// Copyright (c) 2005 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
// 
// See scriptaculous.js for full license.

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

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  
    }, 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);
  },

  isContained: function(element, drop) {
    var parentNode = element.parentNode;
    return drop._containers.detect(function(c) { return parentNode == 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;
    
    if(this.last_active) this.deactivate(this.last_active);
    this.drops.each( function(drop) {
      if(Droppables.isAffected(point, element, drop)) {
        if(drop.onHover)
           drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
        if(drop.greedy) { 
          Droppables.activate(drop);
          throw $break;
        }
      }
    });
  },

  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) {
    window.focus(); // allows keypress events if window isn't currently focused, fails for Safari
    this.activeDraggable = draggable;
  },
  
  deactivate: function(draggbale) {
    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.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);
      });
  },
  
  _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.prototype = {
  initialize: function(element) {
    var options = Object.extend({
      handle: false,
      starteffect: function(element) { 
        new Effect.Opacity(element, {duration:0.2, from:1.0, to:0.7}); 
      },
      reverteffect: function(element, top_offset, left_offset) {
        var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;
        element._revert = new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur});
      },
      endeffect: function(element) { 
        new Effect.Opacity(element, {duration:0.2, from:0.7, to:1.0}); 
      },
      zindex: 1000,
      revert: false,
      snap: false   // false, or xy or [x,y] or function(x,y){ return [x,y] }
    }, arguments[1] || {});

    this.element = $(element);
    
    if(options.handle && (typeof options.handle == 'string'))
      this.handle = Element.childrenWithClassName(this.element, options.handle)[0];  
    if(!this.handle) this.handle = $(options.handle);
    if(!this.handle) this.handle = this.element;

    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(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=='BUTTON' ||
        src.tagName=='TEXTAREA')) return;
        
      if(this.element._revert) {
        this.element._revert.cancel();
        this.element._revert = null;
      }
      
      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);
    }
    
    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);
    
    // 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.finishDrag(event, true);
    Event.stop(event);
  },
  
  draw: function(point) {
    var pos = Position.cumulativeOffset(this.element);
    var d = this.currentDelta();
    pos[0] -= d[0]; pos[1] -= d[1];
    
    var p = [0,1].map(function(i){ return (point[i]-pos[i]-this.offset[i]) }.bind(this));
    
    if(this.options.snap) {
      if(typeof this.options.snap == 'function') {
        p = this.options.snap(p[0],p[1]);
      } else {
      if(this.options.snap instanceof Array) {
        p = p.map( function(v, i) {
          return Math.round(v/this.options.snap[i])*this.options.snap[i] }.bind(this))
      } else {
        p = p.map( function(v) {
          return Math.round(v/this.options.snap)*this.options.snap }.bind(this))
      }
    }}
    
    var style = this.element.style;
    if((!this.options.constraint) || (this.options.constraint=='horizontal'))
      style.left = p[0] + "px";
    if((!this.options.constraint) || (this.options.constraint=='vertical'))
      style.top  = p[1] + "px";
    if(style.visibility=="hidden") style.visibility = ""; // fix gecko rendering
  }
}

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

var SortableObserver = Class.create();
SortableObserver.prototype = {
  initialize: function(element, observer) {
    this.element   = $(element);
    this.observer  = observer;
    this.lastValue = Sortable.serialize(this.element);
  },
  
  onStart: function() {
    this.lastValue = Sortable.serialize(this.element);
  },
  
  onEnd: function() {
    Sortable.unmark();
    if(this.lastValue != Sortable.serialize(this.element))
      this.observer(this.element)
  }
}

var Sortable = {
  sortables: new Array(),
  
  options: function(element){
    element = $(element);
    return this.sortables.detect(function(s) { return s.element == element });
  },
  
  destroy: function(element){
    element = $(element);
    this.sortables.findAll(function(s) { return s.element == element }).each(function(s){
      Draggables.removeObserver(s.element);
      s.droppables.each(function(d){ Droppables.remove(d) });
      s.draggables.invoke('destroy');
    });
    this.sortables = this.sortables.reject(function(s) { return s.element == element });
  },
  
  create: function(element) {
    element = $(element);
    var options = Object.extend({ 
      element:     element,
      tag:         'li',       // assumes li children, override with tag: 'tagname'
      dropOnEmpty: false,
      tree:        false,      // fixme: unimplemented
      overlap:     'vertical', // one of 'vertical', 'horizontal'
      constraint:  'vertical', // one of 'vertical', 'horizontal', false
      containment: element,    // also takes array of elements (or id's); or false
      handle:      false,      // or a CSS class
      only:        false,
      hoverclass:  null,
      ghosting:    false,
      format:      null,
      onChange:    Prototype.emptyFunction,
      onUpdate:    Prototype.emptyFunction
    }, arguments[1] || {});

    // clear any old sortable with same element
    this.destroy(element);

    // build options for the draggables
    var options_for_draggable = {
      revert:      true,
      ghosting:    options.ghosting,
      constraint:  options.constraint,
      handle:      options.handle };

    if(options.starteffect)
      options_for_draggable.starteffect = options.starteffect;

    if(options.reverteffect)
      options_for_draggable.reverteffect = options.reverteffect;
    else
      if(options.ghosting) options_for_draggable.reverteffect = function(element) {
        element.style.top  = 0;
        element.style.left = 0;
      };

    if(options.endeffect)
      options_for_draggable.endeffect = options.endeffect;

    if(options.zindex)
      options_for_draggable.zindex = options.zindex;

    // build options for the droppables  
    var options_for_droppable = {
      overlap:     options.overlap,
      containment: options.containment,
      hoverclass:  options.hoverclass,
      onHover:     Sortable.onHover,
      greedy:      !options.dropOnEmpty
    }

    // fix for gecko engine
    Element.cleanWhitespace(element); 

    options.draggables = [];
    options.droppables = [];

    // make it so

    // drop on empty handling
    if(options.dropOnEmpty) {
      Droppables.add(element,
        {containment: options.containment, onHover: Sortable.onEmptyHover, greedy: false});
      options.droppables.push(element);
    }

    (this.findElements(element, options) || []).each( function(e) {
      // handles are per-draggable
      var handle = options.handle ? 
        Element.childrenWithClassName(e, options.handle)[0] : e;    
      options.draggables.push(
        new Draggable(e, Object.extend(options_for_draggable, { handle: handle })));
      Droppables.add(e, options_for_droppable);
      options.droppables.push(e);      
    });

    // keep reference
    this.sortables.push(options);

    // for onupdate
    Draggables.addObserver(new SortableObserver(element, options.onUpdate));

  },

  // return all suitable-for-sortable elements in a guaranteed order
  findElements: function(element, options) {
    if(!element.hasChildNodes()) return null;
    var elements = [];
    $A(element.childNodes).each( function(e) {
      if(e.tagName && e.tagName.toUpperCase()==options.tag.toUpperCase() &&
        (!options.only || (Element.hasClassName(e, options.only))))
          elements.push(e);
      if(options.tree) {
        var grandchildren = this.findElements(e, options);
        if(grandchildren) elements.push(grandchildren);
      }
    });

    return (elements.length>0 ? elements.flatten() : null);
  },

  onHover: function(element, dropon, overlap) {
    if(overlap>0.5) {
      Sortable.mark(dropon, 'before');
      if(dropon.previousSibling != element) {
        var oldParentNode = element.parentNode;
        element.style.visibility = "hidden"; // fix gecko rendering
        dropon.parentNode.insertBefore(element, dropon);
        if(dropon.parentNode!=oldParentNode) 
          Sortable.options(oldParentNode).onChange(element);
        Sortable.options(dropon.parentNode).onChange(element);
      }
    } else {
      Sortable.mark(dropon, 'after');
      var nextElement = dropon.nextSibling || null;
      if(nextElement != element) {
        var oldParentNode = element.parentNode;
        element.style.visibility = "hidden"; // fix gecko rendering
        dropon.parentNode.insertBefore(element, nextElement);
        if(dropon.parentNode!=oldParentNode) 
          Sortable.options(oldParentNode).onChange(element);
        Sortable.options(dropon.parentNode).onChange(element);
      }
    }
  },

  onEmptyHover: function(element, dropon) {
    if(element.parentNode!=dropon) {
      var oldParentNode = element.parentNode;
      dropon.appendChild(element);
      Sortable.options(oldParentNode).onChange(element);
      Sortable.options(dropon).onChange(element);
    }
  },

  unmark: function() {
    if(Sortable._marker) Element.hide(Sortable._marker);
  },

  mark: function(dropon, position) {
    // mark on ghosting only
    var sortable = Sortable.options(dropon.parentNode);
    if(sortable && !sortable.ghosting) return; 

    if(!Sortable._marker) {
      Sortable._marker = $('dropmarker') || document.createElement('DIV');
      Element.hide(Sortable._marker);
      Element.addClassName(Sortable._marker, 'dropmarker');
      Sortable._marker.style.position = 'absolute';
      document.getElementsByTagName("body").item(0).appendChild(Sortable._marker);
    }    
    var offsets = Position.cumulativeOffset(dropon);
    Sortable._marker.style.left = offsets[0] + 'px';
    Sortable._marker.style.top = offsets[1] + 'px';
    
    if(position=='after')
      if(sortable.overlap == 'horizontal') 
        Sortable._marker.style.left = (offsets[0]+dropon.clientWidth) + 'px';
      else
        Sortable._marker.style.top = (offsets[1]+dropon.clientHeight) + 'px';
    
    Element.show(Sortable._marker);
  },

  serialize: function(element) {
    element = $(element);
    var sortableOptions = this.options(element);
    var options = Object.extend({
      tag:  sortableOptions.tag,
      only: sortableOptions.only,
      name: element.id,
      format: sortableOptions.format || /^[^_]*_(.*)$/
    }, arguments[1] || {});
    return $(this.findElements(element, options) || []).map( function(item) {
      return (encodeURIComponent(options.name) + "[]=" + 
              encodeURIComponent(item.id.match(options.format) ? item.id.match(options.format)[1] : ''));
    }).join("&");
  }
}