custom_llm.py

from typing import Any, List, Mapping, Optional

from langchain_core.callbacks.manager import CallbackManagerForLLMRun
from langchain_core.language_models.llms import LLM
from typing import Literal
import requests
from langchain.prompts import PromptTemplate, ChatPromptTemplate
from operator import itemgetter

from langchain.memory import ChatMessageHistory, ConversationBufferMemory
from langchain.prompts import ChatPromptTemplate, MessagesPlaceholder
from langchain_community.chat_models import ChatOpenAI
from langchain_core.runnables import RunnableLambda, RunnablePassthrough
from langchain_core.messages import AIMessage, HumanMessage

from langchain_community.document_loaders import DirectoryLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.document_loaders import PyMuPDFLoader
import os
from langchain.embeddings import HuggingFaceEmbeddings
from langchain.vectorstores import FAISS


def create_vectorstore():
    loader = os.getenv('knowledge_base')
    
    splitter = RecursiveCharacterTextSplitter(chunk_size=512, chunk_overlap=20)
    
    docs = splitter.create_documents([loader])
    
    emb_model = HuggingFaceEmbeddings(model_name='sentence-transformers/paraphrase-multilingual-mpnet-base-v2', encode_kwargs={'normalize_embeddings': True})
    db = FAISS.from_documents(docs, emb_model)
    return db

def custom_chain_with_history(llm, memory):

    prompt = PromptTemplate.from_template("""<s><INST><|system|>
    You are a college student at Gunadarma University, majoring in Informatics / Computer Science. Your name is Jonathan Jordan, but people call you Jojo. You have expertise in Artificial Intelligence and Data Science. You are also good at Data Engineering with AirFlow and Apache Spark. You currently live in Tegal Alur, Kalideres, West Jakarta, Jakarta, Indonesia. You are 21 years old. Your birthday is Friday, 21 June 2002.
    
    Below are the detailed personal information about you:
    {context} 
    
    Respond to the user with the following chat history between you and the user, if there is no relevant information that means you regard the information as a secret and you are not willing to share the information to the user:
    {chat_history}
    <|user|>
    {question}
    <|you|>
    """)
    
    def prompt_memory(_):
      t = ""
      # for x in memory.chat_memory.messages:
      for x in memory.messages:
        t += f"<|assistant|>\n<s>{x.content}</s>\n" if type(x) is AIMessage else f"<|user|>\n{x.content}\n"
      return "" if len(t) == 0 else t
    
    def format_docs(docs):
      print(len(docs))
      return "\n".join([f"{i+1}. {d.page_content}" for i,d in enumerate(docs)])
    
    # prompt = ChatPromptTemplate.from_messages(
    #     [
    #         ("system", "You are a helpful chatbot"),
    #         MessagesPlaceholder(variable_name="history"),
    #         ("human", "{input}"),
    #     ]
    # )
    
    return {"chat_history":prompt_memory, "context":create_vectorstore().as_retriever(search_type="similarity", search_kwargs={"k": 8}) | format_docs, "question": RunnablePassthrough()} | prompt | llm

class CustomLLM(LLM):
    repo_id : str
    api_token : str
    model_type: Literal["text2text-generation", "text-generation"]
    max_new_tokens: int = None
    temperature: float = 0.001
    timeout: float = None
    top_p: float = None
    top_k : int = None
    repetition_penalty : float = None
    stop : List[str] = []


    @property
    def _llm_type(self) -> str:
        return "custom"

    def _call(
        self,
        prompt: str,
        stop: Optional[List[str]] = None,
        run_manager: Optional[CallbackManagerForLLMRun] = None,
        **kwargs: Any,
    ) -> str:

        headers = {"Authorization": f"Bearer {self.api_token}"}
        API_URL = f"https://api-inference.huggingface.co/models/{self.repo_id}"

        parameters_dict = {
          'max_new_tokens': self.max_new_tokens,
          'temperature': self.temperature,
          'timeout': self.timeout,
          'top_p': self.top_p,
          'top_k': self.top_k,
          'repetition_penalty': self.repetition_penalty,
          'stop':self.stop
        }

        if self.model_type == 'text-generation':
          parameters_dict["return_full_text"]=False

        data = {"inputs": prompt, "parameters":parameters_dict, "options":{"wait_for_model":True}}
        data = requests.post(API_URL, headers=headers, json=data).json()
        return data[0]['generated_text']

    @property
    def _identifying_params(self) -> Mapping[str, Any]:
        """Get the identifying parameters."""
        return  {
          'repo_id': self.repo_id,
          'model_type':self.model_type,
          'stop_sequences':self.stop,
          'max_new_tokens': self.max_new_tokens,
          'temperature': self.temperature,
          'timeout': self.timeout,
          'top_p': self.top_p,
          'top_k': self.top_k,
          'repetition_penalty': self.repetition_penalty
      }