refs skygragon#22: show chinese question name.

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

plugins/leetcode.cn.js

@@ -1,12 +1,18 @@
+'use strict'
+var request = require('request');
+
 var config = require('../config');
+var h = require('../helper');
+var log = require('../log');
 var Plugin = require('../plugin');
+var session = require('../session');
 
 //
 // [Usage]
 //
 // https://github.com/skygragon/leetcode-cli-plugins/blob/master/docs/leetcode.cn.md
 //
-var plugin = new Plugin(15, 'leetcode.cn', '2018.11.18',
+var plugin = new Plugin(15, 'leetcode.cn', '2018.11.25',
     'Plugin to talk with leetcode-cn APIs.');
 
 plugin.init = function() {
@@ -27,4 +33,94 @@ plugin.init = function() {
   config.sys.urls.favorite_delete = 'https://leetcode-cn.com/list/api/questions/$hash/$id';
 };
 
+// FIXME: refactor those
+// update options with user credentials
+function signOpts(opts, user) {
+  opts.headers.Cookie = 'LEETCODE_SESSION=' + user.sessionId +
+                        ';csrftoken=' + user.sessionCSRF + ';';
+  opts.headers['X-CSRFToken'] = user.sessionCSRF;
+  opts.headers['X-Requested-With'] = 'XMLHttpRequest';
+}
+
+function makeOpts(url) {
+  const opts = {};
+  opts.url = url;
+  opts.headers = {};
+
+  if (session.isLogin())
+    signOpts(opts, session.getUser());
+  return opts;
+}
+
+function checkError(e, resp, expectedStatus) {
+  if (!e && resp && resp.statusCode !== expectedStatus) {
+    const code = resp.statusCode;
+    log.debug('http error: ' + code);
+
+    if (code === 403 || code === 401) {
+      e = session.errors.EXPIRED;
+    } else {
+      e = {msg: 'http error', statusCode: code};
+    }
+  }
+  return e;
+}
+
+plugin.getProblems = function(cb) {
+  plugin.next.getProblems(function(e, problems) {
+    if (e) return cb(e);
+
+    plugin.getProblemsTitle(function(e, titles) {
+      if (e) return cb(e);
+
+      problems.forEach(function(problem) {
+        const title = titles[problem.fid];
+        if (title)
+          problem.name = title;
+      });
+
+      return cb(null, problems);
+    });
+  });
+};
+
+plugin.getProblemsTitle = function(cb) {
+  log.debug('running leetcode.cn.getProblemNames');
+
+  const opts = makeOpts(config.sys.urls.graphql);
+  opts.headers.Origin = config.sys.urls.base;
+  opts.headers.Referer = 'https://leetcode-cn.com/api/problems/algorithms/';
+
+  opts.json = true;
+  opts.body = {
+    query: [
+      'query getQuestionTranslation($lang: String) {',
+      '  translations: allAppliedQuestionTranslations(lang: $lang) {',
+      '    title',
+      '    question {',
+      '      questionId',
+      '    }',
+      '  }',
+      '}',
+      ''
+    ].join('\n'),
+    variables:     {},
+    operationName: 'getQuestionTranslation'
+  };
+
+  const spin = h.spin('Downloading questions titles');
+  request.post(opts, function(e, resp, body) {
+    spin.stop();
+    e = checkError(e, resp, 200);
+    if (e) return cb(e);
+
+    const titles = [];
+    body.data.translations.forEach(function(x) {
+      titles[x.question.questionId] = x.title;
+    });
+
+    return cb(null, titles);
+  });
+};
+
 module.exports = plugin;