# json 文件实现

import json

from storage.base_storage import BaseStorage


class JSONStorage(BaseStorage):
    def __init__(self, filename="data.json"):
        self.filename = filename
        # 如果文件不存在，先创建空字典
        try:
            with open(self.filename, "r") as f:
                pass
        except OSError:
            with open(self.filename, "w") as f:
                f.write("{}")

    def _read_all(self):
        with open(self.filename, "r") as f:
            return json.load(f)

    def _write_all(self, data):
        with open(self.filename, "w") as f:
            json.dump(data, f)

    def save(self, key, value):
        data = self._read_all()
        data[key] = value
        self._write_all(data)

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

    def delete(self, key):
        data = self._read_all()
        if key in data:
            del data[key]
            self._write_all(data)