[Cache] Add cache command.

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

Author: skygragon

lib/cache.js

@@ -1,4 +1,5 @@
 var fs = require('fs');
+var path = require('path');
 
 var h = require('./helper');
 
@@ -29,4 +30,19 @@ cache.del = function(k) {
   return true;
 };
 
+cache.list = function() {
+  var dir = h.getCacheDir();
+  if (!fs.existsSync(dir)) return [];
+
+  return fs.readdirSync(dir).map(function(filename) {
+    var k = path.basename(filename, '.json');
+    var stat = fs.statSync(h.getCacheFile(k));
+    return {
+      name:  k,
+      size:  stat.size,
+      mtime: stat.mtimeMs
+    };
+  });
+};
+
 module.exports = cache;

lib/commands/cache.js

@@ -0,0 +1,49 @@
+var log = require('loglevel');
+var sprintf = require('sprintf-js').sprintf;
+var _ = require('underscore');
+
+var cache = require('../cache');
+var h = require('../helper');
+
+var cmd = {
+  command: 'cache',
+  desc:    'show cached problems',
+  builder: {
+    all: {
+      alias:    'a',
+      type:     'boolean',
+      describe: 'Delete all cached problems',
+      default:  false
+    },
+    delete: {
+      alias:    'd',
+      type:     'string',
+      describe: 'Delete specific cached problem'
+    }
+  }
+};
+
+cmd.handler = function(argv) {
+  if (argv.delete === undefined) {
+    _.sortBy(cache.list(), function(f) {
+      var x = parseInt(f.name.split('.')[0], 10);
+      if (_.isNaN(x)) x = 0;
+      return x;
+    })
+    .forEach(function(f) {
+      log.info(sprintf('%-50s %8s    %s ago',
+            f.name,
+            h.prettySize(f.size),
+            h.prettyTime(f.mtime)));
+    });
+  } else if (argv.all) {
+    cache.list().forEach(function(f) {
+      if (f.name === '.user') return;
+      cache.del(f.name);
+    });
+  } else {
+    cache.del(argv.delete);
+  }
+};
+
+module.exports = cmd;

lib/helper.js

@@ -23,6 +23,35 @@ h.prettyText = function(text, yesNo) {
   }
 };
 
+h.prettySize = function(size) {
+  var units = 'BKMG';
+  var i = 0;
+  while (size >= 1024 && i < units.length) {
+    size /= 1024.0;
+    ++i;
+  }
+  return size.toFixed(2) + units[i];
+};
+
+h.prettyTime = function(t) {
+  var units = [
+    [60, 'secs'],
+    [60, 'mins'],
+    [24, 'hours'],
+    [7, 'weeks'],
+    [4, 'months'],
+    [12, 'years']
+  ];
+
+  var d = (Date.now() - t) / 1000;
+  var i = 0;
+  while (d > units[i][0] && i < units.length) {
+    d /= units[i][0];
+    ++i;
+  }
+  return d.toFixed(0) + ' ' + units[i][1];
+};
+
 h.levelToName = function(level) {
   switch (level) {
     case 1:  return 'Easy';