#!/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
import itertools


# Example 2
it = itertools.chain([1, 2, 3], [4, 5, 6])
print(list(it))


# Example 3
it = itertools.repeat('hello', 3)
print(list(it))


# Example 4
it = itertools.cycle([1, 2])
result = [next(it) for _ in range (10)]
print(result)


# Example 5
it1, it2, it3 = itertools.tee(['first', 'second'], 3)
print(list(it1))
print(list(it2))
print(list(it3))


# Example 6
keys = ['one', 'two', 'three']
values = [1, 2]

normal = list(zip(keys, values))
print('zip:        ', normal)

it = itertools.zip_longest(keys, values, fillvalue='nope')
longest = list(it)
print('zip_longest:', longest)


# Example 7
values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

first_five = itertools.islice(values, 5)
print('First five: ', list(first_five))

middle_odds = itertools.islice(values, 2, 8, 2)
print('Middle odds:', list(middle_odds))


# Example 8
values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
less_than_seven = lambda x: x < 7
it = itertools.takewhile(less_than_seven, values)
print(list(it))


# Example 9
values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
less_than_seven = lambda x: x < 7
it = itertools.dropwhile(less_than_seven, values)
print(list(it))


# Example 10
values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
evens = lambda x: x % 2 == 0

filter_result = filter(evens, values)
print('Filter:      ', list(filter_result))

filter_false_result = itertools.filterfalse(evens, values)
print('Filter false:', list(filter_false_result))


# Example 11
values = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
sum_reduce = itertools.accumulate(values)
print('Sum:   ', list(sum_reduce))

def sum_modulo_20(first, second):
    output = first + second
    return output % 20

modulo_reduce = itertools.accumulate(values, sum_modulo_20)
print('Modulo:', list(modulo_reduce))


# Example 12
single = itertools.product([1, 2], repeat=2)
print('Single:  ', list(single))

multiple = itertools.product([1, 2], ['a', 'b'])
print('Multiple:', list(multiple))


# Example 13
it = itertools.permutations([1, 2, 3, 4], 2)
original_print = print
print = pprint
print(list(it))
print = original_print


# Example 14
it = itertools.combinations([1, 2, 3, 4], 2)
print(list(it))


# Example 15
it = itertools.combinations_with_replacement([1, 2, 3, 4], 2)
original_print = print
print = pprint
print(list(it))
print = original_print