var Effect = {
  _elementDoesNotExistError: {
    name: 'ElementDoesNotExistError',
    message: 'The specified DOM element does not exist, but is required for this effect to operate'
  },
  Transitions: {
    sinoidal: function(pos) {
      return (-Math.cos(pos*Math.PI)/2) + 0.5;
    }
  },
  DefaultOptions: {
    duration:   1.0,   // seconds
    fps:        100,   // 100= assume 66fps max.
    sync:       false, // true for combining
    from:       0.0,
    to:         1.0,
    delay:      0.0,
    queue:      'parallel'
  },
  PAIRS: {'slide':  ['SlideDown','SlideUp']},
  toggle: function(element, effect) {
    element = $(element);
    effect = (effect || 'appear').toLowerCase();
    var options = Object.extend({
      queue: { position:'end', scope:(element.id || 'global'), limit: 1 }
    }, arguments[2] || { });
    Effect[element.visible() ? 
      Effect.PAIRS[effect][1] : Effect.PAIRS[effect][0]](element, options);
  }
};

Effect.DefaultOptions.transition = Effect.Transitions.sinoidal;

/* ------------- core effects ------------- */

Effect.ScopedQueue = Class.create(Enumerable, {
  initialize: function() {
    this.effects  = [];
    this.interval = null;    
  },
  add: function(effect) {
    var timestamp = new Date().getTime();
    
    effect.startOn  += timestamp;
    effect.finishOn += timestamp;

    if (!effect.options.queue.limit || (this.effects.length < effect.options.queue.limit))
      this.effects.push(effect);
    
    if (!this.interval)
      this.interval = setInterval(this.loop.bind(this), 15);
  },
  remove: function(effect) {
    this.effects = this.effects.reject(function(e) { return e==effect });
    if (this.effects.length == 0) {
      clearInterval(this.interval);
      this.interval = null;
    }
  },
  loop: function() {
    var timePos = new Date().getTime();
    for(var i=0, len=this.effects.length;i<len;i++) 
      this.effects[i] && this.effects[i].loop(timePos);
  }
});

Effect.Queues = {
  instances: $H(),
  get: function(queueName) {
    if (!Object.isString(queueName)) return queueName; 
    if (!this.instances[queueName])
      this.instances[queueName] = new Effect.ScopedQueue();
      
    return this.instances[queueName];
  }
};
Effect.Queue = Effect.Queues.get('global');

Effect.Base = Class.create();
Effect.Base.prototype = {
  start: function(options) {
    function codeForEvent(options,eventName){
      return (
        (options[eventName+'Internal'] ? 'this.options.'+eventName+'Internal(this);' : '') +
        (options[eventName] ? 'this.options.'+eventName+'(this);' : '')
      );
    }
    if (options && options.transition === false) options.transition = Effect.Transitions.linear;
    this.options      = Object.extend(Object.extend({ },Effect.DefaultOptions), options || { });
    this.currentFrame = 0;
    this.state        = 'idle';
    this.startOn      = this.options.delay*1000;
    this.finishOn     = this.startOn+(this.options.duration*1000);
    this.fromToDelta  = this.options.to-this.options.from;
    this.totalTime    = this.finishOn-this.startOn;
    this.totalFrames  = this.options.fps*this.options.duration;
    
    eval('this.render = function(pos){ '+
      'if (this.state=="idle"){this.state="running";'+
      codeForEvent(this.options,'beforeSetup')+
      (this.setup ? 'this.setup();':'')+ 
      codeForEvent(this.options,'afterSetup')+
      '};if (this.state=="running"){'+
      'pos=this.options.transition(pos)*'+this.fromToDelta+'+'+this.options.from+';'+
      'this.position=pos;'+
      codeForEvent(this.options,'beforeUpdate')+
      (this.update ? 'this.update(pos);':'')+
      codeForEvent(this.options,'afterUpdate')+
      '}}');
    
    this.event('beforeStart');
    if (!this.options.sync)
      Effect.Queues.get(Object.isString(this.options.queue) ? 
        'global' : this.options.queue.scope).add(this);
  },
  loop: function(timePos) {
    if (timePos >= this.startOn) {
      if (timePos >= this.finishOn) {
        this.render(1.0);
        this.cancel();
        this.event('beforeFinish');
        if (this.finish) this.finish(); 
        this.event('afterFinish');
        return;  
      }
      var pos   = (timePos - this.startOn) / this.totalTime,
          frame = (pos * this.totalFrames).round();
      if (frame > this.currentFrame) {
        this.render(pos);
        this.currentFrame = frame;
      }
    }
  },
  cancel: function() {
    if (!this.options.sync)
      Effect.Queues.get(Object.isString(this.options.queue) ? 
        'global' : this.options.queue.scope).remove(this);
    this.state = 'finished';
  },
  event: function(eventName) {
    if (this.options[eventName + 'Internal']) this.options[eventName + 'Internal'](this);
    if (this.options[eventName]) this.options[eventName](this);
  }
};

Effect.Scale = Class.create(Effect.Base, {
  initialize: function(element, percent) {
    this.element = $(element);
    if (!this.element) throw(Effect._elementDoesNotExistError);
    var options = Object.extend({
      scaleX: true,
      scaleY: true,
      scaleContent: true,
      scaleFromCenter: false,
      scaleMode: 'box',        // 'box' or 'contents' or { } with provided values
      scaleFrom: 100.0,
      scaleTo:   percent
    }, arguments[2] || { });
    this.start(options);
  },
  setup: function() {
    this.restoreAfterFinish = this.options.restoreAfterFinish || false;
    this.elementPositioning = this.element.getStyle('position');
    
    this.originalStyle = { };
    ['top','left','width','height','fontSize'].each( function(k) {
      this.originalStyle[k] = this.element.style[k];
    }.bind(this));
      
    this.originalTop  = this.element.offsetTop;
    this.originalLeft = this.element.offsetLeft;
    
    var fontSize = this.element.getStyle('font-size') || '100%';
    ['em','px','%','pt'].each( function(fontSizeType) {
      if (fontSize.indexOf(fontSizeType)>0) {
        this.fontSize     = parseFloat(fontSize);
        this.fontSizeType = fontSizeType;
      }
    }.bind(this));
    
    this.factor = (this.options.scaleTo - this.options.scaleFrom)/100;
    
    this.dims = null;
    if (this.options.scaleMode=='box')
      this.dims = [this.element.offsetHeight, this.element.offsetWidth];
    if (/^content/.test(this.options.scaleMode))
      this.dims = [this.element.scrollHeight, this.element.scrollWidth];
    if (!this.dims)
      this.dims = [this.options.scaleMode.originalHeight,
                   this.options.scaleMode.originalWidth];
  },
  update: function(position) {
    var currentScale = (this.options.scaleFrom/100.0) + (this.factor * position);
    if (this.options.scaleContent && this.fontSize)
      this.element.setStyle({fontSize: this.fontSize * currentScale + this.fontSizeType });
    this.setDimensions(this.dims[0] * currentScale, this.dims[1] * currentScale);
  },
  finish: function(position) {
    if (this.restoreAfterFinish) this.element.setStyle(this.originalStyle);
  },
  setDimensions: function(height, width) {
    var d = { };
    if (this.options.scaleX) d.width = width.round() + 'px';
    if (this.options.scaleY) d.height = height.round() + 'px';
    if (this.options.scaleFromCenter) {
      var topd  = (height - this.dims[0])/2;
      var leftd = (width  - this.dims[1])/2;
      if (this.elementPositioning == 'absolute') {
        if (this.options.scaleY) d.top = this.originalTop-topd + 'px';
        if (this.options.scaleX) d.left = this.originalLeft-leftd + 'px';
      } else {
        if (this.options.scaleY) d.top = -topd + 'px';
        if (this.options.scaleX) d.left = -leftd + 'px';
      }
    }
    this.element.setStyle(d);
  }
});

Effect.SlideDown = function(element) {
  element = $(element).cleanWhitespace();
  // SlideDown need to have the content of the element wrapped in a container element with fixed height!
  var oldInnerBottom = element.down().getStyle('bottom');
  var elementDimensions = element.getDimensions();
  return new Effect.Scale(element, 100, Object.extend({ 
    scaleContent: false, 
    scaleX: false, 
    scaleFrom: window.opera ? 0 : 1,
    scaleMode: {originalHeight: elementDimensions.height, originalWidth: elementDimensions.width},
    restoreAfterFinish: true,
    afterSetup: function(effect) {
      effect.element.makePositioned();
      effect.element.down().makePositioned();
      if (window.opera) effect.element.setStyle({top: ''});
      effect.element.makeClipping().setStyle({height: '0px'}).show(); 
    },
    afterUpdateInternal: function(effect) {
      effect.element.down().setStyle({bottom:
        (effect.dims[0] - effect.element.clientHeight) + 'px' }); 
    },
    afterFinishInternal: function(effect) {
      effect.element.undoClipping().undoPositioned();
      effect.element.down().undoPositioned().setStyle({bottom: oldInnerBottom}); }
    }, arguments[1] || { })
  );
};

Effect.SlideUp = function(element) {
  element = $(element).cleanWhitespace();
  var oldInnerBottom = element.down().getStyle('bottom');
  var elementDimensions = element.getDimensions();
  return new Effect.Scale(element, window.opera ? 0 : 1,
   Object.extend({ scaleContent: false, 
    scaleX: false, 
    scaleMode: 'box',
    scaleFrom: 100,
    scaleMode: {originalHeight: elementDimensions.height, originalWidth: elementDimensions.width},
    restoreAfterFinish: true,
    afterSetup: function(effect) {
      effect.element.makePositioned();
      effect.element.down().makePositioned();
      if (window.opera) effect.element.setStyle({top: ''});
      effect.element.makeClipping().show();
    },  
    afterUpdateInternal: function(effect) {
      effect.element.down().setStyle({bottom:
        (effect.dims[0] - effect.element.clientHeight) + 'px' });
    },
    afterFinishInternal: function(effect) {
      effect.element.hide().undoClipping().undoPositioned();
      effect.element.down().undoPositioned().setStyle({bottom: oldInnerBottom});
    }
   }, arguments[1] || { })
  );
};