pplx.py

"""PerplexityChat wrapper."""
from __future__ import annotations

import logging
from typing import (
    Any,
    AsyncIterator,
    Callable,
    Dict,
    Iterator,
    List,
    Mapping,
    Optional,
    Tuple,
    Type,
    Union,
)

from tenacity import (
    before_sleep_log,
    retry,
    retry_if_exception_type,
    stop_after_attempt,
    wait_exponential,
)

from langchain.callbacks.manager import (
    AsyncCallbackManagerForLLMRun,
    CallbackManagerForLLMRun,
)
from langchain.chat_models.base import (
    BaseChatModel,
    _agenerate_from_stream,
    _generate_from_stream,
)
from langchain.pydantic_v1 import Field, root_validator
from langchain.schema import (
    AIMessage,
    BaseMessage,
    ChatGeneration,
    ChatMessage,
    ChatResult,
    FunctionMessage,
    HumanMessage,
    SystemMessage,
)
from langchain.schema.messages import (
    AIMessageChunk,
    BaseMessageChunk,
    ChatMessageChunk,
    HumanMessageChunk,
    SystemMessageChunk,
)
from langchain.schema.output import ChatGenerationChunk
from langchain.utils import get_from_dict_or_env, get_pydantic_field_names

logger = logging.getLogger(__name__)


def _create_retry_decorator(llm: PerplexityChat) -> Callable[[Any], Any]:
    import openai

    min_seconds = 1
    max_seconds = 60
    # Wait 2^x * 1 second between each retry starting with
    # 4 seconds, then up to 10 seconds, then 10 seconds afterwards
    return retry(
        reraise=True,
        stop=stop_after_attempt(llm.max_retries),
        wait=wait_exponential(multiplier=1, min=min_seconds, max=max_seconds),
        retry=(
                retry_if_exception_type(openai.error.Timeout)
                | retry_if_exception_type(openai.error.APIError)
                | retry_if_exception_type(openai.error.APIConnectionError)
                | retry_if_exception_type(openai.error.RateLimitError)
                | retry_if_exception_type(openai.error.ServiceUnavailableError)
        ),
        before_sleep=before_sleep_log(logger, logging.WARNING),
    )


async def acompletion_with_retry(llm: PerplexityChat, **kwargs: Any) -> Any:
    """Use tenacity to retry the async completion call."""
    retry_decorator = _create_retry_decorator(llm)

    @retry_decorator
    async def _completion_with_retry(**kwargs: Any) -> Any:
        # Use OpenAI's async api https://github.com/openai/openai-python#async-api
        return await llm.client.acreate(**kwargs)

    return await _completion_with_retry(**kwargs)


def _convert_delta_to_message_chunk(
        _dict: Mapping[str, Any], default_class: Type[BaseMessageChunk]
) -> BaseMessageChunk:
    role = _dict.get("role")
    content = _dict.get("content") or ""

    if role == "user" or default_class == HumanMessageChunk:
        return HumanMessageChunk(content=content)
    elif role == "assistant" or default_class == AIMessageChunk:
        return AIMessageChunk(content=content)
    elif role == "system" or default_class == SystemMessageChunk:
        return SystemMessageChunk(content=content)
    elif role or default_class == ChatMessageChunk:
        return ChatMessageChunk(content=content, role=role)
    else:
        return default_class(content=content)


def _convert_dict_to_message(_dict: Mapping[str, Any]) -> BaseMessage:
    role = _dict["role"]
    if role == "user":
        return HumanMessage(content=_dict["content"])
    elif role == "assistant":
        content = _dict["content"] or ""
        return AIMessage(content=content)
    elif role == "system":
        return SystemMessage(content=_dict["content"])
    else:
        return ChatMessage(content=_dict["content"], role=role)


def _convert_message_to_dict(message: BaseMessage) -> dict:
    if isinstance(message, ChatMessage):
        message_dict = {"role": message.role, "content": message.content}
    elif isinstance(message, HumanMessage):
        message_dict = {"role": "user", "content": message.content}
    elif isinstance(message, AIMessage):
        message_dict = {"role": "assistant", "content": message.content}
    elif isinstance(message, SystemMessage):
        message_dict = {"role": "system", "content": message.content}
    elif isinstance(message, FunctionMessage):
        message_dict = {
            "role": "function",
            "name": message.name,
            "content": message.content,
        }
    else:
        raise ValueError(f"Got unknown type {message}")
    if "name" in message.additional_kwargs:
        message_dict["name"] = message.additional_kwargs["name"]
    return message_dict


class PerplexityChat(BaseChatModel):
    """`Perplexity AI` Chat models API.

    To use, you should have the ``openai`` python package installed, and the
    environment variable ``PPLX_API_KEY`` set to your API key, which you
    can generate at https://www.perplexity.ai.

    Any parameters that are valid to be passed to the openai.create call can be passed
    in, even if not explicitly saved on this class.

    Example:
        .. code-block:: python

            from langchain.chat_models import PerplexityChat
            chat = PerplexityChat()
    """

    @property
    def lc_secrets(self) -> Dict[str, str]:
        return {"pplx_api_key": "PPLX_API_KEY"}

    @classmethod
    def is_lc_serializable(cls) -> bool:
        """Return whether this model can be serialized by Langchain."""
        return True

    client: Any  #: :meta private:
    temperature: float = 0.7
    """What sampling temperature to use."""
    model_kwargs: Dict[str, Any] = Field(default_factory=dict)
    """Holds any model parameters valid for `create` call not explicitly specified."""
    pplx_api_key: Optional[str] = None
    """Base URL path for API requests, 
    leave blank if not using a proxy or service emulator."""
    request_timeout: Optional[Union[float, Tuple[float, float]]] = None
    """Timeout for requests to PerplexityChat completion API. Default is 600 seconds."""
    max_retries: int = 6
    """Maximum number of retries to make when generating."""
    streaming: bool = False
    """Whether to stream the results or not."""
    max_tokens: Optional[int] = None
    """Maximum number of tokens to generate."""
    model_name: str = Field(default="mistral-7b-instruct", alias="model")


    class Config:
        """Configuration for this pydantic object."""

        allow_population_by_field_name = True

    @root_validator(pre=True)
    def build_extra(cls, values: Dict[str, Any]) -> Dict[str, Any]:
        """Build extra kwargs from additional params that were passed in."""
        all_required_field_names = get_pydantic_field_names(cls)
        extra = values.get("model_kwargs", {})
        for field_name in list(values):
            if field_name in extra:
                raise ValueError(f"Found {field_name} supplied twice.")
            if field_name not in all_required_field_names:
                logger.warning(
                    f"""WARNING! {field_name} is not a default parameter.
                    {field_name} was transferred to model_kwargs.
                    Please confirm that {field_name} is what you intended."""
                )
                extra[field_name] = values.pop(field_name)

        invalid_model_kwargs = all_required_field_names.intersection(extra.keys())
        if invalid_model_kwargs:
            raise ValueError(
                f"Parameters {invalid_model_kwargs} should be specified explicitly. "
                f"Instead they were passed in as part of `model_kwargs` parameter."
            )

        values["model_kwargs"] = extra
        return values

    @root_validator()
    def validate_environment(cls, values: Dict) -> Dict:
        """Validate that api key and python package exists in environment."""
        values["pplx_api_key"] = get_from_dict_or_env(
            values, "pplx_api_key", "PPLX_API_KEY"
        )
        try:
            import openai

        except ImportError:
            raise ValueError(
                "Could not import openai python package. "
                "Please install it with `pip install openai`."
            )
        try:
            values["client"] = openai.ChatCompletion
        except AttributeError:
            raise ValueError(
                "`openai` has no `ChatCompletion` attribute, this is likely "
                "due to an old version of the openai package. Try upgrading it "
                "with `pip install --upgrade openai`."
            )
        return values

    @property
    def _default_params(self) -> Dict[str, Any]:
        """Get the default parameters for calling PerplexityChat API."""
        return {
            "request_timeout": self.request_timeout,
            "max_tokens": self.max_tokens,
            "stream": self.streaming,
            "temperature": self.temperature,
            **self.model_kwargs,
        }

    def _create_retry_decorator(self) -> Callable[[Any], Any]:
        import openai

        min_seconds = 1
        max_seconds = 60
        # Wait 2^x * 1 second between each retry starting with
        # 4 seconds, then up to 10 seconds, then 10 seconds afterwards
        return retry(
            reraise=True,
            stop=stop_after_attempt(self.max_retries),
            wait=wait_exponential(multiplier=1, min=min_seconds, max=max_seconds),
            retry=(
                    retry_if_exception_type(openai.error.Timeout)
                    | retry_if_exception_type(openai.error.APIError)
                    | retry_if_exception_type(openai.error.APIConnectionError)
                    | retry_if_exception_type(openai.error.RateLimitError)
                    | retry_if_exception_type(openai.error.ServiceUnavailableError)
            ),
            before_sleep=before_sleep_log(logger, logging.WARNING),
        )

    def completion_with_retry(self, **kwargs: Any) -> Any:
        """Use tenacity to retry the completion call."""
        retry_decorator = self._create_retry_decorator()

        @retry_decorator
        def _completion_with_retry(**kwargs: Any) -> Any:
            # Remove the line below that sets custom stop words
            kwargs.pop("stop", None)
            return self.client.create(**kwargs)

        return _completion_with_retry(**kwargs)

    def _combine_llm_outputs(self, llm_outputs: List[Optional[dict]]) -> dict:
        overall_token_usage: dict = {}
        for output in llm_outputs:
            if output is None:
                # Happens in streaming
                continue
            token_usage = output["token_usage"]
            for k, v in token_usage.items():
                if k in overall_token_usage:
                    overall_token_usage[k] += v
                else:
                    overall_token_usage[k] = v
        return {"token_usage": overall_token_usage}

    def _stream(
            self,
            messages: List[BaseMessage],
            stop: Optional[List[str]] = None,
            run_manager: Optional[CallbackManagerForLLMRun] = None,
            **kwargs: Any,
    ) -> Iterator[ChatGenerationChunk]:
        message_dicts, params = self._create_message_dicts(messages, stop)
        params = {**params, **kwargs, "stream": True}

        default_chunk_class = AIMessageChunk
        for chunk in self.completion_with_retry(messages=message_dicts, **params):
            delta = chunk["choices"][0]["delta"]
            chunk = _convert_delta_to_message_chunk(delta, default_chunk_class)
            default_chunk_class = chunk.__class__
            yield ChatGenerationChunk(message=chunk)
            if run_manager:
                run_manager.on_llm_new_token(chunk.content)

    def _generate(
            self,
            messages: List[BaseMessage],
            stop: Optional[List[str]] = None,
            run_manager: Optional[CallbackManagerForLLMRun] = None,
            **kwargs: Any,
    ) -> ChatResult:
        if self.streaming:
            stream_iter = self._stream(
                messages=messages, stop=stop, run_manager=run_manager, **kwargs
            )
            return _generate_from_stream(stream_iter)

        message_dicts, params = self._create_message_dicts(messages, stop)
        params = {**params, **kwargs}
        response = self.completion_with_retry(messages=message_dicts, **params)
        return self._create_chat_result(response)

    def _create_message_dicts(
            self, messages: List[BaseMessage], stop: Optional[List[str]]
    ) -> Tuple[List[Dict[str, Any]], Dict[str, Any]]:
        params = dict(self._invocation_params)
        if stop is not None:
            if "stop" in params:
                raise ValueError("`stop` found in both the input and default params.")
            params["stop"] = stop
        message_dicts = [_convert_message_to_dict(m) for m in messages]
        return message_dicts, params

    def _create_chat_result(self, response: Mapping[str, Any]) -> ChatResult:
        generations = []
        for res in response["choices"]:
            message = _convert_dict_to_message(res["message"])
            gen = ChatGeneration(message=message)
            generations.append(gen)
        llm_output = {"token_usage": response["usage"]}
        return ChatResult(generations=generations, llm_output=llm_output)

    async def _astream(
            self,
            messages: List[BaseMessage],
            stop: Optional[List[str]] = None,
            run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
            **kwargs: Any,
    ) -> AsyncIterator[ChatGenerationChunk]:
        message_dicts, params = self._create_message_dicts(messages, stop)
        params = {**params, **kwargs, "stream": True}

        default_chunk_class = AIMessageChunk
        async for chunk in await acompletion_with_retry(
                self, messages=message_dicts, **params
        ):
            delta = chunk["choices"][0]["delta"]
            chunk = _convert_delta_to_message_chunk(delta, default_chunk_class)
            default_chunk_class = chunk.__class__
            yield ChatGenerationChunk(message=chunk)
            if run_manager:
                await run_manager.on_llm_new_token(chunk.content)

    async def _agenerate(
            self,
            messages: List[BaseMessage],
            stop: Optional[List[str]] = None,
            run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
            **kwargs: Any,
    ) -> ChatResult:
        if self.streaming:
            stream_iter = self._astream(
                messages=messages, stop=stop, run_manager=run_manager, **kwargs
            )
            return await _agenerate_from_stream(stream_iter)

        message_dicts, params = self._create_message_dicts(messages, stop)
        params = {**params, **kwargs}
        response = await acompletion_with_retry(self, messages=message_dicts, **params)
        return self._create_chat_result(response)

    @property
    def _invocation_params(self) -> Mapping[str, Any]:
        """Get the parameters used to invoke the model."""
        pplx_creds: Dict[str, Any] = {
            "api_key": self.pplx_api_key,
            "api_base": "https://api.perplexity.ai",
            "model": "mistral-7b-instruct",
        }
        return {**pplx_creds, **self._default_params}

    @property
    def _llm_type(self) -> str:
        """Return type of chat model."""
        return "perplexitychat"

    def __init__(self, model_name, temperature, verbose, **kwargs):
        super().__init__(**kwargs)
        self.model_name = model_name
        self.temperature = temperature
        self.verbose = verbose