package com.sunda.spmsoversea.util;

import java.util.UUID;

/**
 * @program: spms
 * @description:
 * @author: Wayne Wu
 * @create: 2022-02-24 15:31
 **/

public class UUID22 {
    /**
     * 采用URL Base64字符，把“+/”换成“-_”
     */
    static private char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=".toCharArray();

    /**
     * Base64 编码
     * @param data
     * @return
     */
    private char[] encode(byte[] data) {
        char[] out = new char[((data.length + 2) / 3) * 4];
        boolean quad, trip;
        for (int i = 0, index = 0; i < data.length; i += 3, index += 4) {
            quad = trip = false;
            int val = (0xFF & (int) data[i]);
            val <<= 8;
            if ((i + 1) < data.length) {
                val |= (0xFF & (int) data[i + 1]);
                trip = true;
            }
            val <<= 8;
            if ((i + 2) < data.length) {
                val |= (0xFF & (int) data[i + 2]);
                quad = true;
            }
            out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 1] = alphabet[val & 0x3F];
            val >>= 6;
            out[index + 0] = alphabet[val & 0x3F];
        }
        return out;
    }

    /**
     * 转成字节
     * @return
     */
    private byte[] toBytes() {
        UUID uuid = UUID.randomUUID();
        long msb = uuid.getMostSignificantBits();
        long lsb = uuid.getLeastSignificantBits();
        byte[] buffer = new byte[16];

        for (int i = 0; i < 8; i++) {
            buffer[i] = (byte) ((msb >>> 8 * (7 - i)) & 0xFF);
            buffer[i + 8] = (byte) ((lsb >>> 8 * (7 - i)) & 0xFF);
        }
        return buffer;
    }

    public String getUUID() {
        char[] res = encode(toBytes());
        System.out.println(new String(res));
        return new String(res, 0, res.length - 2);
    }


    /**
     * 将随机UUID转换成22位字符串
     * @return
     */
    public static String getUUID22() {
        UUID uuid = UUID.randomUUID();
		System.out.println(uuid.toString());
        long msb = uuid.getMostSignificantBits();
        long lsb = uuid.getLeastSignificantBits();
        char[] out = new char[24];
        int tmp = 0, idx = 0;

        // 循环写法
        int bit = 0, bt1 = 8, bt2 = 8;
        int mask = 0x00, offsetm = 0, offsetl = 0;

        for(; bit < 16; bit += 3, idx += 4) {
            offsetm = 64 - (bit + 3) * 8;
            offsetl = 0;
            tmp = 0;

            if(bt1 > 3) {
                mask = (1 << 8 * 3) - 1;
            } else if(bt1 >= 0) {
                mask = (1 << 8 * bt1) - 1;
                bt2 -= 3 - bt1;
            } else {
                mask = (1 << 8 * ((bt2 > 3) ? 3 : bt2)) - 1;
                bt2 -= 3;
            }
            if(bt1 > 0) {
                bt1 -= 3;
                tmp = (int) ((offsetm < 0) ? msb : (msb >>> offsetm) & mask);
                if(bt1 < 0) {
                    tmp <<= Math.abs(offsetm);
                    mask = (1 << 8 * Math.abs(bt1)) - 1;
                }
            }
            if(offsetm < 0) {
                offsetl = 64 + offsetm;
                tmp |= ((offsetl < 0) ? lsb : (lsb >>> offsetl)) & mask;
            }

            if(bit == 15) {
                out[idx + 3] = alphabet[64];
                out[idx + 2] = alphabet[64];
                tmp <<= 4;
            } else {
                out[idx + 3] = alphabet[tmp & 0x3f];
                tmp >>= 6;
                out[idx + 2] = alphabet[tmp & 0x3f];
                tmp >>= 6;
            }
            out[idx + 1] = alphabet[tmp & 0x3f];
            tmp >>= 6;
            out[idx] = alphabet[tmp & 0x3f];
        }
        return new String(out, 0, 22);
    }


    public static void main(String[] args) {
        for (int i = 0; i < 20; i ++){
            System.out.println(getUUID22());
        }
    }
}