function setAmount(invoice_bodyid,removeid)
{
	var quan=document.frm.quantity.value;
	var up=document.frm.unit_price.value;
	
	if(quan!="" && up!="")
	{
		var amt=quan*up;
		document.getElementById('amount').value=amt;
		document.getElementById('gross_total').value=amt;
		
		if(invoice_bodyid>0)
		{
			var amtnew=0; var grandtamt=0;
			
			for(var i=1;i<=invoice_bodyid;i++)
			{
				var newquan=document.getElementById('quantity'+i).value;
				var newup=document.getElementById('unit_price'+i).value;	
				amtnew=newquan*newup;

				document.getElementById('amount'+i).value=amtnew;
				var tamt=document.getElementById('amount'+i).value;
				grandtamt= parseInt(grandtamt)+parseInt(tamt);
			}	
			document.getElementById('gross_total').value=parseInt(grandtamt)+parseInt(amt);
		}
	}
}

var invoice_bodyid_total=0;
// code for adding more form 
function addFormField() 
{
	var invoice_bodyid = document.getElementById("invoice_bodyid").value;
	invoice_bodyid_total++;

$("#divTxt").append("<table cellpadding=\"0\" cellspacing=\"1\" id='invoicebody" + invoice_bodyid + "' align=\"center\" width=\"100%\" border=\"1\"><tr><td nowrap=\"nowrap\" width=\"30%\" class=\"admin_form_label\">Quantity : *</td><td class=\"admin_form_field\"><input type=\"text\" name=\"quantity"+invoice_bodyid+"\" id=\"quantity"+invoice_bodyid+"\" onblur='setAmount("+invoice_bodyid+");' /></td></tr><tr><td nowrap=\"nowrap\" width=\"30%\" class=\"admin_form_label\">Unit Price : *</td><td class=\"admin_form_field\"><input type=\"text\" name=\"unit_price"+invoice_bodyid+"\" id=\"unit_price"+invoice_bodyid+"\" class=\"unit_price\" onblur='setAmount("+invoice_bodyid+");' /></td></tr><tr><td nowrap=\"nowrap\" width=\"30%\" class=\"admin_form_label\">Amount :</td><td class=\"admin_form_field\" ><input type=\"text\" name=\"amount"+invoice_bodyid+"\" id=\"amount"+invoice_bodyid+"\" readonly=\"true\"/>	</td></tr><tr><td nowrap=\"nowrap\" width=\"30%\" class=\"admin_form_label\" colspan=\"2\" align=\"right\"><a href=\"#\" onClick='removeFormField(\"#invoicebody" + invoice_bodyid + "\","+ invoice_bodyid +"); return false;'>Remove</a></td></tr></table>");
	
	invoice_bodyid = (invoice_bodyid - 1) + 2;
	document.getElementById("invoice_bodyid").value = invoice_bodyid;
}


function setAmountMinus(invoice_bodyid,removeid)
{
	if(invoice_bodyid>0)
	{
		var amtnew=0; var grandtamt=0;
		for(var i=1;i<=invoice_bodyid;i++)
		{	
			if(i==removeid)
			{
				// problem is here.. it could not found value of i
				var rnewquan=document.getElementById("quantity"+i).value;
				var rnewup=document.getElementById("unit_price"+i).value;
				var ramtnew=rnewquan*rnewup;
			}
		}
		grandtamt=document.getElementById("gross_total").value;
		grandtamt=parseInt(grandtamt)-parseInt(ramtnew);
		document.getElementById("gross_total").value=grandtamt;
	}
}
	
function removeFormField(invoice_bodyid, removeid) 
{
	// remove html section
	$(invoice_bodyid).remove();
	// minus the amount of removed block
	setAmountMinus(invoice_bodyid_total,removeid);
}