# 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.
"""Abstractions to interact with service models."""
from collections import defaultdict

from botocore.utils import CachedProperty, instance_cache
from botocore.compat import OrderedDict


NOT_SET = object()


class NoShapeFoundError(Exception):
    pass


class InvalidShapeError(Exception):
    pass


class OperationNotFoundError(Exception):
    pass


class InvalidShapeReferenceError(Exception):
    pass


class UndefinedModelAttributeError(Exception):
    pass


class Shape(object):
    """Object representing a shape from the service model."""
    # To simplify serialization logic, all shape params that are
    # related to serialization are moved from the top level hash into
    # a 'serialization' hash.  This list below contains the names of all
    # the attributes that should be moved.
    SERIALIZED_ATTRS = ['locationName', 'queryName', 'flattened', 'location',
                        'payload', 'streaming', 'timestampFormat',
                        'xmlNamespace', 'resultWrapper', 'xmlAttribute']
    METADATA_ATTRS = ['required', 'min', 'max', 'sensitive', 'enum',
                      'idempotencyToken']
    MAP_TYPE = OrderedDict

    def __init__(self, shape_name, shape_model, shape_resolver=None):
        """

        :type shape_name: string
        :param shape_name: The name of the shape.

        :type shape_model: dict
        :param shape_model: The shape model.  This would be the value
            associated with the key in the "shapes" dict of the
            service model (i.e ``model['shapes'][shape_name]``)

        :type shape_resolver: botocore.model.ShapeResolver
        :param shape_resolver: A shape resolver object.  This is used to
            resolve references to other shapes.  For scalar shape types
            (string, integer, boolean, etc.), this argument is not
            required.  If a shape_resolver is not provided for a complex
            type, then a ``ValueError`` will be raised when an attempt
            to resolve a shape is made.

        """
        self.name = shape_name
        self.type_name = shape_model['type']
        self.documentation = shape_model.get('documentation', '')
        self._shape_model = shape_model
        if shape_resolver is None:
            # If a shape_resolver is not provided, we create an object
            # that will throw errors if you attempt to resolve
            # a shape.  This is actually ok for scalar shapes
            # because they don't need to resolve shapes and shouldn't
            # be required to provide an object they won't use.
            shape_resolver = UnresolvableShapeMap()
        self._shape_resolver = shape_resolver
        self._cache = {}

    @CachedProperty
    def serialization(self):
        """Serialization information about the shape.

        This contains information that may be needed for input serialization
        or response parsing.  This can include:

            * name
            * queryName
            * flattened
            * location
            * payload
            * streaming
            * xmlNamespace
            * resultWrapper
            * xmlAttribute

        :rtype: dict
        :return: Serialization information about the shape.

        """
        model = self._shape_model
        serialization = {}
        for attr in self.SERIALIZED_ATTRS:
            if attr in self._shape_model:
                serialization[attr] = model[attr]
        # For consistency, locationName is renamed to just 'name'.
        if 'locationName' in serialization:
            serialization['name'] = serialization.pop('locationName')
        return serialization

    @CachedProperty
    def metadata(self):
        """Metadata about the shape.

        This requires optional information about the shape, including:

            * min
            * max
            * enum
            * sensitive
            * required
            * idempotencyToken

        :rtype: dict
        :return: Metadata about the shape.

        """
        model = self._shape_model
        metadata = {}
        for attr in self.METADATA_ATTRS:
            if attr in self._shape_model:
                metadata[attr] = model[attr]
        return metadata

    @CachedProperty
    def required_members(self):
        """A list of members that are required.

        A structure shape can define members that are required.
        This value will return a list of required members.  If there
        are no required members an empty list is returned.

        """
        return self.metadata.get('required', [])

    def _resolve_shape_ref(self, shape_ref):
        return self._shape_resolver.resolve_shape_ref(shape_ref)

    def __repr__(self):
        return "<%s(%s)>" % (self.__class__.__name__,
                             self.name)


class StructureShape(Shape):
    @CachedProperty
    def members(self):
        members = self._shape_model['members']
        # The members dict looks like:
        #    'members': {
        #        'MemberName': {'shape': 'shapeName'},
        #        'MemberName2': {'shape': 'shapeName'},
        #    }
        # We return a dict of member name to Shape object.
        shape_members = self.MAP_TYPE()
        for name, shape_ref in members.items():
            shape_members[name] = self._resolve_shape_ref(shape_ref)
        return shape_members


class ListShape(Shape):
    @CachedProperty
    def member(self):
        return self._resolve_shape_ref(self._shape_model['member'])


class MapShape(Shape):
    @CachedProperty
    def key(self):
        return self._resolve_shape_ref(self._shape_model['key'])

    @CachedProperty
    def value(self):
        return self._resolve_shape_ref(self._shape_model['value'])


class StringShape(Shape):
    @CachedProperty
    def enum(self):
        return self.metadata.get('enum', [])


class ServiceModel(object):
    """

    :ivar service_description: The parsed service description dictionary.

    """

    def __init__(self, service_description, service_name=None):
        """

        :type service_description: dict
        :param service_description: The service description model.  This value
            is obtained from a botocore.loader.Loader, or from directly loading
            the file yourself::

                service_description = json.load(
                    open('/path/to/service-description-model.json'))
                model = ServiceModel(service_description)

        :type service_name: str
        :param service_name: The name of the service.  Normally this is
            the endpoint prefix defined in the service_description.  However,
            you can override this value to provide a more convenient name.
            This is done in a few places in botocore (ses instead of email,
            emr instead of elasticmapreduce).  If this value is not provided,
            it will default to the endpointPrefix defined in the model.

        """
        self._service_description = service_description
        # We want clients to be able to access metadata directly.
        self.metadata = service_description.get('metadata', {})
        self._shape_resolver = ShapeResolver(
            service_description.get('shapes', {}))
        self._signature_version = NOT_SET
        self._service_name = service_name
        self._instance_cache = {}

    def shape_for(self, shape_name, member_traits=None):
        return self._shape_resolver.get_shape_by_name(
            shape_name, member_traits)

    def resolve_shape_ref(self, shape_ref):
        return self._shape_resolver.resolve_shape_ref(shape_ref)

    @instance_cache
    def operation_model(self, operation_name):
        try:
            model = self._service_description['operations'][operation_name]
        except KeyError:
            raise OperationNotFoundError(operation_name)
        return OperationModel(model, self, operation_name)

    @CachedProperty
    def documentation(self):
        return self._service_description.get('documentation', '')

    @CachedProperty
    def operation_names(self):
        return list(self._service_description.get('operations', []))

    @CachedProperty
    def service_name(self):
        """The name of the service.

        This defaults to the endpointPrefix defined in the service model.
        However, this value can be overriden when a ``ServiceModel`` is
        created.  If a service_name was not provided when the ``ServiceModel``
        was created and if there is no endpointPrefix defined in the
        service model, then an ``UndefinedModelAttributeError`` exception
        will be raised.

        """
        if self._service_name is not None:
            return self._service_name
        else:
            return self.endpoint_prefix

    @CachedProperty
    def signing_name(self):
        """The name to use when computing signatures.

        If the model does not define a signing name, this
        value will be the endpoint prefix defined in the model.
        """
        signing_name = self.metadata.get('signingName')
        if signing_name is None:
            signing_name = self.endpoint_prefix
        return signing_name

    @CachedProperty
    def api_version(self):
        return self._get_metadata_property('apiVersion')

    @CachedProperty
    def protocol(self):
        return self._get_metadata_property('protocol')

    @CachedProperty
    def endpoint_prefix(self):
        return self._get_metadata_property('endpointPrefix')

    def _get_metadata_property(self, name):
        try:
            return self.metadata[name]
        except KeyError:
            raise UndefinedModelAttributeError(
                '"%s" not defined in the metadata of the the model: %s' %
                (name, self))

    # Signature version is one of the rare properties
    # than can be modified so a CachedProperty is not used here.

    @property
    def signature_version(self):
        if self._signature_version is NOT_SET:
            signature_version = self.metadata.get('signatureVersion')
            self._signature_version = signature_version
        return self._signature_version

    @signature_version.setter
    def signature_version(self, value):
        self._signature_version = value


class OperationModel(object):
    def __init__(self, operation_model, service_model, name=None):
        """

        :type operation_model: dict
        :param operation_model: The operation model.  This comes from the
            service model, and is the value associated with the operation
            name in the service model (i.e ``model['operations'][op_name]``).

        :type service_model: botocore.model.ServiceModel
        :param service_model: The service model associated with the operation.

        :type name: string
        :param name: The operation name.  This is the operation name exposed to
            the users of this model.  This can potentially be different from
            the "wire_name", which is the operation name that *must* by
            provided over the wire.  For example, given::

               "CreateCloudFrontOriginAccessIdentity":{
                 "name":"CreateCloudFrontOriginAccessIdentity2014_11_06",