import csv
import json
from datasets import load_dataset_builder, DatasetInfo, DownloadConfig, GeneratorBasedBuilder, datasets

class CustomSQuADFormatDataset(GeneratorBasedBuilder):
    """A custom dataset similar to SQuAD but tailored for 'ArabicaQA' hosted on Hugging Face."""

    VERSION = datasets.Version("1.0.0")
    BUILDER_CONFIGS = [
        datasets.BuilderConfig(
            name="ArabicaQA",
            version=VERSION,
            description="Custom dataset similar to SQuAD format, including CSV data."
        )
    ]

    def _info(self):
        return DatasetInfo(
            description="This dataset is formatted similarly to the SQuAD dataset.",
            features=datasets.Features(
                {
                    "id": datasets.Value("string"),
                    "title": datasets.Value("string"),
                    "context": datasets.Value("string"),
                    "question": datasets.Value("string"),
                    "answers": datasets.features.Sequence(
                        {
                            "text": datasets.Value("string"),
                            "answer_start": datasets.Value("int32"),
                        }
                    ),
                    # Additional fields from the CSV can be added here if needed
                }
            ),
            supervised_keys=None,
            homepage="https://huggingface.co/datasets/abdoelsayed/ArabicaQA",
            citation="",
        )

    def _split_generators(self, dl_manager: DownloadConfig):
        urls_to_download = {
            "train": "https://huggingface.co/datasets/abdoelsayed/ArabicaQA/raw/main/MRC/train.json",
            "dev": "https://huggingface.co/datasets/abdoelsayed/ArabicaQA/raw/main/MRC/val.json",
            "test": "https://huggingface.co/datasets/abdoelsayed/ArabicaQA/raw/main/MRC/test.json",
            "csv": "https://huggingface.co/datasets/abdoelsayed/ArabicaQA/raw/main/MRC/all_data_meta.csv"
        }
        downloaded_files = dl_manager.download(urls_to_download)

        return [
            datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"json_filepath": downloaded_files["train"], "csv_filepath": downloaded_files["csv"]}),
            datasets.SplitGenerator(name=datasets.Split.VALIDATION, gen_kwargs={"json_filepath": downloaded_files["dev"], "csv_filepath": downloaded_files["csv"]}),
            datasets.SplitGenerator(name=datasets.Split.TEST, gen_kwargs={"json_filepath": downloaded_files["test"], "csv_filepath": downloaded_files["csv"]}),
        ]

    def _generate_examples(self, json_filepath, csv_filepath):
        # Read the CSV file and store it in memory
        csv_data = {}
        with open(csv_filepath, encoding="utf-8") as csv_file:
            csv_reader = csv.DictReader(csv_file)
            for row in csv_reader:
                csv_data[row['question_id']] = row

        # Read the JSON file and yield examples
        with open(json_filepath, encoding="utf-8") as f:
            squad_data = json.load(f)["data"]
            for article in squad_data:
                title = article.get("title", "")
                for paragraph in article["paragraphs"]:
                    context = paragraph["context"]
                    for qa in paragraph["qas"]:
                        id_ = qa["id"]
                        question = qa["question"]
                        answers = [{"text": answer["text"], "answer_start": answer["answer_start"]} for answer in qa.get("answers", [])]

                        # Combine data from the CSV if present
                        additional_csv_data = csv_data.get(id_, {})
                        # Include additional fields from the CSV in the example if necessary
                        example = {
                            "title": title,
                            "context": context,
                            "question": question,
                            "answers": answers,
                            # Add additional fields from the CSV here
                        }
                        yield id_, example