import os
import datasets

_DESCRIPTION = """\
UTS_WTK
"""

_CITATION = """\
"""

_BASE_URL = "https://huggingface.co/datasets/undertheseanlp/UTS_WTK/raw/main/data/"
TRAIN_FILE = "train.txt"
DEV_FILE = "dev.txt"
TEST_FILE = "test.txt"


class UTSWTK(datasets.GeneratorBasedBuilder):
    def _info(self):
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "id": datasets.Value("string"),
                    "tokens": datasets.Sequence(datasets.Value("string")),
                    "tags": datasets.Sequence(
                        datasets.features.ClassLabel(names=["B-W", "I-W"])
                    ),
                }
            ),
            supervised_keys=None,
            homepage=None,
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager):
        """Returns SplitGenerators."""
        train_file = dl_manager.download(os.path.join(_BASE_URL, TRAIN_FILE))
        dev_file = dl_manager.download(os.path.join(_BASE_URL, DEV_FILE))
        test_file = dl_manager.download(os.path.join(_BASE_URL, TEST_FILE))

        splits = [
            datasets.SplitGenerator(
                name=datasets.Split.TRAIN,
                gen_kwargs={"filepath": train_file}
            ),
            datasets.SplitGenerator(
                name=datasets.Split.VALIDATION,
                gen_kwargs={"filepath": dev_file},
            ),
            datasets.SplitGenerator(
                name=datasets.Split.TEST,
                gen_kwargs={"filepath": test_file}
            ),
        ]
        return splits

    def _generate_examples(self, filepath):
        with open(filepath, encoding="utf-8") as f:
            guid = 0
            tokens = []
            tags = []
            for line in f:
                if line == "" or line == "\n":
                    if tokens:
                        yield guid, {
                            "id": str(guid),
                            "tokens": tokens,
                            "tags": tags,
                        }
                        guid += 1
                        tokens = []
                        tags = []
                else:
                    # each line is tab separated
                    splits = line.strip().split("\t")
                    tokens.append(splits[0])
                    tags.append(splits[1])