# -*- coding: utf-8 -*-
# This file is a part of DDT (https://github.com/txels/ddt)
# Copyright 2012-2015 Carles Barrobés and DDT contributors
# For the exact contribution history, see the git revision log.
# DDT is licensed under the MIT License, included in
# https://github.com/txels/ddt/blob/master/LICENSE.md

import inspect
import json
import os
import re
import sys
from functools import wraps

__version__ = '1.0.0'

# These attributes will not conflict with any real python attribute
# They are added to the decorated test method and processed later
# by the `ddt` class decorator.

DATA_ATTR = '%values'      # store the data the test must run with
FILE_ATTR = '%file_path'   # store the path to JSON file
UNPACK_ATTR = '%unpack'    # remember that we have to unpack values


def unpack(func):
    """
    Method decorator to add unpack feature.

    """
    setattr(func, UNPACK_ATTR, True)
    return func


def data(*values):
    """
    Method decorator to add to your test methods.

    Should be added to methods of instances of ``unittest.TestCase``.

    """
    def wrapper(func):
        setattr(func, DATA_ATTR, values)
        return func
    return wrapper


def file_data(value):
    """
    Method decorator to add to your test methods.

    Should be added to methods of instances of ``unittest.TestCase``.

    ``value`` should be a path relative to the directory of the file
    containing the decorated ``unittest.TestCase``. The file
    should contain JSON encoded data, that can either be a list or a
    dict.

    In case of a list, each value in the list will correspond to one
    test case, and the value will be concatenated to the test method
    name.

    In case of a dict, keys will be used as suffixes to the name of the
    test case, and values will be fed as test data.

    """
    def wrapper(func):
        setattr(func, FILE_ATTR, value)
        return func
    return wrapper


def is_hash_randomized():
    return (((sys.hexversion >= 0x02070300 and
              sys.hexversion < 0x03000000) or
             (sys.hexversion >= 0x03020300)) and
            sys.flags.hash_randomization and
            'PYTHONHASHSEED' not in os.environ)


def mk_test_name(name, value, index=0):
    """
    Generate a new name for a test case.

    It will take the original test name and append an ordinal index and a
    string representation of the value, and convert the result into a valid
    python identifier by replacing extraneous characters with ``_``.

    If hash randomization is enabled (a feature available since 2.7.3/3.2.3
    and enabled by default since 3.3) and a "non-trivial" value is passed
    this will omit the name argument by default. Set `PYTHONHASHSEED`
    to a fixed value before running tests in these cases to get the
    names back consistently or use the `__name__` attribute on data values.

    A "trivial" value is a plain scalar, or a tuple or list consisting
    only of trivial values.

    """

    # We avoid doing str(value) if all of the following hold:
    #
    # * Python version is 2.7.3 or newer (for 2 series) or 3.2.3 or
    #   newer (for 3 series). Also sys.flags.hash_randomization didn't
    #   exist before these.
    # * sys.flags.hash_randomization is set to True
    # * PYTHONHASHSEED is **not** defined in the environment
    # * Given `value` argument is not a trivial scalar (None, str,
    #   int, float).
    #
    # Trivial scalar values are passed as is in all cases.

    trivial_types = (type(None), bool, str, int, float)
    try:
        trivial_types += (unicode,)
    except NameError:
        pass

    def is_trivial(value):
        if isinstance(value, trivial_types):
            return True

        if isinstance(value, (list, tuple)):
            return all(map(is_trivial, value))

        return False

    if is_hash_randomized() and not is_trivial(value):
        return "{0}_{1}".format(name, index + 1)

    try:
        value = str(value)
    except UnicodeEncodeError:
        # fallback for python2
        value = value.encode('ascii', 'backslashreplace')
    test_name = "{0}_{1}_{2}".format(name, index + 1, value)
    return re.sub('\W|^(?=\d)', '_', test_name)


def feed_data(func, new_name, *args, **kwargs):
    """
    This internal method decorator feeds the test data item to the test.

    """
    @wraps(func)
    def wrapper(self):
        return func(self, *args, **kwargs)
    wrapper.__name__ = new_name
    return wrapper


def add_test(cls, test_name, func, *args, **kwargs):
    """
    Add a test case to this class.

    The test will be based on an existing function but will give it a new
    name.

    """
    setattr(cls, test_name, feed_data(func, test_name, *args, **kwargs))


def process_file_data(cls, name, func, file_attr):
    """
    Process the parameter in the `file_data` decorator.

    """
    cls_path = os.path.abspath(inspect.getsourcefile(cls))
    data_file_path = os.path.join(os.path.dirname(cls_path), file_attr)

    def _raise_ve(*args):  # pylint: disable-msg=W0613
        raise ValueError("%s does not exist" % file_attr)

    if os.path.exists(data_file_path) is False:
        test_name = mk_test_name(name, "error")
        add_test(cls, test_name, _raise_ve, None)
    else:
        data = json.loads(open(data_file_path).read())
        for i, elem in enumerate(data):
            if isinstance(data, dict):
                key, value = elem, data[elem]
                test_name = mk_test_name(name, key, i)
            elif isinstance(data, list):
                value = elem
                test_name = mk_test_name(name, value, i)
            add_test(cls, test_name, func, value)


def ddt(cls):
    """
    Class decorator for subclasses of ``unittest.TestCase``.

    Apply this decorator to the test case class, and then
    decorate test methods with ``@data``.

    For each method decorated with ``@data``, this will effectively create as
    many methods as data items are passed as parameters to ``@data``.

    The names of the test methods follow the pattern
    ``original_test_name_{ordinal}_{data}``. ``ordinal`` is the position of the
    data argument, starting with 1.

    For data we use a string representation of the data value converted into a
    valid python identifier.  If ``data.__name__`` exists, we use that instead.

    For each method decorated with ``@file_data('test_data.json')``, the
    decorator will try to load the test_data.json file located relative
    to the python file containing the method that is decorated. It will,
    for each ``test_name`` key create as many methods in the list of values
    from the ``data`` key.

    """
    for name, func in list(cls.__dict__.items()):
        if hasattr(func, DATA_ATTR):
            for i, v in enumerate(getattr(func, DATA_ATTR)):
                test_name = mk_test_name(name, getattr(v, "__name__", v), i)
                if hasattr(func, UNPACK_ATTR):
                    if isinstance(v, tuple) or isinstance(v, list):
                        add_test(cls, test_name, func, *v)
                    else:
                        # unpack dictionary
                        add_test(cls, test_name, func, **v)
                else:
                    add_test(cls, test_name, func, v)
            delattr(cls, name)
        elif hasattr(func, FILE_ATTR):
            file_attr = getattr(func, FILE_ATTR)
            process_file_data(cls, name, func, file_attr)
            delattr(cls, name)
    return cls
