import json
from typing import Any, Dict, List, Optional

from langchain_core.embeddings import Embeddings
from langchain_core.pydantic_v1 import BaseModel, Extra, root_validator

from langchain.utils import get_from_dict_or_env

DEFAULT_MODEL = "sentence-transformers/all-mpnet-base-v2"
VALID_TASKS = ("feature-extraction",)


class HuggingFaceHubEmbeddings(BaseModel, Embeddings):
    """HuggingFaceHub embedding models.

    To use, you should have the ``huggingface_hub`` python package installed, and the
    environment variable ``HUGGINGFACEHUB_API_TOKEN`` set with your API token, or pass
    it as a named parameter to the constructor.

    Example:
        .. code-block:: python

            from langchain.embeddings import HuggingFaceHubEmbeddings
            model = "sentence-transformers/all-mpnet-base-v2"
            hf = HuggingFaceHubEmbeddings(
                model=model,
                task="feature-extraction",
                huggingfacehub_api_token="my-api-key",
            )
    """

    client: Any  #: :meta private:
    model: Optional[str] = None
    """Model name to use."""
    repo_id: Optional[str] = None
    """Huggingfacehub repository id, for backward compatibility."""
    task: Optional[str] = "feature-extraction"
    """Task to call the model with."""
    model_kwargs: Optional[dict] = None
    """Keyword arguments to pass to the model."""

    huggingfacehub_api_token: Optional[str] = None

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

        extra = Extra.forbid

    @root_validator()
    def validate_environment(cls, values: Dict) -> Dict:
        """Validate that api key and python package exists in environment."""
        huggingfacehub_api_token = get_from_dict_or_env(
            values, "huggingfacehub_api_token", "HUGGINGFACEHUB_API_TOKEN"
        )
        try:
            from huggingface_hub import InferenceClient

            if values["model"]:
                values["repo_id"] = values["model"]
            elif values["repo_id"]:
                values["model"] = values["repo_id"]
            else:
                values["model"] = DEFAULT_MODEL
                values["repo_id"] = DEFAULT_MODEL

            client = InferenceClient(
                model=values["model"],
                token=huggingfacehub_api_token,
            )
            if values["task"] not in VALID_TASKS:
                raise ValueError(
                    f"Got invalid task {values['task']}, "
                    f"currently only {VALID_TASKS} are supported"
                )
            values["client"] = client
        except ImportError:
            raise ImportError(
                "Could not import huggingface_hub python package. "
                "Please install it with `pip install huggingface_hub`."
            )
        return values

    def embed_documents(self, texts: List[str]) -> List[List[float]]:
        """Call out to HuggingFaceHub's embedding endpoint for embedding search docs.

        Args:
            texts: The list of texts to embed.

        Returns:
            List of embeddings, one for each text.
        """
        # replace newlines, which can negatively affect performance.
        texts = [text.replace("\n", " ") for text in texts]
        _model_kwargs = self.model_kwargs or {}
        responses = self.client.post(
            json={"inputs": texts, "parameters": _model_kwargs, "task": self.task}
        )
        return json.loads(responses.decode())

    def embed_query(self, text: str) -> List[float]:
        """Call out to HuggingFaceHub's embedding endpoint for embedding query text.

        Args:
            text: The text to embed.

        Returns:
            Embeddings for the text.
        """
        response = self.embed_documents([text])[0]
        return response
