#支付系统对账设计

public class ReconcileFileDownloader {

    public void downloadYesterdayFiles() {
        String yesterday = DateUtil.formatDate(DateUtil.addDays(new Date(), -1));

        // 下载支付宝对账文件
        try {
            AlipayReconcileFile file = alipayApi.downloadBill(yesterday);
            saveToOSS(file.getFileName(), file.getContent());
        } catch (Exception e) {
            log.error("支付宝对账文件下载失败", e);
            alert("支付宝对账文件下载失败");
        }

        // 下载微信对账文件
        try {
            WechatReconcileFile file = wechatApi.downloadBill(yesterday);
            saveToOSS(file.getFileName(), file.getContent());
        } catch (Exception e) {
            log.error("微信对账文件下载失败", e);
            alert("微信对账文件下载失败");
        }
    }

    private void saveToOSS(String fileName, byte[] content) {
        String ossKey = "reconcile/" + DateUtil.today() + "/" + fileName;
        ossClient.putObject(bucketName, ossKey, new ByteArrayInputStream(content));
        log.info("对账文件已上传OSS: {}", ossKey);
    }
}

public class ReconcileProcessor {

    @Transactional
    public ReconcileReport reconcile(String date, String channel) {
        // Step 1: 获取文件
        List<String> channelRecords = parseChannelFile(date, channel);

        // Step 2: 查询本地流水
        List<PaymentDO> localRecords = paymentDAO.selectByDateAndChannel(date, channel);

        // Step 3: 构建核对Map
        Map<String, ChannelRecord> channelMap = buildChannelMap(channelRecords);
        Map<String, PaymentDO> localMap = buildLocalMap(localRecords);

        // Step 4: 逐条核对
        List<Difference> differences = new ArrayList<>();

        // 4.1: 我有你无（渠道有，平台没有）
        for (String key : channelMap.keySet()) {
            if (!localMap.containsKey(key)) {
                differences.add(new Difference(key, channelMap.get(key), null, "我无你有"));
            }
        }

        // 4.2: 我有你无（平台有，渠道没有）
        for (String key : localMap.keySet()) {
            if (!channelMap.containsKey(key)) {
                differences.add(new Difference(key, null, localMap.get(key), "我有你无"));
            }
        }

        // 4.3: 金额不符
        for (String key : channelMap.keySet()) {
            PaymentDO local = localMap.get(key);
            ChannelRecord channel = channelMap.get(key);
            if (local != null && local.getAmount().compareTo(channel.getAmount()) != 0) {
                differences.add(new Difference(key, channel, local, "金额不符"));
            }
        }

        // Step 5: 保存报告
        ReconcileReport report = new ReconcileReport();
        report.setDate(date);
        report.setChannel(channel);
        report.setChannelCount(channelMap.size());
        report.setLocalCount(localMap.size());
        report.setDiffCount(differences.size());
        report.setDifferences(differences);
        report.setCreateTime(new Date());
        reportDAO.insert(report);

        // Step 6: 告警
        if (differences.size() > 0) {
            alert("对账发现 " + differences.size() + " 条差异，请及时处理");
        }

        return report;
    }
}

public class DifferenceHandler {

    /**
     * 处理"我无你有"：补录缺失记录
     */
    public void handleMissingRecord(Difference diff) {
        ChannelRecord channel = diff.getChannelRecord();

        // 1. 核实渠道记录真实性
        boolean verified = verifyWithChannel(channel.getTradeNo());
        if (!verified) {
            diff.setStatus(DifferenceStatus.FAKE);
            return;
        }

        // 2. 创建补录流水
        PaymentDO supplement = new PaymentDO();
        supplement.setOrderId(channel.getMerchantOrderNo());
        supplement.setChannel(channel.getChannel());
        supplement.setChannelTradeNo(channel.getTradeNo());
        supplement.setAmount(channel.getAmount());
        supplement.setStatus(PaymentStatus.SUCCESS);
        supplement.setPayTime(channel.getTradeTime());
        supplement.setIsSupplement(true);  // 标记为补录
        paymentDAO.insert(supplement);

        // 3. 通知下游系统
        mqService.sendPaymentSuccessNotification(supplement);

        // 4. 更新差异状态
        diff.setStatus(DifferenceStatus.RESOLVED);
        diff.setResolvedBy("auto_supplement");
        diff.setResolvedTime(new Date());
    }

    /**
     * 处理"我有你无"：核实是否重复
     */
    public void handleExtraRecord(Difference diff) {
        PaymentDO local = diff.getLocalRecord();

        // 1. 核实渠道是否真的没有
        boolean confirmed = confirmMissingWithChannel(local.getChannelTradeNo());
        if (!confirmed) {
            // 渠道有记录，可能是文件还没同步，继续等待
            return;
        }

        // 2. 如果确认没有，可能是重复记录，标记待核实
        diff.setStatus(DifferenceStatus.PENDING_MANUAL_REVIEW);
    }
}