"""教师端班级和分组管理。"""

from __future__ import annotations

import sqlite3


class TeacherGroupAdminMixin:

    def switch_class(self, class_name: str) -> tuple[bool, str]:
        with self.lock:
            row = self.connection.execute(
                "SELECT COUNT(*) AS n FROM students WHERE class_name=?", (class_name,)
            ).fetchone()
        if row["n"] == 0:
            return False, "班级不存在"
        self.set_setting("active_class", class_name)
        return True, f"已切换到 {class_name} 班，仅该班学生可登录"

    def set_locked(self, class_name: str, locked: bool) -> tuple[bool, str]:
        with self.lock:
            exists = self.connection.execute(
                "SELECT 1 FROM students WHERE class_name=? LIMIT 1", (class_name,)
            ).fetchone()
        if not exists:
            return False, "班级不存在"
        with self.lock, self.connection:
            self.connection.execute(
                """INSERT INTO class_controls(class_name,locked) VALUES(?,?)
                ON CONFLICT(class_name) DO UPDATE SET locked=excluded.locked""",
                (class_name, int(locked)),
            )
        return True, ("已停止学生操作" if locked else "已恢复学生操作")

    def _require_teacher_group(self, class_name: str) -> tuple[bool, str, sqlite3.Row | None]:
        if not any(item["class_name"] == class_name for item in self.class_list()):
            return False, "班级不存在", None
        return True, "", None

    def teacher_create_group(self, class_name: str, name: str) -> tuple[bool, str]:
        if not self._require_teacher_group(class_name)[0]:
            return False, "班级不存在"
        name = name.strip() or "未命名小组"
        with self.lock, self.connection:
            self.connection.execute(
                "INSERT INTO groups(class_name,name,leader_student_id) VALUES(?,?,NULL)",
                (class_name, name),
            )
        return True, f"小组“{name}”已创建"

    def teacher_rename_group(self, group_id: int, name: str) -> tuple[bool, str]:
        name = name.strip()
        if not name:
            return False, "组名不能为空"
        with self.lock, self.connection:
            cursor = self.connection.execute("UPDATE groups SET name=? WHERE id=?", (name, group_id))
            if cursor.rowcount == 0:
                return False, "小组不存在"
        return True, "组名已保存"

    def teacher_set_leader(self, group_id: int, student_id: int | None) -> tuple[bool, str]:
        with self.lock, self.connection:
            group = self.connection.execute("SELECT * FROM groups WHERE id=?", (group_id,)).fetchone()
            if group is None:
                return False, "小组不存在"
            if student_id is None:
                self.connection.execute(
                    "UPDATE groups SET leader_student_id=NULL WHERE id=?", (group_id,)
                )
                return True, "已取消组长"
            member = self.connection.execute(
                "SELECT 1 FROM group_members WHERE group_id=? AND student_id=?",
                (group_id, student_id),
            ).fetchone()
            if not member:
                return False, "组长必须是该组成员"
            self.connection.execute(
                "UPDATE groups SET leader_student_id=? WHERE id=?", (student_id, group_id)
            )
        return True, "组长已设置"

    def teacher_add_member(self, group_id: int, student_id: int) -> tuple[bool, str]:
        with self.lock, self.connection:
            group = self.connection.execute("SELECT * FROM groups WHERE id=?", (group_id,)).fetchone()
            student = self.connection.execute("SELECT * FROM students WHERE id=?", (student_id,)).fetchone()
            if group is None or student is None:
                return False, "小组或学生不存在"
            if group["class_name"] != student["class_name"]:
                return False, "不能跨班调整"
            current_group = self.connection.execute(
                "SELECT group_id FROM group_members WHERE student_id=?", (student_id,)
            ).fetchone()
            if current_group and current_group["group_id"] == group_id:
                return False, "学生已在该组"
            count = self.connection.execute(
                "SELECT COUNT(*) AS n FROM group_members WHERE group_id=?", (group_id,)
            ).fetchone()["n"]
            group_limit = self.group_limit()
            if count >= group_limit:
                return False, f"该组已有 {group_limit} 人；请先移出一人"
            if current_group:
                self.connection.execute(
                    "DELETE FROM group_members WHERE student_id=?", (student_id,)
                )
                self.connection.execute(
                    "UPDATE groups SET leader_student_id=NULL WHERE id=? AND leader_student_id=?",
                    (current_group["group_id"], student_id),
                )
            self.connection.execute(
                "INSERT INTO group_members(group_id,student_id) VALUES(?,?)",
                (group_id, student_id),
            )
        return True, "已加入小组"

    def teacher_remove_member(self, student_id: int) -> tuple[bool, str]:
        with self.lock, self.connection:
            membership = self.connection.execute(
                "SELECT * FROM group_members WHERE student_id=?", (student_id,)
            ).fetchone()
            if not membership:
                return False, "学生当前未分组"
            self.connection.execute(
                "DELETE FROM group_members WHERE student_id=?", (student_id,)
            )
            self.connection.execute(
                """UPDATE groups SET leader_student_id=NULL
                WHERE leader_student_id=?""", (student_id,)
            )
        return True, "已移出小组"

    def teacher_disband_group(self, group_id: int) -> tuple[bool, str]:
        with self.lock, self.connection:
            cursor = self.connection.execute("DELETE FROM groups WHERE id=?", (group_id,))
            if cursor.rowcount == 0:
                return False, "小组不存在"
        return True, "小组已解散"