var QUERY_DEFAULT_TEXT = 'zoekwoorden';
var QUERY_ELEMENT_ID = 'query';
var	SEARCH_FORM_ID = 'zoeken-form';
var SEARCH_BUTTON_ID = 'search-submit-button';
var ARROW_CLASS = 'arrow';

function getQueryElement()
{
	return document.getElementById(QUERY_ELEMENT_ID);
}

function queryOnFocus()
{
	performDefaultValueProtectionCheck();
}

function queryOnBlur()
{
	revertDefaultValueProtectionCheck();
}

function performDefaultValueProtectionCheck()
{
	if ( getQueryElement().value == QUERY_DEFAULT_TEXT )
	{
		getQueryElement().value = "";
	}
}

function revertDefaultValueProtectionCheck()
{
	if ( getQueryElement().value == "" )
	{
		getQueryElement().value = QUERY_DEFAULT_TEXT;
	}
}

function submitSearchForm(event)
{
	event.preventDefault();
	performDefaultValueProtectionCheck();
	document.forms[SEARCH_FORM_ID].submit();
}

function initZoeken()
{
	var queryField = document.getElementById(QUERY_ELEMENT_ID);
	queryField.onfocus = queryOnFocus;
	queryField.onblur = queryOnBlur;
	var searchButton = document.getElementById(SEARCH_BUTTON_ID);
	var searchLink = document.createElement('a');
	searchLink.className = ARROW_CLASS;
	searchLink.innerHTML = searchButton.value;
	$(searchLink).click(submitSearchForm);
	searchLink.href = '#';
	searchButton.parentNode.replaceChild(searchLink, searchButton);
}

if ( window.attachEvent )
{
	window.attachEvent('onload', initZoeken);
}
else
{
	window.addEventListener('load', initZoeken, true);
}