$(function(){

  var inDuration = 3000,
      loopDuration = 5000;

  //ノード作成
  var addAnimationElements = function () {
    var mainimg = $('#topwrap'),
        prefix = 'img/mainimg_',
        extension = '.jpg',
        addElm = [];
    var linkhref = ['/corp/logistics/','/corp/customs-clearance/','/corp/sewing-inspection/','/corp/studio/'];
    if (!mainimg.length) return;
    for(var i = 1; i <= max; i++) {
      var linktag = $('<a />').attr('href',linkhref[i-1]);
      addElm[i-1] = $('<p class="main_bgimg">').css({
        "height" : '447px',
        "background" : "url('" +  prefix + i + extension + "') no-repeat scroll 50% 0 transparent"
          }).hide();

      mainimg.append(linktag.append(addElm[i-1]));
    }
    return addElm;
  };
  
  //fadeIn処理
  var timerID;
  var mainAnimate = function(fn) {
    var arg = arguments;
    this.css({'zIndex':'1'}).fadeIn(loopDuration,function(){
      var self = this;
      if (typeof fn === 'function') {
        if (timerID) {
          clearTimeout(timerID);
          timerID = null;
        }
        timeID = setTimeout(function(){
        fn(self);
        },inDuration);
      }
      return this;
    });
  };
  
  //実行箇所
  var max = 4,
      iterate = 0,
      oldnum,
      outerTimer,
      addElms = addAnimationElements();
  if (typeof addElms !== 'undefined') {
    outerTimer = setTimeout(function changeMainimg(old){
      if (outerTimer) {
        clearTimeout(outerTimer);
        outerTimer = null;
      }
      
      if (iterate === max) iterate = 0;
      var interateTemp = iterate;
      if (typeof oldnum !== 'undefined') {   //２回目以降
        oldnum = iterate === 0 ? max-1 : iterate-1;
        //console.log('非表示に：'+oldnum, '表示に:'+iterate);
        $(old).css({'zIndex':'0'}).fadeOut(loopDuration); //１回前のエレメントを処理
        var ret = mainAnimate.call(addElms[iterate++],changeMainimg);

      } else { //1回目
        mainAnimate.call(addElms[iterate++],changeMainimg);
        oldnum = iterate;
      }
    },250);
  }
});