text: /*global Buffer require exports console setTimeout */
  
  var net = require("net"),
      util = require("./lib/util"),
      Queue = require("./lib/queue"),
      to_array = require("./lib/to_array"),
      events = require("events"),
      crypto = require("crypto"),
      parsers = [], commands,
      connection_id = 0,
      default_port = 6379,
      default_host = "127.0.0.1";
  
  // can set this to true to enable for all connections
  exports.debug_mode = false;
  
  var arraySlice = Array.prototype.slice
  function trace() {
      if (!exports.debug_mode) return;
      console.log.apply(null, arraySlice.call(arguments))
  }
  
  // hiredis might not be installed
  try {
      require("./lib/parser/hiredis");
      parsers.push(require("./lib/parser/hiredis"));
  } catch (err) {
      if (exports.debug_mode) {
          console.warn("hiredis parser not installed.");
      }
  }
  
  parsers.push(require("./lib/parser/javascript"));
  
  function RedisClient(stream, options) {
      this.stream = stream;
      this.options = options = options || {};
  
      this.connection_id = ++connection_id;
      this.connected = false;
      this.ready = false;
      this.connections = 0;
      if (this.options.socket_nodelay === undefined) {
          this.options.socket_nodelay = true;
      }
      this.should_buffer = false;
      this.command_queue_high_water = this.options.command_queue_high_water || 1000;
      this.command_queue_low_water = this.options.command_queue_low_water || 0;
      this.max_attempts = null;
      if (options.max_attempts && !isNaN(options.max_attempts) && options.max_attempts > 0) {
          this.max_attempts = +options.max_attempts;
      }
      this.command_queue = new Queue(); // holds sent commands to de-pipeline them
      this.offline_queue = new Queue(); // holds commands issued but not able to be sent
      this.commands_sent = 0;
      this.connect_timeout = false;
      if (options.connect_timeout && !isNaN(options.connect_timeout) && options.connect_timeout > 0) {
          this.connect_timeout = +options.connect_timeout;
      }
      this.enable_offline_queue = true;
      if (typeof this.options.enable_offline_queue === "boolean") {
          this.enable_offline_queue = this.options.enable_offline_queue;
      }
      this.retry_max_delay = null;
      if (options.retry_max_delay !== undefined && !isNaN(options.retry_max_delay) && options.retry_max_delay > 0) {
          this.retry_max_delay = options.retry_max_delay;
      }
  
      this.initialize_retry_vars();
      this.pub_sub_mode = false;
      this.subscription_set = {};
      this.monitoring = false;
      this.closing = false;
      this.server_info = {};
      this.auth_pass = null;
      if (options.auth_pass !== undefined) {
          this.auth_pass = options.auth_pass;
      }
      this.parser_module = null;
      this.selected_db = null;	// save the selected db here, used when reconnecting
  
      this.old_state = null;
  
      var self = this;
  
      this.stream.on("connect", function () {
          self.on_connect();
      });
  
      this.stream.on("data", function (buffer_from_socket) {
          self.on_data(buffer_from_socket);
      });
  
      this.stream.on("error", function (msg) {
          self.on_error(msg.message);
      });
  
      this.stream.on("close", function () {
          self.connection_gone("close");
      });
  
      this.stream.on("end", function () {
          self.connection_gone("end");
      });
  
      this.stream.on("drain", function () {
          self.should_buffer = false;
          self.emit("drain");
      });
  
      events.EventEmitter.call(this);
  }
  util.inherits(RedisClient, events.EventEmitter);
  exports.RedisClient = RedisClient;
  
  RedisClient.prototype.initialize_retry_vars = function () {
      this.retry_timer = null;
      this.retry_totaltime = 0;
      this.retry_delay = 150;
      this.retry_backoff = 1.7;
      this.attempts = 1;
  };
  
  RedisClient.prototype.unref = function () {
      trace("User requesting to unref the connection");
      if (this.connected) {
          trace("unref'ing the socket connection");
          this.stream.unref();
      }
      else {
          trace("Not connected yet, will unref later");
          this.once("connect", function () {
              this.unref();
          })
      }
  };
  
  // flush offline_queue and command_queue, erroring any items with a callback first
  RedisClient.prototype.flush_and_error = function (message) {
      var command_obj, error;
  
      error = new Error(message);
  
      while (this.offline_queue.length > 0) {
          command_obj = this.offline_queue.shift();
          if (typeof command_obj.callback === "function") {
              try {
                  command_obj.callback(error);
              } catch (callback_err) {
                  this.emit("error", callback_err);
              }
          }
      }
      this.offline_queue = new Queue();
  
      while (this.command_queue.length > 0) {
          command_obj = this.command_queue.shift();
          if (typeof command_obj.callback === "function") {
              try {
                  command_obj.callback(error);
              } catch (callback_err) {
                  this.emit("error", callback_err);
              }
          }
      }
      this.command_queue = new Queue();
  };
  
  RedisClient.prototype.on_error = function (msg) {
      var message = "Redis connection to " + this.host + ":" + this.port + " failed - " + msg;
  
      if (this.closing) {
          return;
      }
  
      if (exports.debug_mode) {
          console.warn(message);
      }
  
      this.flush_and_error(message);
  
      this.connected = false;
      this.ready = false;
  
      this.emit("error", new Error(message));
      // "error" events get turned into exceptions if they aren't listened for.  If the user handled this error
      // then we should try to reconnect.
      this.connection_gone("error");
  };
  
  RedisClient.prototype.do_auth = function () {
      var self = this;
  
      if (exports.debug_mode) {
          console.log("Sending auth to " + self.host + ":" + self.port + " id " + self.connection_id);
      }
      self.send_anyway = true;
      self.send_command("auth", [this.auth_pass], function (err, res) {
          if (err) {
              if (err.toString().match("LOADING")) {
                  // if redis is still loading the db, it will not authenticate and everything else will fail
                  console.log("Redis still loading, trying to authenticate later");
                  setTimeout(function () {
                      self.do_auth();
                  }, 2000); // TODO - magic number alert
                  return;
              } else if (err.toString().match("no password is set")) {
                  console.log("Warning: Redis server does not require a password, but a password was supplied.")
                  err = null;
                  res = "OK";
              } else {
                  return self.emit("error", new Error("Auth error: " + err.message));
              }
          }
          if (res.toString() !== "OK") {
              return self.emit("error", new Error("Auth failed: " + res.toString()));
          }
          if (exports.debug_mode) {
              console.log("Auth succeeded " + self.host + ":" + self.port + " id " + self.connection_id);
          }
          if (self.auth_callback) {
              self.auth_callback(err, res);
              self.auth_callback = null;
          }
  
          // now we are really connected
          self.emit("connect");
          self.initialize_retry_vars();
  
          if (self.options.no_ready_check) {
              self.on_ready();
          } else {
              self.ready_check();
          }
      });
      self.send_anyway = false;
  };
  
  RedisClient.prototype.on_connect = function () {
      if (exports.debug_mode) {
          console.log("Stream connected " + this.host + ":" + this.port + " id " + this.connection_id);
      }
  
      this.connected = true;
      this.ready = false;
      this.connections += 1;
      this.command_queue = new Queue();
      this.emitted_end = false;
      if (this.options.socket_nodelay) {
          this.stream.setNoDelay();
      }
      this.stream.setTimeout(0);
  
      this.init_parser();
  
      if (this.auth_pass) {
          this.do_auth();
      } else {
          this.emit("connect");
          this.initialize_retry_vars();
  
          if (this.options.no_ready_check) {
              this.on_ready();
          } else {
              this.ready_check();
          }
      }
  };
  
  RedisClient.prototype.init_parser = function () {
      var self = this;
  
      if (this.options.parser) {
          if (! parsers.some(function (parser) {
              if (parser.name === self.options.parser) {
                  self.parser_module = parser;
                  if (exports.debug_mode) {
                      console.log("Using parser module: " + self.parser_module.name);
                  }
                  return true;
              }
          })) {
              throw new Error("Couldn't find named parser " + self.options.parser + " on this system");
          }
      } else {
          if (exports.debug_mode) {
              console.log("Using default parser module: " + parsers[0].name);
          }
          this.parser_module = parsers[0];
      }
  
      this.parser_module.debug_mode = exports.debug_mode;
  
      // return_buffers sends back Buffers from parser to callback. detect_buffers sends back Buffers from parser, but
      // converts to Strings if the input arguments are not Buffers.
      this.reply_parser = new this.parser_module.Parser({
          return_buffers: self.options.return_buffers || self.options.detect_buffers || false
      });
  
      // "reply error" is an error sent back by Redis
      this.reply_parser.on("reply error", function (reply) {
          if (reply instanceof Error) {
              self.return_error(reply);
          } else {
              self.return_error(new Error(reply));
          }
      });
      this.reply_parser.on("reply", function (reply) {
          self.return_reply(reply);
      });
      // "error" is bad.  Somehow the parser got confused.  It'll try to reset and continue.
      this.reply_parser.on("error", function (err) {
          self.emit("error", new Error("Redis reply parser error: " + err.stack));
      });
  };
  
  RedisClient.prototype.on_ready = function () {
      var self = this;
  
      this.ready = true;
  
      if (this.old_state !== null) {
          this.monitoring = this.old_state.monitoring;
          this.pub_sub_mode = this.old_state.pub_sub_mode;
          this.selected_db = this.old_state.selected_db;
          this.old_state = null;
      }
  
      // magically restore any modal commands from a previous connection
      if (this.selected_db !== null) {
          // this trick works if and only if the following send_command
          // never goes into the offline queue
          var pub_sub_mode = this.pub_sub_mode;
          this.pub_sub_mode = false;
          this.send_command('select', [this.selected_db]);
          this.pub_sub_mode = pub_sub_mode;
      }
      if (this.pub_sub_mode === true) {
          // only emit "ready" when all subscriptions were made again
          var callback_count = 0;
          var callback = function () {
              callback_count--;
              if (callback_count === 0) {
                  self.emit("ready");
              }
          };
          Object.keys(this.subscription_set).forEach(function (key) {
              var parts = key.split(" ");
              if (exports.debug_mode) {
                  console.warn("sending pub/sub on_ready " + parts[0] + ", " + parts[1]);
              }
              callback_count++;
              self.send_command(parts[0] + "scribe", [parts[1]], callback);
          });
          return;
      } else if (this.monitoring) {
          this.send_command("monitor");
      } else {
          this.send_offline_queue();
      }
      this.emit("ready");
  };
  
  RedisClient.prototype.on_info_cmd = function (err, res) {
      var self = this, obj = {}, lines, retry_time;
  
      if (err) {
          return self.emit("error", new Error("Ready check failed: " + err.message));
      }
  
      lines = res.toString().split("\r\n");
  
      lines.forEach(function (line) {
          var parts = line.split(':');
          if (parts[1]) {
              obj[parts[0]] = parts[1];
          }
      });
  
      obj.versions = [];
      if( obj.redis_version ){
          obj.redis_version.split('.').forEach(function (num) {
              obj.versions.push(+num);
          });
      }
  
      // expose info key/vals to users
      this.server_info = obj;
  
      if (!obj.loading || (obj.loading && obj.loading === "0")) {
          if (exports.debug_mode) {
              console.log("Redis server ready.");
          }
          this.on_ready();
      } else {
          retry_time = obj.loading_eta_seconds * 1000;
          if (retry_time > 1000) {
              retry_time = 1000;
          }
          if (exports.debug_mode) {
              console.log("Redis server still loading, trying again in " + retry_time);
          }
          setTimeout(function () {
              self.ready_check();
          }, retry_time);
      }
  };
  
  RedisClient.prototype.ready_check = function () {
      var self = this;
  
      if (exports.debug_mode) {
          console.log("checking server ready state...");
      }
  
      this.send_anyway = true;  // secret flag to send_command to send something even if not "ready"
      this.info(function (err, res) {
          self.on_info_cmd(err, res);
      });
      this.send_anyway = false;
  };
  
  RedisClient.prototype.send_offline_queue = function () {
      var command_obj, buffered_writes = 0;
  
      while (this.offline_queue.length > 0) {
          command_obj = this.offline_queue.shift();
          if (exports.debug_mode) {
              console.log("Sending offline command: " + command_obj.command);
          }
          buffered_writes += !this.send_command(command_obj.command, command_obj.args, command_obj.callback);
      }
      this.offline_queue = new Queue();
      // Even though items were shifted off, Queue backing store still uses memory until next add, so just get a new Queue
  
      if (!buffered_writes) {
          this.should_buffer = false;
          this.emit("drain");
      }
  };
  
  RedisClient.prototype.connection_gone = function (why) {
      var self = this;
  
      // If a retry is already in progress, just let that happen
      if (this.retry_timer) {
          return;
      }
  
      if (exports.debug_mode) {
          console.warn("Redis connection is gone from " + why + " event.");
      }
      this.connected = false;
      this.ready = false;
  
      if (this.old_state === null) {
          var state = {
              monitoring: this.monitoring,
              pub_sub_mode: this.pub_sub_mode,
              selected_db: this.selected_db
          };
          this.old_state = state;
          this.monitoring = false;
          this.pub_sub_mode = false;
          this.selected_db = null;
      }
  
      // since we are collapsing end and close, users don't expect to be called twice
      if (! this.emitted_end) {
          this.emit("end");
          this.emitted_end = true;
      }
  
      this.flush_and_error("Redis connection gone from " + why + " event.");
  
      // If this is a requested shutdown, then don't retry
      if (this.closing) {
          this.retry_timer = null;
          if (exports.debug_mode) {
              console.warn("connection ended from quit command, not retrying.");
          }
          return;
      }
  
      var nextDelay = Math.floor(this.retry_delay * this.retry_backoff);
      if (this.retry_max_delay !== null && nextDelay > this.retry_max_delay) {
          this.retry_delay = this.retry_max_delay;
      } else {
          this.retry_delay = nextDelay;
      }
  
      if (exports.debug_mode) {
          console.log("Retry connection in " + this.retry_delay + " ms");
      }
  
      if (this.max_attempts && this.attempts >= this.max_attempts) {
          this.retry_timer = null;
          // TODO - some people need a "Redis is Broken mode" for future commands that errors immediately, and others
          // want the program to exit.  Right now, we just log, which doesn't really help in either case.
          console.error("node_redis: Couldn't get Redis connection after " + this.max_attempts + " attempts.");
          return;
      }
  
      this.attempts += 1;
      this.emit("reconnecting", {
          delay: self.retry_delay,
          attempt: self.attempts
      });
      this.retry_timer = setTimeout(function () {
          if (exports.debug_mode) {
              console.log("Retrying connection...");
          }
  
          self.retry_totaltime += self.retry_delay;
  
          if (self.connect_timeout && self.retry_totaltime >= self.connect_timeout) {
              self.retry_timer = null;
              // TODO - engage Redis is Broken mode for future commands, or whatever
              console.error("node_redis: Couldn't get Redis connection after " + self.retry_totaltime + "ms.");
              return;
          }
  
          self.stream.connect(self.port, self.host);
          self.retry_timer = null;
      }, this.retry_delay);
  };
  
  RedisClient.prototype.on_data = function (data) {
      if (exports.debug_mode) {
          console.log("net read " + this.host + ":" + this.port + " id " + this.connection_id + ": " + data.toString());
      }
  
      try {
          this.reply_parser.execute(data);
      } catch (err) {
          // This is an unexpected parser problem, an exception that came from the parser code itself.
          // Parser should emit "error" events if it notices things are out of whack.
          // Callbacks that throw exceptions will land in return_reply(), below.
          // TODO - it might be nice to have a different "error" event for different types of errors
          this.emit("error", err);
      }
  };
  
  RedisClient.prototype.return_error = function (err) {
      var command_obj = this.command_queue.shift(), queue_len = this.command_queue.getLength();
  
      if (this.pub_sub_mode === false && queue_len === 0) {
          this.command_queue = new Queue();
          this.emit("idle");
      }
      if (this.should_buffer && queue_len <= this.command_queue_low_water) {
          this.emit("drain");
          this.should_buffer = false;
      }
  
      if (command_obj && typeof command_obj.callback === "function") {
          try {
              command_obj.callback(err);
          } catch (callback_err) {
              this.emit("error", callback_err);
          }
      } else {
          console.log("node_redis: no callback to send error: " + err.message);
          this.emit("error", err);
      }
  };
  
  // if a callback throws an exception, re-throw it on a new stack so the parser can keep going.
  // if a domain is active, emit the error on the domain, which will serve the same function.
  // put this try/catch in its own function because V8 doesn't optimize this well yet.
  function try_callback(client, callback, reply) {
      try {
          callback(null, reply);
      } catch (err) {
          if (process.domain) {
              process.domain.emit('error', err);
              process.domain.exit();
          } else {
              client.emit("error", err);
          }
      }
  }
  
  // hgetall converts its replies to an Object.  If the reply is empty, null is returned.
  function reply_to_object(reply) {
      var obj = {}, j, jl, key, val;
  
      if (reply.length === 0) {
          return null;
      }
  
      for (j = 0, jl = reply.length; j < jl; j += 2) {
          key = reply[j].toString('binary');
          val = reply[j + 1];
          obj[key] = val;
      }
  
      return obj;
  }
  
  function reply_to_strings(reply) {
      var i;
  
      if (Buffer.isBuffer(reply)) {
          return reply.toString();
      }
  
      if (Array.isArray(reply)) {
          for (i = 0; i < reply.length; i++) {
              if (reply[i] !== null && reply[i] !== undefined) {
                  reply[i] = reply[i].toString();
              }
          }
          return reply;
      }
  
      return reply;
  }
  
  RedisClient.prototype.return_reply = function (reply) {
      var command_obj, len, type, timestamp, argindex, args, queue_len;
  
      // If the "reply" here is actually a message received asynchronously due to a
      // pubsub subscription, don't pop the command queue as we'll only be consuming
      // the head command prematurely.
      if (Array.isArray(reply) && reply.length > 0 && reply[0]) {
          type = reply[0].toString();
      }
  
      if (this.pub_sub_mode && (type == 'message' || type == 'pmessage')) {
          trace("received pubsub message");
      }
      else {
          command_obj = this.command_queue.shift();
      }
  
      queue_len = this.command_queue.getLength();
  
      if (this.pub_sub_mode === false && queue_len === 0) {
          this.command_queue = new Queue();  // explicitly reclaim storage from old Queue
          this.emit("idle");
      }
      if (this.should_buffer && queue_len <= this.command_queue_low_water) {
          this.emit("drain");
          this.should_buffer = false;
      }
  
      if (command_obj && !command_obj.sub_command) {
          if (typeof command_obj.callback === "function") {
              if (this.options.detect_buffers && command_obj.buffer_args === false) {
                  // If detect_buffers option was specified, then the reply from the parser will be Buffers.
                  // If this command did not use Buffer arguments, then convert the reply to Strings here.
                  reply = reply_to_strings(reply);
              }
  
              // TODO - confusing and error-prone that hgetall is special cased in two places
              if (reply && 'hgetall' === command_obj.command.toLowerCase()) {
                  reply = reply_to_object(reply);
              }
  
              try_callback(this, command_obj.callback, reply);
          } else if (exports.debug_mode) {
              console.log("no callback for reply: " + (reply && reply.toString && reply.toString()));
          }
      } else if (this.pub_sub_mode || (command_obj && command_obj.sub_command)) {
          if (Array.isArray(reply)) {
              type = reply[0].toString();
  
              if (type === "message") {
                  this.emit("message", reply[1].toString(), reply[2]); // channel, message
              } else if (type === "pmessage") {
                  this.emit("pmessage", reply[1].toString(), reply[2].toString(), reply[3]); // pattern, channel, message
              } else if (type === "subscribe" || type === "unsubscribe" || type === "psubscribe" || type === "punsubscribe") {
                  if (reply[2] === 0) {
                      this.pub_sub_mode = false;
                      if (this.debug_mode) {
                          console.log("All subscriptions removed, exiting pub/sub mode");
                      }
                  } else {
                      this.pub_sub_mode = true;
                  }
                  // subscribe commands take an optional callback and also emit an event, but only the first response is included in the callback
                  // TODO - document this or fix it so it works in a more obvious way
                  // reply[1] can be null
                  var reply1String = (reply[1] === null) ? null : reply[1].toString();
                  if (command_obj && typeof command_obj.callback === "function") {
                      try_callback(this, command_obj.callback, reply1String);
                  }
                  this.emit(type, reply1String, reply[2]); // channel, count
              } else {
                  throw new Error("subscriptions are active but got unknown reply type " + type);
              }
          } else if (! this.closing) {
              throw new Error("subscriptions are active but got an invalid reply: " + reply);
          }
      } else if (this.monitoring) {
          len = reply.indexOf(" ");
          timestamp = reply.slice(0, len);
          argindex = reply.indexOf('"');
          args = reply.slice(argindex + 1, -1).split('" "').map(function (elem) {
              return elem.replace(/\\"/g, '"');
          });
          this.emit("monitor", timestamp, args);
      } else {
          throw new Error("node_redis command queue state error. If you can reproduce this, please report it.");
      }
  };
  
  // This Command constructor is ever so slightly faster than using an object literal, but more importantly, using
  // a named constructor helps it show up meaningfully in the V8 CPU profiler and in heap snapshots.
  function Command(command, args, sub_command, buffer_args, callback) {
      this.command = command;
      this.args = args;
      this.sub_command = sub_command;
      this.buffer_args = buffer_args;
      this.callback = callback;
  }
  
  RedisClient.prototype.send_command = function (command, args, callback) {
      var arg, command_obj, i, il, elem_count, buffer_args, stream = this.stream, command_str = "", buffered_writes = 0, last_arg_type, lcaseCommand;
  
      if (typeof command !== "string") {
          throw new Error("First argument to send_command must be the command name string, not " + typeof command);
      }
  
      if (Array.isArray(args)) {
          if (typeof callback === "function") {
              // probably the fastest way:
              //     client.command([arg1, arg2], cb);  (straight passthrough)
              //         send_command(command, [arg1, arg2], cb);
          } else if (! callback) {
              // most people find this variable argument length form more convenient, but it uses arguments, which is slower
              //     client.command(arg1, arg2, cb);   (wraps up arguments into an array)
              //       send_command(command, [arg1, arg2, cb]);
              //     client.command(arg1, arg2);   (callback is optional)
              //       send_command(command, [arg1, arg2]);
              //     client.command(arg1, arg2, undefined);   (callback is undefined)
              //       send_command(command, [arg1, arg2, undefined]);
              last_arg_type = typeof args[args.length - 1];
              if (last_arg_type === "function" || last_arg_type === "undefined") {
                  callback = args.pop();
              }
          } else {
              throw new Error("send_command: last argument must be a callback or undefined");
          }
      } else {
          throw new Error("send_command: second argument must be an array");
      }
  
      if (callback && process.domain) callback = process.domain.bind(callback);
  
      // if the last argument is an array and command is sadd or srem, expand it out:
      //     client.sadd(arg1, [arg2, arg3, arg4], cb);
      //  converts to:
      //     client.sadd(arg1, arg2, arg3, arg4, cb);
      lcaseCommand = command.toLowerCase();
      if ((lcaseCommand === 'sadd' || lcaseCommand === 'srem') && args.length > 0 && Array.isArray(args[args.length - 1])) {
          args = args.slice(0, -1).concat(args[args.length - 1]);
      }
  
      // if the value is undefined or null and command is set or setx, need not to send message to redis
      if (command === 'set' || command === 'setex') {
          if(args[args.length - 1] === undefined || args[args.length - 1] === null) {
              var err = new Error('send_command: ' + command + ' value must not be undefined or null');
              return callback && callback(err);
          }
      }
  
      buffer_args = false;
      for (i = 0, il = args.length, arg; i < il; i += 1) {
          if (Buffer.isBuffer(args[i])) {
              buffer_args = true;
          }
      }
  
      command_obj = new Command(command, args, false, buffer_args, callback);
  
      if ((!this.ready && !this.send_anyway) || !stream.writable) {
          if (exports.debug_mode) {
              if (!stream.writable) {
                  console.log("send command: stream is not writeable.");
              }
          }
  
          if (this.enable_offline_queue) {
              if (exports.debug_mode) {
                  console.log("Queueing " + command + " for next server connection.");
              }
              this.offline_queue.push(command_obj);
              this.should_buffer = true;
          } else {
              var not_writeable_error = new Error('send_command: stream not writeable. enable_offline_queue is false');
              if (command_obj.callback) {
                  command_obj.callback(not_writeable_error);
              } else {
                  throw not_writeable_error;
              }
          }
  
          return false;
      }
  
      if (command === "subscribe" || command === "psubscribe" || command === "unsubscribe" || command === "punsubscribe") {
          this.pub_sub_command(command_obj);
      } else if (command === "monitor") {
          this.monitoring = true;
      } else if (command === "quit") {
          this.closing = true;
      } else if (this.pub_sub_mode === true) {
          throw new Error("Connection in subscriber mode, only subscriber commands may be used");
      }
      this.command_queue.push(command_obj);
      this.commands_sent += 1;
  
      elem_count = args.length + 1;
  
      // Always use "Multi bulk commands", but if passed any Buffer args, then do multiple writes, one for each arg.
      // This means that using Buffers in commands is going to be slower, so use Strings if you don't already have a Buffer.
  
      command_str = "*" + elem_count + "\r\n$" + command.length + "\r\n" + command + "\r\n";
  
      if (! buffer_args) { // Build up a string and send entire command in one write
          for (i = 0, il = args.length, arg; i < il; i += 1) {
              arg = args[i];
              if (typeof arg !== "string") {
                  arg = String(arg);
              }
              command_str += "$" + Buffer.byteLength(arg) + "\r\n" + arg + "\r\n";
          }
          if (exports.debug_mode) {
              console.log("send " + this.host + ":" + this.port + " id " + this.connection_id + ": " + command_str);
          }
          buffered_writes += !stream.write(command_str);
      } else {
          if (exports.debug_mode) {
              console.log("send command (" + command_str + ") has Buffer arguments");
          }
          buffered_writes += !stream.write(command_str);
  
          for (i = 0, il = args.length, arg; i < il; i += 1) {
              arg = args[i];
              if (!(Buffer.isBuffer(arg) || arg instanceof String)) {
                  arg = String(arg);
              }
  
              if (Buffer.isBuffer(arg)) {
                  if (arg.length === 0) {
                      if (exports.debug_mode) {
                          console.log("send_command: using empty string for 0 length buffer");
                      }
                      buffered_writes += !stream.write("$0\r\n\r\n");
                  } else {
                      buffered_writes += !stream.write("$" + arg.length + "\r\n");
                      buffered_writes += !stream.write(arg);
                      buffered_writes += !stream.write("\r\n");
                      if (exports.debug_mode) {
                          console.log("send_command: buffer send " + arg.length + " bytes");
                      }
                  }
              } else {
                  if (exports.debug_mode) {
                      console.log("send_command: string send " + Buffer.byteLength(arg) + " bytes: " + arg);
                  }
                  buffered_writes += !stream.write("$" + Buffer.byteLength(arg) + "\r\n" + arg + "\r\n");
              }
          }
      }
      if (exports.debug_mode) {
          console.log("send_command buffered_writes: " + buffered_writes, " should_buffer: " + this.should_buffer);
      }
      if (buffered_writes || this.command_queue.getLength() >= this.command_queue_high_water) {
          this.should_buffer = true;
      }
      return !this.should_buffer;
  };
  
  RedisClient.prototype.pub_sub_command = function (command_obj) {
      var i, key, command, args;
  
      if (this.pub_sub_mode === false && exports.debug_mode) {
          console.log("Entering pub/sub mode from " + command_obj.command);
      }
      this.pub_sub_mode = true;
      command_obj.sub_command = true;
  
      command = command_obj.command;
      args = command_obj.args;
      if (command === "subscribe" || command === "psubscribe") {
          if (command === "subscribe") {
              key = "sub";
          } else {
              key = "psub";
          }
          for (i = 0; i < args.length; i++) {
              this.subscription_set[key + " " + args[i]] = true;
          }
      } else {
          if (command === "unsubscribe") {
              key = "sub";
          } else {
              key = "psub";
          }
          for (i = 0; i < args.length; i++) {
              delete this.subscription_set[key + " " + args[i]];
          }
      }
  };
  
  RedisClient.prototype.end = function () {
      this.stream._events = {};
      this.connected = false;
      this.ready = false;
      this.closing = true;
      return this.stream.destroySoon();
  };
  
  function Multi(client, args) {
      this._client = client;
      this.queue = [["MULTI"]];
      if (Array.isArray(args)) {
          this.queue = this.queue.concat(args);
      }
  }
  
  exports.Multi = Multi;
  
  // take 2 arrays and return the union of their elements
  function set_union(seta, setb) {
      var obj = {};
  
      seta.forEach(function (val) {
          obj[val] = true;
      });
      setb.forEach(function (val) {
          obj[val] = true;
      });
      return Object.keys(obj);
  }
  
  // This static list of commands is updated from time to time.  ./lib/commands.js can be updated with generate_commands.js
  commands = set_union(["get", "set", "setnx", "setex", "append", "strlen", "del", "exists", "setbit", "getbit", "setrange", "getrange", "substr",
      "incr", "decr", "mget", "rpush", "lpush", "rpushx", "lpushx", "linsert", "rpop", "lpop", "brpop", "brpoplpush", "blpop", "llen", "lindex",
      "lset", "lrange", "ltrim", "lrem", "rpoplpush", "sadd", "srem", "smove", "sismember", "scard", "spop", "srandmember", "sinter", "sinterstore",
      "sunion", "sunionstore", "sdiff", "sdiffstore", "smembers", "zadd", "zincrby", "zrem", "zremrangebyscore", "zremrangebyrank", "zunionstore",
      "zinterstore", "zrange", "zrangebyscore", "zrevrangebyscore", "zcount", "zrevrange", "zcard", "zscore", "zrank", "zrevrank", "hset", "hsetnx",
      "hget", "hmset", "hmget", "hincrby", "hdel", "hlen", "hkeys", "hvals", "hgetall", "hexists", "incrby", "decrby", "getset", "mset", "msetnx",
      "randomkey", "select", "move", "rename", "renamenx", "expire", "expireat", "keys", "dbsize", "auth", "ping", "echo", "save", "bgsave",
      "bgrewriteaof", "shutdown", "lastsave", "type", "multi", "exec", "discard", "sync", "flushdb", "flushall", "sort", "info", "monitor", "ttl",
      "persist", "slaveof", "debug", "config", "subscribe", "unsubscribe", "psubscribe", "punsubscribe", "publish", "watch", "unwatch", "cluster",
      "restore", "migrate", "dump", "object", "client", "eval", "evalsha"], require("./lib/commands"));
  
  commands.forEach(function (fullCommand) {
      var command = fullCommand.split(' ')[0];
  
      RedisClient.prototype[command] = function (args, callback) {
          if (Array.isArray(args) && typeof callback === "function") {
              return this.send_command(command, args, callback);
          } else {
              return this.send_command(command, to_array(arguments));
          }
      };
      RedisClient.prototype[command.toUpperCase()] = RedisClient.prototype[command];
  
      Multi.prototype[command] = function () {
          this.queue.push([command].concat(to_array(arguments)));
          return this;
      };
      Multi.prototype[command.toUpperCase()] = Multi.prototype[command];
  });
  
  // store db in this.select_db to restore it on reconnect
  RedisClient.prototype.select = function (db, callback) {
      var self = this;
  
      this.send_command('select', [db], function (err, res) {
          if (err === null) {
              self.selected_db = db;
          }
          if (typeof(callback) === 'function') {
              callback(err, res);
          } else if (err) {
              self.emit('error', err);
          }
      });
  };
  RedisClient.prototype.SELECT = RedisClient.prototype.select;
  
  // Stash auth for connect and reconnect.  Send immediately if already connected.
  RedisClient.prototype.auth = function () {
      var args = to_array(arguments);
      this.auth_pass = args[0];
      this.auth_callback = args[1];
      if (exports.debug_mode) {
          console.log("Saving auth as " + this.auth_pass);
      }
  
      if (this.connected) {
          this.send_command("auth", args);
      }
  };
  RedisClient.prototype.AUTH = RedisClient.prototype.auth;
  
  RedisClient.prototype.hmget = function (arg1, arg2, arg3) {
      if (Array.isArray(arg2) && typeof arg3 === "function") {
          return this.send_command("hmget", [arg1].concat(arg2), arg3);
      } else if (Array.isArray(arg1) && typeof arg2 === "function") {
          return this.send_command("hmget", arg1, arg2);
      } else {
          return this.send_command("hmget", to_array(arguments));
      }
  };
  RedisClient.prototype.HMGET = RedisClient.prototype.hmget;
  
  RedisClient.prototype.hmset = function (args, callback) {
      var tmp_args, tmp_keys, i, il, key;
  
      if (Array.isArray(args) && typeof callback === "function") {
          return this.send_command("hmset", args, callback);
      }
  
      args = to_array(arguments);
      if (typeof args[args.length - 1] === "function") {
          callback = args[args.length - 1];
          args.length -= 1;
      } else {
          callback = null;
      }
  
      if (args.length === 2 && (typeof args[0] === "string" || typeof args[0] === "number") && typeof args[1] === "object") {
          // User does: client.hmset(key, {key1: val1, key2: val2})
          // assuming key is a string, i.e. email address
  
          // if key is a number, i.e. timestamp, convert to string
          if (typeof args[0] === "number") {
              args[0] = args[0].toString();
          }
  
          tmp_args = [ args[0] ];
          tmp_keys = Object.keys(args[1]);
          for (i = 0, il = tmp_keys.length; i < il ; i++) {
              key = tmp_keys[i];
              tmp_args.push(key);
              tmp_args.push(args[1][key]);
          }
          args = tmp_args;
      }
  
      return this.send_command("hmset", args, callback);
  };
  RedisClient.prototype.HMSET = RedisClient.prototype.hmset;
  
  Multi.prototype.hmset = function () {
      var args = to_array(arguments), tmp_args;
      if (args.length >= 2 && typeof args[0] === "string" && typeof args[1] === "object") {
          tmp_args = [ "hmset", args[0] ];
          Object.keys(args[1]).map(function (key) {
              tmp_args.push(key);
              tmp_args.push(args[1][key]);
          });
          if (args[2]) {
              tmp_args.push(args[2]);
          }
          args = tmp_args;
      } else {
          args.unshift("hmset");
      }
  
      this.queue.push(args);
      return this;
  };
  Multi.prototype.HMSET = Multi.prototype.hmset;
  
  Multi.prototype.exec = function (callback) {
      var self = this;
      var errors = [];
      // drain queue, callback will catch "QUEUED" or error
      // TODO - get rid of all of these anonymous functions which are elegant but slow
      this.queue.forEach(function (args, index) {
          var command = args[0], obj;
          if (typeof args[args.length - 1] === "function") {
              args = args.slice(1, -1);
          } else {
              args = args.slice(1);
          }
          if (args.length === 1 && Array.isArray(args[0])) {
              args = args[0];
          }
          if (command.toLowerCase() === 'hmset' && typeof args[1] === 'object') {
              obj = args.pop();
              Object.keys(obj).forEach(function (key) {
                  args.push(key);
                  args.push(obj[key]);
              });
          }
          this._client.send_command(command, args, function (err, reply) {
              if (err) {
                  var cur = self.queue[index];
                  if (typeof cur[cur.length - 1] === "function") {
                      cur[cur.length - 1](err);
                  } else {
                      errors.push(new Error(err));
                  }
              }
          });
      }, this);
  
      // TODO - make this callback part of Multi.prototype instead of creating it each time
      return this._client.send_command("EXEC", [], function (err, replies) {
          if (err) {
              if (callback) {
                  errors.push(new Error(err));
                  callback(errors);
                  return;
              } else {
                  throw new Error(err);
              }
          }
  
          var i, il, reply, args;
  
          if (replies) {
              for (i = 1, il = self.queue.length; i < il; i += 1) {
                  reply = replies[i - 1];
                  args = self.queue[i];
  
                  // TODO - confusing and error-prone that hgetall is special cased in two places
                  if (reply && args[0].toLowerCase() === "hgetall") {
                      replies[i - 1] = reply = reply_to_object(reply);
                  }
  
                  if (typeof args[args.length - 1] === "function") {
                      args[args.length - 1](null, reply);
                  }
              }
          }
  
          if (callback) {
              callback(null, replies);
          }
      });
  };
  Multi.prototype.EXEC = Multi.prototype.exec;
  
  RedisClient.prototype.multi = function (args) {
      return new Multi(this, args);
  };
  RedisClient.prototype.MULTI = function (args) {
      return new Multi(this, args);
  };
  
  
  // stash original eval method
  var eval_orig = RedisClient.prototype.eval;
  // hook eval with an attempt to evalsha for cached scripts
  RedisClient.prototype.eval = RedisClient.prototype.EVAL = function () {
      var self = this,
          args = to_array(arguments),
          callback;
  
      if (typeof args[args.length - 1] === "function") {
          callback = args.pop();
      }
  
      if (Array.isArray(args[0])) {
          args = args[0];
      }
  
      // replace script source with sha value
      var source = args[0];
      args[0] = crypto.createHash("sha1").update(source).digest("hex");
  
      self.evalsha(args, function (err, reply) {
          if (err && /NOSCRIPT/.test(err.message)) {
              args[0] = source;
              eval_orig.call(self, args, callback);
  
          } else if (callback) {
              callback(err, reply);
          }
      });
  };
  
  
  exports.createClient = function (port_arg, host_arg, options) {
      var port = port_arg || default_port,
          host = host_arg || default_host,
          redis_client, net_client;
  
      net_client = net.createConnection(port, host);
  
      redis_client = new RedisClient(net_client, options);
  
      redis_client.port = port;
      redis_client.host = host;
  
      return redis_client;
  };
  
  exports.print = function (err, reply) {
      if (err) {
          console.log("Error: " + err);
      } else {
          console.log("Reply: " + reply);
      }
  };
  