class Bit(object):
    """
    Represents a single Bit.
    """
    def __init__(self, number, is_set=True):
        self.number = number
        self.is_set = bool(is_set)
        self.mask = 2 ** int(number)
        if not self.is_set:
            self.mask = ~self.mask

    def __repr__(self):
        return '<%s: number=%d, is_set=%s>' % (self.__class__.__name__, self.number, self.is_set)

    # def __str__(self):
    #     if self.is_set:
    #         return 'Yes'
    #     return 'No'

    def __int__(self):
        return self.mask

    def __nonzero__(self):
        return self.is_set

    def __eq__(self, value):
        if isinstance(value, Bit):
            return value.number == self.number and value.is_set == self.is_set
        elif isinstance(value, bool):
            return value == self.is_set
        elif isinstance(value, int):
            return value == self.mask
        return value == self.is_set

    def __ne__(self, value):
        return not self == value

    def __coerce__(self, value):
        return (self.is_set, bool(value))

    def __invert__(self):
        return self.__class__(self.number, not self.is_set)

    def __and__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return value & self.mask

    def __rand__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return self.mask & value

    def __or__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return value | self.mask

    def __ror__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return self.mask | value

    def __lshift__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return value << self.mask

    def __rlshift__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return self.mask << value

    def __rshift__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return value >> self.mask

    def __rrshift__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return self.mask >> value

    def __xor__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return value ^ self.mask

    def __rxor__(self, value):
        if isinstance(value, Bit):
            value = value.mask
        return self.mask ^ value

    def __sentry__(self):
        return repr(self)

    def prepare(self, evaluator, query, allow_joins):
        return self

    def evaluate(self, evaluator, qn, connection):
        return self.mask, []


class BitHandler(object):
    """
    Represents an array of bits, each as a ``Bit`` object.
    """
    def __init__(self, value, keys):
        # TODO: change to bitarray?
        if value:
            self._value = int(value)
        else:
            self._value = 0
        self._keys = keys

    def __eq__(self, other):
        if not isinstance(other, BitHandler):
            return False
        return self._value == other._value

    def __repr__(self):
        return '<%s: %s>' % (self.__class__.__name__, ', '.join('%s=%s' % (k, self.get_bit(n).is_set) for n, k in enumerate(self._keys)),)

    def __str__(self):
        return str(self._value)

    def __int__(self):
        return self._value

    def __nonzero__(self):
        return bool(self._value)

    def __and__(self, value):
        return BitHandler(self._value & int(value), self._keys)

    def __or__(self, value):
        return BitHandler(self._value | int(value), self._keys)

    def __add__(self, value):
        return BitHandler(self._value + int(value), self._keys)

    def __sub__(self, value):
        return BitHandler(self._value - int(value), self._keys)

    def __lshift__(self, value):
        return BitHandler(self._value << int(value), self._keys)

    def __rshift__(self, value):
        return BitHandler(self._value >> int(value), self._keys)

    def __xor__(self, value):
        return BitHandler(self._value ^ int(value), self._keys)

    def __contains__(self, key):
        bit_number = self._keys.index(key)
        return bool(self.get_bit(bit_number))

    def __getattr__(self, key):
        if key.startswith('_'):
            return object.__getattribute__(self, key)
        if key not in self._keys:
            raise AttributeError('%s is not a valid flag' % key)
        return self.get_bit(self._keys.index(key))

    def __setattr__(self, key, value):
        if key.startswith('_'):
            return object.__setattr__(self, key, value)
        if key not in self._keys:
            raise AttributeError('%s is not a valid flag' % key)
        self.set_bit(self._keys.index(key), value)

    def __iter__(self):
        return self.iteritems()

    def __sentry__(self):
        return repr(self)

    def _get_mask(self):
        return self._value
    mask = property(_get_mask)

    def prepare(self, evaluator, query, allow_joins):
        return self

    def evaluate(self, evaluator, qn, connection):
        return self.mask, []

    def get_bit(self, bit_number):
        mask = 2 ** int(bit_number)
        return Bit(bit_number, self._value & mask != 0)

    def set_bit(self, bit_number, true_or_false):
        mask = 2 ** int(bit_number)
        if true_or_false:
            self._value |= mask
        else:
            self._value &= (~mask)
        return Bit(bit_number, self._value & mask != 0)

    def keys(self):
        return self._keys

    def iterkeys(self):
        return iter(self._keys)

    def items(self):
        return list(self.iteritems())

    def iteritems(self):
        for k in self._keys:
            yield (k, getattr(self, k).is_set)