package com.nova.sankuai.domain.api.yinsheng;

import com.nova.sankuai.infra.config.ServerName;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.security.SecureRandom;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;

/**
 * 随机序列生成器
 */
@Component
public class SerialGenerator {

    /**
     * 以随机种子初始化random对象
     */
    private static final Random RANDOM = new SecureRandom();

    /**
     * 内部交易码长度
     */
    private static final int INTER_TRANS_ID_LENGTH = 32;

    /**
     * 日期格式化模板
     */
    private static ThreadLocal<SimpleDateFormat> dateFormatFactory = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyyMMddHHmmssSSS"));

    private static final String DEFAULT_TANSID_TYPE = "10";

    private static final char[] mm = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

    @Resource
    ServerName serverName;

    /**
     * 生成规则 17位日期毫秒数 + 消息类型（10) + 随机数补齐32位
     */
    public static String getOrder() {
        StringBuilder sb = new StringBuilder();
        sb.append(dateFormatFactory.get().format(new Date())).append(DEFAULT_TANSID_TYPE)
                .append(generateRandomSerial(INTER_TRANS_ID_LENGTH - sb.length()));
        return sb.toString();
    }

    /**
     * 获取带有服务器名作为后缀的订单号
     * @return 订单号
     */
    public String getOrderWithServerName() {
        StringBuilder sb = new StringBuilder();
        sb.append(dateFormatFactory.get().format(new Date())).append(DEFAULT_TANSID_TYPE)
                .append(generateRandomSerial(INTER_TRANS_ID_LENGTH - sb.length())).append(serverName.getServerName());
        return sb.toString();
    }


    /**
     * 生成len长度的随机数序列
     *
     * @return String randomString
     */
    public static String generateRandomSerial(int len) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < len; i++) {
            sb.append(mm[RANDOM.nextInt(mm.length)]);
        }
        return sb.toString();
    }

}