app.py

# app.py
import gradio as gr
import logging

# ==== ① 向量检索 & LLM ====
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)

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

# --- 2) 加载（较轻量）LLM ---
# 如果 7B 跑不动，可以先用 openchat-mini 试试
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)

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

# ==== ② Gradio UI ====

def simple_qa(user_query):
    """智能问答：检索 + 生成（单轮演示版）"""
    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。"

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

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():
        # ---------- 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")

            # 单轮：把问答显示在 Chatbot
            def update_chat(message, chat_history):
                reply = simple_qa(message)
                chat_history.append((message, reply))
                return "", chat_history

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

        # ---------- 生成学习大纲 ----------
        with gr.TabItem("生成学习大纲"):
            gr.Markdown("（学习大纲模块，待开发）")
            topic_input = gr.Textbox(label="主题/章节名称", placeholder="如：线性代数 第五章 特征值")
            gen_outline_btn = gr.Button("生成大纲")
            gen_outline_btn.click(placeholder_fn, inputs=topic_input, outputs=topic_input)

        # ---------- 自动出题 ----------
        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)

        # ---------- 答案批改 ----------
        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()