app.py

import gradio as gr
import os

from langchain_community.document_loaders import PyPDFLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.vectorstores import Chroma
from langchain.chains import ConversationalRetrievalChain
from langchain_community.embeddings import HuggingFaceEmbeddings 
from langchain_community.llms import HuggingFacePipeline
from langchain.memory import ConversationBufferMemory

from pathlib import Path
import chromadb
from unidecode import unidecode

from transformers import AutoTokenizer, pipeline
import transformers
import torch
import re

# Lista de modelos 100% abertos e gratuitos
list_llm = [
    "google/flan-t5-xxl",          # Modelo para tarefas text-to-text
    "TinyLlama/TinyLlama-1.1B-Chat-v1.0",  # Modelo leve para diálogo
    "microsoft/phi-2",             # Modelo para raciocínio lógico
    "facebook/opt-1.3b",           # Modelo de geração de texto
    "EleutherAI/gpt-neo-1.3B",     # Versão open-source do GPT-3
    "bigscience/bloom-1b7",        # Modelo multilíngue
    "RWKV/rwkv-4-169m-pile",       # Modelo eficiente em RAM
    "gpt2-medium",                 # Clássico modelo de GPT-2
    "databricks/dolly-v2-3b",      # Modelo para instruções
    "mosaicml/mpt-7b-instruct"     # Modelo para instruções
]

list_llm_simple = [os.path.basename(llm) for llm in list_llm]

# Função para carregar documentos PDF
def load_doc(list_file_path, chunk_size, chunk_overlap):
    loaders = [PyPDFLoader(x) for x in list_file_path]
    pages = []
    for loader in loaders:
        pages.extend(loader.load())
    text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=chunk_size, 
        chunk_overlap=chunk_overlap
    )
    return text_splitter.split_documents(pages)

# Função para criar banco de dados vetorial
def create_db(splits, collection_name):
    embedding = HuggingFaceEmbeddings()
    return Chroma.from_documents(
        documents=splits,
        embedding=embedding,
        client=chromadb.EphemeralClient(),
        collection_name=collection_name
    )

# Função para inicializar o modelo LLM
def initialize_llmchain(llm_model, temperature, max_tokens, top_k, vector_db, progress=gr.Progress()):
    progress(0.1, desc="Carregando tokenizer...")
    
    tokenizer = AutoTokenizer.from_pretrained(llm_model)
    
    progress(0.4, desc="Inicializando pipeline...")
    pipeline_obj = pipeline(
        "text-generation",
        model=llm_model,
        tokenizer=tokenizer,
        torch_dtype=torch.bfloat16,
        device_map="auto",
        max_new_tokens=max_tokens,
        do_sample=True,
        top_k=top_k,
        temperature=temperature
    )
    
    llm = HuggingFacePipeline(pipeline=pipeline_obj)
    
    progress(0.7, desc="Configurando memória...")
    memory = ConversationBufferMemory(
        memory_key="chat_history",
        return_messages=True
    )
    
    progress(0.8, desc="Criando cadeia...")
    return ConversationalRetrievalChain.from_llm(
        llm=llm,
        retriever=vector_db.as_retriever(),
        memory=memory,
        chain_type="stuff",
        return_source_documents=True
    )

# Interface Gradio
def demo():
    with gr.Blocks(theme=gr.themes.Soft()) as demo:
        vector_db = gr.State()
        qa_chain = gr.State()
        
        gr.Markdown("## 🤖 Chatbot para PDFs com Modelos Gratuitos")
        
        with gr.Tab("📤 Upload PDF"):
            pdf_input = gr.Files(label="Selecione seus PDFs", file_types=[".pdf"])
            
        with gr.Tab("⚙️ Processamento"):
            chunk_size = gr.Slider(100, 1000, value=500, label="Tamanho dos Chunks")
            chunk_overlap = gr.Slider(0, 200, value=50, label="Sobreposição")
            process_btn = gr.Button("Processar PDFs")
            
        with gr.Tab("🧠 Modelo"):
            model_selector = gr.Dropdown(list_llm_simple, label="Selecione o Modelo", value=list_llm_simple[0])
            temperature = gr.Slider(0, 1, value=0.7, label="Criatividade")
            load_model_btn = gr.Button("Carregar Modelo")
            
        with gr.Tab("💬 Chat"):
            chatbot = gr.Chatbot(height=400)
            msg = gr.Textbox(label="Sua mensagem")
            clear_btn = gr.ClearButton([msg, chatbot])
            
        # Eventos
        process_btn.click(
            lambda files, cs, co: create_db(load_doc([f.name for f in files], cs, co), "docs"),
            inputs=[pdf_input, chunk_size, chunk_overlap],
            outputs=vector_db
        )
        
        load_model_btn.click(
            lambda model, temp: initialize_llmchain(list_llm[list_llm_simple.index(model)], temp, 512, 3, vector_db.value),
            inputs=[model_selector, temperature],
            outputs=qa_chain
        )
        
        def respond(message, chat_history):
            result = qa_chain.value({"question": message, "chat_history": chat_history})
            response = result["answer"]
            sources = "\n".join([f"📄 Página {doc.metadata['page']+1}: {doc.page_content[:50]}..." 
                               for doc in result["source_documents"][:2]])
            return f"{response}\n\n🔍 Fontes:\n{sources}"
        
        msg.submit(respond, [msg, chatbot], chatbot)
        
    demo.launch()

if __name__ == "__main__":
    demo()