define([
    'dojo/_base/declare',
    'dijit/registry'
],function(declare,registry){

    var Content = declare(null,{
        _started: false,
        _container: null,
        _previousContent: null,
        _dirty: false,
        startup: function() {
            if ( this._started ) { return; }

            this._container = registry.byId('content');
            if ( !this._container || !this._container.addChild ) {
                throw new Error("Cannot find container widget with id 'content'.");
            }

            this._toaster = registry.byId('toaster');
            if ( !this._toaster || !this._toaster.setContent ) {
                throw new Error("Cannot find toaster widget with id 'toaster'.");
            }

            this._started = true;
        },
        set: function(widget) {
            if ( !this._started ) {
                throw new Error('Call startup() before setting content.');
            }
            if ( this._previousContent ) {
                this._previousContent.destroyRecursive();
                this._previousContent = null;
            }
            widget.region = 'center';
            this._previousContent = widget;
            this._container.addChild(widget);
        },
        notify: function(text,type) {
            if ( !this._started ) {
                throw new Error('Call startup() before setting content.');
            }
            this._toaster.setContent(text,type || 'message');
        },
        markDirty: function() {
            this._dirty = true;
        },
        markClean:function() {
            this._dirty = false;
        },
        isDirty: function() {
            return this._dirty;
        }
    });

    return new Content();
});