dojo.provide("dojo.data.util.simpleFetch");
dojo.require("dojo.data.util.sorter");

dojo.data.util.simpleFetch.fetch = function(/* Object? */ request){
	//	summary:
	//		The simpleFetch mixin is designed to serve as a set of function(s) that can
	//		be mixed into other datastore implementations to accelerate their development.  
	//		The simpleFetch mixin should work well for any datastore that can respond to a _fetchItems() 
	//		call by returning an array of all the found items that matched the query.  The simpleFetch mixin
	//		is not designed to work for datastores that respond to a fetch() call by incrementally
	//		loading items, or sequentially loading partial batches of the result
	//		set.  For datastores that mixin simpleFetch, simpleFetch 
	//		implements a fetch method that automatically handles eight of the fetch()
	//		arguments -- onBegin, onItem, onComplete, onError, start, count, sort and scope
	//		The class mixing in simpleFetch should not implement fetch(),
	//		but should instead implement a _fetchItems() method.  The _fetchItems() 
	//		method takes three arguments, the keywordArgs object that was passed 
	//		to fetch(), a callback function to be called when the result array is
	//		available, and an error callback to be called if something goes wrong.
	//		The _fetchItems() method should ignore any keywordArgs parameters for
	//		start, count, onBegin, onItem, onComplete, onError, sort, and scope.  
	//		The _fetchItems() method needs to correctly handle any other keywordArgs
	//		parameters, including the query parameter and any optional parameters 
	//		(such as includeChildren).  The _fetchItems() method should create an array of 
	//		result items and pass it to the fetchHandler along with the original request object 
	//		-- or, the _fetchItems() method may, if it wants to, create an new request object 
	//		with other specifics about the request that are specific to the datastore and pass 
	//		that as the request object to the handler.
	//
	//		For more information on this specific function, see dojo.data.api.Read.fetch()
	request = request || {};
	if(!request.store){
		request.store = this;
	}
	var self = this;

	var _errorHandler = function(errorData, requestObject){
		if(requestObject.onError){
			var scope = requestObject.scope || dojo.global;
			requestObject.onError.call(scope, errorData, requestObject);
		}
	};

	var _fetchHandler = function(items, requestObject){
		var oldAbortFunction = requestObject.abort || null;
		var aborted = false;

		var startIndex = requestObject.start?requestObject.start:0;
		var endIndex   = (requestObject.count && (requestObject.count !== Infinity))?(startIndex + requestObject.count):items.length;

		requestObject.abort = function(){
			aborted = true;
			if(oldAbortFunction){
				oldAbortFunction.call(requestObject);
			}
		};

		var scope = requestObject.scope || dojo.global;
		if(!requestObject.store){
			requestObject.store = self;
		}
		if(requestObject.onBegin){
			requestObject.onBegin.call(scope, items.length, requestObject);
		}
		if(requestObject.sort){
			items.sort(dojo.data.util.sorter.createSortFunction(requestObject.sort, self));
		}
		if(requestObject.onItem){
			for(var i = startIndex; (i < items.length) && (i < endIndex); ++i){
				var item = items[i];
				if(!aborted){
					requestObject.onItem.call(scope, item, requestObject);
				}
			}
		}
		if(requestObject.onComplete && !aborted){
			var subset = null;
			if (!requestObject.onItem) {
				subset = items.slice(startIndex, endIndex);
			}
			requestObject.onComplete.call(scope, subset, requestObject);   
		}
	};
	this._fetchItems(request, _fetchHandler, _errorHandler);
	return request;	// Object
};