fix: avbv转换

lib/utils/id_utils.dart

@@ -1,51 +1,52 @@
-// ignore_for_file: constant_identifier_names
+// ignore_for_file: constant_identifier_names, non_constant_identifier_names
 
 import 'dart:convert';
-import 'dart:math';
-
-import 'package:flutter/material.dart';
 
 class IdUtils {
-  static const String TABLE =
-      'fZodR9XQDSUm21yCkr6zBqiveYah8bt4xsWpHnJE7jL5VG3guMTKNPAwcF';
-  static const List<int> S = [11, 10, 3, 8, 4, 6]; // 位置编码表
-  static const int XOR = 177451812; // 固定异或值
-  static const int ADD = 8728348608; // 固定加法值
-  static const List<String> r = [
-    'B',
-    'V',
-    '1',
-    '',
-    '',
-    '4',
-    '',
-    '1',
-    '',
-    '7',
-    '',
-    ''
-  ];
+  static final XOR_CODE = BigInt.parse('23442827791579');
+  static final MASK_CODE = BigInt.parse('2251799813685247');
+  static final MAX_AID = BigInt.one << (BigInt.from(51)).toInt();
+  static final BASE = BigInt.from(58);
+
+  static const data =
+      'FcwAPNKTMug3GV5Lj7EJnHpWsx4tb8haYeviqBz6rkCy12mUSDQX9RdoZf';
 
   /// av转bv
-  static String av2bv(int av) {
-    int x_ = (av ^ XOR) + ADD;
-    List<String> newR = [];
-    newR.addAll(r);
-    for (int i = 0; i < S.length; i++) {
-      newR[S[i]] =
-          TABLE.characters.elementAt((x_ / pow(58, i).toInt() % 58).toInt());
+  static String av2bv(int aid) {
+    List<String> bytes = List.filled(12, '0', growable: false);
+    int bvIndex = bytes.length - 1;
+    BigInt tmp = (MAX_AID | BigInt.from(aid)) ^ XOR_CODE;
+    while (tmp > BigInt.zero) {
+      bytes[bvIndex] = data[(tmp % BASE).toInt()];
+      tmp = tmp ~/ BASE;
+      bvIndex -= 1;
     }
-    return newR.join();
+    final tmpValue = bytes[3];
+    bytes[3] = bytes[9];
+    bytes[9] = tmpValue;
+
+    final tmpValue2 = bytes[4];
+    bytes[4] = bytes[7];
+    bytes[7] = tmpValue2;
+
+    return bytes.join();
   }
 
-  /// bv转bv
-  static int bv2av(String bv) {
-    int r = 0;
-    for (int i = 0; i < S.length; i++) {
-      r += (TABLE.indexOf(bv.characters.elementAt(S[i])).toInt()) *
-          pow(58, i).toInt();
-    }
-    return (r - ADD) ^ XOR;
+  /// bv转av
+  static int bv2av(String bvid) {
+    List<String> bvidArr = bvid.split('');
+    final tmpValue = bvidArr[3];
+    bvidArr[3] = bvidArr[9];
+    bvidArr[9] = tmpValue;
+
+    final tmpValue2 = bvidArr[4];
+    bvidArr[4] = bvidArr[7];
+    bvidArr[7] = tmpValue2;
+
+    bvidArr.removeRange(0, 3);
+    BigInt tmp = bvidArr.fold(BigInt.zero,
+        (pre, bvidChar) => pre * BASE + BigInt.from(data.indexOf(bvidChar)));
+    return ((tmp & MASK_CODE) ^ XOR_CODE).toInt();
   }
 
   // 匹配