Web Utilities

class WebUtils {
    /**
     * Returns the path within the application for the given request.
     *
     * @param request the HTTP servlet request
     * @return the path within the application
     */
    public static String getPathWithinApplication(HttpServletRequest request);
    
    /**
     * Returns the context path for the given request.
     *
     * @param request the HTTP servlet request
     * @return the context path
     */
    public static String getContextPath(HttpServletRequest request);
    
    /**
     * Retrieves the WebEnvironment from the ServletContext.
     *
     * @param servletContext the servlet context
     * @return the WebEnvironment instance
     */
    public static WebEnvironment getWebEnvironment(ServletContext servletContext);
    
    /**
     * Issues a redirect to the specified URL.
     *
     * @param request the servlet request
     * @param response the servlet response
     * @param url the URL to redirect to
     * @throws IOException if redirect fails
     */
    public static void issueRedirect(ServletRequest request, ServletResponse response, String url) throws IOException;
    
    /**
     * Issues a redirect with query parameters.
     *
     * @param request the servlet request
     * @param response the servlet response
     * @param url the URL to redirect to
     * @param queryParams query parameters to append
     * @param contextRelative whether URL is context-relative
     * @param http10Compatible whether to use HTTP 1.0 compatible redirect
     * @throws IOException if redirect fails
     */
    public static void issueRedirect(ServletRequest request, ServletResponse response, String url, 
                                   Map<String, ?> queryParams, boolean contextRelative, boolean http10Compatible) 
                                   throws IOException;
    
    /**
     * Saves the current request for later restoration.
     *
     * @param request the servlet request to save
     */
    public static void saveRequest(ServletRequest request);
    
    /**
     * Retrieves a previously saved request.
     *
     * @param request the current servlet request
     * @return the saved request or null if none exists
     */
    public static SavedRequest getSavedRequest(ServletRequest request);
    
    /**
     * Retrieves and clears a previously saved request.
     *
     * @param request the current servlet request
     * @return the saved request or null if none exists
     */
    public static SavedRequest getAndClearSavedRequest(ServletRequest request);
    
    /**
     * Redirects to a previously saved request.
     *
     * @param request the servlet request
     * @param response the servlet response
     * @param fallbackUrl URL to redirect to if no saved request exists
     * @throws IOException if redirect fails
     */
    public static void redirectToSavedRequest(ServletRequest request, ServletResponse response, String fallbackUrl) 
                                            throws IOException;
    
    /**
     * Converts a ServletRequest to HttpServletRequest.
     *
     * @param request the servlet request
     * @return the HTTP servlet request
     */
    public static HttpServletRequest toHttp(ServletRequest request);
    
    /**
     * Converts a ServletResponse to HttpServletResponse.
     *
     * @param response the servlet response
     * @return the HTTP servlet response
     */
    public static HttpServletResponse toHttp(ServletResponse response);
    
    /**
     * Returns whether the request is an HTTP request.
     *
     * @param request the servlet request
     * @return true if request is HTTP
     */
    public static boolean isHttp(ServletRequest request);
}

class SavedRequest implements Serializable {
    /**
     * Creates a SavedRequest from the given HTTP request.
     *
     * @param request the HTTP servlet request to save
     */
    public SavedRequest(HttpServletRequest request);
    
    /**
     * Returns the HTTP method of the saved request.
     *
     * @return the HTTP method (GET, POST, etc.)
     */
    public String getMethod();
    
    /**
     * Returns the query string of the saved request.
     *
     * @return the query string
     */
    public String getQueryString();
    
    /**
     * Returns the request URI of the saved request.
     *
     * @return the request URI
     */
    public String getRequestURI();
    
    /**
     * Returns the request URL of the saved request.
     *
     * @return the request URL
     */
    public String getRequestURL();
    
    /**
     * Returns the parameter map of the saved request.
     *
     * @return Map of parameter names to value arrays
     */
    public Map<String, String[]> getParameterMap();
    
    /**
     * Returns the headers of the saved request.
     *
     * @return Map of header names to value lists
     */
    public Map<String, List<String>> getHeaders();
    
    /**
     * Returns the locales of the saved request.
     *
     * @return List of Locale objects
     */
    public List<Locale> getLocales();
}

interface RequestPairSource {
    /**
     * Returns the servlet request.
     *
     * @return the ServletRequest instance
     */
    ServletRequest getServletRequest();
    
    /**
     * Returns the servlet response.
     *
     * @return the ServletResponse instance
     */
    ServletResponse getServletResponse();
}

public class LoginController {
    
    public void handleLogin(HttpServletRequest request, HttpServletResponse response) {
        Subject currentUser = SecurityUtils.getSubject();
        
        if (!currentUser.isAuthenticated()) {
            // Save the original request before redirecting to login
            WebUtils.saveRequest(request);
            WebUtils.issueRedirect(request, response, "/login");
            return;
        }
        
        // User is authenticated, redirect to saved request or default
        WebUtils.redirectToSavedRequest(request, response, "/dashboard");
    }
    
    public void processLogin(HttpServletRequest request, HttpServletResponse response, 
                           String username, String password) {
        try {
            Subject currentUser = SecurityUtils.getSubject();
            UsernamePasswordToken token = new UsernamePasswordToken(username, password);
            currentUser.login(token);
            
            // Login successful, redirect to saved request
            WebUtils.redirectToSavedRequest(request, response, "/dashboard");
            
        } catch (AuthenticationException e) {
            // Login failed, redirect back to login page
            WebUtils.issueRedirect(request, response, "/login?error=true");
        }
    }
}

public class SecurityUtils {
    
    public boolean isSecurePath(HttpServletRequest request) {
        String path = WebUtils.getPathWithinApplication(request);
        return path.startsWith("/admin/") || path.startsWith("/secure/");
    }
    
    public String buildAbsoluteUrl(HttpServletRequest request, String relativePath) {
        String contextPath = WebUtils.getContextPath(request);
        String scheme = request.getScheme();
        String serverName = request.getServerName();
        int serverPort = request.getServerPort();
        
        StringBuilder url = new StringBuilder();
        url.append(scheme).append("://").append(serverName);
        
        if ((scheme.equals("http") && serverPort != 80) || 
            (scheme.equals("https") && serverPort != 443)) {
            url.append(":").append(serverPort);
        }
        
        url.append(contextPath).append(relativePath);
        return url.toString();
    }
    
    public void enforceHttps(HttpServletRequest request, HttpServletResponse response) 
            throws IOException {
        if (!"https".equals(request.getScheme())) {
            String httpsUrl = buildAbsoluteUrl(request, request.getRequestURI())
                .replace("http://", "https://");
            WebUtils.issueRedirect(request, response, httpsUrl);
        }
    }
}

public class CustomRedirectHandler {
    
    public void redirectWithMessage(ServletRequest request, ServletResponse response, 
                                  String url, String message) throws IOException {
        Map<String, String> params = new HashMap<>();
        params.put("message", message);
        
        WebUtils.issueRedirect(request, response, url, params, true, false);
    }
    
    public void redirectToLogin(ServletRequest request, ServletResponse response, 
                              String reason) throws IOException {
        // Save current request
        WebUtils.saveRequest(request);
        
        // Redirect to login with reason
        Map<String, String> params = new HashMap<>();
        params.put("reason", reason);
        
        WebUtils.issueRedirect(request, response, "/login", params, true, false);
    }
    
    public void handleLogout(HttpServletRequest request, HttpServletResponse response) 
            throws IOException {
        Subject currentUser = SecurityUtils.getSubject();
        currentUser.logout();
        
        // Clear any saved requests
        WebUtils.getAndClearSavedRequest(request);
        
        // Redirect to home page
        WebUtils.issueRedirect(request, response, "/?logout=success");
    }
}

public class RequestAnalyzer {
    
    public void analyzeRequest(HttpServletRequest request) {
        String path = WebUtils.getPathWithinApplication(request);
        String contextPath = WebUtils.getContextPath(request);
        
        System.out.println("Request Analysis:");
        System.out.println("  Context Path: " + contextPath);
        System.out.println("  Path within App: " + path);
        System.out.println("  Full Request URI: " + request.getRequestURI());
        System.out.println("  Query String: " + request.getQueryString());
        
        // Check for saved requests
        SavedRequest savedRequest = WebUtils.getSavedRequest(request);
        if (savedRequest != null) {
            System.out.println("  Saved Request:");
            System.out.println("    Method: " + savedRequest.getMethod());
            System.out.println("    URI: " + savedRequest.getRequestURI());
            System.out.println("    Query: " + savedRequest.getQueryString());
        }
    }
    
    public boolean isSameOrigin(HttpServletRequest request, String url) {
        try {
            URL requestUrl = new URL(request.getRequestURL().toString());
            URL targetUrl = new URL(url);
            
            return requestUrl.getProtocol().equals(targetUrl.getProtocol()) &&
                   requestUrl.getHost().equals(targetUrl.getHost()) &&
                   requestUrl.getPort() == targetUrl.getPort();
        } catch (MalformedURLException e) {
            return false;
        }
    }
}