"""基于课时核对表 MonthlySnapshot 的统计汇总（Excel 导入数据）"""
from __future__ import annotations

from typing import Optional

from sqlalchemy import func

from models import db, MonthlySnapshot, StudentAccount, Course, ClassRecord
from keshi_display import get_latest_period, list_period_stats


def _recharge_expr():
    return (
        func.coalesce(MonthlySnapshot.new_signup_amount, 0)
        + func.coalesce(MonthlySnapshot.renewal_amount, 0)
    )


def _snapshot_query(year: Optional[int] = None, month: Optional[int] = None):
    q = db.session.query(MonthlySnapshot)
    if year is not None:
        q = q.filter(MonthlySnapshot.year == year)
    if month is not None:
        q = q.filter(MonthlySnapshot.month == month)
    return q


def period_overview(year: int, month: int) -> dict:
    """单月概览：充值、消课、退费、新签人数"""
    base = _snapshot_query(year, month)
    recharge = base.with_entities(func.coalesce(func.sum(_recharge_expr()), 0)).scalar() or 0
    consumed_h = base.with_entities(
        func.coalesce(func.sum(MonthlySnapshot.consumed_lessons), 0),
    ).scalar() or 0
    consumed_amt = base.with_entities(
        func.coalesce(func.sum(MonthlySnapshot.consumed_amount), 0),
    ).scalar() or 0
    refund = base.with_entities(
        func.coalesce(func.sum(MonthlySnapshot.refund_amount), 0),
    ).scalar() or 0
    end_balance = base.with_entities(
        func.coalesce(func.sum(MonthlySnapshot.end_balance), 0),
    ).scalar() or 0
    new_signups = (
        db.session.query(func.count(func.distinct(StudentAccount.student_id)))
        .select_from(MonthlySnapshot)
        .join(StudentAccount, MonthlySnapshot.account_id == StudentAccount.id)
        .filter(
            MonthlySnapshot.year == year,
            MonthlySnapshot.month == month,
            db.or_(
                MonthlySnapshot.new_signup_amount > 0,
                MonthlySnapshot.new_signup_lessons > 0,
            ),
        )
        .scalar()
        or 0
    )
    active_accounts = base.count()
    return {
        'recharge': float(recharge),
        'consumed_hours': float(consumed_h),
        'consumed_amount': float(consumed_amt),
        'refund': float(refund),
        'end_balance': float(end_balance),
        'new_signups': int(new_signups),
        'active_accounts': int(active_accounts),
    }


def year_overview(year: int) -> dict:
    """年度汇总（该年各月快照之和）"""
    base = _snapshot_query(year, None)
    recharge = base.with_entities(func.coalesce(func.sum(_recharge_expr()), 0)).scalar() or 0
    consumed_h = base.with_entities(
        func.coalesce(func.sum(MonthlySnapshot.consumed_lessons), 0),
    ).scalar() or 0
    refund = base.with_entities(
        func.coalesce(func.sum(MonthlySnapshot.refund_amount), 0),
    ).scalar() or 0
    new_signups = (
        db.session.query(func.count(func.distinct(StudentAccount.student_id)))
        .select_from(MonthlySnapshot)
        .join(StudentAccount, MonthlySnapshot.account_id == StudentAccount.id)
        .filter(
            MonthlySnapshot.year == year,
            db.or_(
                MonthlySnapshot.new_signup_amount > 0,
                MonthlySnapshot.new_signup_lessons > 0,
            ),
        )
        .scalar()
        or 0
    )
    return {
        'recharge': float(recharge),
        'consumed_hours': float(consumed_h),
        'refund': float(refund),
        'new_signups': int(new_signups),
    }


def cumulative_finance() -> dict:
    """全库累计（所有已导入月份）"""
    recharge = (
        db.session.query(func.coalesce(func.sum(_recharge_expr()), 0)).scalar() or 0
    )
    refund = (
        db.session.query(func.coalesce(func.sum(MonthlySnapshot.refund_amount), 0)).scalar()
        or 0
    )
    consumed_amt = (
        db.session.query(func.coalesce(func.sum(MonthlySnapshot.consumed_amount), 0)).scalar()
        or 0
    )
    return {
        'total_recharge': float(recharge),
        'total_refund': float(refund),
        'net_income': float(recharge) - float(refund),
        'total_consumed_amount': float(consumed_amt),
    }


def course_stats_for_period(year: int, month: int) -> list[dict]:
    """各课程：充值、消课课时、消课金额、月末余额"""
    rows = (
        db.session.query(
            Course.name,
            Course.course_code,
            func.coalesce(func.sum(_recharge_expr()), 0),
            func.coalesce(func.sum(MonthlySnapshot.consumed_lessons), 0),
            func.coalesce(func.sum(MonthlySnapshot.consumed_amount), 0),
            func.coalesce(func.sum(MonthlySnapshot.refund_amount), 0),
            func.coalesce(func.sum(MonthlySnapshot.end_balance), 0),
        )
        .select_from(MonthlySnapshot)
        .join(StudentAccount, MonthlySnapshot.account_id == StudentAccount.id)
        .join(Course, StudentAccount.course_id == Course.id)
        .filter(MonthlySnapshot.year == year, MonthlySnapshot.month == month)
        .group_by(Course.id, Course.name, Course.course_code)
        .order_by(func.sum(_recharge_expr()).desc())
        .all()
    )
    return [
        {
            'name': name,
            'code': code or name,
            'recharge': float(r or 0),
            'consumed_hours': float(h or 0),
            'consumed_amount': float(a or 0),
            'refund': float(rf or 0),
            'end_balance': float(bal or 0),
        }
        for name, code, r, h, a, rf, bal in rows
        if float(r or 0) or float(h or 0) or float(rf or 0) or float(bal or 0)
    ]


def refund_breakdown(year: int, month: int) -> list[dict]:
    """有退费金额的记录按课程汇总"""
    rows = (
        db.session.query(
            Course.name,
            func.count(MonthlySnapshot.id),
            func.coalesce(func.sum(MonthlySnapshot.refund_amount), 0),
            func.coalesce(func.sum(MonthlySnapshot.refund_lessons), 0),
        )
        .select_from(MonthlySnapshot)
        .join(StudentAccount, MonthlySnapshot.account_id == StudentAccount.id)
        .join(Course, StudentAccount.course_id == Course.id)
        .filter(
            MonthlySnapshot.year == year,
            MonthlySnapshot.month == month,
            MonthlySnapshot.refund_amount > 0,
        )
        .group_by(Course.id, Course.name)
        .order_by(func.sum(MonthlySnapshot.refund_amount).desc())
        .all()
    )
    return [
        {
            'name': name,
            'count': int(cnt),
            'amount': float(amt or 0),
            'lessons': float(less or 0),
        }
        for name, cnt, amt, less in rows
    ]


def monthly_trend_from_snapshots() -> list[dict]:
    """已导入各月充值/消课/退费趋势"""
    stats = list_period_stats()
    if not stats:
        return []
    trend = []
    for p in sorted(stats, key=lambda x: (x['year'], x['month'])):
        ov = period_overview(p['year'], p['month'])
        trend.append({
            'month': f"{p['year']}-{p['month']:02d}",
            'label': f"{p['month']}月",
            'recharge': ov['recharge'],
            'consumption': ov['consumed_hours'],
            'refund': ov['refund'],
            'count': p['count'],
        })
    return trend


def class_activity_for_period(year: int, month: int) -> list[dict]:
    """上课记录按课程汇总（人次/课时）"""
    rows = (
        db.session.query(
            Course.name,
            func.count(ClassRecord.id),
            func.coalesce(func.sum(ClassRecord.lessons_consumed), 0),
        )
        .select_from(ClassRecord)
        .join(StudentAccount, ClassRecord.account_id == StudentAccount.id)
        .join(Course, StudentAccount.course_id == Course.id)
        .filter(ClassRecord.year == year, ClassRecord.month == month)
        .group_by(Course.id, Course.name)
        .order_by(func.count(ClassRecord.id).desc())
        .limit(15)
        .all()
    )
    return [
        {'name': name, 'sessions': int(cnt), 'lessons': float(less or 0)}
        for name, cnt, less in rows
    ]


def resolve_report_period(
    year: Optional[int] = None,
    month: Optional[int] = None,
) -> tuple[int, int]:
    if year and month:
        return int(year), int(month)
    py, pm = get_latest_period()
    if py and pm:
        return py, pm
    row = (
        db.session.query(MonthlySnapshot.year, MonthlySnapshot.month)
        .order_by(MonthlySnapshot.year.desc(), MonthlySnapshot.month.desc())
        .first()
    )
    if row:
        return int(row[0]), int(row[1])
    from datetime import date
    t = date.today()
    return t.year, t.month