switch를 이용하여 1번 or 번역을 입력하면 번역이 되야됨.

+var express = require('express');
+var app = express();
+const line = require('@line/bot-sdk');
+const config = require('./config');
+
+//papago api
+var request = require('request');
+
+//번역 api_url
+var translate_api_url = 'https://openapi.naver.com/v1/papago/n2mt';
+
+//언어감지 api_url
+var languagedetect_api_url = 'https://openapi.naver.com/v1/papago/detectLangs';
+
+//eng grammar check
+
+var EnGrammarCheck_api_url = 'https://api.textgears.com/check.php';
+
+
+
+// create LINE SDK client
+const client = new line.Client(config.line_config);
+
+// create Express app
+// about Express itself: https://expressjs.com/
+
+// register a webhook handler with middleware
+// about the middleware, please refer to doc
+app.post('/webhook', line.middleware(config.line_config), (req, res) => {
+  Promise
+    .all(req.body.events.map(handleEvent))
+    .then((result) => res.json(result))
+    .catch((err) => {
+      console.error(err);      res.status(200).end();
+    });
+});
+
+function handleEvent(event) {
+  if (event.type !== 'message' || event.message.type !== 'text' ) {
+    // ignore non-text-message event
+    return Promise.resolve(null);
+  }
+  return new Promise(function(resolve, reject) {
+    //언어 감지 option
+    var detect_options = {
+      url : languagedetect_api_url,
+      form : {'query': event.message.text},
+      headers: config.naver_header
+    };
+    //papago 언어 감지
+    request.post(detect_options,function(error,response,body){
+      console.log(response.statusCode);
+      if(!error && response.statusCode == 200){
+        var detect_body = JSON.parse(response.body);
+        var source = '';
+        var target = '';
+        var result = { type: 'text', text:''};
+
+        //언어 감지가 제대로 됐는지 확인
+        console.log(detect_body.langCode);
+
+
+app.post('/message',function(req,res){  var msg = req.body.content;
+  console.log('전달받은 메시지: ' +msg);
+
+  var sent ={};
+
+  switch(msg)
+  {
+    case '번역':
+    case '1':
+    if(detect_body.langCode == 'ko'||detect_body.langCode == 'en'){
+      source = detect_body.langCode == 'ko' ? 'ko':'en';
+      target = source == 'ko' ? 'en':'ko';
+      //papago 번역 option
+      var options = {
+          url:  translate_api_url,
+          // 한국어(source : ko), 영어(target: en), 카톡에서 받는 메시지(text)
+          form: {'source':source, 'target':target, 'text':event.message.text},
+          headers: config.naver_header
+      };
+      request.post(options, function(error, response, body){
+          // Translate API Sucess
+          if(!error && response.statusCode == 200){
+              // JSON
+              var objBody = JSON.parse(response.body);
+              // Message 잘 찍히는지 확인
+
+              result.text = objBody.message.result.translatedText;
+              //console.log(result.text);
+              //번역된 문장 보내기
+              client.replyMessage(event.replyToken,result).then(resolve).catch(reject);
+          }
+      });
+}
+     send={
+       'message':{
+         'text': result.text
+       }
+     }
+    break;
+    case '문법':
+    case '문법체크':
+    case '2':
+
+    break;
+
+  }
+
+
+
+
+});
+
+}
+});
+