"""
SQLModel 表模型：关系库实体定义，与业务模块一一对应。
"""
from __future__ import annotations
from datetime import datetime
from enum import Enum
from typing import Optional
from uuid import UUID, uuid4
from sqlalchemy import Column, Text
from sqlmodel import Field, SQLModel

#角色枚举：教师/学生
class UserRole(str, Enum):
    teacher = "teacher"
    student = "student"

#用户表
class User(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    username: str = Field(index=True, unique=True)
    password_hash: str
    role: UserRole = Field(index=True)
    created_at: datetime = Field(default_factory=datetime.utcnow)

#知识点表
class KnowledgePoint(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    subject: str = Field(default="math", index=True) #学科
    grade: str = Field(default="junior", index=True)  #年级
    name: str = Field(index=True) #知识点名称
    code: str = Field(index=True, unique=True)  #知识点编码（唯一）

#习题表
class Exercise(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    title: str
    body: str
    # 题目元数据（教师维护）
    question_type: Optional[str] = Field(default=None, index=True)  # "选择" | "填空" | "计算" | "判断"
    correct_answer: Optional[str] = Field(default=None, sa_column=Column(Text, nullable=True))
    resolution: Optional[str] = Field(default=None, sa_column=Column(Text, nullable=True))  # 题目解析
    # 由主knowledge_code从Neo4j回填，便于筛选与学情统计
    knowledge_grade: Optional[str] = Field(default=None, index=True)
    knowledge_category: Optional[str] = Field(default=None, index=True)
    knowledge_point_name: Optional[str] = Field(default=None, index=True)
    knowledge_code: Optional[str] = Field(default=None, index=True)
    difficulty: Optional[int] = Field(default=None, index=True)  # 1-5
    # 个性化权重：答错+1，答对-1（不低于 0），供推荐排序
    weight: int = Field(default=0, index=True)

#做题记录表
class ExerciseAttempt(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    user_id: UUID = Field(index=True)
    exercise_id: UUID = Field(index=True)
    answer: str
    is_correct: Optional[bool] = Field(default=None, index=True)
    score: Optional[float] = Field(default=None)
    created_at: datetime = Field(default_factory=datetime.utcnow, index=True)

#数字人会话记录表
class ChatSession(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    user_id: UUID = Field(index=True)
    topic: Optional[str] = Field(default=None, index=True)
    created_at: datetime = Field(default_factory=datetime.utcnow, index=True)

class ChatMessage(SQLModel, table=True):
    """会话消息表。"""
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    session_id: UUID = Field(index=True)
    sender: str = Field(index=True)
    content: str = Field(sa_column=Column(Text, nullable=False))
    created_at: datetime = Field(default_factory=datetime.utcnow, index=True)

#推荐记录表
class RecommendationItem(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    user_id: UUID = Field(index=True)
    item_type: str = Field(index=True)
    item_ref: str = Field(index=True) 
    reason: Optional[str] = None
    created_at: datetime = Field(default_factory=datetime.utcnow, index=True)

#错题本
class WrongBookItem(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    user_id: UUID = Field(index=True)
    exercise_id: UUID = Field(index=True)
    knowledge_code: str = Field(index=True)
    wrong_answer: str
    correct_answer: Optional[str] = None
    created_at: datetime = Field(default_factory=datetime.utcnow, index=True)

#模块登记表
class ModuleService(SQLModel, table=True):
    id: UUID = Field(default_factory=uuid4, primary_key=True)
    name: str = Field(index=True, unique=True)
    base_url: str
    is_enabled: bool = Field(default=True, index=True)
    updated_at: datetime = Field(default_factory=datetime.utcnow, index=True)