hapic/hapic/decorator.py

# -*- coding: utf-8 -*-
import json

import functools
import typing
try:  # Python 3.5+
    from http import HTTPStatus
except ImportError:
    from http import client as HTTPStatus

from multidict import MultiDict
from hapic.data import HapicData
from hapic.description import ControllerDescription
from hapic.exception import ProcessException
from hapic.exception import OutputValidationException
from hapic.context import ContextInterface
from hapic.processor import ProcessorInterface
from hapic.processor import RequestParameters
from hapic.error import ErrorBuilderInterface

# TODO: Ensure usage of DECORATION_ATTRIBUTE_NAME is documented and
# var names correctly choose.  see #6
DECORATION_ATTRIBUTE_NAME = '_hapic_decoration_token'


class ControllerReference(object):
    def __init__(
        self,
        wrapper: typing.Callable[..., typing.Any],
        wrapped: typing.Callable[..., typing.Any],
        token: str,
    ) -> None:
        """
        This class is a centralization of different ways to match
        final controller with decorated function:
          - wrapper will match if final controller is the hapic returned
            wrapper
          - wrapped will match if final controller is the controller itself
          - token will match if only apposed token still exist: This case
            happen when hapic decoration is make on class function and final
            controller is the same function but as instance function.

        :param wrapper: Wrapper returned by decorator
        :param wrapped: Function wrapped by decorator
        :param token: String token set on these both functions
        """
        self.wrapper = wrapper
        self.wrapped = wrapped
        self.token = token

    def get_doc_string(self) -> str:
        if self.wrapper.__doc__:
            return self.wrapper.__doc__.strip()

        if self.wrapped.__doc__:
            return self.wrapper.__doc__.strip()

        return ''


class ControllerWrapper(object):
    def before_wrapped_func(
        self,
        func_args: typing.Tuple[typing.Any, ...],
        func_kwargs: typing.Dict[str, typing.Any],
    ) -> typing.Union[None, typing.Any]:
        pass

    def after_wrapped_function(self, response: typing.Any) -> typing.Any:
        return response

    def get_wrapper(
        self,
        func: 'typing.Callable[..., typing.Any]',
    ) -> 'typing.Callable[..., typing.Any]':
        def wrapper(*args, **kwargs) -> typing.Any:
            # Note: Design of before_wrapped_func can be to update kwargs
            # by reference here
            replacement_response = self.before_wrapped_func(args, kwargs)
            if replacement_response:
                return replacement_response

            response = self._execute_wrapped_function(func, args, kwargs)
            new_response = self.after_wrapped_function(response)
            return new_response
        return functools.update_wrapper(wrapper, func)

    def _execute_wrapped_function(
        self,
        func,
        func_args,
        func_kwargs,
    ) -> typing.Any:
        return func(*func_args, **func_kwargs)


class InputOutputControllerWrapper(ControllerWrapper):
    def __init__(
        self,
        context: typing.Union[ContextInterface, typing.Callable[[], ContextInterface]],  # nopep8
        processor: ProcessorInterface,
        error_http_code: HTTPStatus=HTTPStatus.BAD_REQUEST,
        default_http_code: HTTPStatus=HTTPStatus.OK,
    ) -> None:
        self._context = context
        self.processor = processor
        self.error_http_code = error_http_code
        self.default_http_code = default_http_code

    @property
    def context(self) -> ContextInterface:
        if callable(self._context):
            return self._context()
        return self._context


class InputControllerWrapper(InputOutputControllerWrapper):
    def before_wrapped_func(
        self,
        func_args: typing.Tuple[typing.Any, ...],
        func_kwargs: typing.Dict[str, typing.Any],
    ) -> typing.Any:
        # Retrieve hapic_data instance or create new one
        # hapic_data is given though decorators
        # Important note here: func_kwargs is update by reference !
        hapic_data = self.ensure_hapic_data(func_kwargs)
        request_parameters = self.get_request_parameters(
            func_args,
            func_kwargs,
        )

        try:
            processed_data = self.get_processed_data(request_parameters)
            self.update_hapic_data(hapic_data, processed_data)
        except ProcessException:
            error_response = self.get_error_response(request_parameters)
            return error_response

    @classmethod
    def ensure_hapic_data(
        cls,
        func_kwargs: typing.Dict[str, typing.Any],
    ) -> HapicData:
        # TODO: Permit other name than "hapic_data" ? see #7
        try:
            return func_kwargs['hapic_data']
        except KeyError:
            hapic_data = HapicData()
            func_kwargs['hapic_data'] = hapic_data
            return hapic_data

    def get_request_parameters(
        self,
        func_args: typing.Tuple[typing.Any, ...],
        func_kwargs: typing.Dict[str, typing.Any],
    ) -> RequestParameters:
        return self.context.get_request_parameters(
            *func_args,
            **func_kwargs
        )

    def get_processed_data(
        self,
        request_parameters: RequestParameters,
    ) -> typing.Any:
        parameters_data = self.get_parameters_data(request_parameters)
        processed_data = self.processor.process(parameters_data)
        return processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> dict:
        raise NotImplementedError()

    def update_hapic_data(
        self,
        hapic_data: HapicData,
        processed_data: typing.Dict[str, typing.Any],
    ) -> None:
        raise NotImplementedError()

    def get_error_response(
        self,
        request_parameters: RequestParameters,
    ) -> typing.Any:
        parameters_data = self.get_parameters_data(request_parameters)
        error = self.processor.get_validation_error(parameters_data)
        error_response = self.context.get_validation_error_response(
            error,
            http_code=self.error_http_code,
        )
        return error_response


class OutputControllerWrapper(InputOutputControllerWrapper):
    def __init__(
        self,
        context: typing.Union[ContextInterface, typing.Callable[[], ContextInterface]],  # nopep8
        processor: ProcessorInterface,
        error_http_code: HTTPStatus=HTTPStatus.INTERNAL_SERVER_ERROR,
        default_http_code: HTTPStatus=HTTPStatus.OK,
    ) -> None:
        super().__init__(
            context,
            processor,
            error_http_code,
            default_http_code,
        )

    def get_error_response(
        self,
        response: typing.Any,
    ) -> typing.Any:
        error = self.processor.get_validation_error(response)
        error_response = self.context.get_validation_error_response(
            error,
            http_code=self.error_http_code,
        )
        return error_response

    def after_wrapped_function(self, response: typing.Any) -> typing.Any:
        try:
            if self.context.by_pass_output_wrapping(response):
                return response

            processed_response = self.processor.process(response)
            prepared_response = self.context.get_response(
                json.dumps(processed_response),
                self.default_http_code,
            )
            return prepared_response
        except ProcessException:
            # TODO: ici ou ailleurs: il faut pas forcement donner le detail
            # de l'erreur (mode debug par exemple)  see #8
            error_response = self.get_error_response(response)
            return error_response


class DecoratedController(object):
    def __init__(
        self,
        reference: ControllerReference,
        description: ControllerDescription,
        name: str='',
    ) -> None:
        self._reference = reference
        self._description = description
        self._name = name

    @property
    def reference(self) -> ControllerReference:
        return self._reference

    @property
    def description(self) -> ControllerDescription:
        return self._description

    @property
    def name(self) -> str:
        return self._name


class OutputBodyControllerWrapper(OutputControllerWrapper):
    pass


class OutputHeadersControllerWrapper(OutputControllerWrapper):
    pass


class OutputFileControllerWrapper(ControllerWrapper):
    def __init__(
        self,
        output_types: typing.List[str],
        default_http_code: HTTPStatus=HTTPStatus.OK,
    ) -> None:
        self.output_types = output_types
        self.default_http_code = default_http_code


class InputPathControllerWrapper(InputControllerWrapper):
    def update_hapic_data(
        self, hapic_data: HapicData,
        processed_data: typing.Any,
    ) -> None:
        hapic_data.path = processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> dict:  # nopep8
        return request_parameters.path_parameters


class InputQueryControllerWrapper(InputControllerWrapper):
    def __init__(
        self,
        context: typing.Union[ContextInterface, typing.Callable[[], ContextInterface]],  # nopep8
        processor: ProcessorInterface,
        error_http_code: HTTPStatus=HTTPStatus.BAD_REQUEST,
        default_http_code: HTTPStatus=HTTPStatus.OK,
        as_list: typing.List[str]=None
    ) -> None:
        super().__init__(
            context,
            processor,
            error_http_code,
            default_http_code,
        )
        self.as_list = as_list or []  # FDV

    def update_hapic_data(
        self, hapic_data: HapicData,
        processed_data: typing.Any,
    ) -> None:
        hapic_data.query = processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> MultiDict:  # nopep8
        # Parameters are updated considering eventual as_list parameters
        if self.as_list:
            query_parameters = MultiDict()
            for parameter_name in request_parameters.query_parameters.keys():
                if parameter_name in query_parameters:
                    continue

                if parameter_name in self.as_list:
                    query_parameters[parameter_name] = \
                        request_parameters.query_parameters.getall(
                            parameter_name,
                        )
                else:
                    query_parameters[parameter_name] = \
                        request_parameters.query_parameters.get(
                            parameter_name,
                        )
            return query_parameters

        return request_parameters.query_parameters


class InputBodyControllerWrapper(InputControllerWrapper):
    def update_hapic_data(
        self, hapic_data: HapicData,
        processed_data: typing.Any,
    ) -> None:
        hapic_data.body = processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> dict:  # nopep8
        return request_parameters.body_parameters


class InputHeadersControllerWrapper(InputControllerWrapper):
    def update_hapic_data(
        self, hapic_data: HapicData,
        processed_data: typing.Any,
    ) -> None:
        hapic_data.headers = processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> dict:  # nopep8
        return request_parameters.header_parameters


class InputFormsControllerWrapper(InputControllerWrapper):
    def update_hapic_data(
        self, hapic_data: HapicData,
        processed_data: typing.Any,
    ) -> None:
        hapic_data.forms = processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> dict:  # nopep8
        return request_parameters.form_parameters


class InputFilesControllerWrapper(InputControllerWrapper):
    def update_hapic_data(
        self, hapic_data: HapicData,
        processed_data: typing.Any,
    ) -> None:
        hapic_data.files = processed_data

    def get_parameters_data(self, request_parameters: RequestParameters) -> dict:  # nopep8
        return request_parameters.files_parameters


class ExceptionHandlerControllerWrapper(ControllerWrapper):
    """
    This wrapper is used to wrap a controller and catch given exception if
    raised. An error will be generated in collaboration with context and
    returned.
    """
    def __init__(
        self,
        handled_exception_class: typing.Type[Exception],
        context: typing.Union[ContextInterface, typing.Callable[[], ContextInterface]],  # nopep8
        error_builder: typing.Union[ErrorBuilderInterface, typing.Callable[[], ErrorBuilderInterface]],  # nopep8
        http_code: HTTPStatus=HTTPStatus.INTERNAL_SERVER_ERROR,
    ) -> None:
        self.handled_exception_class = handled_exception_class
        self._context = context
        self.http_code = http_code
        self._error_builder = error_builder

    @property
    def context(self) -> ContextInterface:
        if callable(self._context):
            return self._context()
        return self._context

    @property
    def error_builder(self) -> ErrorBuilderInterface:
        if callable(self._error_builder):
            return self._error_builder()
        return self._error_builder

    def _execute_wrapped_function(
        self,
        func,
        func_args,
        func_kwargs,
    ) -> typing.Any:
        try:
            return super()._execute_wrapped_function(
                func,
                func_args,
                func_kwargs,
            )
        except self.handled_exception_class as exc:
            response_content = self.error_builder.build_from_exception(exc)

            # Check error format
            dumped = self.error_builder.dump(response_content).data
            unmarshall = self.error_builder.load(dumped)
            if unmarshall.errors:
                raise OutputValidationException(
                    'Validation error during dump of error response: {}'
                    .format(
                        str(unmarshall.errors)
                    )
                )

            error_response = self.context.get_response(
                json.dumps(response_content),
                self.http_code,
            )
            return error_response