app.py

import os
import time
import re
import threading
from typing import List, Dict

import torch
import gradio as gr
from langchain_community.docstore import InMemoryDocstore
from langchain_community.document_loaders import TextLoader
from langchain_community.llms.huggingface_pipeline import HuggingFacePipeline
from langchain_community.vectorstores import FAISS
from langchain.docstore.document import Document as LangchainDocument
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.vectorstores.utils import DistanceStrategy
from sentence_transformers import SentenceTransformer
from transformers import AutoTokenizer, AutoModelForCausalLM, BitsAndBytesConfig, TextIteratorStreamer, pipeline

class BSIChatbot:
    def __init__(self, model_paths: Dict[str, str], docs_path: str):
        self.embedding_model = None
        self.llmpipeline = None
        self.llmtokenizer = None
        self.vectorstore = None
        self.reranking_model = None
        self.streamer = None
        self.images = [None]

        self.llm_path = model_paths['llm_path']
        self.word_and_embed_model_path = model_paths['embed_model_path']
        self.docs = docs_path
        self.rerank_model_path = model_paths['rerank_model_path']

    def initialize_embedding_model(self, rebuild_embeddings: bool):
        raw_knowledge_base = []

        # Initialize embedding model
        self.embedding_model = HuggingFaceEmbeddings(
            model_name=self.word_and_embed_model_path,
            multi_process=True,
            model_kwargs={"device": "cuda"},
            encode_kwargs={"normalize_embeddings": True},
        )

        if rebuild_embeddings:
            # Load documents
            for doc in os.listdir(self.docs):
                file_path = os.path.join(self.docs, doc)
                if doc.endswith(".md") or doc.endswith(".txt"):
                    with open(file_path, 'r', encoding='utf-8' if doc.endswith(".md") else 'cp1252') as file:
                        content = file.read()
                        metadata = {"source": doc}
                        raw_knowledge_base.append(LangchainDocument(page_content=content, metadata=metadata))

            # Split documents into chunks
            tokenizer = AutoTokenizer.from_pretrained(self.word_and_embed_model_path)
            text_splitter = RecursiveCharacterTextSplitter.from_huggingface_tokenizer(
                tokenizer=tokenizer,
                chunk_size=512,
                chunk_overlap=0,
                add_start_index=True,
                strip_whitespace=True,
            )

            processed_docs = []
            for doc in raw_knowledge_base:
                chunks = text_splitter.split_documents([doc])
                for chunk in chunks:
                    chunk.metadata.update({"source": doc.metadata['source']})
                processed_docs.extend(chunks)

            # Create and save vector store
            self.vectorstore = FAISS.from_documents(processed_docs, self.embedding_model, distance_strategy=DistanceStrategy.COSINE)
            self.vectorstore.save_local(os.path.join(self.docs, "_embeddings"))
        else:
            # Load existing vector store
            self.vectorstore = FAISS.load_local(os.path.join(self.docs, "_embeddings"), self.embedding_model)

    def retrieve_similar_embedding(self, query: str):
        query = f"Instruct: Given a search query, retrieve the relevant passages that answer the query\nQuery:{query}"
        return self.vectorstore.similarity_search(query=query, k=20)

    def initialize_llm(self):
        bnb_config = BitsAndBytesConfig(load_in_8bit=True)
        llm = AutoModelForCausalLM.from_pretrained(self.llm_path, quantization_config=bnb_config)
        self.llmtokenizer = AutoTokenizer.from_pretrained(self.llm_path)
        self.streamer = TextIteratorStreamer(self.llmtokenizer, skip_prompt=True)
        self.llmpipeline = pipeline(
            model=llm,
            tokenizer=self.llmtokenizer,
            task="text-generation",
            do_sample=True,
            temperature=0.7,
            repetition_penalty=1.1,
            return_full_text=False,
            streamer=self.streamer,
            max_new_tokens=500,
        )

    def rag_prompt(self, query: str, rerank: bool, history: List[Dict]):
        retrieved_chunks = self.retrieve_similar_embedding(query)
        retrieved_texts = [f"{chunk.metadata['source']}:\n{chunk.page_content}" for chunk in retrieved_chunks]

        if rerank and self.reranking_model:
            retrieved_texts = self.reranking_model.rerank(query, retrieved_texts, k=5)

        context = "\n".join(retrieved_texts)
        history_text = "\n".join([h['content'] for h in history])
        final_prompt = f"""Context:
        {context}
        ---
        History:
        {history_text}
        ---
        Question: {query}"""

        generation_thread = threading.Thread(target=self.llmpipeline, args=(final_prompt,))
        generation_thread.start()

        return self.streamer

    def launch_interface(self):
        with gr.Blocks() as demo:
            chatbot = gr.Chatbot(type="messages")
            msg = gr.Textbox()
            clear = gr.Button("Clear")
            reset = gr.Button("Reset")

            def user_input(user_message, history):
                return "", history + [{"role": "user", "content": user_message}]

            def bot_response(history):
                response = self.rag_prompt(history[-1]['content'], True, history)
                history.append({"role": "assistant", "content": ""})
                for token in response:
                    history[-1]['content'] += token
                    yield history

            msg.submit(user_input, [msg, chatbot], [msg, chatbot]).then(bot_response, chatbot, chatbot)
            clear.click(lambda: None, None, chatbot)
            reset.click(lambda: [], outputs=chatbot)

        demo.launch()

if __name__ == '__main__':
    model_paths = {
        'llm_path': 'meta-llama/Llama-3.2-3B-Instruct',
        'embed_model_path': 'intfloat/multilingual-e5-large-instruct',
        'rerank_model_path': 'domci/ColBERTv2-mmarco-de-0.1'
    }
    docs_path = '/docs'

    bot = BSIChatbot(model_paths, docs_path)
    bot.initialize_embedding_model(rebuild_embeddings=False)
    bot.initialize_llm()
    bot.launch_interface()