fixes #58: random pick one problem.

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

Author: skygragon

lib/commands/show.js

@@ -12,7 +12,7 @@ var config = require('../config');
 var core = require('../core');
 
 var cmd = {
-  command: 'show <keyword>',
+  command: 'show [keyword]',
   desc:    'show problem by name or index',
   builder: {
     gen: {

lib/core.js

@@ -79,11 +79,25 @@ core.getProblem = function(keyword, cb) {
 
     keyword = Number(keyword) || keyword;
 
-    var problem = _.find(problems, function(x) {
-      return x.id === keyword ||
-             x.name === keyword ||
-             x.slug === keyword;
-    });
+    var problem;
+    if (keyword === undefined) {
+      log.debug('random select problem');
+      var user = core.getUser();
+      // random select one that not AC-ed yet
+      problems = _.filter(problems, function(x) {
+        if (x.state === 'ac') return false;
+        if (!user.paid && x.locked) return false;
+        return true;
+      });
+      problem = problems[_.random(problems.length - 1)];
+    } else {
+      problem = _.find(problems, function(x) {
+        return x.id === keyword ||
+               x.name === keyword ||
+               x.slug === keyword;
+      });
+    }
+
     if (!problem)
       return cb('Problem not found!');