLASSES = ["O", "B-PER", "I-PER", "B-ORG", "I-ORG", "B-LOC", "I-LOC"]
_VERSION = "1.0"


class TLUnifiedNERConfig(datasets.BuilderConfig):
    def __init__(self, **kwargs):
        super(TLUnifiedNER, self).__init__(**kwargs)


class TLUnifiedNER(datasets.GeneratorBasedBuilder):
    """Contains an annotated version of the TLUnified dataset from Cruz and Cheng (2021)."""

    VERSION = datasets.Version(_VERSION)

    def _info() -> "datasets.DatasetInfo":
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "id": datasets.Value("string"),
                    "tokens": datasets.Sequence(datasets.Value("string")),
                    "ner_tags": datasets.Sequence(
                        datasets.feature.ClassLabel(names=_CLASSES)
                    ),
                }
            ),
            supervised_keys=None,
        )

    def _split_generators(
        self, dl_manager: "datasets.builder.DownloadManager"
    ) -> List["datasets.SplitGenerator"]:
        """Return a list of SplitGenerators that organizes the splits."""
        # The file extracts into {train,dev,test}.spacy files. The _generate_examples function
        # below will define how these files are parsed.
        corpus_dir = "corpus/iob"
        data_files = {
            "train": os.path.join(corpus_dir, "train.iob"),
            "dev": os.path.join(corpus_dir, "dev.iob"),
            "test": os.path.join(corpus_dir, "test.iob"),
        }

        return [
            # fmt: off
            datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"filepath": data_files["train"]}),
            datasets.SplitGenerator(name=datasets.Split.VALIDATION, gen_kwargs={"filepath": data_files["dev"]}),
            datasets.SplitGenerator(name=datasets.Split.TEST, gen_kwargs={"filepath": data_files["test"]}),
            # fmt: on
        ]

    def _generate_examples(self, filepath: str):
        """Defines how examples are parsed from the IOB file."""
        logger.info("⏳ Generating examples from = %s", filepath)
        with open(filepath, encoding="utf-8") as f:
            guid = 0
            tokens = []
            ner_tags = []
            for line in f:
                if line.startswith("-DOCSTART-") or line == "" or line == "\n":
                    if tokens:
                        yield guid, {
                            "id": str(guid),
                            "tokens": tokens,
                            "ner_tags": ner_tags,
                        }
                        guid += 1
                        tokens = []
                        ner_tags = []
                else:
                    # TLUnified-NER iob are separated by \t
                    token, ner_tag = line.split("\t")
                    tokens.append(token)
                    ner_tags.append(ner_tag.rstrip())
            # Last example
            if tokens:
                yield guid, {
                    "id": str(guid),
                    "tokens": tokens,
                    "ner_tags": ner_tags,
                }