# Copyright 2016 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.
import copy

from botocore.compat import OrderedDict
from botocore.endpoint import DEFAULT_TIMEOUT, MAX_POOL_CONNECTIONS
from botocore.exceptions import (
    InvalidMaxRetryAttemptsError,
    InvalidRetryConfigurationError,
    InvalidRetryModeError,
    InvalidS3AddressingStyleError,
)


class Config:
    """Advanced configuration for Botocore clients.

    :type region_name: str
    :param region_name: The region to use in instantiating the client

    :type signature_version: str
    :param signature_version: The signature version when signing requests.

    :type user_agent: str
    :param user_agent: The value to use in the User-Agent header.

    :type user_agent_extra: str
    :param user_agent_extra: The value to append to the current User-Agent
        header value.

    :type user_agent_appid: str
    :param user_agent_appid: A value that gets included in the User-Agent
        string in the format "app/<user_agent_appid>". Allowed characters are
        ASCII alphanumerics and ``!#$%&'*+-.^_`|~``. All other characters will
        be replaced by a ``-``.

    :type connect_timeout: float or int
    :param connect_timeout: The time in seconds till a timeout exception is
        thrown when attempting to make a connection. The default is 60
        seconds.

    :type read_timeout: float or int
    :param read_timeout: The time in seconds till a timeout exception is
        thrown when attempting to read from a connection. The default is
        60 seconds.

    :type parameter_validation: bool
    :param parameter_validation: Whether parameter validation should occur
        when serializing requests. The default is True.  You can disable
        parameter validation for performance reasons.  Otherwise, it's
        recommended to leave parameter validation enabled.

    :type max_pool_connections: int
    :param max_pool_connections: The maximum number of connections to
        keep in a connection pool.  If this value is not set, the default
        value of 10 is used.

    :type proxies: dict
    :param proxies: A dictionary of proxy servers to use by protocol or
        endpoint, e.g.:
        {'http': 'foo.bar:3128', 'http://hostname': 'foo.bar:4012'}.
        The proxies are used on each request.

    :type proxies_config: dict
    :param proxies_config: A dictionary of additional proxy configurations.
        Valid keys are:

        * 'proxy_ca_bundle' -- The path to a custom certificate bundle to use
          when establishing SSL/TLS connections with proxy.

        * 'proxy_client_cert' -- The path to a certificate for proxy
          TLS client authentication.

          When a str is provided it is treated as a path to a proxy client
          certificate. When a two element tuple is provided, it will be
          interpreted as the path to the client certificate, and the path
          to the certificate key.

        * 'proxy_use_forwarding_for_https' -- For HTTPS proxies,
          forward your requests to HTTPS destinations with an absolute
          URI. We strongly recommend you only use this option with
          trusted or corporate proxies. Value must be boolean.

    :type s3: dict
    :param s3: A dictionary of s3 specific configurations.
        Valid keys are:

        * 'use_accelerate_endpoint' -- Refers to whether to use the S3
          Accelerate endpoint. The value must be a boolean. If True, the
          client will use the S3 Accelerate endpoint. If the S3 Accelerate
          endpoint is being used then the addressing style will always
          be virtual.

        * 'payload_signing_enabled' -- Refers to whether or not to SHA256
          sign sigv4 payloads. By default, this is disabled for streaming
          uploads (UploadPart and PutObject).

        * 'addressing_style' -- Refers to the style in which to address
          s3 endpoints. Values must be a string that equals:

          * auto -- Addressing style is chosen for user. Depending
            on the configuration of client, the endpoint may be addressed in
            the virtual or the path style. Note that this is the default
            behavior if no style is specified.

          * virtual -- Addressing style is always virtual. The name of the
            bucket must be DNS compatible or an exception will be thrown.
            Endpoints will be addressed as such: mybucket.s3.amazonaws.com

          * path -- Addressing style is always by path. Endpoints will be
            addressed as such: s3.amazonaws.com/mybucket

        * ``disable_s3_express_session_auth`` -- Refers to whether to use S3
          Express session authentication. The value must be a boolean. If True, the
          client will NOT use S3 Express session authentication.

    :type retries: dict
    :param retries: A dictionary for retry specific configurations.
        Valid keys are:

        * 'max_attempts' -- An integer representing the maximum number of total
        attempts that will be made on a single API call, including the initial
        attempt. For example, setting this value to 3 will result in the
        request being retried at most two times after the initial request.
        Setting this value to 1 will result in no retries ever being attempted
        on the initial request. If not provided, the number of retries will
        default to whatever is modeled, which is typically four retries.
        * 'mode' -- A string representing the type of retry mode botocore
          should use.  Valid values are:
              * ``standard`` - The standardized set of retry rules.  This
                will also default to 3 max attempts unless overridden.
              * ``adaptive`` - Retries with additional client side throttling.

    :type client_cert: str, (str, str)
    :param client_cert: The path to a certificate for TLS client authentication.

        When a str is provided it is treated as a path to a client certificate
        to be used when creating a TLS connection.

        If a client key is to be provided alongside the client certificate the
        client_cert should be set to a tuple of length two where the first
        element is the path to the client certificate and the second element is
        the path to the certificate key.

    :type inject_host_prefix: bool
    :param inject_host_prefix: Whether host prefix injection should occur.

        Defaults to None.

        The default of None is equivalent to setting to True, which enables
        the injection of operation parameters into the prefix of the hostname.
        Setting this to False disables the injection of operation parameters
        into the prefix of the hostname. Setting this to False is useful for
        clients providing custom endpoints that should not have their host
        prefix modified.

    :type use_dualstack_endpoint: bool
    :param use_dualstack_endpoint: Setting to True enables dualstack
        endpoint resolution.

        Defaults to None.

    :type use_fips_endpoint: bool
    :param use_fips_endpoint: Setting to True enables fips
        endpoint resolution.

        Defaults to None.

    :type ignore_configured_endpoint_urls: bool
    :param ignore_configured_endpoint_urls: Setting to True disables use
        of endpoint URLs provided via environment variables and
        the shared configuration file.

        Defaults to None.

    :type request_min_compression_size_bytes: int
    :param request_min_compression_bytes: The minimum size in bytes that a
    request body should be to trigger compression. All requests with streaming
    input that don't contain the `requiresLength` trait will be compressed
    regardless of this setting.

        Defaults to None.

    :type disable_request_compression: bool
    :param disable_request_compression: Disables request body compression if
    set to True.

        Defaults to None.

    :type client_context_params: dict
    :param client_context_params: A dictionary of parameters specific to
        individual services. If available, valid parameters can be found in
        the ``Client Context Parameters`` section of the service client's
        documentation. Invalid parameters or ones that are not used by the
        specified service will be ignored.

        Defaults to None.

    :type sigv4a_signing_region_set: string
    :param sigv4a_signing_region_set: A set of AWS regions to apply the signature for
        when using SigV4a for signing. Set to ``*`` to represent all regions.
        Defaults to None.

    :type request_checksum_calculation: str
    :param request_checksum_calculation: Determines when a checksum will be
        calculated for request payloads. Valid values are:

        * ``when_supported`` -- When set, a checksum will be calculated for
          all request payloads of operations modeled with the ``httpChecksum``
          trait where ``requestChecksumRequired`` is ``true`` or a
          ``requestAlgorithmMember`` is modeled.

        * ``when_required`` -- When set, a checksum will only be calculated
          for request payloads of operations modeled with the ``httpChecksum``
          trait where ``requestChecksumRequired`` is ``true`` or where a
          ``requestAlgorithmMember`` is modeled and supplied.

        Defaults to None.

    :type response_checksum_validation: str
    :param response_checksum_validation: Determines when checksum validation
        will be performed on response payloads. Valid values are:

        * ``when_supported`` -- When set, checksum validation is performed on
          all response payloads of operations modeled with the ``httpChecksum``
          trait where ``responseAlgorithms`` is modeled, except when no modeled
          checksum algorithms are supported.

        * ``when_required`` -- When set, checksum validation is not performed
          on response payloads of operations unless the checksum algorithm is
          supported and the ``requestValidationModeMember`` member is set to ``ENABLED``.

        Defaults to None.

    :type account_id_endpoint_mode: str
    :param account_id_endpoint_mode: The value used to determine the client's
        behavior for account ID based endpoint routing. Valid values are:

        * ``preferred`` - The endpoint should include account ID if available.
        * ``disabled`` - A resolved endpoint does not include account ID.
        * ``required`` - The endpoint must include account ID. If the account ID
          isn't available, an exception will be raised.

        If a value is not provided, the client will default to ``preferred``.

        Defaults to None.

    :type auth_scheme_preference: str
    :param auth_scheme_preference: A comma-delimited string of case-sensitive
        auth scheme names used to determine the client's auth scheme preference.

        Defaults to None.
    """

    OPTION_DEFAULTS = OrderedDict(
        [
            ('region_name', None),
            ('signature_version', None),
            ('user_agent', None),
            ('user_agent_extra', None),
            ('user_agent_appid', None),
            ('connect_timeout', DEFAULT_TIMEOUT),
            ('read_timeout', DEFAULT_TIMEOUT),
            ('parameter_validation', True),
            ('max_pool_connections', MAX_POOL_CONNECTIONS),
            ('proxies', None),
            ('proxies_config', None),
            ('s3', None),
            ('s3_disable_express_session_auth', None),
            ('retries', None),
            ('client_cert', None),
            ('inject_host_prefix', None),
            ('endpoint_discovery_enabled', None),
            ('use_dualstack_endpoint', None),
            ('use_fips_endpoint', None),
            ('ignore_configured_endpoint_urls', None),
            ('request_min_compression_size_bytes', None),
            ('disable_request_compression', None),
            ('client_context_params', None),
            ('sigv4a_signing_region_set', None),
            ('request_checksum_calculation', None),
            ('response_checksum_validation', None),
            ('account_id_endpoint_mode', None),
            ('auth_scheme_preference', None),
        ]
    )

    # The original default value of the inject_host_prefix parameter was True.
    # This prevented the ability to override the value from other locations in
    # the parameter provider chain, like env vars or the shared configuration
    # file. TO accomplish this, we need to disambiguate when the value was set
    # by the user or not. This overrides the parameter with a property so the
    # default value of inject_host_prefix is still True if it is not set by the
    # user.
    @property
    def inject_host_prefix(self):
        if self._inject_host_prefix == "UNSET":
            return True

        return self._inject_host_prefix

    # Override the setter for the case where the user does supply a value;
    # _inject_host_prefix will no longer be "UNSET".
    @inject_host_prefix.setter
    def inject_host_prefix(self, value):
        self._inject_host_prefix = value

    def __init__(self, *args, **kwargs):
        self._user_provided_options = self._record_user_provided_options(
            args, kwargs
        )

        # By default, we use a value that indicates the user did not
        # set it. This value MUST persist on the Config object to be used
        # elsewhere.
        self._inject_host_prefix = 'UNSET'

        # Merge the user_provided options onto the default options
        config_vars = copy.copy(self.OPTION_DEFAULTS)
        config_vars.update(self._user_provided_options)

        # Set the attributes based on the config_vars
        for key, value in config_vars.items():
            # Default values for the Config object are set here. We don't want
            # to use `setattr` in the case where the user already supplied a
            # value.
            if (
                key == 'inject_host_prefix'
                and 'inject_host_prefix'
                not in self._user_provided_options.keys()
            ):
                continue
            setattr(self, key, value)

        # Validate the s3 options
        self._validate_s3_configuration(self.s3)

        self._validate_retry_configuration(self.retries)

    def _record_user_provided_options(self, args, kwargs):
        option_order = list(self.OPTION_DEFAULTS)
        user_provided_options = {}

        # Iterate through the kwargs passed through to the constructor and
        # map valid keys to the dictionary
        for key, value in kwargs.items():
            if key in self.OPTION_DEFAULTS:
                user_provided_options[key] = value
            # The key must exist in the available options
            else:
                raise TypeError(f'Got unexpected keyword argument \'{key}\'')

        # The number of args should not be longer than the allowed
        # options
        if len(args) > len(option_order):
            raise TypeError(
                f'Takes at most {len(option_order)} arguments ({len(args)} given)'
            )

        # Iterate through the args passed through to the constructor and map
        # them to appropriate keys.
        for i, arg in enumerate(args):
            # If it a kwarg was specified for the arg, then error out
            if option_order[i] in user_provided_options:
                raise TypeError(
                    f'Got multiple values for keyword argument \'{option_order[i]}\''
                )
            user_provided_options[option_order[i]] = arg

        return user_provided_options

    def _validate_s3_configuration(self, s3):
        if s3 is not None:
            addressing_style = s3.get('addressing_style')
            if addressing_style not in ['virtual', 'auto', 'path', None]:
                raise InvalidS3AddressingStyleError(
                    s3_addressing_style=addressing_style
                )

    def _validate_retry_configuration(self, retries):
        if retries is not None:
            for key, value in retries.items():
                if key not in ['max_attempts', 'mode']:
                    raise InvalidRetryConfigurationError(
                        retry_config_option=key
                    )
                if key == 'max_attempts' and value < 1:
                    raise InvalidMaxRetryAttemptsError(
                        provided_max_attempts=value
                    )
                if key == 'mode' and value not in ['standard', 'adaptive']:
                    raise InvalidRetryModeError(provided_retry_mode=value)

    def merge(self, other_config):
        """Merges the config object with another config object

        This will merge in all non-default values from the provided config
        and return a new config object

        :type other_config: botocore.config.Config
        :param other config: Another config object to merge with. The values
            in the provided config object will take precedence in the merging

        :returns: A config object built from the merged values of both
            config objects.
        """
        # Make a copy of the current attributes in the config object.
        config_options = copy.copy(self._user_provided_options)

        # Merge in the user provided options from the other config
        config_options.update(other_config._user_provided_options)

        # Return a new config object with the merged properties.
        return Config(**config_options)
