"""学生表（需求 2.1），系统的主表。

关于「年龄」的一个设计取舍
--------------------------------------------------------------------------
需求里把年龄列成了学生字段。这里**不落 age 字段**，只存 birth_date：

* 年龄 = 按今天算出来的派生值。今天是 24 岁，明年今天还是 24 就错了，
  必须靠定时任务去刷，多一个必定会脏的字段。
* 需要"按年龄筛选"的场景（需求 2.6.1）用 SQL 表达式算：
  ``app.core.utils.age_expression()`` 把 birth_date 折成年数参与 WHERE。
* 出参同时给 birth_date 和算好的 age，前端拿来直接用。

唯一例外：录入时对方只知道年龄不知道生日，入参允许只传 age，
service 会用 ``guess_birth_date()`` 折算一个占位生日并标记 ``birth_date_estimated=True``。
"""

from __future__ import annotations

from datetime import date

from sqlalchemy import Date, ForeignKey, String, Text
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.model.base import Base, SoftDeleteMixin, TimestampMixin
from app.model.constants import GENDER_TEXT, STUDENT_STATUS_TEXT, StudentStatus
from app.core.utils import calc_age


class Student(Base, TimestampMixin, SoftDeleteMixin):
    __tablename__ = "student"
    __table_args__ = {"comment": "学生基本信息表"}

    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    stu_no: Mapped[str] = mapped_column(String(30), unique=True, nullable=False, index=True, comment="学号（按规则生成，非自增）")
    name: Mapped[str] = mapped_column(String(30), nullable=False, index=True, comment="姓名")
    gender: Mapped[int] = mapped_column(default=1, nullable=False, index=True, comment="性别 1=男 2=女")
    birth_date: Mapped[date | None] = mapped_column(Date, comment="出生日期（年龄由此实时计算，不落库）")
    birth_date_estimated: Mapped[int] = mapped_column(default=0, nullable=False, comment="生日是否为按年龄推算的占位值 0=否 1=是")

    native_place: Mapped[str | None] = mapped_column(String(60), comment="籍贯")
    graduate_school: Mapped[str | None] = mapped_column(String(80), comment="毕业院校")
    major: Mapped[str | None] = mapped_column(String(60), comment="专业")
    education: Mapped[str | None] = mapped_column(String(20), comment="学历")

    enroll_date: Mapped[date | None] = mapped_column(Date, comment="入学时间")
    graduate_date: Mapped[date | None] = mapped_column(Date, comment="毕业时间")

    phone: Mapped[str | None] = mapped_column(String(20), comment="联系电话")
    id_card: Mapped[str | None] = mapped_column(String(30), comment="身份证号")

    class_id: Mapped[int | None] = mapped_column(ForeignKey("clazz.id"), index=True, comment="所属班级")
    advisor_id: Mapped[int | None] = mapped_column(ForeignKey("advisor.id"), index=True, comment="顾问编号")

    status: Mapped[int] = mapped_column(
        default=int(StudentStatus.STUDYING), nullable=False, index=True,
        comment="状态 1=在读 2=进入就业 3=已就业",
    )
    remark: Mapped[str | None] = mapped_column(Text, comment="备注（成绩预警会自动追加）")

    # ---------------- 关系 ----------------
    klass: Mapped["Clazz"] = relationship(  # noqa: F821
        back_populates="students", lazy="joined", foreign_keys=[class_id]
    )
    advisor: Mapped["Advisor"] = relationship(lazy="joined")  # noqa: F821
    scores: Mapped[list["Score"]] = relationship(  # noqa: F821
        back_populates="student",
        lazy="selectin",
        order_by="Score.exam_seq",
        cascade="all, delete-orphan",
    )
    employment: Mapped["Employment"] = relationship(  # noqa: F821
        back_populates="student",
        uselist=False,
        lazy="joined",
    )

    # ---------------- 出参派生字段 ----------------
    @property
    def age(self) -> int | None:
        return calc_age(self.birth_date)

    @property
    def gender_text(self) -> str | None:
        return GENDER_TEXT.get(self.gender)

    @property
    def status_text(self) -> str:
        return STUDENT_STATUS_TEXT.get(self.status, "未知")

    @property
    def class_name(self) -> str | None:
        return self.klass.name if self.klass and self.klass.is_del == 0 else None

    @property
    def class_no(self) -> str | None:
        return self.klass.class_no if self.klass and self.klass.is_del == 0 else None

    @property
    def advisor_name(self) -> str | None:
        return self.advisor.name if self.advisor and self.advisor.is_del == 0 else None

    @property
    def score_count(self) -> int:
        return len([s for s in self.scores if s.is_del == 0])

    @property
    def avg_score(self) -> float | None:
        valid = [float(s.score) for s in self.scores if s.is_del == 0 and s.score is not None]
        return round(sum(valid) / len(valid), 2) if valid else None

    @property
    def fail_count(self) -> int:
        return len([s for s in self.scores if s.is_del == 0 and s.flag == 1])