// you might need to change the lines where I use js-routes (the Router).
// also it assumes that you have a variable authenticity_token defined

function createUploader(buttonId, containerId, customCallbacks) {

  var defaultCallbacks = {
    ready: function(){
      $btn = $('#uploadContainer .btn').removeClass('disabled');
      $('#uploadContainer .btn span.text').text($btn.attr('ready'));
    },
    newFile: $.noop,
    fileRemoved: $.noop,
    preparationStarted: $.noop,
    uploadStarted: $.noop,
    uploadProgress: $.noop,
    uploadDone: $.noop,
    uploadDoneNotified: $.noop,
    error: $.noop
  };

  var callbacks = $.extend({}, defaultCallbacks, customCallbacks);

  var uploader = new plupload.Uploader({
    runtimes : 'flash',
    multipart: true,
    browse_button : buttonId,
    container: containerId,
    url: Router.authorize_upload_path(),
    flash_swf_url : '/flash/flex/plupload.swf',
    silverlight_xap_url : '/javascripts/plupload/plupload.silverlight.xap'
  });

  uploader.bind('Init', function(up, params) {
    up.authorizedQueueState = "INACTIVE";
    callbacks.ready();
  });

  uploader.bind('FilesAdded', function(up, files) {
    $.each(files, function(i, file) {
      callbacks.newFile(file);
    });

    setTimeout(function() {
      up.trigger('StartAuthorizedQueue');
    }, 0);
  });

  uploader.bind('PrepareUploadFile', function(up, file) {
    if(file.cancelled) {
      return true;
    }

    callbacks.preparationStarted(file);

    $.ajax({
      type: 'GET',
      url: Router.authorize_upload_path(),
      dataType: 'json',
      data: {
        authenticity_token: authenticity_token,
        file_size: file.size,
        file_name: file.name,
      },
      success: function(data) {
        if(!data.ok) {
          up.trigger('Error', {
            message: data.errors.join(', '),
            file: file
          });
          up.trigger('ContinueAuthorizedQueue');
          return;
        }

        if(file.cancelled) {
          up.trigger('ContinueAuthorizedQueue');
          return;
        }

        file.headers  = data.headers;
        file.params   = data.params;
        file.uploadTo = data.url;
        file.handle   = data.file;

        setTimeout(function() {
          up.settings.headers          = file.headers;
          up.settings.multipart_params = file.params;
          up.settings.url              = file.uploadTo;
          up.trigger('UploadFile', file);
        }, 0);
      },
      error: function() {
        up.trigger('Error', {
          message: "Request failed.",
          file: file
        });
        up.trigger('ContinueAuthorizedQueue');
      }
    });
  });

  uploader.bind('StartAuthorizedQueue', function(up) {
    if(up.authorizedQueueState === "ACTIVE") {
      return;
    }

    if(typeof(up.fileIndex) === "undefined") {
      up.fileIndex = 0;
    }

    up.trigger('ContinueAuthorizedQueue');
  });

  uploader.bind('ContinueAuthorizedQueue', function(up) {
    if(up.fileIndex > up.files.length) {
      up.fileIndex = up.files.length;
    }

    if(up.fileIndex < up.files.length) {
      up.authorizedQueueState = "ACTIVE";
      up.trigger('PrepareUploadFile', up.files[up.fileIndex++]);
    } else {
      up.authorizedQueueState = "INACTIVE";
    }
  });

  uploader.bind('FilesRemoved', function(up, files) {
    $.each(files, function(i, file) {
      file.cancelled = true;
      callbacks.fileRemoved(file);
    });
  });

  uploader.bind('FileUploaded', function(up, file, response) {
    callbacks.uploadDone(file);

    $.ajax({
      url: Router.finalize_upload_path(),
      type: 'POST',
      dataType: 'xml',
      data: {
        authenticity_token: authenticity_token,
        file: file.handle
      },
      success: function(data) {
        file.notificationResponse = data;
        callbacks.uploadDoneNotified(file, data);
        up.trigger('ContinueAuthorizedQueue');
      }
    });
  });

  uploader.bind('UploadFile', function(up, file) {
    callbacks.uploadStarted(file);
  });

  uploader.bind('UploadProgress', function(up, file) {
    if(file.status === plupload.UPLOADING) {
      callbacks.uploadProgress(file);
    }
  });

  uploader.bind('Error', function(up, err) {
    callbacks.error(err, err.file);
  });

  uploader.init();

  return uploader;
}