import hashlib
from pathlib import Path

LOG_DIR = Path("./instance/log")

class StreamNumber:
    def __init__(self, file_path):
        self.path = Path(file_path)
        if not self.path.exists():
            raise FileNotFoundError(self.path)
        self.hash = hashlib.sha1(str(self.path).encode()).hexdigest()[:10]

    def __repr__(self):
        return f"<StreamNumber {self.path.name}>"

    def stream(self, chunk_size=4096):
        """Yield chunks of digits as strings."""
        with open(self.path, "r", encoding="utf-8") as f:
            while chunk := f.read(chunk_size):
                yield chunk.strip().replace(",", ".")

    def write_stage(self, stage, data: str):
        """Write intermediate stage result."""
        stage_file = LOG_DIR / f"{self.hash}_stage_{stage}.bin"
        with open(stage_file, "wb") as f:
            f.write(data.encode())
        return stage_file