app.py

from langchain.embeddings import OpenAIEmbeddings
from langchain.vectorstores import Chroma
from langchain.llms import OpenAI
from langchain.chains.question_answering import load_qa_chain
import os
import fitz
import re
import gradio as gr
import time





def preprocess(text):
    text = text.replace('\n', '')
    return text

def pdf_to_text(path, start_page=1, end_page=None):
    doc = fitz.open(path)
    total_pages = doc.page_count

    if end_page is None:
        end_page = total_pages

    text_list = []

    for i in range(start_page - 1, end_page):
        text = doc.load_page(i).get_text("text")
        text_list.append(text)

    doc.close()
    return text_list

def law_split(path,name):
    text_list=pdf_to_text(path)
    text= ''.join(text_list)
    text_split=re.split(r'第.+条\s',text)[1:]

    for index, text in enumerate(text_split):
        text=preprocess(text)
        text_split[index]=f'《中华人民共和国{name}》 第{index+1}条 '+text
    
    return text_split


def folder_read(path):
    text_list=[]
    paths=os.listdir(path)
    for file in paths:
        name=file.split('.')[0]
        suffix=file.split('.')[-1]
        if suffix=='pdf':
            text_list+=law_split(f'{path}/{file}',name)
        
        
    return text_list


text_list=folder_read('laws')
embeddings = OpenAIEmbeddings()
vectordb = Chroma.from_texts(texts=text_list, embedding=embeddings)
llm = OpenAI(temperature=0.5,max_tokens=1024)




prompt='''
请根据给出的法律条文回答问题，给出适当的法律建议。回答时要说出你引用的法律条文是第几条，并说出引用的每一条是哪部法律中的。
引用的法律条文不要超过两条，回答尽量简明扼要
如果问题与搜索结果无关，就仅回答"该问题与青少年法律无关"即可。
'''


def generate_answer(question):
    start_time = time.time()
    most_relevant_texts = vectordb.max_marginal_relevance_search(question, k=5)
    print(most_relevant_texts)
    chain = load_qa_chain(llm)
    answer = chain.run(input_documents=most_relevant_texts, question=question+prompt)
    
    run_time = time.time() - start_time
    return (answer,
            '\n'.join([t.page_content for t in most_relevant_texts]),
            run_time
           )                  


    
def ask_api(question):
    
    if question.strip() == '':
        return '[ERROR]: 未输入问题'

    return generate_answer(question)






with gr.Blocks() as demo:
    gr.Markdown(
    """
    # 青少年法律科普问答
    本bot旨在根据中华人民共和国的法律回答有关青少年的问题，目前囊括的法律有

   《未成年人保护法》

   《义务教育法》

   《预防未成年人犯罪法》

   《妇女儿童权益保护法》
    """)
    
    with gr.Column():
        text_input = gr.Textbox(label='请输入与青少年法律相关的问题')
        text_button = gr.Button("提交")
        gr.Examples(
        [["未成年遭受网络欺凌该怎么办？"],['年满多少岁的儿童应当接受义务教育？'],['遇到离家出走的未成年应该如何处理？']],
        [text_input],
        label='示例问题'

    )
        text_output = [gr.Textbox(label='参考回答'),
                       gr.Textbox(label='相关法律原文'),
                       gr.Number(label="运行时长(s)")]
        

    text_button.click(generate_answer, inputs=text_input, outputs=text_output)

demo.launch()