# Licensed to the Software Freedom Conservancy (SFC) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The SFC licenses this file
# to you 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.

import abc
import os
from selenium.webdriver.common.utils import keys_to_typing


class FileDetector(object):
    """
    Used for identifying whether a sequence of chars represents the path to a
    file.
    """
    __metaclass__ = abc.ABCMeta

    @abc.abstractmethod
    def is_local_file(self, *keys):
        return


class UselessFileDetector(FileDetector):
    """
    A file detector that never finds anything.
    """
    def is_local_file(self, *keys):
        return None


class LocalFileDetector(FileDetector):
    """
    Detects files on the local disk.
    """
    def is_local_file(self, *keys):
        file_path = ''.join(keys_to_typing(keys))

        if not file_path:
            return None

        try:
            if os.path.isfile(file_path):
                return file_path
        except:
            pass
        return None