text: # Copyright 2019 The TensorTrade Authors.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License
  
  
  import operator
  
  from abc import abstractmethod, ABCMeta
  from typing import Callable
  
  
  CriteriaType = Callable[['Order', 'Exchange'], bool]
  
  
  class Criteria(object, metaclass=ABCMeta):
      """A criteria to be satisfied before an order will be executed."""
  
      @abstractmethod
      def check(self, order: 'Order', exchange: 'Exchange') -> bool:
          raise NotImplementedError
  
      def __call__(self, order: 'Order', exchange: 'Exchange') -> bool:
          if not exchange.is_pair_tradable(order.pair):
              return False
          return self.check(order, exchange)
  
      def __and__(self, other: CriteriaType) -> 'Criteria':
          return AndCriteria(self, other)
  
      def __or__(self, other: CriteriaType) -> 'Criteria':
          return OrCriteria(self, other)
  
      def __xor__(self, other: CriteriaType) -> 'Criteria':
          return XorCriteria(self, other)
  
      def __invert__(self):
          return NotCriteria(self)
  
      def __repr__(self):
          return str(self)
  
  
  class CriteriaBinOp(Criteria):
  
      def __init__(self,
                   left: CriteriaType,
                   right: CriteriaType,
                   op: Callable[[bool, bool], bool],
                   op_str: str):
          self.left = left
          self.right = right
          self.op = op
          self.op_str = op_str
  
      def check(self, order: 'Order', exchange: 'Exchange') -> bool:
          left = self.left(order, exchange)
          right = self.right(order, exchange)
  
          return self.op(left, right)
  
      def __str__(self):
          is_left_op = isinstance(self.left, CriteriaBinOp)
          is_right_op = isinstance(self.right, CriteriaBinOp)
  
          if is_left_op and is_right_op:
              return "({}) {} ({})".format(self.left, self.op_str, self.right)
          elif is_left_op and not is_right_op:
              return "({}) {} {}".format(self.left, self.op_str, self.right)
          elif not is_left_op and is_right_op:
              return "{} {} ({})".format(self.left, self.op_str, self.right)
  
          return "{} {} {}".format(self.left, self.op_str, self.right)
  
  
  class AndCriteria(CriteriaBinOp):
  
      def __init__(self, left: CriteriaType, right: CriteriaType):
          super().__init__(left, right, operator.and_, "&")
  
  
  class OrCriteria(CriteriaBinOp):
  
      def __init__(self, left: CriteriaType, right: CriteriaType):
          super().__init__(left, right, operator.or_, "|")
  
  
  class XorCriteria(CriteriaBinOp):
  
      def __init__(self, left: CriteriaType, right: CriteriaType):
          super().__init__(left, right, operator.xor, "^")
  
  
  class NotCriteria(Criteria):
  
      def __init__(self, criteria: CriteriaType):
          self.criteria = criteria
  
      def check(self, order: 'Order', exchange: 'Exchange') -> bool:
          return not self.criteria(order, exchange)
  
      def __str__(self):
          if isinstance(self.criteria, CriteriaBinOp):
              return "~({})".format(self.criteria)
          return "~{}".format(self.criteria)
  