#!/usr/bin/env PYTHONHASHSEED=1234 python3

# Copyright 2014-2019 Brett Slatkin, Pearson Education Inc.
#
# 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.

# Reproduce book environment
import random
random.seed(1234)

import logging
from pprint import pprint
from sys import stdout as STDOUT

# Write all output to a temporary directory
import atexit
import gc
import io
import os
import tempfile

TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)

# Make sure Windows processes exit cleanly
OLD_CWD = os.getcwd()
atexit.register(lambda: os.chdir(OLD_CWD))
os.chdir(TEST_DIR.name)

def close_open_files():
 everything = gc.get_objects()
 for obj in everything:
 if isinstance(obj, io.IOBase):
 obj.close()

atexit.register(close_open_files)


# Example 1
class Meta(type):
 def __new__(meta, name, bases, class_dict):
 global print
 orig_print = print
 print(f'* Running {meta}.__new__ for {name}')
 print('Bases:', bases)
 print = pprint
 print(class_dict) 
 print = orig_print
 return type.__new__(meta, name, bases, class_dict)

class MyClass(metaclass=Meta):
 stuff = 123

 def foo(self):
 pass

class MySubclass(MyClass):
 other = 567

 def bar(self):
 pass


# Example 2
class ValidatePolygon(type):
 def __new__(meta, name, bases, class_dict):
 # Only validate subclasses of the Polygon class
 if bases:
 if class_dict['sides'] < 3:
 raise ValueError('Polygons need 3+ sides')
 return type.__new__(meta, name, bases, class_dict)

class Polygon(metaclass=ValidatePolygon):
 sides = None # Must be specified by subclasses

 @classmethod
 def interior_angles(cls):
 return (cls.sides - 2) * 180

class Triangle(Polygon):
 sides = 3

class Rectangle(Polygon):
 sides = 4

class Nonagon(Polygon):
 sides = 9

assert Triangle.interior_angles() == 180
assert Rectangle.interior_angles() == 360
assert Nonagon.interior_angles() == 1260


# Example 3
try:
 print('Before class')
 
 class Line(Polygon):
 print('Before sides')
 sides = 2
 print('After sides')
 
 print('After class')
except:
 logging.exception('Expected')
else:
 assert False


# Example 4
class BetterPolygon:
 sides = None # Must be specified by subclasses

 def __init_subclass__(cls):
 super().__init_subclass__()
 if cls.sides < 3:
 raise ValueError('Polygons need 3+ sides') 

 @classmethod
 def interior_angles(cls):
 return (cls.sides - 2) * 180

class Hexagon(BetterPolygon):
 sides = 6

assert Hexagon.interior_angles() == 720


# Example 5
try:
 print('Before class')
 
 class Point(BetterPolygon):
 sides = 1
 
 print('After class')
except:
 logging.exception('Expected')
else:
 assert False


# Example 6
class ValidateFilled(type):
 def __new__(meta, name, bases, class_dict):
 # Only validate subclasses of the Filled class
 if bases:
 if class_dict['color'] not in ('red', 'green'):
 raise ValueError('Fill color must be supported')
 return type.__new__(meta, name, bases, class_dict)

class Filled(metaclass=ValidateFilled):
 color = None # Must be specified by subclasses


# Example 7
try:
 class RedPentagon(Filled, Polygon):
 color = 'blue'
 sides = 5
except:
 logging.exception('Expected')
else:
 assert False


# Example 8
class ValidatePolygon(type):
 def __new__(meta, name, bases, class_dict):
 # Only validate non-root classes
 if not class_dict.get('is_root'):
 if class_dict['sides'] < 3:
 raise ValueError('Polygons need 3+ sides')
 return type.__new__(meta, name, bases, class_dict)

class Polygon(metaclass=ValidatePolygon):
 is_root = True
 sides = None # Must be specified by subclasses

class ValidateFilledPolygon(ValidatePolygon):
 def __new__(meta, name, bases, class_dict):
 # Only validate non-root classes
 if not class_dict.get('is_root'):
 if class_dict['color'] not in ('red', 'green'):
 raise ValueError('Fill color must be supported')
 return super().__new__(meta, name, bases, class_dict)

class FilledPolygon(Polygon, metaclass=ValidateFilledPolygon):
 is_root = True
 color = None # Must be specified by subclasses


# Example 9
class GreenPentagon(FilledPolygon):
 color = 'green'
 sides = 5

greenie = GreenPentagon()
assert isinstance(greenie, Polygon)


# Example 10
try:
 class OrangePentagon(FilledPolygon):
 color = 'orange'
 sides = 5
except:
 logging.exception('Expected')
else:
 assert False


# Example 11
try:
 class RedLine(FilledPolygon):
 color = 'red'
 sides = 2
except:
 logging.exception('Expected')
else:
 assert False


# Example 12
class Filled:
 color = None # Must be specified by subclasses

 def __init_subclass__(cls):
 super().__init_subclass__()
 if cls.color not in ('red', 'green', 'blue'):
 raise ValueError('Fills need a valid color') 


# Example 13
class RedTriangle(Filled, Polygon):
 color = 'red'
 sides = 3

ruddy = RedTriangle()
assert isinstance(ruddy, Filled)
assert isinstance(ruddy, Polygon)


# Example 14
try:
 print('Before class')
 
 class BlueLine(Filled, Polygon):
 color = 'blue'
 sides = 2
 
 print('After class')
except:
 logging.exception('Expected')
else:
 assert False


# Example 15
try:
 print('Before class')
 
 class BeigeSquare(Filled, Polygon):
 color = 'beige'
 sides = 4
 
 print('After class')
except:
 logging.exception('Expected')
else:
 assert False


# Example 16
class Top:
 def __init_subclass__(cls):
 super().__init_subclass__()
 print(f'Top for {cls}')

class Left(Top):
 def __init_subclass__(cls):
 super().__init_subclass__()
 print(f'Left for {cls}')

class Right(Top):
 def __init_subclass__(cls):
 super().__init_subclass__()
 print(f'Right for {cls}')

class Bottom(Left, Right):
 def __init_subclass__(cls):
 super().__init_subclass__()
 print(f'Bottom for {cls}')