var Transform = require("stream").Transform;
var util = require("util");
var Store = require("buffer-queue");

/**
 * Transform stream that limits writes to 1MB at a time
 */
function ThrottleStream (limit) {
  this.limit = limit || 1024 * 1024;
  this.store = new Store();
  Transform.call(this);
}
util.inherits(ThrottleStream, Transform);

ThrottleStream.prototype._transform = function (chunk, enc, callback) {
  this.store.push(chunk);
  var data;

  // While we have more in our store than the limit, then push
  // out a chunk
  while (this.store.length() > this.limit && data = this.store.shift(this.limit)) {
    this.push(data);
  }
  callback();
};

ThrottleStream.prototype._flush = function (callback) {
  var data;
  while (data = this.store.shift(this.limit)) {
    this.push(data);
  }
  callback();
};