main.py

from fastapi import FastAPI, File, UploadFile, Request
from pydantic import BaseModel
from pathlib import Path
from fastapi import Form
from fastapi.responses import JSONResponse
from langchain.text_splitter import RecursiveCharacterTextSplitter
from PyPDF2 import PdfReader
from fastapi import Depends
#在FastAPI中，Depends()函数用于声明依赖项

from langchain.chains.question_answering import load_qa_chain
from langchain import PromptTemplate, LLMChain
from langchain import HuggingFaceHub
from langchain.document_loaders import TextLoader
import torch

import requests
import random
import string
import sys
import timeit
import datetime
import io

import os
from dotenv import load_dotenv
load_dotenv()

HUGGINGFACEHUB_API_TOKEN = os.getenv('HUGGINGFACEHUB_API_TOKEN')
model_id = os.getenv('model_id')
hf_token = os.getenv('hf_token')
repo_id = os.getenv('repo_id')

def get_embeddings(input_str_texts):
    response = requests.post(api_url, headers=headers, json={"inputs": input_str_texts, "options":{"wait_for_model":True}})
    return response.json()

def generate_random_string(length):
    letters = string.ascii_lowercase
    return ''.join(random.choice(letters) for i in range(length))  

def remove_context(text):
    if 'Context:' in text:
        end_of_context = text.find('\n\n')
        return text[end_of_context + 2:] 
    else:
        return text

api_url = f"https://api-inference.huggingface.co/pipeline/feature-extraction/{model_id}"
headers = {"Authorization": f"Bearer {hf_token}"}

llm = HuggingFaceHub(repo_id=repo_id,
                     model_kwargs={"min_length":100,
                                   "max_new_tokens":1024, "do_sample":True,
                                   "temperature":0.1,
                                   "top_k":50,
                                   "top_p":0.95, "eos_token_id":49155})

prompt_template = """
You are a very helpful AI assistant. Please ONLY use {context} to answer the user's question {question}. If you don't know the answer, just say that you don't know. DON'T try to make up an answer.
Your response should be full and easy to understand.
"""
PROMPT = PromptTemplate(template=prompt_template, input_variables=["context", "question"])

chain = load_qa_chain(llm=llm, chain_type="stuff", prompt=PROMPT)

app = FastAPI()

class FileToProcess(BaseModel):
    uploaded_file: UploadFile = File(...)

@app.get("/")
async def home():
    return "API Working!"

@app.post("/fastapi_file_upload_process")
#async def upload_file(username: str, file_to_process: FileToProcess = Depends()):
async def pdf_file_qa_process(username: str, request: Request, file_to_process: FileToProcess = Depends()):    
    uploaded_file = file_to_process.uploaded_file
    print("File received:"+uploaded_file.filename)

    username = request.query_params.get("username")
    filename = request.query_params.get("filename")
    print(username)
    print(filename)   
        
    random_string = generate_random_string(20)
    file_path = Path.cwd() / random_string
    file_path.mkdir(parents=True, exist_ok=True)
    file_saved_in_api = file_path / uploaded_file.filename
    print(file_saved_in_api)
    print(file_saved_in_api.resolve())
    
    with open(file_saved_in_api, "wb+") as file_object:
        file_object.write(uploaded_file.file.read())   

    text_splitter = RecursiveCharacterTextSplitter(        
        #separator = "\n",
        chunk_size = 500,
        chunk_overlap  = 100, #striding over the text
        length_function = len,
    )        

    doc_reader = PdfReader(file_saved_in_api)
    raw_text = ''
    for i, page in enumerate(doc_reader.pages):
        text = page.extract_text()
        if text:
            raw_text += text
    temp_texts = text_splitter.split_text(raw_text)    
    texts=temp_texts
    initial_embeddings=get_embeddings(temp_texts)
    db_embeddings = torch.FloatTensor(initial_embeddings) 
    print("db_embeddings created...")

    #question = var_query.query    
    question = username
    print("API Call Query Received: "+question)
    q_embedding=get_embeddings(question)
    final_q_embedding = torch.FloatTensor(q_embedding)
    from sentence_transformers.util import semantic_search
    hits = semantic_search(final_q_embedding, torch.FloatTensor(db_embeddings), top_k=5)
   
    page_contents = []
    for i in range(len(hits[0])):
        page_content = texts[hits[0][i]['corpus_id']]
        page_contents.append(page_content)
    
    temp_page_contents=str(page_contents)        
    final_page_contents = temp_page_contents.replace('\\n', '')         
    random_string_2=generate_random_string(20)
    file_path = random_string_2 + ".txt" 
    with open(file_path, "w", encoding="utf-8") as file:
        file.write(final_page_contents)            

    loader = TextLoader(file_path, encoding="utf-8")
    loaded_documents = loader.load()

    temp_ai_response = chain({"input_documents": loaded_documents, "question": question}, return_only_outputs=False)
    
    initial_ai_response=temp_ai_response['output_text']

    cleaned_initial_ai_response = remove_context(initial_ai_response)
    
    #final_ai_response = cleaned_initial_ai_response.partition('¿Cuál es')[0].strip().replace('\n\n', '\n').replace('<|end|>', '').replace('<|user|>', '').replace('<|system|>', '').replace('<|assistant|>', '')
    final_ai_response = cleaned_initial_ai_response.partition('¿Cuál es')[0].strip()
    final_ai_response = final_ai_response.partition('¿Cuáles')[0].strip()
    final_ai_response = final_ai_response.partition('<|end|>')[0].strip().replace('\n\n', '\n').replace('<|end|>', '').replace('<|user|>', '').replace('<|system|>', '').replace('<|assistant|>', '')
    new_final_ai_response = final_ai_response.split('Unhelpful Answer:')[0].strip()
    new_final_ai_response = new_final_ai_response.split('Note:')[0].strip()
    new_final_ai_response = new_final_ai_response.split('Please provide feedback on how to improve the chatbot.')[0].strip()     
    
    api_call_msg={"INFO": f"File '{file_saved_in_api}' saved to your profile."}    
    print(api_call_msg)

    print(api_call_msg["INFO"])
    print()
    print(api_call_msg["INFO"].replace("uploaded_file", uploaded_file.filename))

    print("API call finished...")

    #return {"INFO": f"File '{uploaded_file.filename}' saved to your profile."}
    #return api_call_msg
    #return {"AIResponse": new_final_ai_response}
    return JSONResponse({"AIResponse": new_final_ai_response})