# Copyright 2015 Amazon.com, Inc. or its affiliates. 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. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file 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 botocore.compat import six

from ebcli.lib import utils
from ebcli.operations import envvarops


class EnvvarCollector(object):
    """
    Immutable class for grouping environment variables to add and remove.
    """

    def __init__(self, envvars_map=None, envvars_to_remove=None):
        """
        Constructor for EnvvarCollector
        :param envvars_map: dict: contains envvars to add
        :param envvars_to_remove: set: keys of environment variables to remove
        """

        self.map = envvars_map or {}
        self.to_remove = envvars_to_remove or set()

    @classmethod
    def from_list(cls, envvars_list):
        if not envvars_list:
            return cls()
        envvars_map, envvars_to_remove = envvarops.create_environment_variables_list(
            envvars_list, as_option_settings=False)
        return cls(envvars_map, envvars_to_remove)

    @classmethod
    def from_str(cls, envvars_str):
        if not envvars_str:
            return cls()
        envvars = envvars_str.split(',')
        envvars_map, envvars_to_remove = envvarops.create_environment_variables_list(
            envvars, as_option_settings=False)
        return cls(envvars_map, envvars_to_remove)

    def filtered(self):
        """
        Return new Envvarcollector with all environment variables in self.map that
        are not in to_remove
        :return EnvvarCollector
        """

        filtered_envvars = {k: v for k, v in six.iteritems(self.map) if k not in
                            self.to_remove}
        return EnvvarCollector(filtered_envvars)

    def merge(self, higher_priority_env):
        """
        Merge self with higher_priority_env.
        :param higher_priority_env: EnvvarCollector: environment to merge with
        :return EnvvarCollector
        """

        envvars_map = utils.merge_dicts(low_priority=self.map,
                                        high_priority=higher_priority_env.map)
        to_remove = self.to_remove | higher_priority_env.to_remove

        return EnvvarCollector(envvars_map, to_remove)