# Copyright 2013 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.
"""
Utility functions to make it easier to work with customizations.

"""
import copy

from botocore.exceptions import ClientError


def rename_argument(argument_table, existing_name, new_name):
    current = argument_table[existing_name]
    argument_table[new_name] = current
    current.name = new_name
    del argument_table[existing_name]


def _copy_argument(argument_table, current_name, copy_name):
    current = argument_table[current_name]
    copy_arg = copy.copy(current)
    copy_arg.name = copy_name
    argument_table[copy_name] = copy_arg
    return copy_arg


def make_hidden_alias(argument_table, existing_name, alias_name):
    """Create a hidden alias for an existing argument.

    This will copy an existing argument object in an arg table,
    and add a new entry to the arg table with a different name.
    The new argument will also be undocumented.

    This is needed if you want to check an existing argument,
    but you still need the other one to work for backwards
    compatibility reasons.

    """
    current = argument_table[existing_name]
    copy_arg = _copy_argument(argument_table, existing_name, alias_name)
    copy_arg._UNDOCUMENTED = True
    if current.required:
        # If the current argument is required, then
        # we'll mark both as not required, but
        # flag _DOCUMENT_AS_REQUIRED so our doc gen
        # knows to still document this argument as required.
        copy_arg.required = False
        current.required = False
        current._DOCUMENT_AS_REQUIRED = True


def rename_command(command_table, existing_name, new_name):
    current = command_table[existing_name]
    command_table[new_name] = current
    current.name = new_name
    del command_table[existing_name]


def alias_command(command_table, existing_name, new_name):
    """Moves an argument to a new name, keeping the old as a hidden alias."""
    current = command_table[existing_name]
    _copy_argument(command_table, existing_name, new_name)
    current._UNDOCUMENTED = True


def validate_mutually_exclusive_handler(*groups):
    def _handler(parsed_args, **kwargs):
        return validate_mutually_exclusive(parsed_args, *groups)
    return _handler


def validate_mutually_exclusive(parsed_args, *groups):
    """Validate mututally exclusive groups in the parsed args."""
    args_dict = vars(parsed_args)
    all_args = set(arg for group in groups for arg in group)
    if not any(k in all_args for k in args_dict if args_dict[k] is not None):
        # If none of the specified args are in a mutually exclusive group
        # there is nothing left to validate.
        return
    current_group = None
    for key in [k for k in args_dict if args_dict[k] is not None]:
        key_group = _get_group_for_key(key, groups)
        if key_group is None:
            # If they key is not part of a mutex group, we can move on.
            continue
        if current_group is None:
            current_group = key_group
        elif not key_group == current_group:
            raise ValueError('The key "%s" cannot be specified when one '
                             'of the following keys are also specified: '
                             '%s' % (key, ', '.join(current_group)))


def _get_group_for_key(key, groups):
    for group in groups:
        if key in group:
            return group


def s3_bucket_exists(s3_client, bucket_name):
    bucket_exists = True
    try:
        # See if the bucket exists by running a head bucket
        s3_client.head_bucket(Bucket=bucket_name)
    except ClientError as e:
        # If a client error is thrown. Check that it was a 404 error.
        # If it was a 404 error, than the bucket does not exist.
        error_code = int(e.response['Error']['Code'])
        if error_code == 404:
            bucket_exists = False
    return bucket_exists


def create_client_from_parsed_globals(session, service_name, parsed_globals,
                                      overrides=None):
    """Creates a service client, taking parsed_globals into account

    Any values specified in overrides will override the returned dict. Note
    that this override occurs after 'region' from parsed_globals has been
    translated into 'region_name' in the resulting dict.
    """
    client_args = {}
    if 'region' in parsed_globals:
        client_args['region_name'] = parsed_globals.region
    if 'endpoint_url' in parsed_globals:
        client_args['endpoint_url'] = parsed_globals.endpoint_url
    if 'verify_ssl' in parsed_globals:
        client_args['verify'] = parsed_globals.verify_ssl
    if overrides:
        client_args.update(overrides)
    return session.create_client(service_name, **client_args)
