dojo.provide("dojox.storage.BehaviorStorageProvider");

dojo.require("dojox.storage.Provider");
dojo.require("dojox.storage.manager");

dojo.declare("dojox.storage.BehaviorStorageProvider", 
[ dojox.storage.Provider ], {

	store: null,
	storeName: '__dojox_BehaviorStorage',
	keys: [],
	
	initialize: function(){
		
		try{
			this.store = this._createStore();
			this.store.load(this.storeName);
		}catch(e){
			throw new Error("Store is not available: " + e);
		}
		
		var keys = this.get('keys','dojoxSystemNS');
		this.keys = keys || [];
		
		this.initialized = true;
		dojox.storage.manager.loaded();
	
	},
	
	isAvailable: function(){ /*Boolean*/
		// This is not completely true. UserData may
		// be disabled in security settings. To *really*
		// check if this is available, one needs to wait
		// until the store is successfully initialized...
		return dojo.isIE && dojo.isIE >= 5;
	},
	
	_createStore: function() {
        var storeNode = dojo.create(
        	'link',
        	{id: this.storeName + 'Node', style: {'display':'none'}},
        	dojo.query('head')[0]
        );
        storeNode.addBehavior('#default#userdata');
        
        return storeNode;
	},

	put: function(	/*string*/ key,
					/*object*/ value, 
					/*function*/ resultsHandler,
					/*string?*/ namespace){
		
		this._assertIsValidKey(key);
		
		namespace = namespace||this.DEFAULT_NAMESPACE;
		this._assertIsValidNamespace(namespace);
		
		var fullKey = this.getFullKey(key,namespace);
		value = dojo.toJson(value);
		
		this.store.setAttribute(fullKey, value);
		this.store.save(this.storeName);
		
		var success = this.store.getAttribute(fullKey) === value;
		if(success){
			this._addKey(fullKey);
			this.store.setAttribute('__dojoxSystemNS_keys', dojo.toJson(this.keys));
			this.store.save(this.storeName);
		}
		
		if(resultsHandler){
			resultsHandler(success ? this.SUCCESS : this.FAILED, key, null, namespace);
		}
	},

	get: function(/*string*/ key, /*string?*/ namespace){ /*Object*/
		this._assertIsValidKey(key);
		
		namespace = namespace||this.DEFAULT_NAMESPACE;
		this._assertIsValidNamespace(namespace);
		
		key = this.getFullKey(key, namespace);
		
		return dojo.fromJson(this.store.getAttribute(key));
	},

	getKeys: function(/*string?*/ namespace){ /*Array*/
		
		namespace = namespace||this.DEFAULT_NAMESPACE;
		this._assertIsValidNamespace(namespace);
		
		namespace = '__'+namespace+'_';
		
		var keys = [];
		for(var i = 0; i < this.keys.length; i++){
			var currentKey = this.keys[i];
			if(this._beginsWith(currentKey,namespace)){
				currentKey = currentKey.substring(namespace.length);
				keys.push(currentKey);
			}
		}
		
		return keys;
	},
	
	clear: function(/*string?*/ namespace){

		namespace = namespace||this.DEFAULT_NAMESPACE;
		this._assertIsValidNamespace(namespace);

		namespace = '__'+namespace+'_'

		var keys = [];
		for(var i = 0; i < this.keys.length; i++){
			var currentKey = this.keys[i];
			if(this._beginsWith(currentKey,namespace)){
				keys.push(currentKey);
			}
		}
		
		dojo.forEach(keys, function(key){
			this.store.removeAttribute(key);
			this._removeKey(key);
		}, this);

		this.put('keys', this.keys, null, 'dojoxSystemNS');
		this.store.save(this.storeName);
	},
  
	remove: function(/*string*/ key, /*string?*/ namespace){
		this._assertIsValidKey(key);
		
		namespace = namespace||this.DEFAULT_NAMESPACE;
		this._assertIsValidNamespace(namespace);
		
		key = this.getFullKey(key, namespace);
		this.store.removeAttribute(key);
		
		this._removeKey(key);
		this.put('keys', this.keys, null, 'dojoxSystemNS');
		this.store.save(this.storeName);
		
	},
	
	getNamespaces: function(){ /*string[]*/
		

		var results = [ this.DEFAULT_NAMESPACE];
		
		var found = {};
		found[this.DEFAULT_NAMESPACE] = true;
		var tester = /^__([^_]*)_/;
		
		for(var i = 0; i < this.keys.length; i++){
			var currentKey = this.keys[i];
			if(tester.test(currentKey) == true){
				var currentNS = currentKey.match(tester)[1];
				if(typeof found[currentNS] == "undefined"){
					found[currentNS] = true;
					results.push(currentNS);
				}
			}
		}
		
		return results;
		
	},

	isPermanent: function(){ /*Boolean*/
		return true;
	},

	getMaximumSize: function(){ /* mixed */
		// this *might* be more, depending on the zone 
		// of the current site. But 64k is guaranteed.
		return 64; 
	},

	hasSettingsUI: function(){ /*Boolean*/
		return false;
	},
	
	isValidKey: function(/*string*/ keyName){ /*Boolean*/
		if(keyName === null || keyName === undefined){
			return false;
		}
			
		return /^[0-9A-Za-z_-]*$/.test(keyName);
	},
	
	isValidNamespace: function(/*string*/ keyName){ /*Boolean*/
		
		if(keyName === null || keyName === undefined){
			return false;
		}
			
		return /^[0-9A-Za-z-]*$/.test(keyName);
	},
	
	getFullKey: function(key, namespace){
		// checks for valid namespace and
		// key are already performed.
		return "__" + namespace + "_" + key;
	},
	
	_beginsWith: function(/* string */ haystack, /* string */ needle) {
		if(needle.length > haystack.length) {
			return false;
		}
		return haystack.substring(0,needle.length) === needle;
	},
	
	_assertIsValidNamespace: function(/* string */ namespace){
		if(this.isValidNamespace(namespace) === false){
			throw new Error("Invalid namespace given: " + namespace);
		}
	},
	
	_assertIsValidKey: function(/* string */ key){
		if(this.isValidKey(key) === false){
			throw new Error("Invalid key given: " + key);
		}
	},
	
	_addKey: function(key){
		this._removeKey(key);
		this.keys.push(key);
	},
	
	_removeKey: function(key){
		this.keys = dojo.filter(this.keys,function(item){ return item !== key;},this);
	}
});

dojox.storage.manager.register("dojox.storage.BehaviorStorageProvider", new dojox.storage.BehaviorStorageProvider());