#!/usr/bin/env python
from dataclasses import dataclass

def validate_positive(name, value):
    '''eine einfache Validierungsfunktion'''
    if value < 0:
        raise ValueError(
            f'The value for {name!r} must be positive, {value!r} is not.')

    
class YearBetweenValidator:
    '''komplexerer Validator, beachte die magische Methode __call__'''
    def __init__(self, mini, maxi):
        self.mini, self.maxi = mini, maxi

    def __call__(self, name, value):
        if value > self.mini and value < self.maxi:
            return True
        raise ValueError(f'The value for {name!r} must be between {self.mini!r} and {self.maxi!r}, {value!r} is not.')

    
class YearDesc:
    '''ein Deskriptor'''
    def __init__(self, type, validators=[]):
        self.type = type
        self.validators = validators
        
    def __set_name__(self, owner, name):
        self.name = name
    
    def __get__(self, obj, objtype=None):
        return getattr(self, self.name)

    def __set__(self, obj, value):
        if not isinstance(value, self.type):
            raise TypeError(f'The value for {self.name!r} must be a {self.type!r}, {value!r} is not.')
        for validate in self.validators:
            validate(self.name, value)
        setattr(self, self.name, value)


@dataclass #(frozen=True)
class Person:
    vorname: str
    nachname: str
    
@dataclass #(frozen=True)
class Student(Person):
    matriculation: int = YearDesc(int, [validate_positive])

@dataclass #(frozen=True)
class Graduate(Student):
    graduation: int = YearDesc(int, [validate_positive, YearBetweenValidator(1990, 2020)])


if __name__ == '__main__':
    try:
        print(Person('Sheeva', 'Plug'))
    except Exception as e:
        print(str(e))

    try:
        print(Student('Sheeva', 'Plug', 1991))
    except Exception as e:
        print(str(e))

    try:
        print(Graduate('Sheeva', 'Plug', 1991, 1995))
    except Exception as e:
        print(str(e))
    
    try:
        print(Graduate('Sheeva', 'Plug', 1991, '1995'))
    except Exception as e:
        print(str(e))

    try:
        print(Graduate('Sheeva', 'Plug', 1991, -1995))
    except Exception as e:
        print(str(e))

    try:
        print(Graduate('Sheeva', 'Plug', 1989, 1989))
    except Exception as e:
        print(str(e))