import gzip
import pandas as pd
from datasets import Dataset, DatasetInfo, GeneratorBasedBuilder, SplitGenerator, Split

class FeverDataset(GeneratorBasedBuilder):
    VERSION = "1.0.0"

    def _info(self):
        return DatasetInfo(
            description="FEVER Dataset with span annotations.",
            features=datasets.Features({
                "query": datasets.Value("string"),
                "document": datasets.Value("string"),
                "spans": datasets.Value("string"),
            }),
            supervised_keys=None,
            homepage="https://huggingface.co/datasets/jinaai/fever-span-annotated",
            license="CC BY 4.0"
        )

    def _split_generators(self, dl_manager):
        # Define dataset splits
        return [
            SplitGenerator(
                name=Split.TEST,
                gen_kwargs={
                    "file_paths": [
                        "data/fever-pairs_shard_000000.tsv.gz",
                        "data/fever-pairs_shard_000001.tsv.gz",
                        "data/fever-pairs_shard_000002.tsv.gz",
                        "data/fever-pairs_shard_000003.tsv.gz",
                        "data/fever-pairs_shard_000004.tsv.gz"
                    ]
                },
            ),
        ]

    def _generate_examples(self, file_path):
        # Open the compressed file
        with gzip.open(file_path, 'rt') as f:
            df = pd.read_csv(f, delimiter='\t')
            for idx, row in df.iterrows():
                yield idx, {
                    "query": row["query"],
                    "document": row["document"],
                    "spans": row["spans"],
                }