// Copyright (c) 2005, 2006 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
//           (c) 2005, 2006 Sammi Williams (http://www.oriontransfer.co.nz, sammi@oriontransfer.co.nz)
// 
// script.aculo.us is freely distributable under the terms of an MIT-style license.
// For details, see the script.aculo.us web site: http://script.aculo.us/

if(typeof Effect == 'undefined')
  throw("dragdrop.js requires including script.aculo.us' effects.js library");

var Droppables = {
  drops: [],

  remove: function(element) {
    this.drops = this.drops.reject(function(d) { return d.element==$(element) });
  },

  add: function(element) {
    element = $(element);
    var options = Object.extend({
      greedy:     true,
      hoverclass: null,
      tree:       false
    }, arguments[1] || {});

    // cache containers
    if(options.containment) {
      options._containers = [];
      var containment = options.containment;
      if((typeof containment == 'object') && 
        (containment.constructor == Array)) {
        containment.each( function(c) { options._containers.push($(c)) });
      } else {
        options._containers.push($(containment));
      }
    }
    
    if(options.accept) options.accept = [options.accept].flatten();

    Element.makePositioned(element); // fix IE
    options.element = element;

    this.drops.push(options);
  },
  
  findDeepestChild: function(drops) {
    deepest = drops[0];
      
    for (i = 1; i < drops.length; ++i)
      if (Element.isParent(drops[i].element, deepest.element))
        deepest = drops[i];
    
    return deepest;
  },

  isContained: function(element, drop) {
    var containmentNode;
    if(drop.tree) {
      containmentNode = element.treeNode; 
    } else {
      containmentNode = element.parentNode;
    }
    return drop._containers.detect(function(c) { return containmentNode == c });
  },
  
  isAffected: function(point, element, drop) {
    return (
      (drop.element!=element) &&
      ((!drop._containers) ||
        this.isContained(element, drop)) &&
      ((!drop.accept) ||
        (Element.classNames(element).detect( 
          function(v) { return drop.accept.include(v) } ) )) &&
      Position.within(drop.element, point[0], point[1]) );
  },

  deactivate: function(drop) {
    if(drop.hoverclass)
      Element.removeClassName(drop.element, drop.hoverclass);
    this.last_active = null;
  },

  activate: function(drop) {
    if(drop.hoverclass)
      Element.addClassName(drop.element, drop.hoverclass);
    this.last_active = drop;
  },

  show: function(point, element) {
    if(!this.drops.length) return;
    var affected = [];
    
    if(this.last_active) this.deactivate(this.last_active);
    this.drops.each( function(drop) {
      if(Droppables.isAffected(point, element, drop))
        affected.push(drop);
    });
        
    if(affected.length>0) {
      drop = Droppables.findDeepestChild(affected);
      Position.within(drop.element, point[0], point[1]);
      if(drop.onHover)
        drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
      
      Droppables.activate(drop);
    }
  },

  fire: function(event, element) {
    if(!this.last_active) return;
    Position.prepare();

    if (this.isAffected([Event.pointerX(event), Event.pointerY(event)], element, this.last_active))
      if (this.last_active.onDrop) 
        this.last_active.onDrop(element, this.last_active.element, event);
  },

  reset: function() {
    if(this.last_active)
      this.deactivate(this.last_active);
  }
}

var Draggables = {
  drags: [],
  observers: [],
  
  register: function(draggable) {
    if(this.drags.length == 0) {
      this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
      this.eventMouseMove = this.updateDrag.bindAsEventListener(this);
      this.eventKeypress  = this.keyPress.bindAsEventListener(this);
      
      Event.observe(document, "mouseup", this.eventMouseUp);
      Event.observe(document, "mousemove", this.eventMouseMove);
      Event.observe(document, "keypress", this.eventKeypress);
    }
    this.drags.push(draggable);
  },
  
  unregister: function(draggable) {
    this.drags = this.drags.reject(function(d) { return d==draggable });
    if(this.drags.length == 0) {
      Event.stopObserving(document, "mouseup", this.eventMouseUp);
      Event.stopObserving(document, "mousemove", this.eventMouseMove);
      Event.stopObserving(document, "keypress", this.eventKeypress);
    }
  },
  
  activate: function(draggable) {
    if(draggable.options.delay) { 
      this._timeout = setTimeout(function() { 
        Draggables._timeout = null; 
        window.focus(); 
        Draggables.activeDraggable = draggable; 
      }.bind(this), draggable.options.delay); 
    } else {
      window.focus(); // allows keypress events if window isn't currently focused, fails for Safari
      this.activeDraggable = draggable;
    }
  },
  
  deactivate: function() {
    this.activeDraggable = null;
  },
  
  updateDrag: function(event) {
    if(!this.activeDraggable) return;
    var pointer = [Event.pointerX(event), Event.pointerY(event)];
    // Mozilla-based browsers fire successive mousemove events with
    // the same coordinates, prevent needless redrawing (moz bug?)
    if(this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;
    this._lastPointer = pointer;
    
    this.activeDraggable.updateDrag(event, pointer);
  },
  
  endDrag: function(event) {
    if(this._timeout) { 
      clearTimeout(this._timeout); 
      this._timeout = null; 
    }
    if(!this.activeDraggable) return;
    this._lastPointer = null;
    this.activeDraggable.endDrag(event);
    this.activeDraggable = null;
  },
  
  keyPress: function(event) {
    if(this.activeDraggable)
      this.activeDraggable.keyPress(event);
  },
  
  addObserver: function(observer) {
    this.observers.push(observer);
    this._cacheObserverCallbacks();
  },
  
  removeObserver: function(element) {  // element instead of observer fixes mem leaks
    this.observers = this.observers.reject( function(o) { return o.element==element });
    this._cacheObserverCallbacks();
  },
  
  notify: function(eventName, draggable, event) {  // 'onStart', 'onEnd', 'onDrag'
    if(this[eventName+'Count'] > 0)
      this.observers.each( function(o) {
        if(o[eventName]) o[eventName](eventName, draggable, event);
      });
    if(draggable.options[eventName]) draggable.options[eventName](draggable, event);
  },
  
  _cacheObserverCallbacks: function() {
    ['onStart','onEnd','onDrag'].each( function(eventName) {
      Draggables[eventName+'Count'] = Draggables.observers.select(
        function(o) { return o[eventName]; }
      ).length;
    });
  }
}

/*--------------------------------------------------------------------------*/

var Draggable = Class.create();
Draggable._dragging    = {};

Draggable.prototype = {
  initialize: function(element) {
    var defaults = {
      handle: false,
      reverteffect: function(element, top_offset, left_offset) {
        var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;
        new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur,
          queue: {scope:'_draggable', position:'end'}
        });
      },
      endeffect: function(element) {
        var toOpacity = typeof element._opacity == 'number' ? element._opacity : 1.0;
        new Effect.Opacity(element, {duration:0.2, from:0.7, to:toOpacity, 
          queue: {scope:'_draggable', position:'end'},
          afterFinish: function(){ 
            Draggable._dragging[element] = false 
          }
        }); 
      },
      zindex: 1000,
      revert: false,
      scroll: false,
      scrollSensitivity: 20,
      scrollSpeed: 15,
      snap: false,  // false, or xy or [x,y] or function(x,y){ return [x,y] }
      delay: 0
    };
    
    if(!arguments[1] || typeof arguments[1].endeffect == 'undefined')
      Object.extend(defaults, {
        starteffect: function(element) {
          element._opacity = Element.getOpacity(element);
          Draggable._dragging[element] = true;
          new Effect.Opacity(element, {duration:0.2, from:element._opacity, to:0.7}); 
        }
      });
    
    var options = Object.extend(defaults, arguments[1] || {});

    this.element = $(element);
    
    if(options.handle && (typeof options.handle == 'string'))
      this.handle = this.element.down('.'+options.handle, 0);
    
    if(!this.handle) this.handle = $(options.handle);
    if(!this.handle) this.handle = this.element;
    
    if(options.scroll && !options.scroll.scrollTo && !options.scroll.outerHTML) {
      options.scroll = $(options.scroll);
      this._isScrollChild = Element.childOf(this.element, options.scroll);
    }

    Element.makePositioned(this.element); // fix IE    

    this.delta    = this.currentDelta();
    this.options  = options;
    this.dragging = false;   

    this.eventMouseDown = this.initDrag.bindAsEventListener(this);
    Event.observe(this.handle, "mousedown", this.eventMouseDown);
    
    Draggables.register(this);
  },
  
  destroy: function() {
    Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
    Draggables.unregister(this);
  },
  
  currentDelta: function() {
    return([
      parseInt(Element.getStyle(this.element,'left') || '0'),
      parseInt(Element.getStyle(this.element,'top') || '0')]);
  },
  
  initDrag: function(event) {
    if(typeof Draggable._dragging[this.element] != 'undefined' &&
      Draggable._dragging[this.element]) return;
    if(Event.isLeftClick(event)) {    
      // abort on form elements, fixes a Firefox issue
      var src = Event.element(event);
      if(src.tagName && (
        src.tagName=='INPUT' ||
        src.tagName=='SELECT' ||
        src.tagName=='OPTION' ||
        src.tagName=='BUTTON' ||
        src.tagName=='TEXTAREA')) return;
        
      var pointer = [Event.pointerX(event), Event.pointerY(event)];
      var pos     = Position.cumulativeOffset(this.element);
      this.offset = [0,1].map( function(i) { return (pointer[i] - pos[i]) });
      
      Draggables.activate(this);
      Event.stop(event);
    }
  },
  
  startDrag: function(event) {
    this.dragging = true;
    
    if(this.options.zindex) {
      this.originalZ = parseInt(Element.getStyle(this.element,'z-index') || 0);
      this.element.style.zIndex = this.options.zindex;
    }
    
    if(this.options.ghosting) {
      this._clone = this.element.cloneNode(true);
      Position.absolutize(this.element);
      this.element.parentNode.insertBefore(this._clone, this.element);
    }
    
    if(this.options.scroll) {
      if (this.options.scroll == window) {
        var where = this._getWindowScroll(this.options.scroll);
        this.originalScrollLeft = where.left;
        this.originalScrollTop = where.top;
      } else {
        this.originalScrollLeft = this.options.scroll.scrollLeft;
        this.originalScrollTop = this.options.scroll.scrollTop;
      }
    }
    
    Draggables.notify('onStart', this, event);
        
    if(this.options.starteffect) this.options.starteffect(this.element);
  },
  
  updateDrag: function(event, pointer) {
    if(!this.dragging) this.startDrag(event);
    Position.prepare();
    Droppables.show(pointer, this.element);
    Draggables.notify('onDrag', this, event);
    
    this.draw(pointer);
    if(this.options.change) this.options.change(this);
    
    if(this.options.scroll) {
      this.stopScrolling();
      
      var p;
      if (this.options.scroll == window) {
        with(this._getWindowScroll(this.options.scroll)) { p = [ left, top, left+width, top+height ]; }
      } else {
        p = Position.page(this.options.scroll);
        p[0] += this.options.scroll.scrollLeft + Position.deltaX;
        p[1] += this.options.scroll.scrollTop + Position.deltaY;
        p.push(p[0]+this.options.scroll.offsetWidth);
        p.push(p[1]+this.options.scroll.offsetHeight);
      }
      var speed = [0,0];
      if(pointer[0] < (p[0]+this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[0]+this.options.scrollSensitivity);
      if(pointer[1] < (p[1]+this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[1]+this.options.scrollSensitivity);
      if(pointer[0] > (p[2]-this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[2]-this.options.scrollSensitivity);
      if(pointer[1] > (p[3]-this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[3]-this.options.scrollSensitivity);
      this.startScrolling(speed);
    }
    
    // fix AppleWebKit rendering
    if(navigator.appVersion.indexOf('AppleWebKit')>0) window.scrollBy(0,0);
    
    Event.stop(event);
  },
  
  finishDrag: function(event, success) {
    this.dragging = false;

    if(this.options.ghosting) {
      Position.relativize(this.element);
      Element.remove(this._clone);
      this._clone = null;
    }

    if(success) Droppables.fire(event, this.element);
    Draggables.notify('onEnd', this, event);

    var revert = this.options.revert;
    if(revert && typeof revert == 'function') revert = revert(this.element);
    
    var d = this.currentDelta();
    if(revert && this.options.reverteffect) {
      this.options.reverteffect(this.element, 
        d[1]-this.delta[1], d[0]-this.delta[0]);
    } else {
      this.delta = d;
    }

    if(this.options.zindex)
      this.element.style.zIndex = this.originalZ;

    if(this.options.endeffect) 
      this.options.endeffect(this.element);
      
    Draggables.deactivate(this);
    Droppables.reset();
  },
  
  keyPress: function(event) {
    if(event.keyCode!=Event.KEY_ESC) return;
    this.finishDrag(event, false);
    Event.stop(event);
  },
  
  endDrag: function(event) {
    if(!this.dragging) return;
    this.stopScrolling();
    this.finishDrag(event, true);
    Event.stop(event);
  },
  
  draw: function(point) {
    var pos = Position.cumulativeOffset(this.element);
    if(this.options.ghosting) {
      var r   = Position.realOffset(this.element);
      pos[0] += r[0] - Position.deltaX; pos[1] += r[1] - Position.deltaY;
    }
    
    var d = this.currentDelta();
    pos[0] -= d[0]; pos[1] -= d[1];
    
    if(this.options.scroll && (this.options.scroll != window && this._isScrollChild)) {
      pos[0] -= this.options.s
    }
  }
}
}