import pickle
from .abc import IOStream, IStream, OStream


class Database:
    def __init__(self, fn) -> None:
        self.fn = fn
        try:
            with open(fn, "rb+") as stream_out:
                self.data = pickle.load(stream_out)
        except:
            self.data = {}

    def write(self, key, entry):
        self.data[key] = entry

    def update(self):
        with open(self.fn, "rb+") as stream_out:
            self.data = pickle.load(stream_out)

    def get(self, key, default=None):
        return self.data.get(key, default)

    def commit(self):
        with open(self.fn, "wb+") as stream_in:
            pickle.dump(self.data, stream_in)

    @classmethod
    def connect(cls, fname):
        return cls(fname)