-- 啟用Redis命令復(fù)制，確保腳本在集群環(huán)境中正確同步
redis.replicate_commands()
 
-- 1. 防重提交校驗(yàn)：通過(guò)用戶(hù)ID+Token判斷是否重復(fù)提交
-- KEYS[2]為用戶(hù)ID（uid），ARGV[2]為本次請(qǐng)求的Token
if redis.call('hexists', KEYS[2], ARGV[2]) == 1 then
    return redis.error_reply('repeat submit')  -- 重復(fù)提交，返回錯(cuò)誤
end 
 
-- 2. 庫(kù)存充足性校驗(yàn)
local product_id = KEYS[1]  -- 商品ID
local stock = redis.call('get', KEYS[1])  -- 獲取當(dāng)前庫(kù)存
if not stock then  -- 庫(kù)存不存在（如商品未上架）
    return redis.error_reply('product not found')
end
if tonumber(stock) < tonumber(ARGV[1]) then  -- 庫(kù)存不足
    return redis.error_reply('stock is not enough')
end 
 
-- 3. 執(zhí)行庫(kù)存扣減
local remaining_stock = tonumber(stock) - tonumber(ARGV[1])
redis.call('set', KEYS[1], tostring(remaining_stock))  -- 更新庫(kù)存
 
-- 4. 記錄交易流水（用于后續(xù)一致性校驗(yàn)）
local time = redis.call('time')  -- 獲取當(dāng)前時(shí)間（秒+微秒）
local currentTimeMillis = (time[1] * 1000) + math.floor(time[2] / 1000)  -- 轉(zhuǎn)換為毫秒時(shí)間戳
-- 存儲(chǔ)流水到Hash結(jié)構(gòu)：用戶(hù)ID → Token → 流水詳情
redis.call('hset', KEYS[2], ARGV[2], 
    cjson.encode({
        action = '扣減庫(kù)存',
        product = product_id,
        from = stock,  -- 扣減前庫(kù)存
        to = remaining_stock,  -- 扣減后庫(kù)存
        change = ARGV[1],  -- 扣減數(shù)量
        token = ARGV[2],
        timestamp = currentTimeMillis
    })
)
 
return remaining_stock  -- 返回扣減后庫(kù)存

@Service
public class SeckillService {
 
    @Autowired
    private StringRedisTemplate redisTemplate;
 
    // 加載Lua腳本
    private DefaultRedisScript<Long> stockScript;
 
    @PostConstruct
    public void init() {
        stockScript = new DefaultRedisScript<>();
        stockScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("seckill.lua")));
        stockScript.setResultType(Long.class);
    }
 
    /**
     * 執(zhí)行Redis庫(kù)存預(yù)扣減
     * @param productId 商品ID
     * @param uid 用戶(hù)ID
     * @param quantity 購(gòu)買(mǎi)數(shù)量
     * @param token 防重Token
     * @return 扣減后庫(kù)存（-1表示失?。?
     */
    public Long preDeductStock(String productId, String uid, Integer quantity, String token) {
        try {
            // 執(zhí)行Lua腳本：KEYS = [商品ID, 用戶(hù)ID]，ARGV = [數(shù)量, Token]
            return redisTemplate.execute(
                stockScript,
                Arrays.asList(productId, uid),
                quantity.toString(),
                token
            );
        } catch (Exception e) {
            log.error("Redis預(yù)扣減失敗", e);
            return -1L;
        }
    }
}

// 發(fā)送半消息
public void sendHalfMessage(String productId, String uid, String token, Integer quantity) {
    // 構(gòu)建消息
    Message message = new Message(
        "seckill_topic",  // 主題
        "stock_deduct",   // 標(biāo)簽
        JSON.toJSONString(new SeckillMessage(productId, uid, token, quantity)).getBytes()
    );
    // 發(fā)送事務(wù)消息
    TransactionSendResult result = rocketMQTemplate.sendMessageInTransaction(
        "seckill_producer_group",  // 生產(chǎn)者組
        message,
        null  // 本地事務(wù)參數(shù)（可傳遞上下文）
    );
    log.info("半消息發(fā)送結(jié)果：{}", result.getSendStatus());
}

@Component
public class SeckillTransactionListener implements TransactionListener {
 
    @Autowired
    private StringRedisTemplate redisTemplate;
 
    // 執(zhí)行本地事務(wù)
    @Override
    public LocalTransactionState executeLocalTransaction(Message msg, Object arg) {
        try {
            SeckillMessage message = JSON.parseObject(new String(msg.getBody()), SeckillMessage.class);
            // 檢查Redis中是否存在對(duì)應(yīng)流水（驗(yàn)證預(yù)扣減成功）
            Boolean flag = redisTemplate.opsForHash().hasKey(
                message.getUid(),  // Hash key：用戶(hù)ID
                message.getToken()  // Hash field：Token
            );
            return flag ? RocketMQLocalTransactionState.COMMIT : RocketMQLocalTransactionState.ROLLBACK;
        } catch (Exception e) {
            return RocketMQLocalTransactionState.UNKNOWN;  // 未知狀態(tài)，觸發(fā)回查
        }
    }
 
    // 消息回查（解決超時(shí)未確認(rèn)問(wèn)題）
    @Override
    public LocalTransactionState checkLocalTransaction(MessageExt msg) {
        SeckillMessage message = JSON.parseObject(new String(msg.getBody()), SeckillMessage.class);
        // 回查邏輯：再次檢查流水是否存在
        Boolean flag = redisTemplate.opsForHash().hasKey(message.getUid(), message.getToken());
        return flag ? RocketMQLocalTransactionState.COMMIT : RocketMQLocalTransactionState.ROLLBACK;
    }
}

@Component
@RocketMQMessageListener(
    topic = "seckill_topic",
    consumerGroup = "seckill_consumer_group",
    messageModel = MessageModel.CLUSTERING
)
public class SeckillConsumer implements RocketMQListener<MessageExt> {
 
    @Autowired
    private JdbcTemplate jdbcTemplate;
 
    @Override
    public void onMessage(MessageExt message) {
        SeckillMessage msg = JSON.parseObject(new String(message.getBody()), SeckillMessage.class);
        String productId = msg.getProductId();
        int quantity = msg.getQuantity();
 
        // 數(shù)據(jù)庫(kù)扣減（使用樂(lè)觀鎖防超賣(mài)）
        String sql = "UPDATE product_stock " +
                    "SET stock = stock - ?, version = version + 1 " +
                    "WHERE product_id = ? AND stock >= ? AND version = ?";
 
        // 1. 查詢(xún)當(dāng)前版本號(hào)
        Integer version = jdbcTemplate.queryForObject(
            "SELECT version FROM product_stock WHERE product_id = ?",
            Integer.class,
            productId
        );
 
        // 2. 執(zhí)行扣減（樂(lè)觀鎖保證原子性）
        int rows = jdbcTemplate.update(sql, quantity, productId, quantity, version);
        if (rows > 0) {
            // 扣減成功：記錄數(shù)據(jù)庫(kù)流水
            jdbcTemplate.update(
                "INSERT INTO stock_flow (product_id, quantity, op_type, create_time) " +
                "VALUES (?, ?, 'SECKILL', NOW())",
                productId, quantity
            );
            // 確認(rèn)消費(fèi)成功（返回ACK）
        } else {
            // 扣減失?。河|發(fā)重試（MQ默認(rèn)重試機(jī)制）
            throw new RuntimeException("數(shù)據(jù)庫(kù)扣減失敗，觸發(fā)重試");
        }
    }
}

@Scheduled(cron = "0 0 */1 * * ?")  // 每小時(shí)執(zhí)行一次
public void reconcileStock() {
    // 1. 掃描Redis中未同步到MySQL的流水
    Set<String> uids = redisTemplate.keys("uid:*");  // 假設(shè)用戶(hù)ID前綴為uid:
    for (String uid : uids) {
        Map<Object, Object> tokenMap = redisTemplate.opsForHash().entries(uid);
        for (Map.Entry<Object, Object> entry : tokenMap.entrySet()) {
            String token = (String) entry.getKey();
            String flowJson = (String) entry.getValue();
            SeckillFlow flow = JSON.parseObject(flowJson, SeckillFlow.class);
 
            // 2. 檢查MySQL是否有對(duì)應(yīng)訂單
            Integer count = jdbcTemplate.queryForObject(
                "SELECT COUNT(1) FROM orders WHERE product_id = ? AND uid = ? AND token = ?",
                Integer.class,
                flow.getProduct(), flow.getUid(), token
            );
 
            if (count == 0) {
                // 3. 未找到訂單 → 人工介入或自動(dòng)回滾Redis庫(kù)存
                log.warn("發(fā)現(xiàn)不一致：Redis有流水但MySQL無(wú)訂單，product={}, uid={}", flow.getProduct(), uid);
                // redisTemplate.opsForValue().increment(flow.getProduct(), Integer.parseInt(flow.getChange()));
            }
        }
    }
}