langchain/libs/experimental/langchain_experimental/comprehend_moderation/base_moderation.py

import uuid
from typing import Any, Callable, Optional, cast

from langchain.callbacks.manager import CallbackManagerForChainRun
from langchain_core.messages import AIMessage, HumanMessage
from langchain_core.prompt_values import ChatPromptValue, StringPromptValue

from langchain_experimental.comprehend_moderation.pii import ComprehendPII
from langchain_experimental.comprehend_moderation.prompt_safety import (
    ComprehendPromptSafety,
)
from langchain_experimental.comprehend_moderation.toxicity import ComprehendToxicity


class BaseModeration:
    """Base class for moderation."""

    def __init__(
        self,
        client: Any,
        config: Optional[Any] = None,
        moderation_callback: Optional[Any] = None,
        unique_id: Optional[str] = None,
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ):
        self.client = client
        self.config = config
        self.moderation_callback = moderation_callback
        self.unique_id = unique_id
        self.chat_message_index = 0
        self.run_manager = run_manager
        self.chain_id = str(uuid.uuid4())

    def _convert_prompt_to_text(self, prompt: Any) -> str:
        input_text = str()

        if isinstance(prompt, StringPromptValue):
            input_text = prompt.text
        elif isinstance(prompt, str):
            input_text = prompt
        elif isinstance(prompt, ChatPromptValue):
            """
            We will just check the last message in the message Chain of a
            ChatPromptTemplate. The typical chronology is
            SystemMessage > HumanMessage > AIMessage and so on. However assuming
            that with every chat the chain is invoked we will only check the last
            message. This is assuming that all previous messages have been checked
            already. Only HumanMessage and AIMessage will be checked. We can perhaps
            loop through and take advantage of the additional_kwargs property in the
            HumanMessage and AIMessage schema to mark messages that have been moderated.
            However that means that this class could generate multiple text chunks
            and moderate() logics would need to be updated. This also means some
            complexity in re-constructing the prompt while keeping the messages in
            sequence.
            """
            message = prompt.messages[-1]
            self.chat_message_index = len(prompt.messages) - 1
            if isinstance(message, HumanMessage):
                input_text = cast(str, message.content)

            if isinstance(message, AIMessage):
                input_text = cast(str, message.content)
        else:
            raise ValueError(
                f"Invalid input type {type(input_text)}. "
                "Must be a PromptValue, str, or list of BaseMessages."
            )
        return input_text

    def _convert_text_to_prompt(self, prompt: Any, text: str) -> Any:
        if isinstance(prompt, StringPromptValue):
            return StringPromptValue(text=text)
        elif isinstance(prompt, str):
            return text
        elif isinstance(prompt, ChatPromptValue):
            # Copy the messages because we may need to mutate them.
            # We don't want to mutate data we don't own.
            messages = list(prompt.messages)

            message = messages[self.chat_message_index]

            if isinstance(message, HumanMessage):
                messages[self.chat_message_index] = HumanMessage(
                    content=text,
                    example=message.example,
                    additional_kwargs=message.additional_kwargs,
                )
            if isinstance(message, AIMessage):
                messages[self.chat_message_index] = AIMessage(
                    content=text,
                    example=message.example,
                    additional_kwargs=message.additional_kwargs,
                )
            return ChatPromptValue(messages=messages)
        else:
            raise ValueError(
                f"Invalid input type {type(input)}. "
                "Must be a PromptValue, str, or list of BaseMessages."
            )

    def _moderation_class(self, moderation_class: Any) -> Callable:
        return moderation_class(
            client=self.client,
            callback=self.moderation_callback,
            unique_id=self.unique_id,
            chain_id=self.chain_id,
        ).validate

    def _log_message_for_verbose(self, message: str) -> None:
        if self.run_manager:
            self.run_manager.on_text(message)

    def moderate(self, prompt: Any) -> str:
        """Moderate the input prompt."""

        from langchain_experimental.comprehend_moderation.base_moderation_config import (  # noqa: E501
            ModerationPiiConfig,
            ModerationPromptSafetyConfig,
            ModerationToxicityConfig,
        )
        from langchain_experimental.comprehend_moderation.base_moderation_exceptions import (  # noqa: E501
            ModerationPiiError,
            ModerationPromptSafetyError,
            ModerationToxicityError,
        )

        try:
            # convert prompt to text
            input_text = self._convert_prompt_to_text(prompt=prompt)
            output_text = str()

            # perform moderation
            filter_functions = {
                "pii": ComprehendPII,
                "toxicity": ComprehendToxicity,
                "prompt_safety": ComprehendPromptSafety,
            }

            filters = self.config.filters  # type: ignore

            for _filter in filters:
                filter_name = (
                    "pii"
                    if isinstance(_filter, ModerationPiiConfig)
                    else (
                        "toxicity"
                        if isinstance(_filter, ModerationToxicityConfig)
                        else (
                            "prompt_safety"
                            if isinstance(_filter, ModerationPromptSafetyConfig)
                            else None
                        )
                    )
                )
                if filter_name in filter_functions:
                    self._log_message_for_verbose(
                        f"Running {filter_name} Validation...\n"
                    )
                    validation_fn = self._moderation_class(
                        moderation_class=filter_functions[filter_name]
                    )
                    input_text = input_text if not output_text else output_text
                    output_text = validation_fn(
                        prompt_value=input_text,
                        config=_filter.dict(),
                    )

            # convert text to prompt and return
            return self._convert_text_to_prompt(prompt=prompt, text=output_text)

        except ModerationPiiError as e:
            self._log_message_for_verbose(f"Found PII content..stopping..\n{str(e)}\n")
            raise e
        except ModerationToxicityError as e:
            self._log_message_for_verbose(
                f"Found Toxic content..stopping..\n{str(e)}\n"
            )
            raise e
        except ModerationPromptSafetyError as e:
            self._log_message_for_verbose(
                f"Found Harmful intention..stopping..\n{str(e)}\n"
            )
            raise e
        except Exception as e:
            raise e