get tags from GraphQL API

Author: AerysNan

lib/config.js

@@ -32,6 +32,52 @@ const DEFAULT_CONFIG = {
       'swift',
       'typescript'
     ],
+    tags: [
+      'array',
+      'backtracking',
+      'binary-indexed-tree',
+      'binary-search',
+      'binary-search-tree',
+      'bit-manipulation',
+      'brainteaser',
+      'breadth-first-search',
+      'depth-first-search',
+      'design',
+      'divide-and-conquer',
+      'dynamic-programming',
+      'geometry',
+      'graph',
+      'greedy',
+      'hash-table',
+      'heap',
+      'line-sweep',
+      'linked-list',
+      'math',
+      'memoization',
+      'minimax',
+      'ordered-map',
+      'queue',
+      'random',
+      'recursion',
+      'rejection-sampling',
+      'reservoir-sampling',
+      'segment-tree',
+      'sliding-window',
+      'sort',
+      'stack',
+      'string',
+      'topological-sort',
+      'tree',
+      'trie',
+      'two-pointers',
+      'union-find',
+      
+      // TODO: these two tags below are included on leetcode.com but not on leetcode-cn.com
+      // Currently comment out for simplicity
+
+      // 'rolling-hash',
+      // 'suffix-array',
+    ],
     urls: {
       // base urls
       base:                      'https://leetcode.com',
@@ -51,6 +97,7 @@ const DEFAULT_CONFIG = {
       linkedin_login_request:    'https://www.linkedin.com/login',
       linkedin_session_request:  'https://www.linkedin.com/checkpoint/lg/login-submit',
       // questions urls
+      tag:                       'https://leetcode.com/tag/$tag/',
       problems:                  'https://leetcode.com/api/problems/$category/',
       problem:                   'https://leetcode.com/problems/$slug/description/',
       test:                      'https://leetcode.com/problems/$slug/interpret_solution/',

lib/plugins/company.js

@@ -1520,9 +1520,6 @@ plugin.getProblems = function(cb) {
       if (id in COMPONIES) {
         problem.companies = (problem.companies || []).concat(COMPONIES[id]);
       }
-      if (id in TAGS) {
-        problem.tags = (problem.tags || []).concat(TAGS[id]);
-      }
     });
     return cb(null, problems);
   });

lib/plugins/leetcode.js

@@ -60,9 +60,9 @@ plugin.getProblems = function(cb) {
   const getCategory = function(category, queue, cb) {
     plugin.getCategoryProblems(category, function(e, _problems) {
       if (e) {
-        log.debug(category + ': failed to getProblems: ' + e.msg);
+        log.debug(category + ': failed to getCategory: ' + e.msg);
       } else {
-        log.debug(category + ': getProblems got ' + _problems.length + ' problems');
+        log.debug(category + ': getCategory got ' + _problems.length + ' problems');
         problems = problems.concat(_problems);
       }
       return cb(e);
@@ -73,10 +73,68 @@ plugin.getProblems = function(cb) {
   const q = new Queue(config.sys.categories, {}, getCategory);
   q.run(null, function(e) {
     spin.stop();
-    return cb(e, problems);
+    if (e) return cb(e);
+    plugin.attachTags(problems, cb);
   });
 };
 
+plugin.attachTags = function(problems, cb) {
+  problems = new Map(problems.map(p => [p.id, p]));
+  const getTag = function (tag, queue, cb) {
+    plugin.getTagProblems(tag, function(e, _problems) {
+      if (e) {
+        log.debug(tag + ': failed to getTag: ' + e.msg);
+      } else if (!_problems) {
+        log.warn(tag + ': retrieve empty tag');
+      } else {
+        log.debug(tag + ': getTag got ' + _problems.length + ' problems');
+        _problems.forEach(function (p) {
+          let id = parseInt(p.questionId);
+          if (problems.has(id)) {
+            problems.get(id).tags.push(tag);
+          }
+        })
+      }
+      return cb(e);
+    }); 
+  };
+  spin = h.spin("Downloading tags");
+  const q = new Queue(config.sys.tags, {}, getTag);
+  q.run(null, function (e) {
+    spin.stop();
+    problems = Array.from(problems.values());
+    return cb(e, problems);
+  });
+}
+
+plugin.getTagProblems = function(tag, cb) {
+  log.debug('running leetcode.getTagProblems: ' + tag);
+  const opts = plugin.makeOpts(config.sys.urls.graphql);
+  opts.headers.Origin = config.sys.urls.base;
+  opts.headers.Referer = config.sys.urls.tag.replace('$tag', tag);
+  opts.json = true;
+  opts.body = {
+    query: [
+      'query getTopicTag($slug: String!) {',
+      '  topicTag(slug: $slug) {',
+      '    slug',
+      '    questions {',
+      '      questionId',
+      '    }',
+      '  }',
+      '}'
+    ].join('\n'),
+    operationName: 'getTopicTag',
+    variables: { slug: tag },
+  };
+  spin.text = 'Downloading tag ' + tag;
+  request(opts, function(e, resp, body) {
+    e = plugin.checkError(e, resp, 200);
+    if (e) return cb(e);
+    return cb(null, body.data.topicTag.questions);
+  });
+}
+
 plugin.getCategoryProblems = function(category, cb) {
   log.debug('running leetcode.getCategoryProblems: ' + category);
   const opts = plugin.makeOpts(config.sys.urls.problems.replace('$category', category));
@@ -109,7 +167,8 @@ plugin.getCategoryProblems = function(category, cb) {
             percent:  p.stat.total_acs * 100 / p.stat.total_submitted,
             level:    h.levelToName(p.difficulty.level),
             starred:  p.is_favor,
-            category: json.category_slug
+            category: json.category_slug,
+            tags:     []
           };
         });