semantic-kernel/python/semantic_kernel/kernel.py

# Copyright (c) Microsoft. All rights reserved.

import logging
from collections.abc import AsyncGenerator, AsyncIterable
from copy import copy
from typing import TYPE_CHECKING, Any, Literal, TypeVar

from semantic_kernel.const import METADATA_EXCEPTION_KEY
from semantic_kernel.contents.chat_history import ChatHistory
from semantic_kernel.contents.function_call_content import FunctionCallContent
from semantic_kernel.contents.function_result_content import FunctionResultContent
from semantic_kernel.contents.streaming_content_mixin import StreamingContentMixin
from semantic_kernel.exceptions import (
    FunctionCallInvalidArgumentsException,
    FunctionExecutionException,
    KernelFunctionNotFoundError,
    KernelInvokeException,
    OperationCancelledException,
    TemplateSyntaxError,
)
from semantic_kernel.filters.auto_function_invocation.auto_function_invocation_context import (
    AutoFunctionInvocationContext,
)
from semantic_kernel.filters.filter_types import FilterTypes
from semantic_kernel.filters.kernel_filters_extension import (
    KernelFilterExtension,
    _rebuild_auto_function_invocation_context,
)
from semantic_kernel.functions.function_result import FunctionResult
from semantic_kernel.functions.kernel_arguments import KernelArguments
from semantic_kernel.functions.kernel_function_extension import KernelFunctionExtension
from semantic_kernel.functions.kernel_function_from_prompt import KernelFunctionFromPrompt
from semantic_kernel.functions.kernel_plugin import KernelPlugin
from semantic_kernel.kernel_types import AI_SERVICE_CLIENT_TYPE
from semantic_kernel.prompt_template.const import KERNEL_TEMPLATE_FORMAT_NAME
from semantic_kernel.reliability.kernel_reliability_extension import KernelReliabilityExtension
from semantic_kernel.services.ai_service_selector import AIServiceSelector
from semantic_kernel.services.kernel_services_extension import KernelServicesExtension
from semantic_kernel.utils.naming import generate_random_ascii_name

if TYPE_CHECKING:
    from semantic_kernel.connectors.ai.function_choice_behavior import (
        FunctionChoiceBehavior,
    )
    from semantic_kernel.functions.kernel_function import KernelFunction

T = TypeVar("T")


logger: logging.Logger = logging.getLogger(__name__)


class Kernel(KernelFilterExtension, KernelFunctionExtension, KernelServicesExtension, KernelReliabilityExtension):
    """The main Kernel class of Semantic Kernel.

    This is the main entry point for the Semantic Kernel. It provides the ability to run
    semantic/native functions, and manage plugins, memory, and AI services.

    Attributes:
        plugins (dict[str, KernelPlugin] | None): The plugins to be used by the kernel
        services (dict[str, AIServiceClientBase]): The services to be used by the kernel
        ai_service_selector (AIServiceSelector): The AI service selector to be used by the kernel
        retry_mechanism (RetryMechanismBase): The retry mechanism to be used by the kernel
    """

    def __init__(
        self,
        plugins: KernelPlugin | dict[str, KernelPlugin] | list[KernelPlugin] | None = None,
        services: (
            AI_SERVICE_CLIENT_TYPE | list[AI_SERVICE_CLIENT_TYPE] | dict[str, AI_SERVICE_CLIENT_TYPE] | None
        ) = None,
        ai_service_selector: AIServiceSelector | None = None,
        **kwargs: Any,
    ) -> None:
        """Initialize a new instance of the Kernel class.

        Args:
            plugins (KernelPlugin | dict[str, KernelPlugin] | list[KernelPlugin] | None):
                The plugins to be used by the kernel, will be rewritten to a dict with plugin name as key
            services (AIServiceClientBase | list[AIServiceClientBase] | dict[str, AIServiceClientBase] | None):
                The services to be used by the kernel, will be rewritten to a dict with service_id as key
            ai_service_selector (AIServiceSelector | None):
                The AI service selector to be used by the kernel,
                default is based on order of execution settings.
            **kwargs (Any): Additional fields to be passed to the Kernel model,
                these are limited to retry_mechanism and function_invoking_handlers
                and function_invoked_handlers, the best way to add function_invoking_handlers
                and function_invoked_handlers is to use the add_function_invoking_handler
                and add_function_invoked_handler methods.
        """
        args = {
            "services": services,
            "plugins": plugins,
            **kwargs,
        }
        if ai_service_selector:
            args["ai_service_selector"] = ai_service_selector
        super().__init__(**args)

    async def invoke_stream(
        self,
        function: "KernelFunction | None" = None,
        arguments: KernelArguments | None = None,
        function_name: str | None = None,
        plugin_name: str | None = None,
        metadata: dict[str, Any] = {},
        return_function_results: bool = False,
        **kwargs: Any,
    ) -> AsyncGenerator[list["StreamingContentMixin"] | FunctionResult | list[FunctionResult], Any]:
        """Execute one or more stream functions.

        This will execute the functions in the order they are provided, if a list of functions is provided.
        When multiple functions are provided only the last one is streamed, the rest is executed as a pipeline.

        Args:
            function (KernelFunction): The function to execute,
                this value has precedence when supplying both this and using function_name and plugin_name,
                if this is none, function_name and plugin_name are used and cannot be None.
            arguments (KernelArguments | None): The arguments to pass to the function(s), optional
            function_name (str | None): The name of the function to execute
            plugin_name (str | None): The name of the plugin to execute
            metadata (dict[str, Any]): The metadata to pass to the function(s)
            return_function_results (bool): If True, the function results are yielded as a list[FunctionResult]
            in addition to the streaming content, otherwise only the streaming content is yielded.
            kwargs (dict[str, Any]): arguments that can be used instead of supplying KernelArguments

        Yields:
            StreamingContentMixin: The content of the stream of the last function provided.
        """
        if arguments is None:
            arguments = KernelArguments(**kwargs)
        else:
            arguments.update(kwargs)
        if not function:
            if not function_name or not plugin_name:
                raise KernelFunctionNotFoundError("No function(s) or function- and plugin-name provided")
            function = self.get_function(plugin_name, function_name)

        function_result: list[list["StreamingContentMixin"] | Any] = []

        async for stream_message in function.invoke_stream(self, arguments):
            if isinstance(stream_message, FunctionResult) and (
                exception := stream_message.metadata.get(METADATA_EXCEPTION_KEY, None)
            ):
                raise KernelInvokeException(
                    f"Error occurred while invoking function: '{function.fully_qualified_name}'"
                ) from exception
            function_result.append(stream_message)
            yield stream_message

        if return_function_results:
            output_function_result: list["StreamingContentMixin"] = []
            for result in function_result:
                for choice in result:
                    if not isinstance(choice, StreamingContentMixin):
                        continue
                    if len(output_function_result) <= choice.choice_index:
                        output_function_result.append(copy(choice))
                    else:
                        output_function_result[choice.choice_index] += choice
            yield FunctionResult(function=function.metadata, value=output_function_result)

    async def invoke(
        self,
        function: "KernelFunction | None" = None,
        arguments: KernelArguments | None = None,
        function_name: str | None = None,
        plugin_name: str | None = None,
        metadata: dict[str, Any] = {},
        **kwargs: Any,
    ) -> FunctionResult | None:
        """Execute a function and return the FunctionResult.

        Args:
            function (KernelFunction): The function or functions to execute,
                this value has precedence when supplying both this and using function_name and plugin_name,
                if this is none, function_name and plugin_name are used and cannot be None.
            arguments (KernelArguments): The arguments to pass to the function(s), optional
            function_name (str | None): The name of the function to execute
            plugin_name (str | None): The name of the plugin to execute
            metadata (dict[str, Any]): The metadata to pass to the function(s)
            kwargs (dict[str, Any]): arguments that can be used instead of supplying KernelArguments

        Raises:
            KernelInvokeException: If an error occurs during function invocation

        """
        if arguments is None:
            arguments = KernelArguments(**kwargs)
        else:
            arguments.update(kwargs)
        if not function:
            if not function_name or not plugin_name:
                raise KernelFunctionNotFoundError("No function, or function name and plugin name provided")
            function = self.get_function(plugin_name, function_name)

        try:
            return await function.invoke(kernel=self, arguments=arguments, metadata=metadata)
        except OperationCancelledException as exc:
            logger.info(f"Operation cancelled during function invocation. Message: {exc}")
            return None
        except Exception as exc:
            logger.error(
                "Something went wrong in function invocation. During function invocation:"
                f" '{function.fully_qualified_name}'. Error description: '{exc!s}'"
            )
            raise KernelInvokeException(
                f"Error occurred while invoking function: '{function.fully_qualified_name}'"
            ) from exc

    async def invoke_prompt(
        self,
        prompt: str,
        function_name: str | None = None,
        plugin_name: str | None = None,
        arguments: KernelArguments | None = None,
        template_format: Literal[
            "semantic-kernel",
            "handlebars",
            "jinja2",
        ] = KERNEL_TEMPLATE_FORMAT_NAME,
        **kwargs: Any,
    ) -> FunctionResult | None:
        """Invoke a function from the provided prompt.

        Args:
            prompt (str): The prompt to use
            function_name (str): The name of the function, optional
            plugin_name (str): The name of the plugin, optional
            arguments (KernelArguments | None): The arguments to pass to the function(s), optional
            template_format (str | None): The format of the prompt template
            kwargs (dict[str, Any]): arguments that can be used instead of supplying KernelArguments

        Returns:
            FunctionResult | list[FunctionResult] | None: The result of the function(s)
        """
        if not arguments:
            arguments = KernelArguments(**kwargs)
        if not prompt:
            raise TemplateSyntaxError("The prompt is either null or empty.")

        function = KernelFunctionFromPrompt(
            function_name=function_name or generate_random_ascii_name(),
            plugin_name=plugin_name,
            prompt=prompt,
            template_format=template_format,
        )
        return await self.invoke(function=function, arguments=arguments)

    async def invoke_prompt_stream(
        self,
        prompt: str,
        function_name: str | None = None,
        plugin_name: str | None = None,
        arguments: KernelArguments | None = None,
        template_format: Literal[
            "semantic-kernel",
            "handlebars",
            "jinja2",
        ] = KERNEL_TEMPLATE_FORMAT_NAME,
        return_function_results: bool | None = False,
        **kwargs: Any,
    ) -> AsyncIterable[list["StreamingContentMixin"] | FunctionResult | list[FunctionResult]]:
        """Invoke a function from the provided prompt and stream the results.

        Args:
            prompt (str): The prompt to use
            function_name (str): The name of the function, optional
            plugin_name (str): The name of the plugin, optional
            arguments (KernelArguments | None): The arguments to pass to the function(s), optional
            template_format (str | None): The format of the prompt template
            return_function_results (bool): If True, the function results are yielded as a list[FunctionResult]
            kwargs (dict[str, Any]): arguments that can be used instead of supplying KernelArguments

        Returns:
            AsyncIterable[StreamingContentMixin]: The content of the stream of the last function provided.
        """
        if not arguments:
            arguments = KernelArguments(**kwargs)
        if not prompt:
            raise TemplateSyntaxError("The prompt is either null or empty.")

        from semantic_kernel.functions.kernel_function_from_prompt import KernelFunctionFromPrompt

        function = KernelFunctionFromPrompt(
            function_name=function_name or generate_random_ascii_name(),
            plugin_name=plugin_name,
            prompt=prompt,
            template_format=template_format,
        )

        function_result: list[list["StreamingContentMixin"] | Any] = []

        async for stream_message in self.invoke_stream(function=function, arguments=arguments):
            if isinstance(stream_message, FunctionResult) and (
                exception := stream_message.metadata.get(METADATA_EXCEPTION_KEY, None)
            ):
                raise KernelInvokeException(
                    f"Error occurred while invoking function: '{function.fully_qualified_name}'"
                ) from exception
            function_result.append(stream_message)
            yield stream_message

        if return_function_results:
            output_function_result: list["StreamingContentMixin"] = []
            for result in function_result:
                for choice in result:
                    if not isinstance(choice, StreamingContentMixin):
                        continue
                    if len(output_function_result) <= choice.choice_index:
                        output_function_result.append(copy(choice))
                    else:
                        output_function_result[choice.choice_index] += choice
            yield FunctionResult(function=function.metadata, value=output_function_result)

    async def invoke_function_call(
        self,
        function_call: FunctionCallContent,
        chat_history: ChatHistory,
        arguments: "KernelArguments | None" = None,
        function_call_count: int | None = None,
        request_index: int | None = None,
        function_behavior: "FunctionChoiceBehavior" = None,  # type: ignore
    ) -> "AutoFunctionInvocationContext | None":
        """Processes the provided FunctionCallContent and updates the chat history."""
        args_cloned = copy(arguments) if arguments else KernelArguments()
        try:
            parsed_args = function_call.to_kernel_arguments()
            if parsed_args:
                args_cloned.update(parsed_args)
        except (FunctionCallInvalidArgumentsException, TypeError) as exc:
            logger.info(f"Received invalid arguments for function {function_call.name}: {exc}. Trying tool call again.")
            frc = FunctionResultContent.from_function_call_content_and_result(
                function_call_content=function_call,
                result="The tool call arguments are malformed. Arguments must be in JSON format. Please try again.",
            )
            chat_history.add_message(message=frc.to_chat_message_content())
            return None

        try:
            if function_call.name is None:
                raise FunctionExecutionException("The function name is required.")
            if function_behavior is not None and function_behavior.filters:
                allowed_functions = [
                    func.fully_qualified_name for func in self.get_list_of_function_metadata(function_behavior.filters)
                ]
                if function_call.name not in allowed_functions:
                    raise FunctionExecutionException(
                        f"Only functions: {allowed_functions} are allowed, {function_call.name} is not allowed."
                    )
            function_to_call = self.get_function(function_call.plugin_name, function_call.function_name)
        except Exception as exc:
            logger.exception(f"The function `{function_call.name}` is not part of the provided functions: {exc}.")
            frc = FunctionResultContent.from_function_call_content_and_result(
                function_call_content=function_call,
                result=(
                    f"The tool call with name `{function_call.name}` is not part of the provided tools, "
                    "please try again with a supplied tool call name and make sure to validate the name."
                ),
            )
            chat_history.add_message(message=frc.to_chat_message_content())
            return None

        num_required_func_params = len([param for param in function_to_call.parameters if param.is_required])
        if parsed_args is None or len(parsed_args) < num_required_func_params:
            msg = (
                f"There are `{num_required_func_params}` tool call arguments required and "
                f"only `{len(parsed_args) if parsed_args is not None else 0}` received. The required arguments are: "
                f"{[param.name for param in function_to_call.parameters if param.is_required]}. "
                "Please provide the required arguments and try again."
            )
            logger.info(msg)
            frc = FunctionResultContent.from_function_call_content_and_result(
                function_call_content=function_call,
                result=msg,
            )
            chat_history.add_message(message=frc.to_chat_message_content())
            return None

        logger.info(f"Calling {function_call.name} function with args: {function_call.arguments}")

        _rebuild_auto_function_invocation_context()
        invocation_context = AutoFunctionInvocationContext(
            function=function_to_call,
            kernel=self,
            arguments=args_cloned,
            chat_history=chat_history,
            function_result=FunctionResult(function=function_to_call.metadata, value=None),
            function_count=function_call_count or 0,
            request_sequence_index=request_index or 0,
        )
        if function_call.index is not None:
            invocation_context.function_sequence_index = function_call.index

        stack = self.construct_call_stack(
            filter_type=FilterTypes.AUTO_FUNCTION_INVOCATION,
            inner_function=self._inner_auto_function_invoke_handler,
        )
        await stack(invocation_context)

        if invocation_context.terminate:
            return invocation_context

        frc = FunctionResultContent.from_function_call_content_and_result(
            function_call_content=function_call, result=invocation_context.function_result
        )
        chat_history.add_message(message=frc.to_chat_message_content())
        return None

    async def _inner_auto_function_invoke_handler(self, context: AutoFunctionInvocationContext):
        """Inner auto function invocation handler."""
        try:
            result = await context.function.invoke(context.kernel, context.arguments)
            if result:
                context.function_result = result
        except Exception as exc:
            logger.exception(f"Error invoking function {context.function.fully_qualified_name}: {exc}.")
            value = f"An error occurred while invoking the function {context.function.fully_qualified_name}: {exc}"
            if context.function_result is not None:
                context.function_result.value = value
            else:
                context.function_result = FunctionResult(function=context.function.metadata, value=value)
            return