# Copyright (c) 2012-2013 Mitch Garnaat http://garnaat.org/
# Copyright 2012-2014 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.

import logging
from botocore.parameters import get_parameter
from botocore.exceptions import MissingParametersError
from botocore.exceptions import UnknownParameterError
from botocore.paginate import Paginator
from botocore.payload import Payload, XMLPayload, JSONPayload
from botocore import BotoCoreObject, xform_name

logger = logging.getLogger(__name__)


class Operation(BotoCoreObject):

    _DEFAULT_PAGINATOR_CLS = Paginator

    def __init__(self, service, op_data, paginator_cls=None):
        self.input = {}
        self.output = {}
        BotoCoreObject.__init__(self, **op_data)
        self.service = service
        if self.service:
            self.session = self.service.session
        else:
            self.session = None
        self.type = 'operation'
        self._params = None
        if paginator_cls is None:
            paginator_cls = self._DEFAULT_PAGINATOR_CLS
        self._paginator_cls = paginator_cls

    def __repr__(self):
        return 'Operation:%s' % self.name

    def call(self, endpoint, **kwargs):
        logger.debug("%s called with kwargs: %s", self, kwargs)
        # It probably seems a little weird to be firing two different
        # events here.  The reason is that the first event is fired
        # with the parameters exactly as supplied.  The second event
        # is fired with the built parameters.  Generally, it's easier
        # to manipulate the former but at times, like with ReST operations
        # that build an XML or JSON payload, you have to wait for
        # build_parameters to do it's job and the latter is necessary.
        event = self.session.create_event('before-parameter-build',
                                          self.service.endpoint_prefix,
                                          self.name)
        self.session.emit(event, operation=self, endpoint=endpoint,
                          params=kwargs)
        params = self.build_parameters(**kwargs)
        event = self.session.create_event('before-call',
                                          self.service.endpoint_prefix,
                                          self.name)
        self.session.emit(event, operation=self, endpoint=endpoint,
                          params=params)
        response = endpoint.make_request(self, params)
        event = self.session.create_event('after-call',
                                          self.service.endpoint_prefix,
                                          self.name)
        self.session.emit(event, operation=self,
                          http_response=response[0],
                          parsed=response[1])
        return response

    @property
    def can_paginate(self):
        return hasattr(self, 'pagination')

    def paginate(self, endpoint, **kwargs):
        """Iterate over the responses of an operation.

        This will return an iterator with each element
        being a tuple of (``http_response``, ``parsed_response``).
        If the operation does not paginate, a ``TypeError`` will
        be raised.  You can check if an operation can be paginated
        by using the ``can_paginate`` arg.
        """
        if not self.can_paginate:
            raise TypeError("Operation cannot be paginated: %s" % self)
        paginator = self._paginator_cls(self)
        return paginator.paginate(endpoint, **kwargs)

    @property
    def params(self):
        if self._params is None:
            self._params = self._create_parameter_objects()
        return self._params

    def _create_parameter_objects(self):
        """
        Build the list of Parameter objects for this operation.
        """
        logger.debug("Creating parameter objects for: %s", self)
        params = []
        if self.input and 'members' in self.input:
            for name, data in self.input['members'].items():
                param = get_parameter(self, name, data)
                params.append(param)
        return params

    def _find_payload(self):
        """
        Searches the parameters for an operation to find the payload
        parameter, if it exists.  Returns that param or None.
        """
        payload = None
        for param in self.params:
            if hasattr(param, 'payload') and param.payload:
                payload = param
                break
        return payload

    def _get_built_params(self):
        d = {}
        if self.service.type in ('rest-xml', 'rest-json'):
            d['uri_params'] = {}
            d['headers'] = {}
            if self.service.type == 'rest-xml':
                payload = self._find_payload()
                if payload and payload.type in ('blob', 'string'):
                    # If we have a payload parameter which is a scalar
                    # type (either string or blob) it means we need a
                    # simple payload object rather than an XMLPayload.
                    d['payload'] = Payload()
                else:
                    # Otherwise, use an XMLPayload.  Since Route53
                    # doesn't actually use the payload attribute, we
                    # have to err on the safe side.
                    namespace = self.service.xmlnamespace
                    root_element_name = None
                    if self.input and 'shape_name' in self.input:
                        root_element_name = self.input['shape_name']
                    d['payload'] = XMLPayload(root_element_name=root_element_name,
                                              namespace=namespace)
            else:
                d['payload'] = JSONPayload()
        return d

    def build_parameters(self, **kwargs):
        """
        Returns a dictionary containing the kwargs for the
        given operation formatted as required to pass to the service
        in a request.
        """
        built_params = self._get_built_params()
        missing = []
        kwargs = self._camel_to_snake_case(kwargs)
        self._check_for_unknown_params(kwargs)
        for param in self.params:
            if param.required:
                missing.append(param)
            if param.py_name in kwargs:
                if missing:
                    missing.pop()
                param.build_parameter(self.service.type,
                                      kwargs[param.py_name],
                                      built_params)
        if missing:
            missing_str = ', '.join([p.py_name for p in missing])
            raise MissingParametersError(missing=missing_str,
                                         object_name=self)
        return built_params

    def _camel_to_snake_case(self, kwargs):
        """
        Converts top level keys in `kwargs` from camel case to snake case
        """
        params = {}
        for key, value in kwargs.items():
            params[xform_name(key)] = value
        return params

    def _check_for_unknown_params(self, kwargs):
        valid_names = [p.py_name for p in self.params]
        for key in kwargs:
            if key not in valid_names:
                raise UnknownParameterError(name=key, operation=self,
                                            choices=', '.join(valid_names))

    def is_streaming(self):
        is_streaming = False
        if self.output:
            for member_name in self.output['members']:
                member_dict = self.output['members'][member_name]
                if member_dict['type'] == 'blob':
                    if member_dict.get('payload', False):
                        if member_dict.get('streaming', False):
                            is_streaming = member_dict.get('xmlname',
                                                           member_name)
        return is_streaming
