# Copyright 2014 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.
"""Protocol input serializes.

This module contains classes that implement input serialization
for the various AWS protocol types.

These classes essentially take user input, a model object that
represents what the expected input should look like, and it returns
a dictionary that contains the various parts of a request.  A few
high level design decisions:


* Each protocol type maps to a separate class, all inherit from
  ``Serializer``.
* The return value for ``serialize_to_request`` (the main entry
  point) returns a dictionary that represents a request.  This
  will have keys like ``url_path``, ``query_string``, etc.  This
  is done so that it's a) easy to test and b) not tied to a
  particular HTTP library.  See the ``serialize_to_request`` docstring
  for more details.

Unicode
-------

The input to the serializers should be text (str/unicode), not bytes,
with the exception of blob types.  Those are assumed to be binary,
and if a str/unicode type is passed in, it will be encoded as utf-8.
"""

import base64
import calendar
import datetime
import decimal
import json
import math
import re
import struct
from xml.etree import ElementTree

from botocore import validate
from botocore.compat import formatdate
from botocore.exceptions import ParamValidationError
from botocore.useragent import register_feature_id
from botocore.utils import (
    has_header,
    is_json_value_header,
    parse_to_aware_datetime,
    percent_encode,
)

# From the spec, the default timestamp format if not specified is iso8601.
DEFAULT_TIMESTAMP_FORMAT = 'iso8601'
ISO8601 = '%Y-%m-%dT%H:%M:%SZ'
# Same as ISO8601, but with microsecond precision.
ISO8601_MICRO = '%Y-%m-%dT%H:%M:%S.%fZ'
HOST_PREFIX_RE = re.compile(r"^[A-Za-z0-9\.\-]+$")

TIMESTAMP_PRECISION_DEFAULT = 'default'
TIMESTAMP_PRECISION_MILLISECOND = 'millisecond'
TIMESTAMP_PRECISION_OPTIONS = (
    TIMESTAMP_PRECISION_DEFAULT,
    TIMESTAMP_PRECISION_MILLISECOND,
)


def create_serializer(
    protocol_name,
    include_validation=True,
    timestamp_precision=TIMESTAMP_PRECISION_DEFAULT,
):
    """Create a serializer for the given protocol.
    :param protocol_name: The protocol name to create a serializer for.
    :type protocol_name: str
    :param include_validation: Whether to include parameter validation.
    :type include_validation: bool
    :param timestamp_precision: Timestamp precision level.
        - 'default': Microseconds for ISO timestamps, seconds for Unix and RFC
        - 'millisecond': Millisecond precision (ISO/Unix), seconds for RFC
    :type timestamp_precision: str
    :return: A serializer instance for the given protocol.
    """
    # TODO: Unknown protocols.
    serializer = SERIALIZERS[protocol_name](
        timestamp_precision=timestamp_precision
    )
    if include_validation:
        validator = validate.ParamValidator()
        serializer = validate.ParamValidationDecorator(validator, serializer)
    return serializer


class Serializer:
    DEFAULT_METHOD = 'POST'
    # Clients can change this to a different MutableMapping
    # (i.e OrderedDict) if they want.  This is used in the
    # compliance test to match the hash ordering used in the
    # tests.
    MAP_TYPE = dict
    DEFAULT_ENCODING = 'utf-8'

    def __init__(self, timestamp_precision=TIMESTAMP_PRECISION_DEFAULT):
        if timestamp_precision not in TIMESTAMP_PRECISION_OPTIONS:
            raise ValueError(
                f"Invalid timestamp precision found while creating serializer: {timestamp_precision}"
            )
        self._timestamp_precision = timestamp_precision

    def serialize_to_request(self, parameters, operation_model):
        """Serialize parameters into an HTTP request.

        This method takes user provided parameters and a shape
        model and serializes the parameters to an HTTP request.
        More specifically, this method returns information about
        parts of the HTTP request, it does not enforce a particular
        interface or standard for an HTTP request.  It instead returns
        a dictionary of:

            * 'url_path'
            * 'host_prefix'
            * 'query_string'
            * 'headers'
            * 'body'
            * 'method'

        It is then up to consumers to decide how to map this to a Request
        object of their HTTP library of choice.  Below is an example
        return value::

            {'body': {'Action': 'OperationName',
                      'Bar': 'val2',
                      'Foo': 'val1',
                      'Version': '2014-01-01'},
             'headers': {},
             'method': 'POST',
             'query_string': '',
             'host_prefix': 'value.',
             'url_path': '/'}

        :param parameters: The dictionary input parameters for the
            operation (i.e the user input).
        :param operation_model: The OperationModel object that describes
            the operation.
        """
        raise NotImplementedError("serialize_to_request")

    def _create_default_request(self):
        # Creates a boilerplate default request dict that subclasses
        # can use as a starting point.
        serialized = {
            'url_path': '/',
            'query_string': '',
            'method': self.DEFAULT_METHOD,
            'headers': {},
            # An empty body is represented as an empty byte string.
            'body': b'',
        }
        return serialized

    # Some extra utility methods subclasses can use.

    def _timestamp_iso8601(self, value):
        """Return ISO8601 timestamp with precision based on timestamp_precision."""
        # Smithy's standard is milliseconds, so we truncate the timestamp if the millisecond flag is set to true
        if self._timestamp_precision == TIMESTAMP_PRECISION_MILLISECOND:
            milliseconds = value.microsecond // 1000
            return (
                value.strftime('%Y-%m-%dT%H:%M:%S') + f'.{milliseconds:03d}Z'
            )
        else:
            # Otherwise we continue supporting microseconds in iso8601 for legacy reasons
            if value.microsecond > 0:
                timestamp_format = ISO8601_MICRO
            else:
                timestamp_format = ISO8601
            return value.strftime(timestamp_format)

    def _timestamp_unixtimestamp(self, value):
        """Return unix timestamp with precision based on timestamp_precision."""
        # As of the addition of the precision flag, we support millisecond precision here as well
        if self._timestamp_precision == TIMESTAMP_PRECISION_MILLISECOND:
            base_timestamp = calendar.timegm(value.timetuple())
            milliseconds = (value.microsecond // 1000) / 1000.0
            return base_timestamp + milliseconds
        else:
            return int(calendar.timegm(value.timetuple()))

    def _timestamp_rfc822(self, value):
        """Return RFC822 timestamp (always second precision - RFC doesn't support sub-second)."""
        # RFC 2822 doesn't support sub-second precision, so always use second precision format
        if isinstance(value, datetime.datetime):
            value = int(calendar.timegm(value.timetuple()))
        return formatdate(value, usegmt=True)

    def _convert_timestamp_to_str(self, value, timestamp_format=None):
        if timestamp_format is None:
            timestamp_format = self.TIMESTAMP_FORMAT
        timestamp_format = timestamp_format.lower()
        datetime_obj = parse_to_aware_datetime(value)
        converter = getattr(self, f'_timestamp_{timestamp_format}')
        final_value = converter(datetime_obj)
        return final_value

    def _get_serialized_name(self, shape, default_name):
        # Returns the serialized name for the shape if it exists.
        # Otherwise it will return the passed in default_name.
        return shape.serialization.get('name', default_name)

    def _get_base64(self, value):
        # Returns the base64-encoded version of value, handling
        # both strings and bytes. The returned value is a string
        # via the default encoding.
        if isinstance(value, str):
            value = value.encode(self.DEFAULT_ENCODING)
        return base64.b64encode(value).strip().decode(self.DEFAULT_ENCODING)

    def _expand_host_prefix(self, parameters, operation_model):
        operation_endpoint = operation_model.endpoint
        if (
            operation_endpoint is None
            or 'hostPrefix' not in operation_endpoint
        ):
            return None

        host_prefix_expression = operation_endpoint['hostPrefix']
        if operation_model.input_shape is None:
            return host_prefix_expression
        input_members = operation_model.input_shape.members
        host_labels = [
            member
            for member, shape in input_members.items()
            if shape.serialization.get('hostLabel')
        ]
        format_kwargs = {}
        bad_labels = []
        for name in host_labels:
            param = parameters[name]
            if not HOST_PREFIX_RE.match(param):
                bad_labels.append(name)
            format_kwargs[name] = param
        if bad_labels:
            raise ParamValidationError(
                report=(
                    f"Invalid value for parameter(s): {', '.join(bad_labels)}. "
                    "Must contain only alphanumeric characters, hyphen, "
                    "or period."
                )
            )
        return host_prefix_expression.format(**format_kwargs)

    def _is_shape_flattened(self, shape):
        return shape.serialization.get('flattened')

    def _handle_float(self, value):
        if value == float("Infinity"):
            value = "Infinity"
        elif value == float("-Infinity"):
            value = "-Infinity"
        elif math.isnan(value):
            value = "NaN"
        return value

    def _handle_query_compatible_trait(self, operation_model, serialized):
        if operation_model.service_model.is_query_compatible:
            serialized['headers']['x-amzn-query-mode'] = 'true'


class QuerySerializer(Serializer):
    TIMESTAMP_FORMAT = 'iso8601'

    def serialize_to_request(self, parameters, operation_model):
        shape = operation_model.input_shape
        serialized = self._create_default_request()
        serialized['method'] = operation_model.http.get(
            'method', self.DEFAULT_METHOD
        )
        serialized['headers'] = {
            'Content-Type': 'application/x-www-form-urlencoded; charset=utf-8'
        }
        # The query serializer only deals with body params so
        # that's what we hand off the _serialize_* methods.
        body_params = self.MAP_TYPE()
        body_params['Action'] = operation_model.name
        body_params['Version'] = operation_model.metadata['apiVersion']
        if shape is not None:
            self._serialize(body_params, parameters, shape)
        serialized['body'] = body_params

        host_prefix = self._expand_host_prefix(parameters, operation_model)
        if host_prefix is not None:
            serialized['host_prefix'] = host_prefix

        return serialized

    def _serialize(self, serialized, value, shape, prefix=''):
        # serialized: The dict that is incrementally added to with the
        #             final serialized parameters.
        # value: The current user input value.
        # shape: The shape object that describes the structure of the
        #        input.
        # prefix: The incrementally built up prefix for the serialized
        #         key (i.e Foo.bar.members.1).
        method = getattr(
            self,
            f'_serialize_type_{shape.type_name}',
            self._default_serialize,
        )
        method(serialized, value, shape, prefix=prefix)

    def _serialize_type_structure(self, serialized, value, shape, prefix=''):
        members = shape.members
        for key, value in value.items():
            member_shape = members[key]
            member_prefix = self._get_serialized_name(member_shape, key)
            if prefix:
                member_prefix = f'{prefix}.{member_prefix}'
            self._serialize(serialized, value, member_shape, member_prefix)

    def _serialize_type_list(self, serialized, value, shape, prefix=''):
        if not value:
            # The query protocol serializes empty lists.
            serialized[prefix] = ''
            return
        if self._is_shape_flattened(shape):
            list_prefix = prefix
            if shape.member.serialization.get('name'):
                name = self._get_serialized_name(shape.member, default_name='')
                # Replace '.Original' with '.{name}'.
                list_prefix = '.'.join(prefix.split('.')[:-1] + [name])
        else:
            list_name = shape.member.serialization.get('name', 'member')
            list_prefix = f'{prefix}.{list_name}'
        for i, element in enumerate(value, 1):
            element_prefix = f'{list_prefix}.{i}'
            element_shape = shape.member
            self._serialize(serialized, element, element_shape, element_prefix)

    def _serialize_type_map(self, serialized, value, shape, prefix=''):
        if self._is_shape_flattened(shape):
            full_prefix = prefix
        else:
            full_prefix = f'{prefix}.entry'
        template = full_prefix + '.{i}.{suffix}'
        key_shape = shape.key
        value_shape = shape.value
        key_suffix = self._get_serialized_name(key_shape, default_name='key')
        value_suffix = self._get_serialized_name(value_shape, 'value')
        for i, key in enumerate(value, 1):
            key_prefix = template.format(i=i, suffix=key_suffix)
            value_prefix = template.format(i=i, suffix=value_suffix)
            self._serialize(serialized, key, key_shape, key_prefix)
            self._serialize(serialized, value[key], value_shape, value_prefix)

    def _serialize_type_blob(self, serialized, value, shape, prefix=''):
        # Blob args must be base64 encoded.
        serialized[prefix] = self._get_base64(value)

    def _serialize_type_timestamp(self, serialized, value, shape, prefix=''):
        serialized[prefix] = self._convert_timestamp_to_str(
            value, shape.serialization.get('timestampFormat')
        )

    def _serialize_type_boolean(self, serialized, value, shape, prefix=''):
        if value:
            serialized[prefix] = 'true'
        else:
            serialized[prefix] = 'false'

    def _default_serialize(self, serialized, value, shape, prefix=''):
        serialized[prefix] = value

    def _serialize_type_float(self, serialized, value, shape, prefix=''):
        serialized[prefix] = self._handle_float(value)

    def _serialize_type_double(self, serialized, value, shape, prefix=''):
        self._serialize_type_float(serialized, value, shape, prefix)


class EC2Serializer(QuerySerializer):
    """EC2 specific customizations to the query protocol serializers.

    The EC2 model is almost, but not exactly, similar to the query protocol
    serializer.  This class encapsulates those differences.  The model
    will have be marked with a ``protocol`` of ``ec2``, so you don't need
    to worry about wiring this class up correctly.

    """

    def _get_serialized_name(self, shape, default_name):
        # Returns the serialized name for the shape if it exists.
        # Otherwise it will return the passed in capitalized default_name.
        if 'queryName' in shape.serialization:
            return shape.serialization['queryName']
        elif 'name' in shape.serialization:
            # A locationName is always capitalized
            # on input for the ec2 protocol.
            name = shape.serialization['name']
            return name[0].upper() + name[1:]
        else:
            return default_name

    def _serialize_type_list(self, serialized, value, shape, prefix=''):
        for i, element in enumerate(value, 1):
            element_prefix = f'{prefix}.{i}'
            element_shape = shape.member
            self._serialize(serialized, element, element_shape, element_prefix)


class JSONSerializer(Serializer):
    TIMESTAMP_FORMAT = 'unixtimestamp'

    def serialize_to_request(self, parameters, operation_model):
        target = '{}.{}'.format(
            operation_model.metadata['targetPrefix'],
            operation_model.name,
        )
        json_version = operation_model.metadata['jsonVersion']
        serialized = self._create_default_request()
        serialized['method'] = operation_model.http.get(
            'method', self.DEFAULT_METHOD
        )
        serialized['headers'] = {
            'X-Amz-Target': target,
            'Content-Type': f'application/x-amz-json-{json_version}',
        }
        self._handle_query_compatible_trait(operation_model, serialized)

        body = self.MAP_TYPE()
        input_shape = operation_model.input_shape
        if input_shape is not None:
            self._serialize(body, parameters, input_shape)
        serialized['body'] = json.dumps(body).encode(self.DEFAULT_ENCODING)

        host_prefix = self._expand_host_prefix(parameters, operation_model)
        if host_prefix is not None:
            serialized['host_prefix'] = host_prefix

        return serialized

    def _serialize(self, serialized, value, shape, key=None):
        method = getattr(
            self,
            f'_serialize_type_{shape.type_name}',
            self._default_serialize,
        )
        method(serialized, value, shape, key)

    def _serialize_type_structure(self, serialized, value, shape, key):
        if shape.is_document_type:
            serialized[key] = value
        else:
            if key is not None:
                # If a key is provided, this is a result of a recursive
                # call so we need to add a new child dict as the value
                # of the passed in serialized dict.  We'll then add
                # all the structure members as key/vals in the new serialized
                # dictionary we just created.
                new_serialized = self.MAP_TYPE()
                serialized[key] = new_serialized
                serialized = new_serialized
            members = shape.members
            for member_key, member_value in value.items():
                member_shape = members[member_key]
                if 'name' in member_shape.serialization:
                    member_key = member_shape.serialization['name']
                self._serialize(
                    serialized, member_value, member_shape, member_key
                )

    def _serialize_type_map(self, serialized, value, shape, key):
        map_obj = self.MAP_TYPE()
        serialized[key] = map_obj
        for sub_key, sub_value in value.items():
            self._serialize(map_obj, sub_value, shape.value, sub_key)

    def _serialize_type_list(self, serialized, value, shape, key):
        list_obj = []
        serialized[key] = list_obj
        for list_item in value:
            wrapper = {}
            # The JSON list serialization is the only case where we aren't
            # setting a key on a dict.  We handle this by using
            # a __current__ key on a wrapper dict to serialize each
            # list item before appending it to the serialized list.
            self._serialize(wrapper, list_item, shape.member, "__current__")
            list_obj.append(wrapper["__current__"])

    def _default_serialize(self, serialized, value, shape, key):
        serialized[key] = value

    def _serialize_type_timestamp(self, serialized, value, shape, key):
        serialized[key] = self._convert_timestamp_to_str(
            value, shape.serialization.get('timestampFormat')
        )

    def _serialize_type_blob(self, serialized, value, shape, key):
        serialized[key] = self._get_base64(value)

    def _serialize_type_float(self, serialized, value, shape, prefix=''):
        if isinstance(value, decimal.Decimal):
            value = float(value)
        serialized[prefix] = self._handle_float(value)

    def _serialize_type_double(self, serialized, value, shape, prefix=''):
        self._serialize_type_float(serialized, value, shape, prefix)


class CBORSerializer(Serializer):
    UNSIGNED_INT_MAJOR_TYPE = 0
    NEGATIVE_INT_MAJOR_TYPE = 1
    BLOB_MAJOR_TYPE = 2
    STRING_MAJOR_TYPE = 3
    LIST_MAJOR_TYPE = 4
    MAP_MAJOR_TYPE = 5
    TAG_MAJOR_TYPE = 6
    FLOAT_AND_SIMPLE_MAJOR_TYPE = 7

    def _serialize_data_item(self, serialized, value, shape, key=None):
        method = getattr(self, f'_serialize_type_{shape.type_name}')
        if method is None:
            raise ValueError(
                f"Unrecognized C2J type: {shape.type_name}, unable to "
                f"serialize request"
            )
        method(serialized, value, shape, key)

    def _serialize_type_integer(self, serialized, value, shape, key):
        if value >= 0:
            major_type = self.UNSIGNED_INT_MAJOR_TYPE
        else:
            major_type = self.NEGATIVE_INT_MAJOR_TYPE
            # The only differences in serializing negative and positive integers is
            # that for negative, we set the major type to 1 and set the value to -1
            # minus the value
            value = -1 - value
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            value
        )
        initial_byte = self._get_initial_byte(major_type, additional_info)
        if num_bytes == 0:
            serialized.extend(initial_byte)
        else:
            serialized.extend(initial_byte + value.to_bytes(num_bytes, "big"))

    def _serialize_type_long(self, serialized, value, shape, key):
        self._serialize_type_integer(serialized, value, shape, key)

    def _serialize_type_blob(self, serialized, value, shape, key):
        if isinstance(value, str):
            value = value.encode('utf-8')
        elif not isinstance(value, (bytes, bytearray)):
            # We support file-like objects for blobs; these already have been
            # validated to ensure they have a read method
            value = value.read()
        length = len(value)
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            length
        )
        initial_byte = self._get_initial_byte(
            self.BLOB_MAJOR_TYPE, additional_info
        )
        if num_bytes == 0:
            serialized.extend(initial_byte)
        else:
            serialized.extend(initial_byte + length.to_bytes(num_bytes, "big"))
        serialized.extend(value)

    def _serialize_type_string(self, serialized, value, shape, key):
        encoded = value.encode('utf-8')
        length = len(encoded)
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            length
        )
        initial_byte = self._get_initial_byte(
            self.STRING_MAJOR_TYPE, additional_info
        )
        if num_bytes == 0:
            serialized.extend(initial_byte + encoded)
        else:
            serialized.extend(
                initial_byte + length.to_bytes(num_bytes, "big") + encoded
            )

    def _serialize_type_list(self, serialized, value, shape, key):
        length = len(value)
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            length
        )
        initial_byte = self._get_initial_byte(
            self.LIST_MAJOR_TYPE, additional_info
        )
        if num_bytes == 0:
            serialized.extend(initial_byte)
        else:
            serialized.extend(initial_byte + length.to_bytes(num_bytes, "big"))
        for item in value:
            self._serialize_data_item(serialized, item, shape.member)

    def _serialize_type_map(self, serialized, value, shape, key):
        length = len(value)
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            length
        )
        initial_byte = self._get_initial_byte(
            self.MAP_MAJOR_TYPE, additional_info
        )
        if num_bytes == 0:
            serialized.extend(initial_byte)
        else:
            serialized.extend(initial_byte + length.to_bytes(num_bytes, "big"))
        for key_item, item in value.items():
            self._serialize_data_item(serialized, key_item, shape.key)
            self._serialize_data_item(serialized, item, shape.value)

    def _serialize_type_structure(self, serialized, value, shape, key):
        if key is not None:
            # For nested structures, we need to serialize the key first
            self._serialize_data_item(serialized, key, shape.key_shape)

        # Remove `None` values from the dictionary
        value = {k: v for k, v in value.items() if v is not None}

        map_length = len(value)
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            map_length
        )
        initial_byte = self._get_initial_byte(
            self.MAP_MAJOR_TYPE, additional_info
        )
        if num_bytes == 0:
            serialized.extend(initial_byte)
        else:
            serialized.extend(
                initial_byte + map_length.to_bytes(num_bytes, "big")
            )

        members = shape.members
        for member_key, member_value in value.items():
            member_shape = members[member_key]
            if 'name' in member_shape.serialization:
                member_key = member_shape.serialization['name']
            if member_value is not None:
                self._serialize_type_string(serialized, member_key, None, None)
                self._serialize_data_item(
                    serialized, member_value, member_shape
                )

    def _serialize_type_timestamp(self, serialized, value, shape, key):
        timestamp = self._convert_timestamp_to_str(value)
        tag = 1  # Use tag 1 for unix timestamp
        initial_byte = self._get_initial_byte(self.TAG_MAJOR_TYPE, tag)
        serialized.extend(initial_byte)  # Tagging the timestamp
        additional_info, num_bytes = self._get_additional_info_and_num_bytes(
            timestamp
        )

        if num_bytes == 0:
            initial_byte = self._get_initial_byte(
                self.UNSIGNED_INT_MAJOR_TYPE, timestamp
            )
            serialized.extend(initial_byte)
        else:
            initial_byte = self._get_initial_byte(
                self.UNSIGNED_INT_MAJOR_TYPE, additional_info
            )
            serialized.extend(
                initial_byte + timestamp.to_bytes(num_bytes, "big")
            )

    def _serialize_type_float(self, serialized, value, shape, key):
        if self._is_special_number(value):
            serialized.extend(
                self._get_bytes_for_special_numbers(value)
            )  # Handle special values like NaN or Infinity
        else:
            initial_byte = self._get_initial_byte(
                self.FLOAT_AND_SIMPLE_MAJOR_TYPE, 26
            )
            serialized.extend(initial_byte + struct.pack(">f", value))

    def _serialize_type_double(self, serialized, value, shape, key):
        if self._is_special_number(value):
            serialized.extend(
                self._get_bytes_for_special_numbers(value)
            )  # Handle special values like NaN or Infinity
        else:
            initial_byte = self._get_initial_byte(
                self.FLOAT_AND_SIMPLE_MAJOR_TYPE, 27
            )
            serialized.extend(initial_byte + struct.pack(">d", value))

    def _serialize_type_boolean(self, serialized, value, shape, key):
        additional_info = 21 if value else 20
        serialized.extend(
            self._get_initial_byte(
                self.FLOAT_AND_SIMPLE_MAJOR_TYPE, additional_info
            )
        )

    def _get_additional_info_and_num_bytes(self, value):
        # Values under 24 can be stored in the initial byte and don't need further
        # encoding
        if value < 24:
            return value, 0
        # Values between 24 and 255 (inclusive) can be stored in 1 byte and
        # correspond to additional info 24
        elif value < 256:
            return 24, 1
        # Values up to 65535 can be stored in two bytes and correspond to additional
        # info 25
        elif value < 65536:
            return 25, 2
        # Values up to 4294967296 can be stored in four bytes and correspond to
        # additional info 26
        elif value < 4294967296:
            return 26, 4
        # The maximum number of bytes in a definite length data items is 8 which
        # to additional info 27
        else:
            return 27, 8

    def _get_initial_byte(self, major_type, additional_info):
        # The highest order three bits are the major type, so we need to bitshift the
        # major type by 5
        major_type_bytes = major_type << 5
        return (major_type_bytes | additional_info).to_bytes(1, "big")

    def _is_special_number(self, value):
        return any(
            [
                value == float('inf'),
                value == float('-inf'),
                math.isnan(value),
            ]
        )

    def _get_bytes_for_special_numbers(self, value):
        additional_info = 25
        initial_byte = self._get_initial_byte(
            self.FLOAT_AND_SIMPLE_MAJOR_TYPE, additional_info
        )
        if value == float('inf'):
            return initial_byte + struct.pack(">H", 0x7C00)
        elif value == float('-inf'):
            return initial_byte + struct.pack(">H", 0xFC00)
        elif math.isnan(value):
            return initial_byte + struct.pack(">H", 0x7E00)


class BaseRestSerializer(Serializer):
    """Base class for rest protocols.

    The only variance between the various rest protocols is the
    way that the body is serialized.  All other aspects (headers, uri, etc.)
    are the same and logic for serializing those aspects lives here.

    Subclasses must implement the ``_serialize_body_params`` method.

    """

    QUERY_STRING_TIMESTAMP_FORMAT = 'iso8601'
    HEADER_TIMESTAMP_FORMAT = 'rfc822'
    # This is a list of known values for the "location" key in the
    # serialization dict.  The location key tells us where on the request
    # to put the serialized value.
    KNOWN_LOCATIONS = ['uri', 'querystring', 'header', 'headers']

    def serialize_to_request(self, parameters, operation_model):
        serialized = self._create_default_request()
        serialized['method'] = operation_model.http.get(
            'method', self.DEFAULT_METHOD
        )
        shape = operation_model.input_shape

        host_prefix = self._expand_host_prefix(parameters, operation_model)
        if host_prefix is not None:
            serialized['host_prefix'] = host_prefix

        if shape is None:
            serialized['url_path'] = operation_model.http['requestUri']
            return serialized
        shape_members = shape.members
        # While the ``serialized`` key holds the final serialized request
        # data, we need interim dicts for the various locations of the
        # request.  We need this for the uri_path_kwargs and the
        # query_string_kwargs because they are templated, so we need
        # to gather all the needed data for the string template,
        # then we render the template.  The body_kwargs is needed
        # because once we've collected them all, we run them through
        # _serialize_body_params, which for rest-json, creates JSON,
        # and for rest-xml, will create XML.  This is what the
        # ``partitioned`` dict below is for.
        partitioned = {
            'uri_path_kwargs': self.MAP_TYPE(),
            'query_string_kwargs': self.MAP_TYPE(),
            'body_kwargs': self.MAP_TYPE(),
            'headers': self.MAP_TYPE(),
        }
        for param_name, param_value in parameters.items():
            if param_value is None:
                # Don't serialize any parameter with a None value.
                continue
            self._partition_parameters(
                partitioned, param_name, param_value, shape_members
            )
        serialized['url_path'] = self._render_uri_template(
            operation_model.http['requestUri'], partitioned['uri_path_kwargs']
        )

        if 'authPath' in operation_model.http:
            serialized['auth_path'] = self._render_uri_template(
                operation_model.http['authPath'],
                partitioned['uri_path_kwargs'],
            )
        # Note that we lean on the http implementation to handle the case
        # where the requestUri path already has query parameters.
        # The bundled http client, requests, already supports this.
        serialized['query_string'] = partitioned['query_string_kwargs']
        if partitioned['headers']:
            serialized['headers'] = partitioned['headers']
        self._serialize_payload(
            partitioned, parameters, serialized, shape, shape_members
        )
        self._serialize_content_type(serialized, shape, shape_members)

        return serialized

    def _render_uri_template(self, uri_template, params):
        # We need to handle two cases::
        #
        # /{Bucket}/foo
        # /{Key+}/bar
        # A label ending with '+' is greedy.  There can only
        # be one greedy key.
        encoded_params = {}
        for template_param in re.findall(r'{(.*?)}', uri_template):
            if template_param.endswith('+'):
                encoded_params[template_param] = percent_encode(
                    params[template_param[:-1]], safe='/~'
                )
            else:
                encoded_params[template_param] = percent_encode(
                    params[template_param]
                )
        return uri_template.format(**encoded_params)

    def _serialize_payload(
        self, partitioned, parameters, serialized, shape, shape_members
    ):
        # partitioned - The user input params partitioned by location.
        # parameters - The user input params.
        # serialized - The final serialized request dict.
        # shape - Describes the expected input shape
        # shape_members - The members of the input struct shape
        payload_member = shape.serialization.get('payload')
        if self._has_streaming_payload(payload_member, shape_members):
            # If it's streaming, then the body is just the
            # value of the payload.
            body_payload = parameters.get(payload_member, b'')
            body_payload = self._encode_payload(body_payload)
            serialized['body'] = body_payload
        elif payload_member is not None:
            # If there's a payload member, we serialized that
            # member to they body.
            body_params = parameters.get(payload_member)
            if body_params is not None:
                serialized['body'] = self._serialize_body_params(
                    body_params, shape_members[payload_member]
                )
            else:
                serialized['body'] = self._serialize_empty_body()
        elif partitioned['body_kwargs']:
            serialized['body'] = self._serialize_body_params(
                partitioned['body_kwargs'], shape
            )
        elif self._requires_empty_body(shape):
            serialized['body'] = self._serialize_empty_body()

    def _serialize_empty_body(self):
        return b''

    def _serialize_content_type(self, serialized, shape, shape_members):
        """
        Some protocols require varied Content-Type headers
        depending on user input. This allows subclasses to apply
        this conditionally.
        """
        pass

    def _requires_empty_body(self, shape):
        """
        Some protocols require a specific body to represent an empty
        payload. This allows subclasses to apply this conditionally.
        """
        return False

    def _has_streaming_payload(self, payload, shape_members):
        """Determine if payload is streaming (a blob or string)."""
        return payload is not None and shape_members[payload].type_name in (
            'blob',
            'string',
        )

    def _encode_payload(self, body):
        if isinstance(body, str):
            return body.encode(self.DEFAULT_ENCODING)
        return body

    def _partition_parameters(
        self, partitioned, param_name, param_value, shape_members
    ):
        # This takes the user provided input parameter (``param``)
        # and figures out where they go in the request dict.
        # Some params are HTTP headers, some are used in the URI, some
        # are in the request body.  This method deals with this.
        member = shape_members[param_name]
        location = member.serialization.get('location')
        key_name = member.serialization.get('name', param_name)
        if location == 'uri':
            uri_path_value = self._get_uri_and_query_string_value(
                param_value, member
            )
            partitioned['uri_path_kwargs'][key_name] = uri_path_value
        elif location == 'querystring':
            if isinstance(param_value, dict):
                partitioned['query_string_kwargs'].update(param_value)
            elif member.type_name == 'list':
                new_param = [
                    self._get_uri_and_query_string_value(value, member.member)
                    for value in param_value
                ]
                partitioned['query_string_kwargs'][key_name] = new_param
            else:
                new_param = self._get_uri_and_query_string_value(
                    param_value, member
                )
                partitioned['query_string_kwargs'][key_name] = new_param
        elif location == 'header':
            shape = shape_members[param_name]
            if not param_value and shape.type_name == 'list':
                # Empty lists should not be set on the headers
                return
            partitioned['headers'][key_name] = self._convert_header_value(
                shape, param_value
            )
        elif location == 'headers':
            # 'headers' is a bit of an oddball.  The ``key_name``
            # is actually really a prefix for the header names:
            header_prefix = key_name
            # The value provided by the user is a dict so we'll be
            # creating multiple header key/val pairs.  The key
            # name to use for each header is the header_prefix (``key_name``)
            # plus the key provided by the user.
            self._do_serialize_header_map(
                header_prefix, partitioned['headers'], param_value
            )
        else:
            partitioned['body_kwargs'][param_name] = param_value

    def _get_uri_and_query_string_value(self, param_value, member):
        if member.type_name == 'boolean':
            return str(param_value).lower()
        elif member.type_name == 'timestamp':
            timestamp_format = member.serialization.get(
                'timestampFormat', self.QUERY_STRING_TIMESTAMP_FORMAT
            )
            return self._convert_timestamp_to_str(
                param_value, timestamp_format
            )
        elif member.type_name in ['float', 'double']:
            return str(self._handle_float(param_value))
        return param_value

    def _do_serialize_header_map(self, header_prefix, headers, user_input):
        for key, val in user_input.items():
            full_key = header_prefix + key
            headers[full_key] = val

    def _serialize_body_params(self, params, shape):
        raise NotImplementedError('_serialize_body_params')

    def _convert_header_value(self, shape, value):
        if shape.type_name == 'timestamp':
            datetime_obj = parse_to_aware_datetime(value)
            timestamp = calendar.timegm(datetime_obj.utctimetuple())
            timestamp_format = shape.serialization.get(
                'timestampFormat', self.HEADER_TIMESTAMP_FORMAT
            )
            return str(
                self._convert_timestamp_to_str(timestamp, timestamp_format)
            )
        elif shape.type_name == 'list':
            if shape.member.type_name == "string":
                converted_value = [
                    self._escape_header_list_string(v)
                    for v in value
                    if v is not None
                ]
            else:
                converted_value = [
                    self._convert_header_value(shape.member, v)
                    for v in value
                    if v is not None
                ]
            return ",".join(converted_value)
        elif is_json_value_header(shape):
            # Serialize with no spaces after separators to save space in
            # the header.
            return self._get_base64(json.dumps(value, separators=(',', ':')))
        elif shape.type_name == 'boolean':
            return str(value).lower()
        elif shape.type_name in ['float', 'double']:
            return str(self._handle_float(value))
        else:
            return str(value)

    def _escape_header_list_string(self, value):
        # Escapes a header list string by wrapping it in double quotes if it contains
        # a comma or a double quote, and escapes any internal double quotes.
        if '"' in value or ',' in value:
            return '"' + value.replace('"', '\\"') + '"'
        else:
            return value


class BaseRpcV2Serializer(Serializer):
    """Base class for RPCv2 protocols.

    The only variance between the various RPCv2 protocols is the
    way that the body is serialized.  All other aspects (headers, uri, etc.)
    are the same and logic for serializing those aspects lives here.

    Subclasses must implement the ``_serialize_body_params``  and
    ``_serialize_headers`` methods.

    """

    def serialize_to_request(self, parameters, operation_model):
        serialized = self._create_default_request()
        service_name = operation_model.service_model.metadata['targetPrefix']
        operation_name = operation_model.name
        serialized['url_path'] = (
            f'/service/{service_name}/operation/{operation_name}'
        )

        input_shape = operation_model.input_shape
        if input_shape is not None:
            self._serialize_payload(parameters, serialized, input_shape)

        host_prefix = self._expand_host_prefix(parameters, operation_model)
        if host_prefix is not None:
            serialized['host_prefix'] = host_prefix

        self._serialize_headers(serialized, operation_model)

        return serialized

    def _serialize_payload(self, parameters, serialized, shape):
        body_payload = self._serialize_body_params(parameters, shape)
        serialized['body'] = body_payload

    def _serialize_headers(self, serialized, operation_model):
        raise NotImplementedError("_serialize_headers")

    def _serialize_body_params(self, parameters, shape):
        raise NotImplementedError("_serialize_body_params")


class RestJSONSerializer(BaseRestSerializer, JSONSerializer):
    def _serialize_empty_body(self):
        return b'{}'

    def _requires_empty_body(self, shape):
        """
        Serialize an empty JSON object whenever the shape has
        members not targeting a location.
        """
        for member, val in shape.members.items():
            if 'location' not in val.serialization:
                return True
        return False

    def _serialize_content_type(self, serialized, shape, shape_members):
        """Set Content-Type to application/json for all structured bodies."""
        payload = shape.serialization.get('payload')
        if self._has_streaming_payload(payload, shape_members):
            # Don't apply content-type to streaming bodies
            return

        has_body = serialized['body'] != b''
        has_content_type = has_header('Content-Type', serialized['headers'])
        if has_body and not has_content_type:
            serialized['headers']['Content-Type'] = 'application/json'

    def _serialize_body_params(self, params, shape):
        serialized_body = self.MAP_TYPE()
        self._serialize(serialized_body, params, shape)
        return json.dumps(serialized_body).encode(self.DEFAULT_ENCODING)


class RestXMLSerializer(BaseRestSerializer):
    TIMESTAMP_FORMAT = 'iso8601'

    def _serialize_body_params(self, params, shape):
        root_name = shape.serialization['name']
        pseudo_root = ElementTree.Element('')
        self._serialize(shape, params, pseudo_root, root_name)
        real_root = list(pseudo_root)[0]
        return ElementTree.tostring(real_root, encoding=self.DEFAULT_ENCODING)

    def _serialize(self, shape, params, xmlnode, name):
        method = getattr(
            self,
            f'_serialize_type_{shape.type_name}',
            self._default_serialize,
        )
        method(xmlnode, params, shape, name)

    def _serialize_type_structure(self, xmlnode, params, shape, name):
        structure_node = ElementTree.SubElement(xmlnode, name)

        self._add_xml_namespace(shape, structure_node)
        for key, value in params.items():
            member_shape = shape.members[key]
            member_name = member_shape.serialization.get('name', key)
            # We need to special case member shapes that are marked as an
            # xmlAttribute.  Rather than serializing into an XML child node,
            # we instead serialize the shape to an XML attribute of the
            # *current* node.
            if value is None:
                # Don't serialize any param whose value is None.
                return
            if member_shape.serialization.get('xmlAttribute'):
                # xmlAttributes must have a serialization name.
                xml_attribute_name = member_shape.serialization['name']
                structure_node.attrib[xml_attribute_name] = value
                continue
            self._serialize(member_shape, value, structure_node, member_name)

    def _serialize_type_list(self, xmlnode, params, shape, name):
        member_shape = shape.member
        if shape.serialization.get('flattened'):
            element_name = name
            list_node = xmlnode
        else:
            element_name = member_shape.serialization.get('name', 'member')
            list_node = ElementTree.SubElement(xmlnode, name)
        self._add_xml_namespace(shape, list_node)
        for item in params:
            self._serialize(member_shape, item, list_node, element_name)

    def _serialize_type_map(self, xmlnode, params, shape, name):
        # Given the ``name`` of MyMap, and input of {"key1": "val1"}
        # we serialize this as:
        #   <MyMap>
        #     <entry>
        #       <key>key1</key>
        #       <value>val1</value>
        #     </entry>
        #  </MyMap>
        if not self._is_shape_flattened(shape):
            node = ElementTree.SubElement(xmlnode, name)
            self._add_xml_namespace(shape, node)

        for key, value in params.items():
            sub_node = (
                ElementTree.SubElement(xmlnode, name)
                if self._is_shape_flattened(shape)
                else ElementTree.SubElement(node, 'entry')
            )
            key_name = self._get_serialized_name(shape.key, default_name='key')
            val_name = self._get_serialized_name(
                shape.value, default_name='value'
            )
            self._serialize(shape.key, key, sub_node, key_name)
            self._serialize(shape.value, value, sub_node, val_name)

    def _serialize_type_boolean(self, xmlnode, params, shape, name):
        # For scalar types, the 'params' attr is actually just a scalar
        # value representing the data we need to serialize as a boolean.
        # It will either be 'true' or 'false'
        node = ElementTree.SubElement(xmlnode, name)
        if params:
            str_value = 'true'
        else:
            str_value = 'false'
        node.text = str_value
        self._add_xml_namespace(shape, node)

    def _serialize_type_blob(self, xmlnode, params, shape, name):
        node = ElementTree.SubElement(xmlnode, name)
        node.text = self._get_base64(params)
        self._add_xml_namespace(shape, node)

    def _serialize_type_timestamp(self, xmlnode, params, shape, name):
        node = ElementTree.SubElement(xmlnode, name)
        node.text = str(
            self._convert_timestamp_to_str(
                params, shape.serialization.get('timestampFormat')
            )
        )
        self._add_xml_namespace(shape, node)

    def _serialize_type_float(self, xmlnode, params, shape, name):
        node = ElementTree.SubElement(xmlnode, name)
        node.text = str(self._handle_float(params))
        self._add_xml_namespace(shape, node)

    def _serialize_type_double(self, xmlnode, params, shape, name):
        self._serialize_type_float(xmlnode, params, shape, name)

    def _default_serialize(self, xmlnode, params, shape, name):
        node = ElementTree.SubElement(xmlnode, name)
        node.text = str(params)
        self._add_xml_namespace(shape, node)

    def _add_xml_namespace(self, shape, structure_node):
        if 'xmlNamespace' in shape.serialization:
            namespace_metadata = shape.serialization['xmlNamespace']
            attribute_name = 'xmlns'
            if isinstance(namespace_metadata, dict):
                if namespace_metadata.get('prefix'):
                    attribute_name += f":{namespace_metadata['prefix']}"
                structure_node.attrib[attribute_name] = namespace_metadata[
                    'uri'
                ]
            elif isinstance(namespace_metadata, str):
                structure_node.attrib[attribute_name] = namespace_metadata


class RpcV2CBORSerializer(BaseRpcV2Serializer, CBORSerializer):
    TIMESTAMP_FORMAT = 'unixtimestamp'

    def serialize_to_request(self, parameters, operation_model):
        register_feature_id('PROTOCOL_RPC_V2_CBOR')
        return super().serialize_to_request(parameters, operation_model)

    def _serialize_body_params(self, parameters, input_shape):
        body = bytearray()
        self._serialize_data_item(body, parameters, input_shape)
        return bytes(body)

    def _serialize_headers(self, serialized, operation_model):
        serialized['headers']['smithy-protocol'] = 'rpc-v2-cbor'

        if operation_model.has_event_stream_output:
            header_val = 'application/vnd.amazon.eventstream'
        else:
            header_val = 'application/cbor'
        self._handle_query_compatible_trait(operation_model, serialized)

        has_body = serialized['body'] != b''
        has_content_type = has_header('Content-Type', serialized['headers'])

        serialized['headers']['Accept'] = header_val
        if not has_content_type and has_body:
            serialized['headers']['Content-Type'] = header_val


SERIALIZERS = {
    'ec2': EC2Serializer,
    'query': QuerySerializer,
    'json': JSONSerializer,
    'rest-json': RestJSONSerializer,
    'rest-xml': RestXMLSerializer,
    'smithy-rpc-v2-cbor': RpcV2CBORSerializer,
}
