#!/usr/bin/env python3
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301, USA.

"""Provides type checking for functions

>>> @type_check
... def has_punctuation(test_string : str, punctuation="?!.") -> bool:
...     for x in range(len(punctuation)):
...         if punctuation[x] in test_string:
...             return True
...     return False
>>> has_punctuation("The cow ran.")
True
>>> has_punctuation("Darn")
False
>>> has_punctuation(12)
Traceback (most recent call last):
...
TypeError: Argument 'test_string' expected type <class 'str'>: received type <class 'int'>
"""

__all__ = ['type_check']
__author__ = "Cody A. Taylor ( codemister99@yahoo.com )"
__version__ = "0.3 alpha"

import inspect, functools

def type_check(function):
    """Check types if a type is provided in the annotations

    Works for both arguments and return annotations
    Does not require that all arguments have an annotation
    """
    annotations = function.__annotations__
    arg_spec = inspect.getfullargspec(function)

    @functools.wraps(function)
    def wrapper(*args, **kwargs):
        for name, arg in list(zip(arg_spec.args, args)) + list(kwargs.items()):
            try:
                if not isinstance(arg, annotations[name]):
                    raise TypeError("Argument '{}' expected type {}: received type {}".format(name, annotations[name], type(arg)))
            except KeyError:
                pass #Ignore if a argument does not have an annotation

        result = function(*args, **kwargs)

        if "return" in annotations.keys() and not isinstance(result, annotations["return"]):
            raise TypeError("Retuen expected type {}: returned type {}".format(annotations["return"], type(result)))

        return result

    return wrapper

@type_check
def has_punctuation(test_string : str, punctuation="?!.") -> bool:
    """Example function for doctests

    Quick test if a character is in a string
    """
    for x in range(len(punctuation)):
        if punctuation[x] in test_string:
            return True
    return False

if __name__ == "__main__":
    import doctest
    doctest.testmod()