package miniforum.action; 
 
import miniforum.data.UserUtils; 
import miniforum.IConstants; 
 
import javax.servlet.*; 
import javax.servlet.http.*; 
import java.io.IOException; 
 
public class AuthenticationFilter implements Filter { 
 
    public void init(FilterConfig aFilterConfig) 
            throws ServletException { 
    } 
 
    public void doFilter(ServletRequest aRequest, 
            ServletResponse aResponse, FilterChain aFilterChain) 
            throws IOException, ServletException { 
        HttpServletRequest httpRequest = 
            (HttpServletRequest) aRequest; 
        HttpServletResponse httpResponse = 
            (HttpServletResponse) aResponse; 
        String requestedPage = getRequestedPage(httpRequest); 
 
        if (requestedPage.equals(IConstants.EMPTY_URL)) { 
            // Accessing root directory redirects to login form 
            httpResponse.sendRedirect(IConstants.LOGIN_FORM); 
            return; 
        } 
 
        if (IConstants.LOGIN_FORM.equals(requestedPage) || 
                IConstants.LOGIN_URL.equals(requestedPage) || 
                IConstants.LOGOUT_URL.equals(requestedPage)) { 
            // Accessing login/logout is always permitted 
            aFilterChain.doFilter(aRequest, aResponse); 
            return; 
        } 
 
        HttpSession session = httpRequest.getSession(); 
        boolean authenticated = 
            (UserUtils.getCurrentUser(session) != null); 
        if (authenticated) { 
            // Authenticated user. Permit the request 
            aFilterChain.doFilter(aRequest, aResponse); 
        } else { 
            // Not authenticated user. Redirect to login form 
            session.setAttribute(IConstants.LAST_ERROR, 
                "Поисканата страница изисква автентикация. " + 
                "Моля първо влезте в системата!"); 
            session.setAttribute(IConstants.ORIGINAL_URL, 
                requestedPage); 
            httpResponse.sendRedirect(IConstants.LOGIN_FORM); 
        } 
    } 
 
    private String getRequestedPage( 
            HttpServletRequest aHttpRequest) { 
        String url = aHttpRequest.getRequestURI(); 
        int firstSlash = url.indexOf("/",1); 
        String requestedPage = null; 
        if (firstSlash != -1) requestedPage = 
            url.substring(firstSlash + 1, url.length()); 
        return requestedPage; 
    } 
 
    public void destroy() { 
    } 
}