function getRandomNumber(min , max)
{
  return Math.floor(Math.random()*(max-min+1)+min);
}

function createBgStrip(stripWidth ,
                       stripHeight ,
                       stripElementWidth ,
                       stripElementHeight ,
                       stripElementQuantity,
                       stripImageURL)
{
  var bgStrip = $('<div class="bgStrip"></div>');
  bgStrip.css('width',stripWidth)
         .css('height',stripHeight)
         .css('overfllow','hidden');

  for(var i = 0 ; i < stripElementQuantity ; i++)
  {
    $('<div class="img"></div>')
            .css('background-image','url("'+stripImageURL+'")')
            .css('background-position','0 '+(getRandomNumber(1,28)*stripElementHeight))
            .css('width',stripElementWidth)
            .css('height',stripElementHeight)
            .appendTo(bgStrip);
  }
  return bgStrip;
}

function drawBg()
{
  var stripElementWidth = 35;
  var stripElementHeight = 300;
  var stripImageURL = 'image/background/wood/sprite.jpg';
  var screenWidth = Math.max(screen.width , $(document).width() , $(window).width() , 1024);
  var screenHeight = Math.max(screen.height , $(document).height() , $(window).height() , 1024);
  var bgStripQuantity = Math.ceil(screenWidth/35);
  var stripWidth = 35;
  var stripHeight = screenHeight+stripElementHeight;
  var stripElementQuantity = stripHeight/stripElementHeight;
  var bgStripPosition;

  $('<div class="bg">'+
      '<div style="display:none;"><img src="'+stripImageURL+'" /></div>'+
    '</div>')
      .css('width',screenWidth)
      .css('height',screenHeight)
      .css('padding',0)
      .css('margin',0)
      .css('overflow','hidden')
      .css('position','relative')
      .css('float','left')
      .appendTo('#background');

  for(var i = 0 ; i < bgStripQuantity ; i++)
  {
    var bgStrip = createBgStrip(stripWidth ,
                                stripHeight ,
                                stripElementWidth ,
                                stripElementHeight ,
                                stripElementQuantity,
                                stripImageURL)

    bgStrip.css('position','absolute')
           .css('left',35*i);

    if((i+1)%2 == 1)
    {
      bgStrip.css('top',-screenHeight);
      bgStripPosition = {top:0};
    }
    else
    {
      bgStrip.css('top',screenHeight);
      bgStripPosition = {top:-stripElementHeight/2};
    }

    bgStrip.appendTo('#background .bg').animate(bgStripPosition,4000);
  }
}

function hidden()
{
  $('#logo').css('display','none');
  $('#innerContent').css('display','none');
  $('#innerFooter').css('display','none');
}

function show()
{
  $('#logo').delay(4000).fadeIn(0);
  $('#innerContent').delay(4500).fadeIn(3000);
  $('#innerFooter').delay(4500).fadeIn(3000);
}

$(document).ready(function(){
  hidden();
  drawBg();
  show();
});