/*

	Copyright (c) 2004-2008, The Dojo Foundation All Rights Reserved.

	Available via Academic Free License >= 2.1 OR the modified BSD license.

	see: http://dojotoolkit.org/license for details

*/





if(!dojo._hasResource["dojo.data.util.sorter"]){ //_hasResource checks added by build. Do not use _hasResource directly in your code.

dojo._hasResource["dojo.data.util.sorter"] = true;

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



dojo.data.util.sorter.basicComparator = function(	/*anything*/ a, 

													/*anything*/ b){

	//	summary:  

	//		Basic comparision function that compares if an item is greater or less than another item

	//	description:  

	//		returns 1 if a > b, -1 if a < b, 0 if equal.

	//		undefined values are treated as larger values so that they're pushed to the end of the list.



	var ret = 0;

	if(a > b || typeof a === "undefined" || a === null){

		ret = 1;

	}else if(a < b || typeof b === "undefined" || b === null){

		ret = -1;

	}

	return ret; //int, {-1,0,1}

};



dojo.data.util.sorter.createSortFunction = function(	/* attributes array */sortSpec,

														/*dojo.data.core.Read*/ store){

	//	summary:  

	//		Helper function to generate the sorting function based off the list of sort attributes.

	//	description:  

	//		The sort function creation will look for a property on the store called 'comparatorMap'.  If it exists

	//		it will look in the mapping for comparisons function for the attributes.  If one is found, it will

	//		use it instead of the basic comparator, which is typically used for strings, ints, booleans, and dates.

	//		Returns the sorting function for this particular list of attributes and sorting directions.

	//

	//	sortSpec: array

	//		A JS object that array that defines out what attribute names to sort on and whether it should be descenting or asending.

	//		The objects should be formatted as follows:

	//		{

	//			attribute: "attributeName-string" || attribute,

	//			descending: true|false;   // Default is false.

	//		}

	//	store: object

	//		The datastore object to look up item values from.

	//

	var sortFunctions=[];   



	function createSortFunction(attr, dir){

		return function(itemA, itemB){

			var a = store.getValue(itemA, attr);

			var b = store.getValue(itemB, attr);

			//See if we have a override for an attribute comparison.

			var comparator = null;

			if(store.comparatorMap){

				if(typeof attr !== "string"){

					 attr = store.getIdentity(attr);

				}

				comparator = store.comparatorMap[attr]||dojo.data.util.sorter.basicComparator;

			}

			comparator = comparator||dojo.data.util.sorter.basicComparator; 

			return dir * comparator(a,b); //int

		};

	}

	var sortAttribute;

	for(var i = 0; i < sortSpec.length; i++){

		sortAttribute = sortSpec[i];

		if(sortAttribute.attribute){

			var direction = (sortAttribute.descending) ? -1 : 1;

			sortFunctions.push(createSortFunction(sortAttribute.attribute, direction));

		}

	}



	return function(rowA, rowB){

		var i=0;

		while(i < sortFunctions.length){

			var ret = sortFunctions[i++](rowA, rowB);

			if(ret !== 0){

				return ret;//int

			}

		}

		return 0; //int  

	};  //  Function

};



}