app.py

# app.py
import gradio as gr
import logging

from langchain_community.vectorstores import Chroma
from langchain_community.embeddings import HuggingFaceEmbeddings
from langchain.chains import RetrievalQA
from transformers import AutoTokenizer, AutoModelForCausalLM, pipeline
from langchain.llms import HuggingFacePipeline

logging.basicConfig(level=logging.INFO)

# === 加载向量库 ===
embedding_model = HuggingFaceEmbeddings(
    model_name="sentence-transformers/paraphrase-multilingual-mpnet-base-v2"
)
vector_store = Chroma(
    persist_directory="vector_store",
    embedding_function=embedding_model,
)

# === 加载 LLM 模型（openchat） ===
model_id = "openchat/openchat-3.5-0106"
tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(
    model_id,
    device_map="auto",
    torch_dtype="auto",
)
gen_pipe = pipeline(
    "text-generation",
    model=model,
    tokenizer=tokenizer,
    max_new_tokens=512,
    temperature=0.7,
    top_p=0.9,
)
llm = HuggingFacePipeline(pipeline=gen_pipe)

# === 构建问答链 ===
qa_chain = RetrievalQA.from_chain_type(
    llm=llm,
    chain_type="stuff",
    retriever=vector_store.as_retriever(search_kwargs={"k": 3}),
)

# === 智能问答函数 ===
def simple_qa(user_query):
    if not user_query.strip():
        return "⚠️ 请输入学习问题，例如：什么是定积分？"
    try:
        answer = qa_chain.run(user_query)
        return answer
    except Exception as e:
        logging.error(f"问答失败: {e}")
        return "抱歉，暂时无法回答，请稍后再试。"

# === 大纲生成函数 ===
def generate_outline(topic: str):
    if not topic.strip():
        return "⚠️ 请输入章节或主题，例如：高等数学 第六章 定积分"
    try:
        docs = vector_store.as_retriever(search_kwargs={"k": 3}).get_relevant_documents(topic)
        snippet = "\n".join([doc.page_content for doc in docs])
        prompt = (
            f"根据以下内容，为“{topic}”生成大学本科层次的结构化学习大纲，格式如下：\n"
            f"一、章节标题\n  1. 节标题\n    （1）要点描述\n...\n\n"
            f"文档内容：\n{snippet}\n\n学习大纲："
        )
        result = llm.generate(prompt).generations[0][0].text.strip()
        return result
    except Exception as e:
        logging.error(f"大纲生成失败: {e}")
        return "⚠️ 抱歉，生成失败，请稍后再试。"

# === 占位函数 ===
def placeholder_fn(*args, **kwargs):
    return "功能尚未实现，请等待后续更新。"

# === Gradio UI ===
with gr.Blocks() as demo:
    gr.Markdown("# 智能学习助手 v2.0\n— 大学生专业课学习助手 —")

    with gr.Tabs():
        # --- 模块 A：智能问答 ---
        with gr.TabItem("智能问答"):
            gr.Markdown("> 示例：什么是函数的定义域？")
            chatbot = gr.Chatbot()
            user_msg = gr.Textbox(placeholder="输入您的学习问题，然后按回车或点击发送")
            send_btn = gr.Button("发送")

            def update_chat(message, chat_history):
                reply = simple_qa(message)
                chat_history.append((message, reply))
                return "", chat_history

            send_btn.click(update_chat, inputs=[user_msg, chatbot], outputs=[user_msg, chatbot])
            user_msg.submit(update_chat, inputs=[user_msg, chatbot], outputs=[user_msg, chatbot])

        # --- 模块 B：生成学习大纲 ---
        with gr.TabItem("生成学习大纲"):
            gr.Markdown("> 示例：高等数学 第六章 定积分")
            topic_input = gr.Textbox(label="章节主题", placeholder="请输入章节名")
            outline_output = gr.Textbox(label="系统生成的大纲", lines=12)
            gen_outline_btn = gr.Button("生成大纲")
            gen_outline_btn.click(fn=generate_outline, inputs=topic_input, outputs=outline_output)

        # --- 模块 C：自动出题（占位） ---
        with gr.TabItem("自动出题"):
            gr.Markdown("（出题模块，待开发）")
            topic2 = gr.Textbox(label="知识点/主题", placeholder="如：高数 第三章 多元函数")
            difficulty2 = gr.Dropdown(choices=["简单", "中等", "困难"], label="难度")
            count2 = gr.Slider(1, 10, step=1, label="题目数量")
            gen_q_btn = gr.Button("开始出题")
            gen_q_btn.click(placeholder_fn, inputs=[topic2, difficulty2, count2], outputs=topic2)

        # --- 模块 D：答案批改（占位） ---
        with gr.TabItem("答案批改"):
            gr.Markdown("（批改模块，待开发）")
            std_ans = gr.Textbox(label="标准答案", lines=5)
            user_ans = gr.Textbox(label="您的作答", lines=5)
            grade_btn = gr.Button("开始批改")
            grade_btn.click(placeholder_fn, inputs=[user_ans, std_ans], outputs=user_ans)

    gr.Markdown("---\n由 HuggingFace 提供支持 • 版本 2.0")

if __name__ == "__main__":
    demo.launch()