var multiplier = 2;
var container = null;
var move = true;

$(window).load(function() {
  container = $("#carousel div.container");
  
  updateOrientation();
});

function set_item_width(num) {
  item_size = num;
  $("#carousel").css({'position': 'relative'});
  container.css({'position': 'absolute', 'left': '0', 'width': (container.children('div.item').length * item_size)+'px'});
  $("#carousel div.item").css({'width': item_size + "px", 'float': 'left', 'height': '121px'});
}

function step_left() {
  if (move) {
    move = false;
    container.animate({'left': '-'+(item_size*multiplier)+'px'}, 1000, null,
      function() {
        container.append(container.children("div.item").slice(0, multiplier).remove());
        container.css({'left': '0px'});
        move = true;
      }
    );
  }
}

function step_right() {
  if (move) {
    move = false;
    container.css({'left': '-'+(item_size*multiplier)+'px'}).prepend(container.children("div.item").slice(-multiplier).remove());
    container.animate({'left': '0'}, 1000, null,
      function() {
        move = true
      }
    );
  }
}

function updateOrientation() {
  switch (window.orientation) {
    case 0:
    case 180:
      divide = 3;
      break;

    case 90:
    case -90:
      divide = 4;
      break;

    default:
      divide = 3;
      break;
  }
  set_item_width(Math.floor($("#carousel").width() / divide));
}