function shiftCover(i,d)
{
	if(d)
	{
	  hideIndex = i;
	  showIndex = hideIndex + 5;
	  nextIndex = i+1;
	}
	else
	{
	  showIndex = i-1;
	  hideIndex = showIndex + 5;
	  nextIndex = i-1;
	}
	
	hideId = 'issue_' + hideIndex;
	showId = 'issue_' + showIndex;
	
	if(document.getElementById(hideId) && document.getElementById(showId))
	{	
	  toggleElement(hideId);
	  toggleElement(showId);
												   
	  updateShiftCover(nextIndex); 
    }
	else
	{
	  updateShiftCover(i);
	}
}

function updateShiftCover(i)
{
  document.getElementById('next-issue').onclick = function(){shiftCover(i, true);}; 
  document.getElementById('previous-issue').onclick = function(){shiftCover(i, false);};
}

function toggleFields()
{
  bokpremiediv = document.getElementById('bokpremier');
	radioboxes = bokpremiediv.getElementsByTagName('input');
	
	if (document.getElementById('strek_order_is_avtalegiro').checked==false)
	{
	  for(var i=0;i<radioboxes.length;i++)
	  {
		radioboxes[i].disabled=true;
	    radioboxes[i].checked=false;
	  }
	}
	else
	{
	  for(var i=0;i<radioboxes.length;i++)
	  {
		  radioboxes[i].disabled=false;
	  }
	}
}

function toggleGiftFields()
{
    gaveabodiv = document.getElementById('gaveabo');
	radioboxes = gaveabodiv.getElementsByTagName('input');
	
	if (document.getElementById('strek_order_is_gift').checked==false)
	{
	  for(var i=0;i<radioboxes.length;i++)
	  {
		radioboxes[i].disabled=true;
	    radioboxes[i].checked=false;
	  }
	}
	else
	{
	  for(var i=0;i<radioboxes.length;i++)
	  {
		  radioboxes[i].disabled=false;
	  }
	  radioboxes[0].checked=true;
	}
}

function disableAvtale()
{
  avtale = document.getElementById('strek_order_is_avtalegiro');
	if(avtale.disabled == false) 
	{
	  avtale.disabled = true;
		avtale.checked = false;
		toggleFields();
	}
}

function enableAvtale()
{
  avtale = document.getElementById('strek_order_is_avtalegiro');
	if(avtale.disabled == true) avtale.disabled = false;
}

function setDefaultCountry(id)
{
  field = document.getElementById(id);
	if(field.value == '') 
	{
	  field.value = 'Norge';
	}
}

function toggleElement(id)
{
  if (document.getElementById(id))
  {
	if (document.getElementById(id).style.display=='none')
	{
	  document.getElementById(id).style.display='block'
	}
	else
	{
	  document.getElementById(id).style.display='none'
	}
  }
}

function showHiddenCovers(start, stop)
{
  for (var i=start;i<=stop ;i++)
  {
	element = 'issue_'+i;
	showElement(element);
  }
}

function showElement(id)
{
  document.getElementById(id).style.display='block'
}