# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF 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.
from __future__ import with_statement

"""
A class which handles loading the pricing files.
"""

import os.path
from os.path import join as pjoin

try:
    import simplejson as json
    JSONDecodeError = json.JSONDecodeError
except ImportError:
    import json
    JSONDecodeError = ValueError

from libcloud.utils.connection import get_response_object

__all__ = [
    'get_pricing',
    'get_size_price',
    'set_pricing',
    'clear_pricing_data',
    'download_pricing_file'
]

# Default URL to the pricing file
DEFAULT_FILE_URL = 'https://git-wip-us.apache.org/repos/asf?p=libcloud.git;a=blob_plain;f=libcloud/data/pricing.json'  # NOQA

CURRENT_DIRECTORY = os.path.dirname(os.path.abspath(__file__))
DEFAULT_PRICING_FILE_PATH = pjoin(CURRENT_DIRECTORY, 'data/pricing.json')
CUSTOM_PRICING_FILE_PATH = os.path.expanduser('~/.libcloud/pricing.json')

# Pricing data cache
PRICING_DATA = {
    'compute': {},
    'storage': {}
}

VALID_PRICING_DRIVER_TYPES = ['compute', 'storage']


def get_pricing_file_path(file_path=None):
    if os.path.exists(CUSTOM_PRICING_FILE_PATH) and \
       os.path.isfile(CUSTOM_PRICING_FILE_PATH):
        # Custom pricing file is available, use it
        return CUSTOM_PRICING_FILE_PATH

    return DEFAULT_PRICING_FILE_PATH


def get_pricing(driver_type, driver_name, pricing_file_path=None):
    """
    Return pricing for the provided driver.

    :type driver_type: ``str``
    :param driver_type: Driver type ('compute' or 'storage')

    :type driver_name: ``str``
    :param driver_name: Driver name

    :type pricing_file_path: ``str``
    :param pricing_file_path: Custom path to a price file. If not provided
                              it uses a default path.

    :rtype: ``dict``
    :return: Dictionary with pricing where a key name is size ID and
             the value is a price.
    """
    if driver_type not in VALID_PRICING_DRIVER_TYPES:
        raise AttributeError('Invalid driver type: %s', driver_type)

    if driver_name in PRICING_DATA[driver_type]:
        return PRICING_DATA[driver_type][driver_name]

    if not pricing_file_path:
        pricing_file_path = get_pricing_file_path(file_path=pricing_file_path)

    with open(pricing_file_path) as fp:
        content = fp.read()

    pricing_data = json.loads(content)
    size_pricing = pricing_data[driver_type][driver_name]

    for driver_type in VALID_PRICING_DRIVER_TYPES:
        # pylint: disable=maybe-no-member
        pricing = pricing_data.get(driver_type, None)
        if pricing:
            PRICING_DATA[driver_type] = pricing

    return size_pricing


def set_pricing(driver_type, driver_name, pricing):
    """
    Populate the driver pricing dictionary.

    :type driver_type: ``str``
    :param driver_type: Driver type ('compute' or 'storage')

    :type driver_name: ``str``
    :param driver_name: Driver name

    :type pricing: ``dict``
    :param pricing: Dictionary where a key is a size ID and a value is a price.
    """

    PRICING_DATA[driver_type][driver_name] = pricing


def get_size_price(driver_type, driver_name, size_id):
    """
    Return price for the provided size.

    :type driver_type: ``str``
    :param driver_type: Driver type ('compute' or 'storage')

    :type driver_name: ``str``
    :param driver_name: Driver name

    :type size_id: ``str`` or ``int``
    :param size_id: Unique size ID (can be an integer or a string - depends on
                    the driver)

    :rtype: ``float``
    :return: Size price.
    """
    pricing = get_pricing(driver_type=driver_type, driver_name=driver_name)
    price = float(pricing[size_id])
    return price


def invalidate_pricing_cache():
    """
    Invalidate pricing cache for all the drivers.
    """
    PRICING_DATA['compute'] = {}
    PRICING_DATA['storage'] = {}


def clear_pricing_data():
    """
    Invalidate pricing cache for all the drivers.

    Note: This method does the same thing as invalidate_pricing_cache and is
    here for backward compatibility reasons.
    """
    invalidate_pricing_cache()


def invalidate_module_pricing_cache(driver_type, driver_name):
    """
    Invalidate the cache for the specified driver.

    :type driver_type: ``str``
    :param driver_type: Driver type ('compute' or 'storage')

    :type driver_name: ``str``
    :param driver_name: Driver name
    """
    if driver_name in PRICING_DATA[driver_type]:
        del PRICING_DATA[driver_type][driver_name]


def download_pricing_file(file_url=DEFAULT_FILE_URL,
                          file_path=CUSTOM_PRICING_FILE_PATH):
    """
    Download pricing file from the file_url and save it to file_path.

    :type file_url: ``str``
    :param file_url: URL pointing to the pricing file.

    :type file_path: ``str``
    :param file_path: Path where a download pricing file will be saved.
    """
    dir_name = os.path.dirname(file_path)

    if not os.path.exists(dir_name):
        # Verify a valid path is provided
        msg = ('Can\'t write to %s, directory %s, doesn\'t exist' %
               (file_path, dir_name))
        raise ValueError(msg)

    if os.path.exists(file_path) and os.path.isdir(file_path):
        msg = ('Can\'t write to %s file path because it\'s a'
               ' directory' % (file_path))
        raise ValueError(msg)

    response = get_response_object(file_url)
    body = response.body

    # Verify pricing file is valid
    try:
        data = json.loads(body)
    except JSONDecodeError:
        msg = 'Provided URL doesn\'t contain valid pricing data'
        raise Exception(msg)

    # pylint: disable=maybe-no-member
    if not data.get('updated', None):
        msg = 'Provided URL doesn\'t contain valid pricing data'
        raise Exception(msg)

    # No need to stream it since file is small
    with open(file_path, 'w') as file_handle:
        file_handle.write(body)
