1import re
  2
  3
  4class Singleton(type):
  5    _instances = {}
  6
  7    def __call__(cls, *args, **kwargs):
  8        if cls not in cls._instances:
  9            cls._instances[cls] = super().__call__(*args, **kwargs)
 10        return cls._instances[cls]
 11    
 12
 13class Santa(metaclass=Singleton):
 14    _MAX_AGE = 5
 15
 16    def __init__(self):
 17        self._wishes = {}
 18
 19    def _get_wish(self, text):
 20        """Get the wish from the letter/call"""
 21        
 22        pattern = r'[\"\']([A-Za-z0-9 ]+)[\"\']'
 23        wish = re.search(pattern, text)
 24        if wish:
 25            return wish.group(1)
 26
 27    def __call__(self, kid, text):
 28        wish = self._get_wish(text)
 29        if wish:
 30           self._wishes[id(kid)] = wish  
 31                
 32    def _get_signature(self, text):
 33        """Get the signature of the kid from the letter"""
 34
 35        pattern = r'\b\d+\b(?=\s*$)'
 36        signature = re.search(pattern, text)
 37        if signature:
 38            return signature.group().strip()
 39    
 40    def __matmul__(self, text):
 41        signature = self._get_signature(text)
 42        wish = self._get_wish(text)
 43        if signature and wish:
 44           self._wishes[int(signature)] = wish  
 45
 46    def __iter__(self):
 47        for val in self._wishes.values():
 48            yield val
 49    
 50    @property
 51    def _get_most_wanted_gift(self):
 52        """Get the most wanted gift"""
 53
 54        wishes = list(self._wishes.values())
 55        return max(wishes, key=wishes.count)
 56    
 57    def _clear_xmas(self):
 58        """Clear the wishes and _naughty_kids"""
 59
 60        self._wishes.clear()
 61        Kid._naughty_kids.clear()
 62
 63    def xmas(self):
 64        Kid._increment_ages()
 65
 66        if not self._wishes:
 67            return
 68        
 69        most_wanted_gift = self._get_most_wanted_gift
 70        for identity, kid in Kid._kids_instances.items():
 71            if Kid._kids_ages[identity] <= self._MAX_AGE:
 72                if kid in Kid._naughty_kids:
 73                    kid('coal')
 74                else:
 75                    if identity in self._wishes:
 76                        wish = self._wishes[identity]
 77                    else:
 78                        wish = most_wanted_gift
 79                    kid(wish)
 80
 81        self._clear_xmas()
 82        
 83
 84class Kid(type):
 85    _kids_ages = {}
 86    _kids_instances = {}
 87    _naughty_kids = set()
 88    
 89    @classmethod
 90    def _check_naughty(cls, method):
 91        def wrapper(self, *args, **kwargs):
 92            """Add the instance to _naughty_kids if an exception is raised in method"""
 93
 94            try:
 95                return method(self, *args, **kwargs)
 96            except Exception:
 97                cls._naughty_kids.add(self)
 98                raise
 99        return wrapper
100
101    def __new__(cls, name, bases, dct):
102        if '__call__' not in dct:
103            raise NotImplementedError('Sorry, but the instance of the class should be callable (dont get angry, please) :)')
104        
105        for attribute_name, attribute_val in dct.items():
106            if callable(attribute_val):
107                if not attribute_name.startswith('_'):
108                    dct[attribute_name] = cls._check_naughty(attribute_val)
109
110        return super().__new__(cls, name, bases, dct)
111    
112    def __call__(cls, *args, **kwargs):      
113        new_kid = super().__call__(*args, **kwargs)
114        identity = id(new_kid)
115        cls._kids_ages[identity] = 0
116        cls._kids_instances[identity] = new_kid
117        return new_kid
118        
119    @classmethod
120    def _increment_ages(cls):
121        """Increment the age of each kid by one year"""
122
123        for identity, age in cls._kids_ages.items():
124            cls._kids_ages[identity] += 1