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

dojo.declare("dojox.storage.Provider", null, {
	// summary: A singleton for working with dojox.storage.
	// description:
	//		dojox.storage exposes the current available storage provider on this
	//		platform. It gives you methods such as dojox.storage.put(),
	//		dojox.storage.get(), etc.
	//		
	//		For more details on dojox.storage, see the primary documentation
	//		page at
	//			http://manual.dojotoolkit.org/storage.html
	//		
	//		Note for storage provider developers who are creating subclasses-
	//		This is the base class for all storage providers Specific kinds of
	//		Storage Providers should subclass this and implement these methods.
	//		You should avoid initialization in storage provider subclass's
	//		constructor; instead, perform initialization in your initialize()
	//		method. 
	constructor: function(){
	},
	
	// SUCCESS: String
	//	Flag that indicates a put() call to a 
	//	storage provider was succesful.
	SUCCESS: "success",
	
	// FAILED: String
	//	Flag that indicates a put() call to 
	//	a storage provider failed.
	FAILED: "failed",
	
	// PENDING: String
	//	Flag that indicates a put() call to a 
	//	storage provider is pending user approval.
	PENDING: "pending",
	
	// SIZE_NOT_AVAILABLE: String
	//	Returned by getMaximumSize() if this storage provider can not determine
	//	the maximum amount of data it can support. 
	SIZE_NOT_AVAILABLE: "Size not available",
	
	// SIZE_NO_LIMIT: String
	//	Returned by getMaximumSize() if this storage provider has no theoretical
	//	limit on the amount of data it can store. 
	SIZE_NO_LIMIT: "No size limit",

	// DEFAULT_NAMESPACE: String
	//	The namespace for all storage operations. This is useful if several
	//	applications want access to the storage system from the same domain but
	//	want different storage silos. 
	DEFAULT_NAMESPACE: "default",
	
	// onHideSettingsUI: Function
	//	If a function is assigned to this property, then when the settings
	//	provider's UI is closed this function is called. Useful, for example,
	//	if the user has just cleared out all storage for this provider using
	//	the settings UI, and you want to update your UI.
	onHideSettingsUI: null,

	initialize: function(){
		// summary: 
		//		Allows this storage provider to initialize itself. This is
		//		called after the page has finished loading, so you can not do
		//		document.writes(). Storage Provider subclasses should initialize
		//		themselves inside of here rather than in their function
		//		constructor.
		console.warn("dojox.storage.initialize not implemented");
	},
	
	isAvailable: function(){ /*Boolean*/
		// summary: 
		//		Returns whether this storage provider is available on this
		//		platform. 
		console.warn("dojox.storage.isAvailable not implemented");
	},

	put: function(	/*string*/ key,
					/*object*/ value, 
					/*function*/ resultsHandler,
					/*string?*/ namespace){
		// summary:
		//		Puts a key and value into this storage system.
		// description:
		//		Example-
		//			var resultsHandler = function(status, key, message, namespace){
		//			  alert("status="+status+", key="+key+", message="+message);
		//			};
		//			dojox.storage.put("test", "hello world", resultsHandler);
		//
		//			Arguments:
		//
		//			status - The status of the put operation, given by
		//								dojox.storage.FAILED, dojox.storage.SUCCEEDED, or
		//								dojox.storage.PENDING
		//			key - The key that was used for the put
		//			message - An optional message if there was an error or things failed.
		//			namespace - The namespace of the key. This comes at the end since
		//									it was added later.
		//	
		//		Important note: if you are using Dojo Storage in conjunction with
		//		Dojo Offline, then you don't need to provide
		//		a resultsHandler; this is because for Dojo Offline we 
		//		use Google Gears to persist data, which has unlimited data
		//		once the user has given permission. If you are using Dojo
		//		Storage apart from Dojo Offline, then under the covers hidden
		//		Flash might be used, which is both asychronous and which might
		//		get denied; in this case you must provide a resultsHandler.
		// key:
		//		A string key to use when retrieving this value in the future.
		// value:
		//		A value to store; this can be any JavaScript type.
		// resultsHandler:
		//		A callback function that will receive three arguments. The
		//		first argument is one of three values: dojox.storage.SUCCESS,
		//		dojox.storage.FAILED, or dojox.storage.PENDING; these values
		//		determine how the put request went. In some storage systems
		//		users can deny a storage request, resulting in a
		//		dojox.storage.FAILED, while in other storage systems a storage
		//		request must wait for user approval, resulting in a
		//		dojox.storage.PENDING status until the request is either
		//		approved or denied, resulting in another call back with
		//		dojox.storage.SUCCESS. 
		//		The second argument in the call back is the key name that was being stored.
		//		The third argument in the call back is an optional message that
		//		details possible error messages that might have occurred during
		//		the storage process.
		//	namespace:
		//		Optional string namespace that this value will be placed into;
		//		if left off, the value will be placed into dojox.storage.DEFAULT_NAMESPACE
		
		console.warn("dojox.storage.put not implemented");
	},

	get: function(/*string*/ key, /*string?*/ namespace){ /*Object*/
		// summary:
		//		Gets the value with the given key. Returns null if this key is
		//		not in the storage system.
		// key:
		//		A string key to get the value of.
		//	namespace:
		//		Optional string namespace that this value will be retrieved from;
		//		if left off, the value will be retrieved from dojox.storage.DEFAULT_NAMESPACE
		// return: Returns any JavaScript object type; null if the key is not present
		console.warn("dojox.storage.get not implemented");
	},

	hasKey: function(/*string*/ key, /*string?*/ namespace){
		// summary: Determines whether the storage has the given key. 
		return !!this.get(key, namespace); // Boolean
	},

	getKeys: function(/*string?*/ namespace){ /*Array*/
		// summary: Enumerates all of the available keys in this storage system.
		// return: Array of available keys
		console.warn("dojox.storage.getKeys not implemented");
	},
	
	clear: function(/*string?*/ namespace){
		// summary: 
		//		Completely clears this storage system of all of it's values and
		//		keys. If 'namespace' is provided just clears the keys in that
		//		namespace.
		console.warn("dojox.storage.clear not implemented");
	},
  
	remove: function(/*string*/ key, /*string?*/ namespace){
		// summary: Removes the given key from this storage system.
		console.warn("dojox.storage.remove not implemented");
	},
	
	getNamespaces: function(){ /*string[]*/
		console.warn("dojox.storage.getNamespaces not implemented");
	},

	isPermanent: function(){ /*Boolean*/
		// summary:
		//		Returns whether this storage provider's values are persisted
		//		when this platform is shutdown. 
		console.warn("dojox.storage.isPermanent not implemented");
	},

	getMaximumSize: function(){ /* mixed */
		// summary: The maximum storage allowed by this provider
		// returns: 
		//	Returns the maximum storage size 
		//	supported by this provider, in 
		//	thousands of bytes (i.e., if it 
		//	returns 60 then this means that 60K 
		//	of storage is supported).
		//
		//	If this provider can not determine 
		//	it's maximum size, then 
		//	dojox.storage.SIZE_NOT_AVAILABLE is 
		//	returned; if there is no theoretical
		//	limit on the amount of storage 
		//	this provider can return, then
		//	dojox.storage.SIZE_NO_LIMIT is 
		//	returned
		console.warn("dojox.storage.getMaximumSize not implemented");
	},
		
	putMultiple: function(	/*array*/ keys,
							/*array*/ values, 
							/*function*/ resultsHandler,
							/*string?*/ namespace){
		// summary:
		//		Puts multiple keys and values into this storage system.
		// description:
		//		Example-
		//			var resultsHandler = function(status, key, message){
		//			  alert("status="+status+", key="+key+", message="+message);
		//			};
		//			dojox.storage.put(["test"], ["hello world"], resultsHandler);
		//	
		//		Important note: if you are using Dojo Storage in conjunction with
		//		Dojo Offline, then you don't need to provide
		//		a resultsHandler; this is because for Dojo Offline we 
		//		use Google Gears to persist data, which has unlimited data
		//		once the user has given permission. If you are using Dojo
		//		Storage apart from Dojo Offline, then under the covers hidden
		//		Flash might be used, which is both asychronous and which might
		//		get denied; in this case you must provide a resultsHandler.
		// keys:
		//		An array of string keys to use when retrieving this value in the future,
		//		one per value to be stored
		// values:
		//		An array of values to store; this can be any JavaScript type, though the
		//		performance of plain strings is considerably better
		// resultsHandler:
		//		A callback function that will receive three arguments. The
		//		first argument is one of three values: dojox.storage.SUCCESS,
		//		dojox.storage.FAILED, or dojox.storage.PENDING; these values
		//		determine how the put request went. In some storage systems
		//		users can deny a storage request, resulting in a
		//		dojox.storage.FAILED, while in other storage systems a storage
		//		request must wait for user approval, resulting in a
		//		dojox.storage.PENDING status until the request is either
		//		approved or denied, resulting in another call back with
		//		dojox.storage.SUCCESS. 
		//		The second argument in the call back is the key name that was being stored.
		//		The third argument in the call back is an optional message that
		//		details possible error messages that might have occurred during
		//		the storage process.
		//	namespace:
		//		Optional string namespace that this value will be placed into;
		//		if left off, the value will be placed into dojox.storage.DEFAULT_NAMESPACE
		
		for(var i = 0; i < keys.length; i++){ 
			dojox.storage.put(keys[i], values[i], resultsHandler, namespace); 
		}
	},

	getMultiple: function(/*array*/ keys, /*string?*/ namespace){ /*Object*/
		// summary:
		//		Gets the valuse corresponding to each of the given keys. 
		//		Returns a null array element for each given key that is
		//		not in the storage system.
		// keys:
		//		An array of string keys to get the value of.
		//	namespace:
		//		Optional string namespace that this value will be retrieved from;
		//		if left off, the value will be retrieved from dojox.storage.DEFAULT_NAMESPACE
		// return: Returns any JavaScript object type; null if the key is not present
		
		var results = []; 
		for(var i = 0; i < keys.length; i++){ 
			results.push(dojox.storage.get(keys[i], namespace)); 
		} 
		
		return results;
	},

	removeMultiple: function(/*array*/ keys, /*string?*/ namespace) {
		// summary: Removes the given keys from this storage system.
		
		for(var i = 0; i < keys.length; i++){ 
			dojox.storage.remove(keys[i], namespace); 
		}
	},
	
	isValidKeyArray: function( keys) {
		if(keys === null || keys === undefined || !dojo.isArray(keys)){
			return false;
		}

		//	JAC: This could be optimized by running the key validity test 
		//  directly over a joined string
		return !dojo.some(keys, function(key){
			return !this.isValidKey(key);
		}, this); // Boolean
	},

	hasSettingsUI: function(){ /*Boolean*/
		// summary: Determines whether this provider has a settings UI.
		return false;
	},

	showSettingsUI: function(){
		// summary: If this provider has a settings UI, determined
		// by calling hasSettingsUI(), it is shown. 
		console.warn("dojox.storage.showSettingsUI not implemented");
	},

	hideSettingsUI: function(){
		// summary: If this provider has a settings UI, hides it.
		console.warn("dojox.storage.hideSettingsUI not implemented");
	},
	
	isValidKey: function(/*string*/ keyName){ /*Boolean*/
		// summary:
		//		Subclasses can call this to ensure that the key given is valid
		//		in a consistent way across different storage providers. We use
		//		the lowest common denominator for key values allowed: only
		//		letters, numbers, and underscores are allowed. No spaces. 
		if(keyName === null || keyName === undefined){
			return false;
		}
			
		return /^[0-9A-Za-z_]*$/.test(keyName);
	},
	
	getResourceList: function(){ /* Array[] */
		// summary:
		//	Returns a list of URLs that this
		//	storage provider might depend on.
		// description:
		//	This method returns a list of URLs that this
		//	storage provider depends on to do its work.
		//	This list is used by the Dojo Offline Toolkit
		//	to cache these resources to ensure the machinery
		//	used by this storage provider is available offline.
		//	What is returned is an array of URLs.
		//  Note that Dojo Offline uses Gears as its native 
		//  storage provider, and does not support using other
		//  kinds of storage providers while offline anymore.
		
		return [];
	}
});