package com.xwad.os.manager;

import android.text.TextUtils;

import com.tencent.mmkv.MMKV;
import com.xwad.os.config.CommonConfig;

import java.util.Random;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class DeviceSNManager {
    private static final String SN_KEY = "device_sn";
    private static final String PREFIX = "CDSN";
    private static final int RANDOM_DIGITS = 9;

    private static MMKV mMMKV = MMKV.mmkvWithID(CommonConfig.MMKV_ID, MMKV.MULTI_PROCESS_MODE);

    public DeviceSNManager() {

    }

    /**
     * 获取设备SN，如果不存在则创建新的
     */
    public static String getDeviceSN() {
        String existingSN = mMMKV.decodeString(SN_KEY, "");

//        if (!TextUtils.isEmpty(existingSN)) {
            return existingSN;
//        }

//        String newSN = generateNewSN();
//        mMMKV.encode(SN_KEY, newSN);
//        return newSN;
    }

    public static void saveDeviceSN(String sn) {
        mMMKV.encode(SN_KEY, sn);
    }


    /**
     * 生成新的设备SN
     * 格式：CDSN202511T923852225
     */
    private static String generateNewSN() {
        StringBuilder snBuilder = new StringBuilder();
        // 添加前缀
        snBuilder.append(PREFIX);
        // 添加年份月份
        String timeYear = formatTimestamp(System.currentTimeMillis());
        snBuilder.append(timeYear);

        // 添加基于时间戳的9位随机数字
        snBuilder.append(generateRandomString(10));

        return snBuilder.toString();
    }

    // 定义可供随机选择的字符池
    private static final String LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static final String LETTERS_AND_DIGITS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

    public static String generateRandomString(int length) {
        if (length < 1) {
            throw new IllegalArgumentException("Length must be at least 1");
        }

        Random random = new Random();
        StringBuilder sb = new StringBuilder(length);

        // 第一位：确保是字母
        sb.append(LETTERS.charAt(random.nextInt(LETTERS.length())));

        // 剩余位数：字母或数字
        for (int i = 1; i < length; i++) {
            sb.append(LETTERS_AND_DIGITS.charAt(random.nextInt(LETTERS_AND_DIGITS.length())));
        }

        return sb.toString();
    }

    /**
     * 删除已存储的SN（用于测试或重新生成）
     */
    public static void clearDeviceSN() {
        mMMKV.removeValueForKey(SN_KEY);
    }

    /**
     * 检查是否已存在SN
     */
    public static boolean hasDeviceSN() {
        return mMMKV.containsKey(SN_KEY) && !TextUtils.isEmpty(mMMKV.decodeString(SN_KEY, ""));
    }

    public static String formatTimestamp(long timestamp) {
        // 创建指定格式的格式化对象，"yyyyMM" 表示6位数字的年份和月份，"'T'" 表示字面量字符 T
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMM'T'");
        Date date = new Date(timestamp);
        // 将 Date 对象格式化为字符串
        return sdf.format(date);
    }
}