models/llamaCustom.py

import os
import pickle
from json import dumps, loads
import time
from typing import Any, List, Mapping, Optional

import numpy as np
import openai
import pandas as pd
import streamlit as st
from dotenv import load_dotenv
from huggingface_hub import HfFileSystem

from transformers import AutoModelForCausalLM, AutoTokenizer, pipeline, Pipeline

# prompts
from assets.prompts import custom_prompts

# llama index
from llama_index.core import (
    StorageContext,
    SimpleDirectoryReader,
    VectorStoreIndex,
    load_index_from_storage,
    PromptHelper,
    PromptTemplate,
)
from llama_index.core.llms import (
    CustomLLM,
    CompletionResponse,
    LLMMetadata,
)
from llama_index.core.memory import ChatMemoryBuffer
from llama_index.core.llms.callbacks import llm_completion_callback
from llama_index.core.base.llms.types import ChatMessage
from llama_index.core import Settings

load_dotenv()
# openai.api_key = os.getenv("OPENAI_API_KEY")
fs = HfFileSystem()

# define prompt helper
# set maximum input size
CONTEXT_WINDOW = 2048
# set number of output tokens
NUM_OUTPUT = 525
# set maximum chunk overlap
CHUNK_OVERLAP_RATION = 0.2

# TODO: use the following prompt to format the answer at the end of the context prompt
ANSWER_FORMAT = """
Use the following example format for your answer:
[FORMAT]
Answer:
    The answer to the user question.
Reference:
    The list of references to the specific sections of the documents that support your answer.    
[END_FORMAT]
"""

CONTEXT_PROMPT_TEMPLATE = """
The following is a friendly conversation between a user and an AI assistant.
The assistant is talkative and provides lots of specific details from its context.
If the assistant does not know the answer to a question, it truthfully says it
does not know.

Here are the relevant documents for the context:

{context_str}

Instruction: Based on the above documents, provide a detailed answer for the user question below. \
Include references to the specific sections of the documents that support your answer. \
Answer "don't know" if not present in the document.
"""

CONDENSE_PROMPT_TEMPLATE = """
Given the following conversation between a user and an AI assistant and a follow up question from user,
rephrase the follow up question to be a standalone question.

Chat History:
{chat_history}
Follow Up Input: {question}
Standalone question:
"""


@st.cache_resource
def load_model(model_name: str):
    # llm_model_name = "bigscience/bloom-560m"
    tokenizer = AutoTokenizer.from_pretrained(model_name)
    model = AutoModelForCausalLM.from_pretrained(model_name, config="T5Config")

    pipe = pipeline(
        task="text-generation",
        model=model,
        tokenizer=tokenizer,
        # device=0, # GPU device number
        # max_length=512,
        do_sample=True,
        top_p=0.95,
        top_k=50,
        temperature=0.7,
    )

    return pipe


class OurLLM(CustomLLM):
    context_window: int = 3900
    num_output: int = 256
    model_name: str = ""
    pipeline: Pipeline = None

    @property
    def metadata(self) -> LLMMetadata:
        """Get LLM metadata."""
        return LLMMetadata(
            context_window=CONTEXT_WINDOW,
            num_output=NUM_OUTPUT,
            model_name=self.model_name,
        )

    # The decorator is optional, but provides observability via callbacks on the LLM calls.
    @llm_completion_callback()
    def complete(self, prompt: str, **kwargs: Any) -> CompletionResponse:
        prompt_length = len(prompt)
        response = self.pipeline(prompt, max_new_tokens=NUM_OUTPUT)[0]["generated_text"]

        # only return newly generated tokens
        text = response[prompt_length:]
        return CompletionResponse(text=text)

    @llm_completion_callback()
    def stream_complete(self, prompt: str, **kwargs: Any):
        response = ""
        for token in self.dummy_response:
            response += token
            yield CompletionResponse(text=response, delta=token)


class LlamaCustom:
    def __init__(self, model_name: str, index: VectorStoreIndex):
        self.model_name = model_name
        self.index = index
        self.chat_mode = "condense_plus_context"
        self.memory = ChatMemoryBuffer.from_defaults()

    def get_response(self, query_str: str, chat_history: List[ChatMessage]):
        # https://docs.llamaindex.ai/en/stable/module_guides/deploying/chat_engines/
        # query_engine = self.index.as_query_engine(
        #     text_qa_template=text_qa_template, refine_template=refine_template
        # )
        chat_engine = self.index.as_chat_engine(
            chat_mode=self.chat_mode,
            memory=self.memory,
            context_prompt=CONTEXT_PROMPT_TEMPLATE,
            condense_prompt=CONDENSE_PROMPT_TEMPLATE,
            # verbose=True,
        )
        # response = query_engine.query(query_str)
        response = chat_engine.chat(message=query_str, chat_history=chat_history)

        return str(response)

    def get_stream_response(self, query_str: str, chat_history: List[ChatMessage]):
        response = self.get_response(query_str=query_str, chat_history=chat_history)
        for word in response.split():
            yield word + " "
            time.sleep(0.05)