function validateFormOnSubmit(theForm) {
	var reason = "";
  
	reason += validateAmount(theForm.amount);
	reason += validateSteamID(theForm.steamid);
	reason += validateNickname(theForm.nickname);
      
	if (reason != "") {
		alert("Some fields need correction:\n" + reason);
		return false;
	}

	return true;
}

function validateAmount(fld) {
	var error="";
	var patternOne = /^[1-9][\d]*$/ ;
	var patternTwo = /[\d]+\.[\d]{1,2}$/ ;
	
	var tfld = trim(fld.value);
	
	if (!patternOne.test(tfld) && !patternTwo.test(tfld)) {
		fld.style.background = 'Red';
        error = "Specified donation amount is invalid.\n";
	}
	else
		fld.style.background = 'White';
	
	return error;
}

function trim(s)
{
  return s.replace(/^\s+|\s+$/, '');
}

function validateNickname(fld) {
    var error="";
    var tfld = trim(fld.value); // value of field with whitespace trimmed off
   
    if (fld.value == "") {
        fld.style.background = 'Red';
        error = "You didn't enter a nickname.\n";
    } else {
        fld.style.background = 'White';
    }
	
    return error;
}

function validateSteamID(fld) {
    var error = "";
    var pattern = /^STEAM_0:[01]:[\d]+$/ ;
	
	var tfld = trim(fld.value);
 
    if (tfld == "") {
        fld.style.background = 'Red'; 
        error = "You didn't enter SteamID.\n";
    } else if (!pattern.test(tfld)) {
        fld.style.background = 'Red'; 
        error = "SteamID has invalid format (valid example: STEAM_0:0:12345678).\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}

function changeCurrencySymbol(selected) {
	if (selected == "dotpay")
		document.getElementById('currencySymbolEl').innerHTML="zł";
	else if (selected == "paypal")
		document.getElementById('currencySymbolEl').innerHTML="€";
}