feat: rename AddDepartmentRequest to DepartmentRequest and implement department editing functionality

src/main/java/com/onixbyte/helix/controller/DepartmentController.java

@@ -2,7 +2,7 @@ package com.onixbyte.helix.controller;
 
 import com.onixbyte.helix.domain.entity.Department;
 import com.onixbyte.helix.domain.common.TreeNode;
-import com.onixbyte.helix.domain.web.request.AddDepartmentRequest;
+import com.onixbyte.helix.domain.web.request.DepartmentRequest;
 import com.onixbyte.helix.service.DepartmentService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.validation.annotation.Validated;
@@ -38,7 +38,15 @@ public class DepartmentController {
     }
 
     @PostMapping
-    public Department addDepartment(@Validated @RequestBody AddDepartmentRequest request) {
+    public Department addDepartment(@Validated @RequestBody DepartmentRequest request) {
         return departmentService.addDepartment(request);
     }
+
+    @PutMapping("/{id:\\d+}")
+    public Department editDepartment(
+            @PathVariable Long id,
+            @Validated @RequestBody DepartmentRequest request
+    ) {
+        return departmentService.editDepartment(id, request);
+    }
 }

src/main/java/com/onixbyte/helix/domain/web/request/DepartmentRequest.java

@@ -26,7 +26,7 @@ import com.onixbyte.helix.enumeration.Status;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 
-public record AddDepartmentRequest(
+public record DepartmentRequest(
         @NotNull(message = "Name of the department should not be null")
         @NotBlank(message = "Name of the department should not be null")
         String name,

src/main/java/com/onixbyte/helix/manager/DepartmentManager.java

@@ -1,12 +1,16 @@
 package com.onixbyte.helix.manager;
 
 import com.onixbyte.helix.domain.entity.Department;
+import com.onixbyte.helix.exception.BizException;
 import com.onixbyte.helix.repository.DepartmentRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Transactional;
 
+import java.time.LocalDateTime;
 import java.util.Optional;
 
 @Component
@@ -34,4 +38,34 @@ public class DepartmentManager {
     public Department save(Department department) {
         return departmentRepository.save(department);
     }
+
+    /**
+     * Fully updates an existing department by ID.
+     * <p>
+     * The method loads the target department, replaces mutable fields ({@code name},
+     * {@code parentId}, {@code sort}, {@code status}), and refreshes {@code updatedAt} to the
+     * current time.
+     *
+     * @param id         the ID of the department to update
+     * @param department the source data carrying new field values
+     * @return the managed and updated {@link Department} entity
+     * @throws BizException if the target department does not exist
+     */
+    @Transactional
+    public Department fullUpdateById(Long id, Department department) {
+        var updatedAt = LocalDateTime.now();
+
+        var departmentToEdit = departmentRepository.findById(id)
+                .orElseThrow(() -> new BizException(
+                        HttpStatus.NOT_FOUND,
+                        "Department (ID: %d) to be edited not found.".formatted(department.getId()))
+                );
+
+        departmentToEdit.setName(department.getName());
+        departmentToEdit.setParentId(department.getParentId());
+        departmentToEdit.setSort(department.getSort());
+        departmentToEdit.setStatus(department.getStatus());
+        departmentToEdit.setUpdatedAt(updatedAt);
+        return departmentToEdit;
+    }
 }

src/main/java/com/onixbyte/helix/service/DepartmentService.java

@@ -2,7 +2,7 @@ package com.onixbyte.helix.service;
 
 import com.onixbyte.helix.domain.common.TreeNode;
 import com.onixbyte.helix.domain.entity.Department;
-import com.onixbyte.helix.domain.web.request.AddDepartmentRequest;
+import com.onixbyte.helix.domain.web.request.DepartmentRequest;
 import com.onixbyte.helix.enumeration.Status;
 import com.onixbyte.helix.manager.DepartmentManager;
 import com.onixbyte.helix.utils.TreeUtil;
@@ -35,7 +35,7 @@ public class DepartmentService {
     }
 
     @Transactional(rollbackFor = Throwable.class)
-    public Department addDepartment(AddDepartmentRequest request) {
+    public Department addDepartment(DepartmentRequest request) {
         var createdAt = LocalDateTime.now();
 
         var parentId = request.parentId();
@@ -51,4 +51,9 @@ public class DepartmentService {
                 .updatedAt(createdAt)
                 .build());
     }
+
+    public Department editDepartment(Long id, DepartmentRequest request) {
+        return departmentManager.fullUpdateById(id, Department.builder()
+                .build());
+    }
 }