String.prototype.endsWith = function(s) 
{
	return this.length >= s.length && this.substr(this.length - s.length) == s;
}

String.prototype.startsWith = function(s) 
{
	return this.length >= s.length && this.substr(0, s.length) == s;
}

function round(value,precision)
{
	var exp = Math.pow(10,precision);
	
	return Math.round(value*exp)/exp;
}

var products = new Array();
var productRatios = new Array();
var activeField;

function addProduct(product,ratio)
{
	var index = products.length;
	products[index] = product;
	productRatios[index] = ratio;	
}

addProduct("Bułka tarta",1.667);
addProduct("Cukier",1.15);
addProduct("Cukier puder",1.37);
addProduct("Fasola drobna",1.25);
addProduct("Groch",1.25);
addProduct("Kasza manna",1.35);
addProduct("Mak",1.676);
addProduct("Margaryna",1.087);
addProduct("Masło",1.087);
addProduct("Mąka kukurydziana",1.25);
addProduct("Mąka pszenna (typ 500)",1.47);
addProduct("Mąka pszenna chlebowa (typ 720)",1.63);
addProduct("Mąka pszenna razowa (typ 2000)",1.73);
addProduct("Mąka żytnia chlebowa (typ 720)", 1.70);
addProduct("Mąka żytnia razowa (typ 2000)", 1.8);
addProduct("Mąka ziemniaczana",1.05);
addProduct("Miód",0.71);
addProduct("Mleko",1);
addProduct("Ocet",1);
addProduct("Olej",1.1);
addProduct("Oliwa z oliwek",1.095);
addProduct("Proszek do pieczenia",1.15);
addProduct("Ryż",1.089);
addProduct("Soczewica",1.25);
addProduct("Sól kuchenna",0.825);
addProduct("Spirytus",1.25);
addProduct("Smalec",1.15);
addProduct("Śmietana 18%",1.12);
addProduct("Wino",1.02);
addProduct("Wódka",1.087);
addProduct("Woda",1);

var amountRatios = new Array();
amountRatios["Gram"] = 1;
amountRatios["Kilogram"] = 1000;
amountRatios["Pound"] = 453.6;
amountRatios["Ounce"] = 28.35;

var amountRounds = new Array();
amountRounds["Gram"] = 0;
amountRounds["Kilogram"] = 2;
amountRounds["Pound"] = 2;
amountRounds["Ounce"] = 1;

var volumeRatios = new Array();
volumeRatios["Glass"] = 250;
volumeRatios["Milliliter"] = 1;
volumeRatios["Teaspoon"] = 5;
volumeRatios["Tablespoon"] = 15;
volumeRatios["Pint"] = 568;
volumeRatios["Ounce"] = 28.41;

var volumeRounds = new Array();
volumeRounds["Glass"] = 2;
volumeRounds["Milliliter"] = 0;
volumeRounds["Teaspoon"] = 1;
volumeRounds["Tablespoon"] = 1;
volumeRounds["Pint"] = 2;
volumeRounds["Ounce"] = 1;

function initialize()
{
	document.chooseForm.amountGram.value = 100;

	fillProducts("");	
}

function fillProducts(filter)
{
	var productsSelect = document.chooseForm.productsSelect;

	if(!filter)
	{
		filter = "";
	}
	filter = filter.toLowerCase();
	
	productsSelect.options.length = 0;
	for(var i=0; i < products.length; i++) 
	{
		if(filter.length==0 || products[i].toLowerCase().indexOf(filter) != -1)
		{
			productsSelect.options[productsSelect.options.length] = new Option(products[i],productRatios[i]);
		}
	}	
	productsSelect.options[0].selected = true;
	
	productSelected();
}

function productSelected()
{
		var productsSelect = document.chooseForm.productsSelect;
		
		if(activeField!==undefined)
		{
			recalculate(activeField);
		} else
			{
				recalculate(document.chooseForm.amountGram);
			}
}

function productSearched()
{
	var searchString = document.chooseForm.productSearch.value;
	
	fillProducts(searchString);
}

function recalculate(field)
{
	//cursorPosition = field.selectionStart;
	//alert(cursorPosition);
	//document.chooseForm.productSearch.value = cursorPosition;
	if(field.value.indexOf(',')>0)
		field.value = field.value.replace(',','.');

	var numberRegExp = new RegExp("^[0-9\.,]*$");		
	if(!numberRegExp.test(field.value))
		field.value = field.value.replace(/[^0-9\.,]*/ig,'');	
	//field.selectionStart = cursorPosition;
	
	//check for double decimal separator
	var firstSep = field.value.indexOf(".");
	var secondSep = firstSep>0?field.value.indexOf(".",firstSep+1):-1;
	if(firstSep>0 && secondSep>firstSep)
	{
		field.value = field.value.substring(0,secondSep);
	}
	
	if(field.value[field.value.length-1]=='.')
		return;
	
	var reset = false;
	if(field.value.length == 0)
	{
		reset = true;
	}
	
	var ratio = 1;
	var volumeRatio = document.chooseForm.productsSelect.options[document.chooseForm.productsSelect.selectedIndex].value;
	
	if(field.id.startsWith("amount"))
	{
		ratio = field.value * amountRatios[field.id.substring(6)];
	}else
	if(field.id.startsWith("volume"))
	{
		ratio = field.value * volumeRatios[field.id.substring(6)] / volumeRatio;
	}
	
    for(var i = 0; i < document.chooseForm.elements.length; i++)
    {
		var currentElement = document.chooseForm.elements[i];
		
		if(currentElement == field)
			continue;
		
		if(currentElement.id.startsWith("amount"))
		{
			if(reset)
			{
				currentElement.value = '';
				continue;
			}
			currentElement.value = round(ratio / amountRatios[currentElement.id.substring(6)], amountRounds[currentElement.id.substring(6)]);
		}
		
		if(currentElement.id.startsWith("volume"))
		{
			if(reset)
			{
				currentElement.value = '';
				continue;
			}
			currentElement.value = round(ratio / volumeRatios[currentElement.id.substring(6)] * volumeRatio, volumeRounds[currentElement.id.substring(6)]);
		}
    }
}

function selectInput(field)
{
	addClass(field,"form-selected");
	activeField = field;
	
	for(var i = 0; i < document.chooseForm.elements.length; i++)
   {
		var currentElement = document.chooseForm.elements[i];
		
		if(currentElement == field)
			continue;
			
		removeClass(currentElement,"form-selected");
	}
}

function addClass(item, classname) 
{
    var obj = item
    if (typeof item=="string") {
        obj = document.getElementById(item)
    }
    obj.className += " " + classname
}

function removeClass(item, classname) 
{
    var obj = item
    if (typeof item=="string") {
        obj = document.getElementById(item)
    }
    var classes = ""+obj.className
    while (classes.indexOf(classname)>-1) {
        classes = classes.replace (classname, "")
    }
    obj.className = classes
}