function getResponses(offset)
{
   	var HttpRequest = false;
   	var request = "offset="+offset;
   	var object = "guestbook";

    if(window.XMLHttpRequest)
    {
    	HttpRequest = new XMLHttpRequest();
    } 
    else if(window.ActiveXObject) 
    {
      	HttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
    }
	  
    HttpRequest.open('POST', 'include/guestbook_init.php', true);
    HttpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    HttpRequest.onreadystatechange = function()
	{
        if (HttpRequest.readyState == 4) {
            update(HttpRequest.responseText, object);
        }
    }
    HttpRequest.send(request);
    
    return false;
}

function addResponse()
{
 	if(document.book.name.value == "")
  	{
	   	alert("Vyplňte prosím jméno (přezdívku).");
   		document.book.name.focus();
   		return false;
	}	

	if(document.book.text.value == "")
	{
		alert("Vyplňte prosím text příspěvku.");
	   	document.book.text.focus();
	   	return false;
	}
	
	if(document.book.check.value == "")
	{
		alert("Vyplňte prosím kontrolní součet proti spamu.");
	   	document.book.check.focus();
	   	return false;
	}
	else
	{
		var checksum = document.getElementById('checksum').value;
		var check = hex_md5(document.book.check.value);
		
		if(checksum != check)
		{
			alert("Kontrolní součet není správně vypočítán.");
	   		document.book.check.focus();
	   		return false;
		}
	}

	var name = document.getElementById('name').value;
    var text = document.getElementById('text').value;

   	var HttpRequest = false;
   	var request = "offset=0&name="+name+"&text="+text;
   	var object = "guestbook";

    if(window.XMLHttpRequest)
    {
    	HttpRequest = new XMLHttpRequest();
    } 
    else if(window.ActiveXObject) 
    {
      	HttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
    }
	  
    HttpRequest.open('POST', 'include/guestbook_init.php', true);
    HttpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    HttpRequest.onreadystatechange = function()
	{
        if (HttpRequest.readyState == 4) {
            update(HttpRequest.responseText, object);
        }
    }
    HttpRequest.send(request);
    
    return false;
}

function deleteResponse(id)
{
	if(confirm("Opravdu si přejete tento příspěvek smazat?"))
	{
	   	var HttpRequest = false;
	   	var request = "offset=0&id="+id;
	   	var object = "guestbook";
	
	    if(window.XMLHttpRequest)
	    {
	    	HttpRequest = new XMLHttpRequest();
	    } 
	    else if(window.ActiveXObject) 
	    {
	      	HttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
	    }
		  
	    HttpRequest.open('POST', 'include/guestbook_init.php', true);
	    HttpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	    HttpRequest.onreadystatechange = function()
		{
	        if (HttpRequest.readyState == 4) {
	            update(HttpRequest.responseText, object);
	        }
	    }
	    HttpRequest.send(request);
	    
	    return false;
	}
	else return false;
}
	
function update(str, object)
{
    document.getElementById(object).innerHTML = str;
}