refs #80: show supported langs.

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

Author: skygragon

lib/commands/show.js

@@ -63,14 +63,24 @@ cmd.handler = function(argv) {
   core.getProblem(argv.keyword, function(e, problem) {
     if (e) return log.fail(e);
 
+    var langlist = problem.templates
+      .map(function(x) {
+        return x.value;
+      })
+      .sort()
+      .join(', ');
+
     var code;
     var needcode = argv.gen || argv.codeonly;
     if (needcode) {
       var template = _.find(problem.templates, function(x) {
         return x.value === argv.lang;
       });
-      if (!template)
-        return log.fail('Unknown language "' + argv.lang + '"');
+      if (!template) {
+        log.fail('Not supported language "' + argv.lang + '"');
+        log.warn('Supported languages: ' + langlist);
+        return;
+      }
 
       var opts = {
         lang: argv.lang,
@@ -115,6 +125,7 @@ cmd.handler = function(argv) {
       log.printf('* Total Submissions: %s', problem.totalSubmit);
     if (problem.testable && problem.testcase)
       log.printf('* Testcase Example:  %s', chalk.yellow(util.inspect(problem.testcase)));
+    log.printf('* Avail Languages:   %s', langlist);
 
     log.info();
     log.info(problem.desc);