import os  # A module to interact with the OS
from typing import Any, Dict, List  # For type hinting

# Importing various modules and classes from a custom library 'langchain' likely used for natural language processing
from langchain.chains import ConversationalRetrievalChain, LLMChain
from langchain.chains.question_answering import load_qa_chain
from langchain.chains.router.llm_router import (LLMRouterChain,
                                                RouterOutputParser)
from langchain.chains.router.multi_prompt_prompt import \
    MULTI_PROMPT_ROUTER_TEMPLATE
from langchain.chat_models import ChatOpenAI, ChatVertexAI
from langchain.chat_models.anthropic import ChatAnthropic
from langchain.docstore.document import Document
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.llms import OpenAI, VertexAI
from langchain.memory import ConversationBufferMemory
from langchain.vectorstores import SupabaseVectorStore
from llm.prompt import LANGUAGE_PROMPT
from llm.prompt.CONDENSE_PROMPT import CONDENSE_QUESTION_PROMPT
from models.chats import \
    ChatMessage  # Importing a custom ChatMessage class for handling chat messages
from models.settings import \
    BrainSettings  # Importing settings related to the 'brain'
from pydantic import (BaseModel,  # For data validation and settings management
                      BaseSettings)
from supabase import (Client,  # For interacting with Supabase database
                      create_client)
from vectorstore.supabase import \
    CustomSupabaseVectorStore  # Custom class for handling vector storage with Supabase


class AnswerConversationBufferMemory(ConversationBufferMemory):
    """
    This class is a specialized version of ConversationBufferMemory.
    It overrides the save_context method to save the response using the 'answer' key in the outputs.
    Reference to some issue comment is given in the docstring.
    """
    
    def save_context(self, inputs: Dict[str, Any], outputs: Dict[str, str]) -> None:
        # Overriding the save_context method of the parent class
        return super(AnswerConversationBufferMemory, self).save_context(
            inputs, {'response': outputs['answer']})


def get_chat_history(inputs) -> str:
    """
    Function to concatenate chat history into a single string.
    :param inputs: List of tuples containing human and AI messages.
    :return: concatenated string of chat history
    """
    res = []
    for human, ai in inputs:
        res.append(f"{human}:{ai}\n")
    return "\n".join(res)


class BrainPicking(BaseModel):
    """
    Main class for the Brain Picking functionality.
    It allows to initialize a Chat model, generate questions and retrieve answers using ConversationalRetrievalChain.
    """
    
    # Default class attributes
    llm_name: str = "gpt-3.5-turbo"
    settings = BrainSettings()
    embeddings: OpenAIEmbeddings = None
    supabase_client: Client = None
    vector_store: CustomSupabaseVectorStore = None
    llm: ChatOpenAI = None
    question_generator: LLMChain = None
    doc_chain: ConversationalRetrievalChain = None
    
    class Config:
        # Allowing arbitrary types for class validation
        arbitrary_types_allowed = True
    
    def init(self, model: str, user_id: str) -> "BrainPicking":
        """
        Initialize the BrainPicking class by setting embeddings, supabase client, vector store, language model and chains.
        :param model: Language model name to be used.
        :param user_id: The user id to be used for CustomSupabaseVectorStore.
        :return: BrainPicking instance
        """
        self.embeddings = OpenAIEmbeddings(openai_api_key=self.settings.openai_api_key)
        self.supabase_client = create_client(self.settings.supabase_url, self.settings.supabase_service_key)
        self.vector_store = CustomSupabaseVectorStore(
            self.supabase_client, self.embeddings, table_name="vectors", user_id=user_id)
        self.llm = ChatOpenAI(temperature=0, model_name=model)
        self.question_generator = LLMChain(llm=self.llm, prompt=CONDENSE_QUESTION_PROMPT)
        self.doc_chain = load_qa_chain(self.llm, chain_type="stuff")
        return self
    
    def _get_qa(self, chat_message: ChatMessage, user_openai_api_key) -> ConversationalRetrievalChain:
        """
        Retrieves a QA chain for the given chat message and API key.
        :param chat_message: The chat message containing history.
        :param user_openai_api_key: The OpenAI API key to be used.
        :return: ConversationalRetrievalChain instance
        """
        # If user provided an API key, update the settings
        if user_openai_api_key is not None and user_openai_api_key != "":
            self.settings.openai_api_key = user_openai_api_key
        
        # Initialize and return a ConversationalRetrievalChain
        qa = ConversationalRetrievalChain(
                retriever=self.vector_store.as_retriever(),
                max_tokens_limit=chat_message.max_tokens, question_generator=self.question_generator,
                combine_docs_chain=self.doc_chain, get_chat_history=get_chat_history)
        return qa

    def generate_answer(self, chat_message: ChatMessage, user_openai_api_key) -> str:
        """
        Generate an answer to a given chat message by interacting with the language model.
        :param chat_message: The chat message containing history.
        :param user_openai_api_key: The OpenAI API key to be used.
        :return: The generated answer.
        """
        transformed_history = []

        # Get the QA chain
        qa = self._get_qa(chat_message, user_openai_api_key)
        
        # Transform the chat history into a list of tuples
        for i in range(0, len(chat_message.history) - 1, 2):
            user_message = chat_message.history[i][1]
            assistant_message = chat_message.history[i + 1][1]
            transformed_history.append((user_message, assistant_message))
        
        # Generate the model response using the QA chain
        model_response = qa({"question": chat_message.question, "chat_history": transformed_history})
        answer = model_response['answer']

        return answer