import yaml
from collections.abc import Mapping
from dataclasses import asdict


class SaveFileObject():
    def asdict(self):
        return asdict(self)

    def update(self, new):
        if new is None:
            new=dict()
        for key, value in new.items():
            if hasattr(self, key):
                setattr(self, key, value)


class SaveFileMapping(Mapping):
    __file =None
    def __init__(self, file=None):
        self.data=dict()
        self.__file=file 
        
 
    def asdict(self):
        return {k: self[k].asdict() for k in self}

    def from_dict(self,d):
        pass

    def to_file(self,fn=None):
        if fn is None: fn=self.__file
        with open(fn,'w') as f:
            f.write(yaml.dump(self.asdict()))
    
    def from_file(self,fn=None):
        if fn is None: fn = self.__file
        try:
            with open(fn,'r') as f:
                d=yaml.load(f,Loader=yaml.Loader)
        except FileNotFoundError as e:
            with open(fn,'w') as f:
                f.write("")
                d={}
        self.from_dict(d)

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

    def __setitem__(self,key,data):
        if not isinstance(data,SaveFileObject):
            raise TypeError("data elements should be derived from SaveFileObject")
        if not callable(getattr(data,"asdict",None)):
            raise TypeError("Dataelements need a method asdict that returns a dict this should be out of the box if you use dataclasses")
    
        self.data[key]= data
        return self.data[key]

    def __iter__(self):
        return iter(self.data)
    def __len__(self):
        return len(self.data)