add packages (email, jwt)

-import jwt from "jsonwebtoken";
 import { PrismaClient } from "@prisma/client";
+import { nouns, adjectives } from "./words";
+import jwt from "jsonwebtoken";
+import nodemailer from "nodemailer";
+import sgTransport from "nodemailer-sendgrid-transport";
 
 export const prisma = new PrismaClient();
 
@@ -12,3 +15,31 @@ export const getUserId = (context) => {
   }
   throw new Error("There is no vaild user");
 };
+
+export const generateSecret = () => {
+  const randomNumber = Math.floor(Math.random() * adjectives.length);
+  return `${adjectives[randomNumber]} ${nouns[randomNumber]}`;
+};
+
+const sendEmail = (email) => {
+  const options = {
+    auth: {
+      api_user: process.env.SENDGRID_USERNAME,
+      api_password: process.env.SENDGRID_PASSWORD,
+    },
+  };
+  const client = nodemailer.createTransport(sgTransport(options));
+  return client.sendMail(email);
+};
+
+export const sendSecretMail = (address, emailSecret, value) => {
+  const email = {
+    from: "vel1024@khu.ac.kr",
+    to: address,
+    subject: `Authentication key for forgotten ${value}`,
+    html: `Hello, This is khuchat, authentication key is <b>${emailSecret}</b>, copy and paste it, Thanks.`,
+  };
+  return sendEmail(email);
+};
+
+export const generateToken = (id) => jwt.sign({ id }, process.env.JWT_SECRET);