index.js

var isBrowser = this.window ? true : false,
objectId = isBrowser ? require("object-id") : require("./object-id"),
inherits = isBrowser ? require("inherit") : require("util").inherits,
EventEmitter = isBrowser ? require("emitter") : require("events").EventEmitter;

module.exports = Node;

function Node(id) {
	EventEmitter.call(this);
	this._id = id || objectId();
	this._childs = {};
	this._childIdsList = [];
	this._parent = null;
	this._data = {};
}

if (isBrowser) {
	EventEmitter(Node.prototype);
} else {
	inherits(Node, EventEmitter);
}

var o = Node.prototype;

o.getChild = function (childId) {
	var child = this._childs[childId];
	if (child) {
		return child;
	} else {
		for (var cid in this._childs) {
			if ((child = this._childs[cid].getChild(childId))) {
				return child;
			}
		}
		return null;
	}
}

/**
 * @member Node#createChild
 * @return {Node} , return new child node.
 */
o.createChild = function () {
	var child = new Node();
	child._parent = this;
	this._childs[child.id] = child;
	this._childIdsList.push(child.id);
    
    this.emit("add",child,this);
    this.emit("child list changed",this,this._childIdsList.concat()); 
    
    var root = this.root;
    if(root !== this){
        root.emit("add",child,this);
        root.emit("child list changed",this,this._childIdsList.concat()); 
    }
    
	return child;
}

/**
 * @member Node#appendChild
 * @param {Node} child , child can't contain root.
 * @return {Node} , self.
 */
o.appendChild = function (child) {
	if (this.root.getChild(child.id) || child._childIdsList.length !== 0) {
		return this;
	} else if (child.parent) {
		child.parent.removeChild(child.id);
	}
	child._parent = this;
	this._childs[child.id] = child;
	this._childIdsList.push(child.id);

    this.emit("add",child,this);
    this.emit("child list changed",this,this._childIdsList.concat()); 
    
    var root = this.root;
    if(root !== this){
        root.emit("add",child,this);
        root.emit("child list changed",this,this._childIdsList.concat()); 
    }
    
	return this;
}

o.removeChild = function (childId) {

	child = this.getChild(childId);

	var parent;

	if (child && (parent = child.parent)) {
		delete parent._childs[childId];
		child._parent = null;
		var index = parent._childIdsList.indexOf(childId);
		parent._childIdsList.splice(index, 1);
        
        parent.emit("remove",child,parent);
        parent.emit("child list changed",parent,parent._childIdsList.concat());    
        
        var root = this.root;
        if(root !== this){
            root.emit("remove",child,parent);
            root.emit("child list changed",parent,parent._childIdsList.concat());  
        }
	}
    
	return this;

}

o.replaceNode = function (child, targetId) {

	var target = this.getChild(targetId);

	if (!child || !target || target.getChild(this.id) || child.getChild(this.id) || target.getChild(child.id)) {
		return this;
	}

	var parent = child.parent;
	if (parent) {
		parent.removeChild(child.id);
	}

	var index = target.position();
    parent = target.parent;
	parent._childIdsList.splice(index, 1, child);
	child._parent = parent;
	delete parent._childs[target.id];
	target._parent = null;
   
    parent.emit("remove",target,parent);
    parent.emit("add",child,parent);
    parent.emit("child list changed",parent,parent._childIdsList.concat());    
    
    var root = this.root;
    if(root !== this){
        root.emit("remove",target,parent);
        root.emit("add",child,parent);
        root.emit("child list changed",parent,parent._childIdsList.concat());
    }
   
	return this;
}

o.position = function (childId) {

	var child = this._getNode(childId);

	if (child) {
		var parent = child.parent;
		return parent ? parent._childIdsList.indexOf(child.id) : null;
	} else {
		return null;
	}

}

o.layer = function (childId) {
	var child = this._getNode(childId),
	layer = 0;

	if (child) {
		var parent = child.parent;
		while (parent) {
			layer += 1;
			parent = parent.parent;
		}
		return layer;
	} else {
		return 0;
	}
}

o.getNode = o._getNode = function (childId) {

	var child;

	if (childId) {
		if (childId === this.id) {
			child = this;
		} else {
			child = this.getChild(childId);
		}
	} else {
		child = this;
	}

	return child;

}

o.top = function (childId) {

	var child = this._getNode(childId),
	parent;
	if (child && (parent = child.parent)) {
		var index = parent._childIdsList.indexOf(childId);
		parent._childIdsList.splice(index, 1);
		parent._childIdsList.unshift(childId);
        
        parent.emit("child list changed",parent,parent._childIdsList.concat());
        var root = this.root;
        if(root !== this){
            root.emit("child list changed",parent,parent._childIdsList.concat());
        }      
	}

	return this;
}

o.up = function (childId) {
	var child = this._getNode(childId),
	parent;
	if (child && (parent = child.parent)) {
		var index = parent._childIdsList.indexOf(child.id);
		parent._childIdsList.splice(index, 1);
		if (index !== 0) {
			parent._childIdsList.splice(index - 1, 0, child.id);
		}
        parent.emit("child list changed",parent,parent._childIdsList.concat());
        var root = this.root;
        if(root !== this){
            root.emit("child list changed",parent,parent._childIdsList.concat());
        }  
	}
	return this;
}

o.down = function (childId) {
	var child = this._getNode(childId),
	parent;
	if (child && (parent = child.parent)) {
		var nextNode = child.nextNode();
		if (nextNode) {
			nextNode.up();
		}
	}
	return this;
}

o.nextNode = function (childId) {
	var child = childId? this._getNode(childId) : this;
		var parent = child.parent;
		if(parent){
		var index = child.position(),
		nextChildId = parent._childIdsList[index + 1];

		if (nextChildId) {
			return parent.getChild(nextChildId);
		}
		}
}

o.nextDepthNode = function nextDeepNode(childId) {
	var node = childId? this._getNode(childId) : this;
	var firstChild = node.firstChild();
	if(firstChild){
		return firstChild;
	}else{
		return node.nextNode();
	}
}

o.prevNode = function (childId) {
	var child = childId ? this._getNode(childId) : this;
		var parent = child.parent;
		if(parent){
            var index = child.position(),
            prevChildId = parent._childIdsList[index - 1];

            if (prevChildId) {
                return parent.getChild(prevChildId);
            }
		}
}

o.prevDepthNode = function prevDeepNode(childId) {
	var child = childId ? this._getNode(childId) : this;
	var prevNode = child.prevNode();
	if(prevNode){
		return child.depthLastChild();
	}else{
		return child.parent;
	}
}

o.firstChild = function(childId){
    var root = childId ? this._getNode(childId) : this;
    if(root && root._childIdsList[0]){
        return root.getNode(root._childIdsList[0]);
    }
}

o.lastChild = function(childId){
    var root = childId ? this._getNode(childId) : this;
    if(root){
        var list = root._childIdsList,len = list.length;
        if(list[len-1]){
            return root.getNode(list[len-1]);
        }
    }
}

o.depthFirstChild = function(childId){
    var rs = null;
    var root = childId ? this._getNode(childId) : this;
    if(root){
        rs = root;goFind = true;
        for(;goFind;){
            var r = rs.firstChild();
            if(!r){
                goFind = false;
            }else{
                rs = r;
            }
        }
    }
    return rs;
}

o.depthLastChild = function(childId){
    var rs = null;
    var root = childId ? this._getNode(childId) : this;
    if(root){
        rs = root;goFind = true;
        for(;goFind;){
            var r = rs.lastChild();
            if(!r){
                goFind = false;
            }else{
                rs = r;
            }
        }
    }
    return rs;
}

// move childId node to  parentId node.
o.move = function (childId, parentId) {

	var child = this.getChild(childId),
	parent = parentId === this.parent ? this : this.getChild(parentId);

	if (child && parent && !child.getChild(parentId)) {
		var childParent = child.parent;
		childParent.removeChild(child.id);
		parent.appendChild(child);        
	}

	return this;

}

o.isRoot = function () {
	return this.parent ? false : true;
}

o.data = function () {

	var obj = {}

	if (arguments.length === 2) {
		obj[arguments[0]] = arguments[1];
	} else if (arguments.length === 1) {
		if (typeof arguments[0] === "string") {
			return this._data[arguments[0]];
		} else {
			obj = arguments[0];
		}
	} else {
		return this._data;
	}

	for (var k in obj) {
		this._data[k] = obj[k];
	}
    
    Object.freeze(obj);
    this.emit("data change",this,obj);
    var root = this.root;
    if(root !== this){
        root.emit("data change",this,obj);
    }
    return this;

}

o.reborn = function (jsonObj) {

	if (this.isRoot()) {
		var self = this;
		this._id = jsonObj.id;
		this._childs = {};
		this._childIdsList = jsonObj.childIdsList;
		this._parent = jsonObj.parent;
		this._data = jsonObj.data;

		jsonObj.childIdsList.forEach(function (cid) {
			var child = new Node();
			child.reborn(jsonObj.childs[cid]);
			child._parent = self;
			self._childs[cid] = child;
		});
        
    this.emit("reborn",jsonObj);
	}
	return this;

}

Object.defineProperties(o, {

	parent : {
		get : function () {
			return this._parent;
		}
	},

	id : {
		get : function () {
			return this._id;
		}
	},

	route : {
		get : function () {
			var route = [this.id],
			parent = this.parent;
			while (parent) {
				route.unshift(parent.id);
				parent = parent.parent;
			}
			return route;
		}
	},

	root : {
		get : function () {
			var root = this.parent;
			while (root) {
                var parent = root.parent;
				if(parent){
                    root = parent;
                }else{
                    return root;
                }
			}
			return this;
		}
	},

	json : {
		get : function () {

			var jsonObj = {
				id : this._id,
				childs : {},
				childIdsList : this._childIdsList,
				parent : this.parent ? this.parent.id : null,
				data : this._data
			},
			self = this;

			this._childIdsList.forEach(function (cid) {
				jsonObj.childs[cid] = self._childs[cid].json;
			})

			return JSON.parse(JSON.stringify(jsonObj));

		}
	},
    
    allChildIds:{
        get:function(){
            var ids = this._childIdsList.concat(),self = this;
            
            this._childIdsList.forEach(function(id){
                ids = ids.concat(self.getChild(id).allChildIds);
            });
            return ids;
        }
    },
    
    childIds:{
        get:function(){
            return this._childIdsList.concat();
        }
    }

});