/**
* Disables/Enables history arrow buttons depending on whether the current page is the first, the
* last page or a middle page.
*
* @param chatPanel the <tt>ChatPanel</tt> which has provoked the change.
*/
public void changeHistoryButtonsState(ChatPanel chatPanel) {
ChatConversationPanel convPanel = chatPanel.getChatConversationPanel();
long firstMsgInHistory = chatPanel.getFirstHistoryMsgTimestamp().getTime();
long lastMsgInHistory = chatPanel.getLastHistoryMsgTimestamp().getTime();
Date firstMsgInPage = convPanel.getPageFirstMsgTimestamp();
Date lastMsgInPage = convPanel.getPageLastMsgTimestamp();
if (firstMsgInHistory == 0 || lastMsgInHistory == 0) {
previousButton.setEnabled(false);
nextButton.setEnabled(false);
return;
}
previousButton.setEnabled(firstMsgInHistory < firstMsgInPage.getTime());
nextButton.setEnabled(
(lastMsgInPage.getTime() > 0) && (lastMsgInHistory > lastMsgInPage.getTime()));
}