import csv
import json
import os
import datasets

_DESCRIPTION = "FIQA Dataset"
_SPLITS = ["corpus", "topics", "qrel"]

_URLs = {
    "corpus": "corpus_pt.tsv",
    "topics": "topics_pt.tsv",
    "qrel": "qrels.tsv",
}

class BEIR(datasets.GeneratorBasedBuilder):
    """BEIR BenchmarkDataset."""

    BUILDER_CONFIGS = [
        datasets.BuilderConfig(
            name=name,
            description=f"This is the {name} in the FiQA dataset.",
        ) for name in _SPLITS
    ]

    def _info(self):

        if self.config.name in ["corpus", "topics"]:
            features = datasets.Features(
                {
                    "id": datasets.Value("string"),
                    "text": datasets.Value("string")
                }
            )
        else:
            features = datasets.Features(
                {
                    "query_id": datasets.Value("string"),
                    "doc_id": datasets.Value("string"),
                    "rel": datasets.Value("string")
                }
            )
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=features
        )

    def _split_generators(self, dl_manager):
        """Returns SplitGenerators."""

        my_urls = _URLs[self.config.name]
        data_dir = dl_manager.download_and_extract(my_urls)

        return [
            datasets.SplitGenerator(
                name=self.config.name,
                # These kwargs will be passed to _generate_examples
                gen_kwargs={"filepath": data_dir},
            ),
        ]

    # method parameters are unpacked from `gen_kwargs` as given in `_split_generators`
    def _generate_examples(self, filepath):
        with open(filepath, encoding="utf-8") as f:
            if self.config.name in ["corpus", "topics"]:
                for line in f:
                    fields = line.strip().split("\t")
                    idx = fields[0]
                    text = fields[1]
                    yield idx, text
            else:
                for line in f:
                    if "query-id" not in line:
                        fields = line.strip().split("\t")
                        query_id = fields[0]
                        doc_id = fields[1]
                        rel = int(fields[2])
                        yield query_id, doc_id, rel