impersonation implementado

src/main/java/com/imprimelibros/erp/users/ImpersonationController.java

@@ -0,0 +1,115 @@
+package com.imprimelibros.erp.users;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.security.access.AccessDeniedException;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.GrantedAuthority;
+import org.springframework.security.core.authority.SimpleGrantedAuthority;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
+
+import com.imprimelibros.erp.config.Sanitizer;
+
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpSession;
+
+@Controller
+public class ImpersonationController {
+
+    private static final String PREVIOUS_ADMIN_ROLE = "ROLE_PREVIOUS_ADMINISTRATOR";
+    private static final String SESSION_ATTR = "IMPERSONATOR_AUTH";
+
+    private final UserService userService;
+    private final Sanitizer sanitizer;
+
+    public ImpersonationController(UserService userService, Sanitizer sanitizer) {
+        this.userService = userService;
+        this.sanitizer = sanitizer;
+    }
+
+    @PostMapping("/impersonate")
+    @PreAuthorize("hasRole('ADMIN') or hasRole('SUPERADMIN')")
+    public String impersonate(
+            @RequestParam("username") String username,
+            Authentication authentication,
+            HttpServletRequest request) {
+
+        if (authentication == null) {
+            return "redirect:/login";
+        }
+
+        if (hasRole(authentication, PREVIOUS_ADMIN_ROLE)) {
+            return "redirect:/";
+        }
+
+        String normalized = sanitizer.plain(username);
+        if (normalized == null || normalized.isBlank()) {
+            return "redirect:/users";
+        }
+        normalized = normalized.trim().toLowerCase();
+
+        if (authentication.getName() != null
+                && authentication.getName().equalsIgnoreCase(normalized)) {
+            return "redirect:/users";
+        }
+
+        UserDetails target;
+        try {
+            target = userService.loadUserByUsername(normalized);
+        } catch (UsernameNotFoundException ex) {
+            throw new AccessDeniedException("No autorizado");
+        }
+
+        boolean currentIsSuperAdmin = hasRole(authentication, "ROLE_SUPERADMIN");
+        boolean targetIsSuperAdmin = target.getAuthorities().stream()
+                .anyMatch(a -> "ROLE_SUPERADMIN".equals(a.getAuthority()));
+        if (targetIsSuperAdmin && !currentIsSuperAdmin) {
+            throw new AccessDeniedException("No autorizado");
+        }
+
+        HttpSession session = request.getSession(true);
+        if (session.getAttribute(SESSION_ATTR) == null) {
+            session.setAttribute(SESSION_ATTR, authentication);
+        }
+
+        List<GrantedAuthority> authorities = new ArrayList<>(target.getAuthorities());
+        authorities.add(new SimpleGrantedAuthority(PREVIOUS_ADMIN_ROLE));
+
+        UsernamePasswordAuthenticationToken newAuth = new UsernamePasswordAuthenticationToken(
+                target, target.getPassword(), authorities);
+        newAuth.setDetails(authentication.getDetails());
+
+        SecurityContextHolder.getContext().setAuthentication(newAuth);
+        return "redirect:/";
+    }
+
+    @PostMapping("/impersonate/exit")
+    @PreAuthorize("hasRole('PREVIOUS_ADMINISTRATOR')")
+    public String exit(HttpServletRequest request) {
+        HttpSession session = request.getSession(false);
+        if (session != null) {
+            Object previous = session.getAttribute(SESSION_ATTR);
+            if (previous instanceof Authentication previousAuth) {
+                SecurityContextHolder.getContext().setAuthentication(previousAuth);
+            } else {
+                SecurityContextHolder.clearContext();
+            }
+            session.removeAttribute(SESSION_ATTR);
+        }
+        return "redirect:/";
+    }
+
+    private static boolean hasRole(Authentication auth, String role) {
+        return auth != null
+                && auth.getAuthorities().stream()
+                        .anyMatch(a -> role.equals(a.getAuthority()));
+    }
+}