import json
import datasets

class YelpDataset(datasets.GeneratorBasedBuilder):
    """Yelp Dataset focusing on restaurant reviews."""
    
    VERSION = datasets.Version("1.1.0")
    
    BUILDER_CONFIGS = [
        datasets.BuilderConfig(name="restaurants", version=VERSION, description="This part of my dataset covers a wide range of restaurants"),
    ]

    DEFAULT_CONFIG_NAME = "restaurants"
    
    _URL = "https://yelpdata.s3.us-west-2.amazonaws.com/"
    _URLS = {
        "business": _URL + "yelp_academic_dataset_business.json",
        "review": _URL + "yelp_academic_dataset_review.json",
    }

    def _info(self):
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "business_id": datasets.Value("string"),
                    "name": datasets.Value("string"),
                    "categories": datasets.Value("string"),
                    "review_id": datasets.Value("string"),
                    "user_id": datasets.Value("string"),
                    "stars": datasets.Value("float"),
                    "text": datasets.Value("string"),
                    "date": datasets.Value("string"),
                }
            ),
            supervised_keys=None,
            homepage="https://www.yelp.com/dataset/download",
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager: datasets.DownloadManager):
        """Returns SplitGenerators."""
        downloaded_files = dl_manager.download_and_extract(self._URLS)
        
        return [
            datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"business_path": downloaded_files["business"], "review_path": downloaded_files["review"], "split": "train"}),
            datasets.SplitGenerator(name=datasets.Split.TEST, gen_kwargs={"business_path": downloaded_files["business"], "review_path": downloaded_files["review"], "split": "test"}),
        ]

    def _generate_examples(self, business_path, review_path, split):
        """Yields examples as (key, example) tuples."""
        
        # Load businesses and filter for restaurants
        with open(business_path, encoding="utf-8") as f:
            businesses = {}
            for line in f:
                business = json.loads(line)
                if business.get("categories") and "Restaurants" in business["categories"]:
                    businesses[business['business_id']] = business
        
        # Generate examples
        with open(review_path, encoding="utf-8") as f:
            for line in f:
                review = json.loads(line)
                business_id = review['business_id']
                if business_id in businesses:
                    yield review['review_id'], {
                        "business_id": business_id,
                        "name": businesses[business_id]['name'],
                        "categories": businesses[business_id]['categories'],
                        "review_id": review['review_id'],
                        "user_id": review['user_id'],
                        "stars": review['stars'],
                        "text": review['text'],
                        "date": review['date'],
                    }