quiz_engine.py

"""出题 + 批改 + SM-2 间隔重复引擎"""

from models import Concept, QuizQuestion, QuizRecord
from state import AppState
from llm_client import chat, chat_json
from datetime import date, timedelta

_GENERATE_SYSTEM = """你是一个专业的教育出题专家。
你的任务是根据给定的知识点，生成高质量的选择题和简答题。

要求：
1. 题目必须围绕提供的知识点，不能偏题
2. 选择题4个选项，只有一个正确答案，干扰项要有迷惑性
3. 简答题需要明确的答题要点
4. 每道题附带详细解析
5. 难度与知识点的难度匹配"""

_GRADE_SYSTEM = """你是一个专业的教育批改专家。
你的任务是对学生的答案进行评分和给出反馈。

评分标准（1-5）：
1: 完全错误，与正确答案毫无关系
2: 有部分关联但不正确
3: 部分正确，但遗漏关键要点
4: 基本正确，有少量不足
5: 完全正确，甚至超出预期

你需要返回JSON: {"score": 1-5, "feedback": "批改意见", "is_correct": true/false}"""


def _sm2_update(record: QuizRecord, quality: int):
    """SM-2 算法核心 — 更新 ease, interval, repetitions, next_review"""
    if quality >= 3:
        if record.sm2_repetitions == 0:
            record.sm2_interval = 1
        elif record.sm2_repetitions == 1:
            record.sm2_interval = 6
        else:
            record.sm2_interval = round(record.sm2_interval * record.sm2_ease)
        record.sm2_repetitions += 1
    else:
        record.sm2_repetitions = 0
        record.sm2_interval = 1

    # 更新 ease 因子
    record.sm2_ease = record.sm2_ease + (0.1 - (5 - quality) * (0.08 + (5 - quality) * 0.02))
    record.sm2_ease = max(1.3, record.sm2_ease)

    record.score = quality
    record.next_review = (date.today() + timedelta(days=record.sm2_interval)).isoformat()
    record.is_correct = quality >= 4


def generate_questions(
    concept_ids: list[str] | None = None,
    count: int = 5,
    q_type: str = "mixed",
) -> list[QuizQuestion]:
    """根据知识点生成题目"""
    state = AppState()

    # 获取目标概念
    if concept_ids:
        concepts = [state.concepts[cid] for cid in concept_ids if cid in state.concepts]
    else:
        concepts = list(state.concepts.values())

    if not concepts:
        return []

    # 取前10个概念（防止token爆炸）
    concepts = concepts[:10]

    # 构建概念描述
    concept_desc = "\n".join(
        f"- {c.name}（{c.category}，难度{c.difficulty}）：{c.description}"
        for c in concepts
    )

    choice_count = count // 2 + count % 2 if q_type == "mixed" else (count if q_type == "choice" else 0)
    short_count = count - choice_count

    prompt = f"""请根据以下知识点生成{count}道题目：

知识点列表：
{concept_desc}

要求生成 {choice_count} 道选择题和 {short_count} 道简答题。

返回JSON格式：
{{
  "questions": [
    {{
      "q_type": "choice",
      "question": "题目内容",
      "options": ["A. xxx", "B. xxx", "C. xxx", "D. xxx"],
      "correct_answer": "A",
      "explanation": "解析",
      "difficulty": 3,
      "concept_names": ["知识点名称"]
    }}
  ]
}}"""

    try:
        result = chat_json(prompt, _GENERATE_SYSTEM, temperature=0.4)
    except Exception as e:
        print(f"[quiz_engine] 出题失败: {e}")
        return []

    questions = []
    for item in result.get("questions", []):
        # 将 concept_names 转为 concept_ids
        cids = []
        for name in item.get("concept_names", []):
            concept = state.get_concept_by_name(name)
            if concept:
                cids.append(concept.id)

        q = QuizQuestion(
            question=item.get("question", "").strip(),
            correct_answer=item.get("correct_answer", "").strip(),
            explanation=item.get("explanation", "").strip(),
            concept_ids=cids,
            q_type=item.get("q_type", "choice"),
            options=item.get("options", []),
            difficulty=min(5, max(1, int(item.get("difficulty", 3)))),
        )
        if q.question:
            questions.append(q)
            state.add_question(q)

    state.save()
    return questions


def grade_answer(question: QuizQuestion, user_answer: str) -> QuizRecord:
    """批改答案，返回 QuizRecord（含 SM-2 参数）"""
    q_type_label = "选择题(选项: " + ", ".join(question.options) + ")" if question.q_type == "choice" else "简答题"

    prompt = f"""请批改以下学生的答案：

题目类型: {q_type_label}
题目: {question.question}
正确答案: {question.correct_answer}
标准解析: {question.explanation}

学生答案: {user_answer}

请评分并给出反馈。返回JSON: {{"score": 1-5, "feedback": "批改意见", "is_correct": true/false}}"""

    try:
        result = chat_json(prompt, _GRADE_SYSTEM, temperature=0.1)
    except Exception as e:
        print(f"[quiz_engine] 批改失败: {e}")
        # 降级：简单字符串匹配
        is_correct = user_answer.strip().upper() == question.correct_answer.strip().upper()
        result = {"score": 5 if is_correct else 1, "feedback": "系统自动判定", "is_correct": is_correct}

    record = QuizRecord(
        question_id=question.id,
        user_answer=user_answer,
        is_correct=result.get("is_correct", False),
        concept_ids=question.concept_ids,
        score=result.get("score", 3),
        feedback=result.get("feedback", ""),
    )

    # SM-2 更新
    _sm2_update(record, record.score)

    state = AppState()
    state.add_record(record)
    state.save()

    return record


def get_today_review() -> list[tuple[QuizRecord, QuizQuestion]]:
    """获取今日待复习题目"""
    state = AppState()
    return state.get_due_reviews()


def get_weakness_report(top_n: int = 10) -> list[tuple[Concept, float]]:
    """获取薄弱知识点报告"""
    state = AppState()
    return state.get_weak_concepts(top_n)