import json
import os
import random


def load_data_dir(d_path: str, max_size: int = 1_000_000, seed: int = 1) -> list:
    records = []
    for root, _dirs, files in os.walk(d_path):  # walks all levels
        if len(records) >= max_size:
            break
        for fn in files:
            if fn.endswith('.ndjson'):
                path = os.path.join(root, fn)
                with open(path, 'r', encoding='utf-8') as f:
                    for line in f:
                        line = line.strip()
                        if not line:
                            continue
                        try:
                            records.append(json.loads(line))
                        except json.JSONDecodeError as e:
                            raise ValueError(f"Invalid JSON in {path}: {e}") from e
    shuffler = random.Random(seed)
    shuffler.shuffle(records)
    return records[:max_size]