Твиттер-клон с использованием Node.js и Redis

ritter.js

var sys = require('sys'),
    client = require('./redis-client').createClient(),
    hash = require('./hashlib');

// set globals
/*client.set('global:nextUserId', 1000, function() {
  client.set('global:nextPostId', 1000, function(a) {
    sys.puts('Global variables ready: ' + a);
  });
});*/

var ritter = {
    registerUser: function(username, password, callback) {
        // check username availability
        client.incr('global:nextUserId', function(err, uid) {
         if (uid) {
          sys.puts('Uid is ' + uid);  
          client.get('username:' + username + ':id', function(err, id) {
            if (!id) {
              client.set('uid:' + uid + ':username', username, function(err) {
                client.set('uid:' + uid + ':password', hash.md5(password), function(err) {
                  client.set('username:' + username + ':id', uid, function(err) {
                    callback(true, parseInt(uid.toString()));
                  });
                });
              });
            } else {
              sys.puts('Username already taken!');
              callback(true, parseInt(id.toString()));
            }
          });
         } else {
            sys.puts('Cannot get UID: ' + err);
            callback(true);
         }
        });
    },

    login: function(username, password, callback) {
        client.get('username:' + username + ':uid', function(err, uid) {
            if (uid) {
              client.get('uid:' + uid + ':password', function(err, password){
                if (hash.md5(password) == password) {
                  callback(false, parseInt(uid.toString()));
                } else {
                  sys.puts('Wrong password');
                  callback(true);
                }
              });
            } else {
              sys.puts('No such user');
              callback(true);
            }
        });
    },

    follow: function(uid, fid, callback) {
        client.sadd('uid:' + uid + ':following', fid, function(err) {
          if (err) {
            sys.puts('Error following');
            callback(true);
          } else {
            client.sadd('uid:' + fid + ':followers', uid, function(err) {
              if (err) {
                callback(true);
                sys.puts('Error following');
              } else {
                callback(false);
              }
            });
          }
        });
    },

    unfollow: function(uid, fid, callback) {
        client.srem('uid:' + uid + ':following', fid, function() {
          client.srem('uid:' + fid + ':followers', uid, function() {
            callback(false);
          });
        });
    },

    post: function(uid, body, callback) {
        client.incr('global:nextPostId', function(err, pid) {
          client.smembers('uid:' + uid + ':followers', function(err, followers) {
            if (err) {
              sys.puts('Error writing to followers');
            }
            client.get('uid:' + uid + ':username', function(err, username) {
              if (!err) {
                client.lpush('uid:' + uid + ':posts', JSON.stringify({'author':uid, 'body':body}), function() {
                  callback(false, pid);
                });
                for (var fid in followers) {
                  sys.puts('To ' + followers[fid] + ' timeline');
                  client.lpush('uid:' + followers[fid] + ':posts', JSON.stringify({'author':uid, 'body':body}), function() {});
                }
              } else {
                sys.puts('Post from non-existing username');
                callback(true);
              }
            });
          })  
        });
    },

    getPosts: function(uid, callback) {
      client.lrange('uid:' + uid + ':posts', 0, 10, function(err, data) {
        if (err) {
          callback(err);
        } else {
          callback(false, data);
        }
      });
    },

    getFollowing: function(uid, callback) {
      client.smembers('uid:' + uid + ':following', function(err, data) {
        if (err) {
          sys.puts('Error getting followers');
          callback(true);
        } else {
          callback(false, data);
        }
      });
    }
};

exports.ritter = ritter;