From 67b38b6e7b7a16d6995d1fbcef936d77002c701d Mon Sep 17 00:00:00 2001
From: "luk.lu" <luk.lu@faronear.org>
Date: Fri, 24 Sep 2021 16:43:05 +0800
Subject: [PATCH]  move aiid2regcode/regcode2aiid to core.tool

---
 index.js | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index ecf4d24..4bbf9aa 100644
--- a/index.js
+++ b/index.js
@@ -36,5 +36,55 @@ module.exports = {
       .replace(/[tuv]/g, 8)
       .replace(/[wxyz]/g, 9)
     return parseInt(port)
-  }
+  },
+
+  /**
+   * 用户编号转邀请码
+   *
+   * @static
+   * @param {*} aiid
+   * @return {*}
+   * @memberof TICrypto
+   */
+  aiid2regcode(aiid) {
+    const alphabet = 'e5fcdg3hqa4b1n0pij2rstuv67mwx89klyz'
+    const base = 16367
+    let num = (aiid + base) * (base - alphabet.length)
+    let code = ''
+    let mod
+    while (num > 0) {
+      mod = num % alphabet.length
+      num = (num - mod) / alphabet.length
+      code = code + alphabet[mod] // 倒序存放
+    }
+    return code
+  },
+
+  /**
+   * 邀请码转用户编号
+   *
+   * @static
+   * @param {*} code
+   * @return {*}
+   * @memberof TICrypto
+   */
+  regcode2aiid(code) {
+    if (typeof code === 'string' && /^[a-zA-Z0-9]+$/.test(code)) {
+      const alphabet = 'e5fcdg3hqa4b1n0pij2rstuv67mwx89klyz'
+      const base = 16367
+      code = code.toLowerCase()
+      let len = code.length
+      let num = 0
+      for (let i = 0; i < len; i++) {
+        num += alphabet.indexOf(code[i]) * Math.pow(alphabet.length, i)
+      }
+      let aiid = num / (base - alphabet.length) - base
+      if (aiid >= 0 && Number.isInteger(aiid)) {
+        // 允许 aiid===0：当第一个用户（aiid==1）登录时，需要一个系统默认的邀请码。
+        return aiid
+      }
+    }
+    return null // null 代表一切非法的regcode
+  },
+
 }
\ No newline at end of file