/*
 * Fading Banner, cross-fading images, version 1.1
 *
 * Copyright (C) 2007 Dmitriy Khudorozhkov
 *
 * This software is provided "as-is", without any express or implied warranty.
 * In no event will the author be held liable for any damages arising from the
 * use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 *
 *  - Dmitriy Khudorozhkov, kh_dmitry2001@mail.ru
 */

function CrossFadingBanner(parentId, type, width, height, bg, timeout, bordersize, gap, yoffset)
{
  this.batches  = [];
  this.current  = -1;
  this.images   = [];
  this.parent   = document.getElementById(parentId);
  this.root     = null;
  this.timeout  = timeout || 5000;
  this.type     = (type == "vertical") ? "vertical" : "horizontal";
  this.bordersize = bordersize;
  this.gap = gap;
  this.yoffset = yoffset;

   while(this.parent.firstChild)
    this.parent.removeChild(this.parent.firstChild);

  return this._construct(width, height, bg);
}

CrossFadingBanner.prototype = {

  // public methods:

  add: function(batch, imageSrc, imageWidth, imageHeight, desc, link)
  {
    var l = this.batches.length;
    for(var i = 0; i < l; i++)
      if(this.batches[i] == batch)
        break;

    if(i == l) this.batches[l] = batch;

    if(!this.images[batch]) this.images[batch] = [];

    var l2 = this.images[batch].length;

    var imag = this.images[batch][l2] = new Object;

    imag.src    = imageSrc;
    imag.desc   = desc;
    imag.link   = link;
    imag.width  = imageWidth;
    imag.height = imageHeight;

    var top = this.bordersize + this.yoffset, left = this.bordersize, isH = (this.type == "horizontal");

    for(i = 0; i < l2; i++)
    {
      var _img = this.images[batch][i];

      if(isH)
      {
        left += _img.width + this.gap;
      }
      else
      {
        top += _img.height + this.gap;
      }
    }

    var a = imag.obj = document.createElement("A");
    if (imag.link != "")
        a.href = imag.link;
    //a.target = "_blank";
    a.style.display = "none";

    var img = document.createElement("IMG");
    img.src = imag.src;
    img.id  = "fb_img_" + this.parent.id + "_" + String(batch) + "_" + String(l2);
    if (imag.desc != "")
        img.alt = imag.desc;
     
    a.appendChild(img);
    this.root.appendChild(a);

    var is = img.style;
    is.position = "absolute";
    is.top      = top + "px";
    is.left     = left + "px";
    is.width    = imag.width;
    is.height   = imag.height;
    is.border   = "0";
    is.opacity  = 1;
    is.filter   = "alpha(opacity=0)";

    this.batches.sort(function (a, b) { return a - b; });
    this.current = this.batches[0];

    return l2 + 1;
  },

  start: function()
  {
    this.root.style.display = "block";

    this._showbatch(true);
  },

  // support methods follow:

  _construct: function(width, height, bg)
  {
    var banner = document.createElement("DIV");
    var bs = banner.style;

    bs.position = "relative";
    bs.top      = "0px";
    bs.left     = "0px";
    bs.width    = this.bordersize * 2 + width + "px";
    bs.height   = this.bordersize * 2 + height + "px";

    bs.display  = "none";
    bs.backgroundColor = bg || "#FFF";

    this.root = this.parent.appendChild(banner);

// NEW STUFF FOR HEADING
/*
    var a = document.createElement("A");
    a.target = "_blank";
    a.style.display = "block";

    var img = document.createElement("IMG");
    img.src = "uploads/images/frontbanner-heads.jpg";
    img.id  = "fb_img_" + this.parent.id + "_head";
     
    a.appendChild(img);
    this.root.appendChild(a);

    var is = img.style;
    is.position = "absolute";
    is.top      = this.bordersize + "px";
    is.left     = this.bordersize + "px";
    is.border   = "0";
*/
    return this;
  },

  _callLater: function(func, param)
  {
    param = param || null;
    return function() { func(param); };
  },

  _next: function(_obj)
  {
    function _go(__obj)
    {
      var cur = __obj.current, l = __obj.images[cur].length;

      for(var i = 0; i < l; i++)
        __obj.images[cur][i].obj.style.display = "none";

      l = __obj.batches.length;
      for(i = 0; i < l; i++)
        if(__obj.current == __obj.batches[i])
          break;

      __obj.current = (i == l - 1) ? __obj.batches[0] : __obj.batches[i + 1];

      __obj._showbatch();
    }

    setTimeout(_obj._callLater(_go, _obj), _obj.timeout);
  },

  _showbatch: function(isFirst)
  {
    var cur = this.current, l = this.images[cur].length;

    var l2 = this.batches.length;
    for(var i = 0; i < l2; i++)
      if(this.current == this.batches[i])
        break;

    for(i = 0; i < l; i++)
    {
      var img = this.images[cur][i];
      img.obj.style.display = "block";
      // FADE IN
      if (isFirst)
          this._fade(img.obj.firstChild.id, 100, 75, 50);
      else this._fade(img.obj.firstChild.id, 100, 75, 2);
    }

    // Nothing to fade when first called
    if(isFirst)
      this._next(this);
    else
    {
      if (cur == 0 )
          prev = l2 - 1;
      else prev = cur - 1;
            
      if(prev != cur)
      {
        l = this.images[prev].length;

        for(i = 0; i < l; i++)
        {
          img = this.images[prev][i];
          img.obj.style.display = "block";

          // FADE OUT 
          if (i == l - 1)
              this._fade(img.obj.firstChild.id, 0, 75, 2, this._callLater(this._next, this));
          else this._fade(img.obj.firstChild.id, 0, 75, 2);
        }
      }
    }
  },

  // delta is the speed of the fade
  // rate governs the smoothness  
  _fade: function(id, destOp, rate, delta, callback)
  {
    var obj = document.getElementById(id);

    if(obj.timer) clearTimeout(obj.timer);

    var curOp = obj.filters ? obj.filters.alpha.opacity : (obj.style.opacity * 100.0);
    var direction = (curOp <= destOp) ? 1 : -1;

    delta  = Math.min(direction * (destOp - curOp), delta);
    curOp += direction * delta;

    if(obj.filters)
      obj.filters.alpha.opacity = curOp;
    else
      obj.style.opacity = curOp / 100.0;

    if(curOp != destOp)
      obj.timer = setTimeout(function() { CrossFadingBanner.prototype._fade(id, destOp, rate, delta, callback); }, rate);
    else
      if(callback) callback();
  }
};