import six
import sys
import json

from os.path import exists
from importlib import import_module


def import_string(dotted_path):
    """
    Import a dotted module path and return the attribute/class designated by the
    last name in the path. Raise ImportError if the import failed.
    :param dotted_path: a string containing the dotted path of the object to be imported
    :type dotted_path: str
    :return: python object of desired type
    """
    try:
        module_path, class_name = dotted_path.rsplit('.', 1)
    except ValueError:
        msg = "%s doesn't look like a module path" % dotted_path
        six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])

    module = import_module(module_path)

    try:
        return getattr(module, class_name)
    except AttributeError:
        msg = 'Module "%s" does not define a "%s" attribute/class' % (
            module_path, class_name)
        six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])


def json_file_to_dict(json_file):
    if not exists(json_file):
        raise FileNotFoundError('The JSON file {} cannot be read'.format(json_file))

    with open(json_file) as json_file:
        dictionary = json.load(json_file)

    return dictionary