delete unused config and make the github login function more clear by review

Author: yihong0618

lib/config.js

@@ -61,13 +61,6 @@ const DEFAULT_CONFIG = {
       favorite_delete:           'https://leetcode.com/list/api/questions/$hash/$id',
       plugin:                    'https://raw.githubusercontent.com/leetcode-tools/leetcode-cli-plugins/master/plugins/$name.js'
     },
-    // login methods enum
-    login_methods: {
-      LeetCode: 'LeetCode',
-      Cookie:   'Cookie',
-      GitHub:   'Github',
-      LinkedIn: 'LinkedIn'
-    }
   },
 
   // but you will want change these

lib/plugins/leetcode.js

@@ -609,35 +609,34 @@ plugin.githubLogin = function(user, cb) {
       if (resp.statusCode !== 200) {
         return cb('GitHub login failed');
       }
-      if (resp.request.uri.href === urls.github_tf_redirect) {
-        // read two-factor code must be sync.
-        const twoFactorcode = require('prompt-sync')()('Please enter your two-factor code: ');
-        const authenticityTokenTwoFactor = body.match(/name="authenticity_token" value="(.*?)"/);
-        if (authenticityTokenTwoFactor === null) {
-          return cb('Get GitHub two-factor token failed');
+      if (resp.request.uri.href !== urls.github_tf_redirect) {
+        return requestLeetcodeAndSave(_request, leetcodeUrl, user, cb);
+      }
+      // read two-factor code must be sync.
+      const twoFactorcode = require('prompt-sync')()('Please enter your two-factor code: ');
+      const authenticityTokenTwoFactor = body.match(/name="authenticity_token" value="(.*?)"/);
+      if (authenticityTokenTwoFactor === null) {
+        return cb('Get GitHub two-factor token failed');
+      }
+      const optionsTwoFactor = {
+        url:     urls.github_tf_session_request,
+        method:  'POST',
+        headers: {
+          'Content-Type': 'application/x-www-form-urlencoded',
+        },
+        followAllRedirects: true,
+        form:               {
+          'otp':                twoFactorcode,
+          'authenticity_token': authenticityTokenTwoFactor[1],
+          'utf8':               encodeURIComponent('✓'),
+        },
+      };
+      _request(optionsTwoFactor, function(e, resp, body) {
+        if (resp.request.uri.href === urls.github_tf_session_request) {
+          return cb('Invalid two-factor code please check');
         }
-        const optionsTwoFactor = {
-          url:     urls.github_tf_session_request,
-          method:  'POST',
-          headers: {
-            'Content-Type': 'application/x-www-form-urlencoded',
-          },
-          followAllRedirects: true,
-          form:               {
-            'otp':                twoFactorcode,
-            'authenticity_token': authenticityTokenTwoFactor[1],
-            'utf8':               encodeURIComponent('✓'),
-          },
-        };
-        _request(optionsTwoFactor, function(e, resp, body) {
-          if (resp.request.uri.href === urls.github_tf_session_request) {
-            return cb('Invalid two-factor code please check');
-          }
-          requestLeetcodeAndSave(_request, leetcodeUrl, user, cb);
-        });
-      } else {
         requestLeetcodeAndSave(_request, leetcodeUrl, user, cb);
-      }
+      });
     });
   });
 };