image.js

var redis = require('redis'),
    client = redis.createClient();

exports.freshKey = function() {
  // create an 5 character alphanumeric string from a random number
  candidate = genKey();
  while (exists(candidate)) {
    candidate = genKey();
  }
  return candidate;
};

exports.create = function(key, callback) {
  // TODO: think of better callback arguments
  if (!exists(key)) {
    client.set(key, Date());
    callback(null);
  } else {
    console.log(key + ' exists!')
    callback(true);
  }
};

var exists = function(key) {
  return client.exists(key, function(err, exists) { return !!exists });
};

var genKey = function() {
  return Math.random().toString(36).substring(2, 7);
};