"""分组数据导出。"""

from __future__ import annotations

from group_system.xlsx_io import export_filename, write_xlsx


class ExportStoreMixin:

    def export_groups(self, class_name: str | None = None) -> tuple[bytes, str]:
        with self.lock:
            if class_name:
                class_filter = "WHERE g.class_name=?"
                params: tuple[Any, ...] = (class_name,)
            else:
                class_filter = ""
                params = ()
                class_name = None
            group_rows = self.connection.execute(
                f"""SELECT g.id,g.class_name,g.name,s1.student_no leader_no,s1.name leader_name
                FROM groups g LEFT JOIN students s1 ON s1.id=g.leader_student_id
                {class_filter} ORDER BY g.class_name,g.id""",
                params,
            ).fetchall()
            member_rows = self.connection.execute(
                f"""SELECT m.group_id,s.student_no,s.name,s.gender,s.class_name
                FROM group_members m JOIN groups g ON g.id=m.group_id
                JOIN students s ON s.id=m.student_id
                {class_filter}
                ORDER BY g.class_name,g.id,CASE WHEN s.id=g.leader_student_id THEN 0 ELSE 1 END,s.student_no""",
                params,
            ).fetchall()
            ungrouped_rows = self.connection.execute(
                f"""SELECT s.class_name,s.student_no,s.name,s.gender
                FROM students s WHERE s.id NOT IN (SELECT student_id FROM group_members)
                {'AND s.class_name=?' if class_name else ''}
                ORDER BY s.class_name,s.student_no""",
                ((class_name,) if class_name else ()),
            ).fetchall()

        by_group: dict[int, list[sqlite3.Row]] = {}
        for row in member_rows:
            by_group.setdefault(row["group_id"], []).append(row)
        summary_headers = ["序号", "班级", "组名", "组内序号", "学号", "姓名", "性别", "是否组长"]
        summary_records = []
        row_number = 0
        for group in group_rows:
            for member_number, member in enumerate(by_group.get(group["id"], []), 1):
                row_number += 1
                summary_records.append(
                    {
                        "序号": row_number,
                        "班级": member["class_name"],
                        "组名": group["name"],
                        "组内序号": member_number,
                        "学号": member["student_no"],
                        "姓名": member["name"],
                        "性别": member["gender"],
                        "是否组长": "是" if member["student_no"] == group["leader_no"] else "否",
                    }
                )
        if not summary_records:
            summary_records.append({
                "序号": "", "班级": "", "组名": "暂无分组", "组内序号": "",
                "学号": "", "姓名": "", "性别": "", "是否组长": "",
            })

        ungrouped_headers = ["序号", "班级", "学号", "姓名", "性别", "说明"]
        ungrouped_records = [
            {
                "序号": index,
                "班级": row["class_name"],
                "学号": row["student_no"],
                "姓名": row["name"],
                "性别": row["gender"],
                "说明": "未分组",
            }
            for index, row in enumerate(ungrouped_rows, 1)
        ]
        if not ungrouped_records:
            ungrouped_records.append({
                "序号": "", "班级": "", "学号": "", "姓名": "", "性别": "", "说明": "全部学生均已分组"
            })

        title = f"{class_name}班" if class_name else "全部班级"
        xlsx = write_xlsx(
            [
                (f"{title}分组", summary_headers, summary_records),
                ("未分组学生", ungrouped_headers, ungrouped_records),
            ]
        )
        return xlsx, export_filename("学生分组", class_name)