1import re
  2
  3
  4class Elf:
  5    """A proxy to a kid, helping Santa with various tasks."""
  6
  7    MAX_YEARS = 5
  8    COAL = 'coal'
  9
 10    def __init__(self, kid):
 11        """Initiate based on a Kid instance."""
 12        self._kid = kid
 13        self._counter = 0
 14        self._naughty = False
 15        self._decorate_naughty_monitor()
 16
 17    def _decorate_naughty_monitor(self):
 18        """Decorate all public methods with naughty monitors."""
 19        for key in dir(self._kid):
 20            val = getattr(self._kid, key)
 21            if not key.startswith('_') and callable(val):
 22                setattr(self._kid, key, self._monitor_naughty(val))
 23
 24    def _monitor_naughty(self, fun):
 25        """Decorate a kid public method to monitor for Exceptions."""
 26        def decorated(*args, **kwargs):
 27            """Decorated version of the public method."""
 28            try:
 29                result = fun(*args, **kwargs)
 30            except Exception:
 31                self._naughty = True
 32                raise
 33            return result
 34        return decorated
 35
 36    def __call__(self, present):
 37        """Send a present to the kid."""
 38        if present is not None:  # Otherwise there is no xmas so no coals
 39            present = self.COAL if self._naughty else present
 40        self._counter += 1
 41        self._naughty = False
 42        if present is not None and self._counter <= self.MAX_YEARS:
 43            self._kid(present)
 44
 45
 46class Santa:
 47    """Santa Claus."""
 48
 49    PRESENT_REGEX = re.compile(r'["\'](?P<present>[a-zA-Z0-9 ]+)["\']')
 50    SIGATURE_REGEX = re.compile(r'^\s*(?P<signature>\d+)\s*$', re.MULTILINE)
 51    _wishes = {}
 52    _elves = {}
 53
 54    @classmethod
 55    def _present_from_text(cls, message):
 56        """Extract the wish from a message."""
 57        return cls.PRESENT_REGEX.search(message)['present']
 58
 59    @classmethod
 60    def _signature_from_text(cls, message):
 61        """Extract the signature from a message."""
 62        return cls.SIGATURE_REGEX.search(message)['signature']
 63
 64    def __new__(cls):
 65        """Create as singleton."""
 66        if not hasattr(cls, '_instance'):
 67            cls._instance = super().__new__(cls)
 68        return cls._instance
 69
 70    def __call__(self, kid, message):
 71        """Receive a wish via calling."""
 72        elf = self._elves[id(kid)]
 73        self._wishes[elf] = self._present_from_text(message)
 74
 75    def __matmul__(self, message):
 76        """Receive a wish via email."""
 77        kid_id = int(self._signature_from_text(message))
 78        elf = self._elves[kid_id]
 79        self._wishes[elf] = self._present_from_text(message)
 80
 81    def __iter__(self):
 82        """Make the class iterable."""
 83        return iter(self._wishes.values())
 84
 85    @property
 86    def _most_wanted(self):
 87        """Get most wanted present."""
 88        if not self._wishes:
 89            return None
 90        presents = list(self._wishes.values())
 91        return max(presents, key=presents.count)
 92
 93    def register_kid(self, kid):
 94        """Register a new kid."""
 95        self._elves[id(kid)] = Elf(kid)
 96
 97    def xmas(self):
 98        """Celebrate Christmas and give presents away."""
 99        for elf in self._elves.values():
100            present = self._wishes.get(elf, self._most_wanted)
101            elf(present)
102        self._wishes = {}
103
104
105class Kid(type):
106
107    def __new__(cls, name, bases, dct):
108        """Creating a new class."""
109        if '__call__' not in dct:
110            raise NotImplementedError('А как ще получиш подарък?')
111        return super().__new__(cls, name, bases, dct)
112
113    def __call__(cls, *args, **kwargs):
114        """Creating new instance of a class."""
115        instance = super().__call__(*args, **kwargs)
116        Santa().register_kid(instance)
117        return instance