# -*- coding: utf-8 -*-
"""次数卡密生成 / 兑换 / 管理。

（自 auth_system.py 拆出，行为与原实现一致；DB 访问已迁移为原生异步。）
"""

import secrets
import time
from typing import Any

from .db import (
    _q,
    write_transaction,
)

# ============ 卡密 ============


async def generate_cards(count: int, credits: int, created_by: str = '',
                         prefix: str = '', note: str = '', valid_days: int = 0) -> list[str]:
    """生成次数卡密（credits = 每张卡可下载次数）
    prefix: 自定义卡密前缀（默认 VIP-）
    note:   备注信息
    valid_days: 有效天数（0 = 永久有效，过期后不可兑换）
    """
    count = max(1, min(int(count), 500))
    prefix = ''.join(ch for ch in (prefix or 'VIP') if ch.isalnum()).upper()[:10] or 'VIP'
    expire_at = int(time.time()) + int(valid_days) * 86400 if valid_days and int(valid_days) > 0 else 0
    codes = []
    async with write_transaction() as conn:
        for _ in range(count):
            code = prefix + '-' + secrets.token_hex(5).upper()
            await conn.execute(
                'INSERT INTO cards (code, minutes, created_by, created_at, note, expire_at) '
                'VALUES (?, ?, ?, ?, ?, ?)',
                (code, int(credits), created_by, int(time.time()), note or '', expire_at))
            codes.append(code)
    return codes


async def list_cards(limit: int = 100, offset: int = 0) -> tuple[list[dict[str, Any]], int]:
    """卡密列表（支持分页 limit/offset，管理路由透传）
    返回 (当页卡密列表, 卡密总数)——总数供前端分页控件用，调用方按元组解包"""
    limit = max(1, min(int(limit), 500))
    offset = max(0, int(offset))
    rows = await _q('SELECT * FROM cards ORDER BY id DESC LIMIT ? OFFSET ?', (limit, offset))
    total_row = await _q('SELECT COUNT(*) AS c FROM cards')
    total = int(total_row[0]['c']) if total_row else 0
    now = time.time()
    cards = []
    for r in rows:
        d = dict(r)
        # 过期判定以服务端时钟为准（前端时钟偏差会误标已过期/未使用）
        d['expired'] = bool(d.get('expire_at') and d['expire_at'] < now)
        cards.append(d)
    return cards, total


async def set_card_disabled(code: str, disabled: bool) -> None:
    """禁用/恢复未使用卡密（已使用卡密无禁用意义，拒绝操作）"""
    code = (code or '').strip().upper()
    async with write_transaction() as conn:
        row = await (await conn.execute('SELECT used_by, disabled FROM cards WHERE code = ?', (code,))).fetchone()
        if not row:
            raise ValueError('卡密不存在')
        if row['used_by']:
            raise ValueError('卡密已被使用，无需禁用')
        if bool(row['disabled']) == bool(disabled):
            raise ValueError('卡密已处于该状态')
        await conn.execute('UPDATE cards SET disabled = ? WHERE code = ?',
                           (1 if disabled else 0, code))


async def delete_card(code: str) -> None:
    """删除未使用卡密（已使用卡密含兑换凭证：使用者/时间，按 owner 规则不可删）"""
    code = (code or '').strip().upper()
    async with write_transaction() as conn:
        row = await (await conn.execute('SELECT used_by FROM cards WHERE code = ?', (code,))).fetchone()
        if not row:
            raise ValueError('卡密不存在')
        if row['used_by']:
            raise ValueError('已使用的卡密不可删除（保留兑换凭证）')
        await conn.execute('DELETE FROM cards WHERE code = ?', (code,))


async def redeem_card(code: str, username: str) -> tuple[int, int]:
    """兑换卡密，返回 (卡密次数, 新剩余次数)（标记已用与加余额同事务，失败整体回滚不吞卡）"""
    code = (code or '').strip().upper()
    async with write_transaction() as conn:
        row = await (await conn.execute('SELECT * FROM cards WHERE code = ?', (code,))).fetchone()
        if not row:
            raise ValueError('卡密不存在')
        if row['used_by']:
            raise ValueError('卡密已被使用')
        if row['disabled']:
            raise ValueError('卡密已被禁用，请联系管理员')
        if row['expire_at'] and row['expire_at'] < time.time():
            raise ValueError('卡密已过期')
        # 卡密标记 + 余额增加同事务：任一失败整体回滚，卡密可重试兑换。
        # WHERE 带 used_by=""/disabled=0 防重标记 + rowcount 校验：命中 0 行
        # （跨进程并发抢卡）立即回滚报错，绝不出现"未标记已用却加了余额"
        cur = await conn.execute(
            'UPDATE cards SET used_by = ?, used_at = ? '
            'WHERE code = ? AND used_by = "" AND disabled = 0',
            (username, int(time.time()), code))
        if cur.rowcount != 1:
            raise ValueError('卡密已被使用')
        urow = await (await conn.execute('SELECT role, duration_seconds FROM users WHERE username = ?',
                                         (username,))).fetchone()
        if not urow:
            raise ValueError('用户不存在')
        minutes = int(row['minutes'])
        remaining = int(urow['duration_seconds'] or 0)
        if urow['role'] == 'admin' or remaining == -1:
            remaining = -1
        else:
            remaining = remaining + minutes
            await conn.execute('UPDATE users SET duration_seconds = ? WHERE username = ?',
                               (remaining, username))
        return minutes, remaining