# Copyright (c) 2016 Cable Television Laboratories, Inc. ("CableLabs")
#                    and others.  All rights reserved.
#
# 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.
import os
import urllib2
import logging

import yaml

__author__ = 'spisarski'

"""
Utilities for basic file handling
"""

logger = logging.getLogger('file_utils')


def file_exists(file_path):
    """
    Returns True if the image file already exists and throws an exception if the path is a directory
    :return:
    """
    if os.path.exists(file_path):
        if os.path.isdir(file_path):
            return False
        return os.path.isfile(file_path)
    return False


def get_file(file_path):
    """
    Returns True if the image file has already been downloaded
    :return: the image file object
    :raise Exception when file cannot be found
    """
    if file_exists(file_path):
        return open(file_path, 'r')
    else:
        raise Exception('File with path cannot be found - ' + file_path)


def download(url, dest_path):
    """
    Download a file to a destination path given a URL
    :rtype : File object
    """
    name = url.rsplit('/')[-1]
    dest = dest_path + '/' + name
    try:
        # Override proxy settings to use localhost to download file
        proxy_handler = urllib2.ProxyHandler({})
        opener = urllib2.build_opener(proxy_handler)
        urllib2.install_opener(opener)
        response = urllib2.urlopen(url)
    except (urllib2.HTTPError, urllib2.URLError):
        raise Exception

    with open(dest, 'wb') as f:
        f.write(response.read())
    return f


def read_yaml(config_file_path):
    """
    Reads the yaml file and returns a dictionary object representation
    :param config_file_path: The file path to config
    :return: a dictionary
    """
    logger.debug('Attempting to load configuration file - ' + config_file_path)
    with open(config_file_path) as config_file:
        config = yaml.safe_load(config_file)
        logger.info('Loaded configuration')
    config_file.close()
    logger.info('Closing configuration file')
    return config


def read_os_env_file(os_env_filename):
    """
    Reads the OS environment source file and returns a map of each key/value
    Will ignore lines beginning with a '#' and will replace any single or double quotes contained within the value
    :param os_env_filename: The name of the OS environment file to read
    :return: a dictionary
    """
    if os_env_filename:
        logger.info('Attempting to read OS environment file - ' + os_env_filename)
        out = {}
        for line in open(os_env_filename):
            line = line.lstrip()
            if not line.startswith('#') and line.startswith('export '):
                line = line.lstrip('export ').strip()
                tokens = line.split('=')
                if len(tokens) > 1:
                    # Remove leading and trailing ' & " characters from value
                    out[tokens[0]] = tokens[1].lstrip('\'').lstrip('\"').rstrip('\'').rstrip('\"')
        return out