update user's phone number value

-import { prisma, generateToken } from "../../../utils";
+import { prisma, generateToken, changePhoneNumber } from "../../../utils";
 import bcrypt from "bcryptjs";
 
 export default {
@@ -6,6 +6,8 @@ export default {
     createAccount: async (_, args) => {
       const { name, password, email, bio, avatarUrl, phoneNum } = args;
       const encryptPw = await bcrypt.hash(password, 10);
+      // TODO: Find user's country code and change new phone number value
+      const newPhoneNumber = await changePhoneNumber(phoneNum, "+82");
       const user = await prisma.user.create({
         data: {
           name,
@@ -13,7 +15,7 @@ export default {
           bio,
           avatarUrl,
           password: encryptPw,
-          phoneNum,
+          phoneNum: newPhoneNumber,
         },
       });
       const token = generateToken(user.id);

@@ -23,6 +23,13 @@ export const isAuthenticated = (request) => {
   return;
 };
 
+export const changePhoneNumber = (phoneNum, locationNum) => {
+  var leftStr = locationNum;
+  var rightStr = phoneNum.slice(1, phoneNum.length());
+  var newStr = leftStr + rightStr;
+  return newStr;
+};
+
 export const generateSecret = () => {
   const randomNumber = Math.floor(Math.random() * adjectives.length);
   return `${adjectives[randomNumber]} ${nouns[randomNumber]}`;