#     Copyright 2016, Kay Hayen, mailto:kay.hayen@gmail.com
#
#     Python tests originally created or extracted from other peoples work. The
#     parts were too small to be protected.
#
#     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.
#
from __future__ import print_function

import sys

x = 0

# This is used to trace the exact interaction with the context manager to
# uncover and decide ordering and correctness of calls.
class MyContextManager(object):
    def __getattribute__(self, attribute_name):
        print("Asking context manager attribute", attribute_name)
        return object.__getattribute__(self, attribute_name)

    def __enter__(self):
        global x
        x += 1

        print("Entered context manager with counter value", x)

        return x

    def __exit__(self, exc_type, exc_value, traceback):
        print("Context manager exit sees", exc_type, exc_value, traceback)
        print("Published to context manager exit is", sys.exc_info())

        return False

print("Use context manager and raise no exception in the body:")
with MyContextManager() as x:
    print("x has become", x)

print("Use context manager and raise an exception in the body:")
try:
    with MyContextManager() as x:
        print("x has become", x)

        raise Exception("Lalala")
        print(x)
except Exception as e:
    print("Caught raised exception", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

# Python3 ranges are not lists
l = list(range(3))

print("Use context manager and assign to subscription target:")
with MyContextManager() as l[0]:
    print("Complex assignment target works", l[0])

try:
    with MyContextManager():
        sys.exit(9)
except BaseException as e:
    print("Caught base exception", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

print("Use context manager and fail to assign to attribute:")
try:
    with MyContextManager() as l.wontwork:
        sys.exit(9)
except BaseException as e:
    print("Caught base exception", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

print("Use context manager to do nothing inside:")
with MyContextManager() as x:
    pass

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

# Use context manager and fail to assign.
def returnFromContextBlock():
    # Use context manager to do nothing.
    with MyContextManager() as x:
        return 7

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

print("Use context manager to return value:")
r = returnFromContextBlock()
print("Return value", r)

class NonContextManager1:
    def __enter__(self):
        return self

class NonContextManager2:
    def __exit__(self):
        return self

print("Use incomplete context managers:")
try:
    with NonContextManager1() as x:
        print(x)
except Exception as e:
    print("Caught for context manager without __exit__", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

try:
    with NonContextManager2() as x:
        print(x)
except Exception as e:
    print("Caught for context manager without __enter__", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

class NotAtAllContextManager:
    pass

try:
    with NotAtAllContextManager() as x:
        print(x)
except Exception as e:
    print("Caught for context manager without any special methods", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)


class MeanContextManager:
    def __enter__(self):
        raise ValueError("Nah, I won't play")

    def __exit__(self):
        print("Called exit, yes")

print("Use mean context manager:")

try:
    with MeanContextManager() as x:
        print(x)
except Exception as e:
    print("Caught from mean manager", repr(e))

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)

class CatchingContextManager(object):

    def __enter__(self):
        pass

    def __exit__(self, exc_type, exc_value, traceback):
        return True

print("Suppressing exception from context manager body:")
with CatchingContextManager():
    raise ZeroDivisionError

if sys.version_info >= (3,):
    assert sys.exc_info() == (None, None, None)
print("OK")
