deviceOrg: get children of root nodes api implementation

components/device-mgt-extensions/io.entgra.device.mgt.core.device.mgt.extensions.device.organization.api/src/main/java/io/entgra/device/mgt/core/device/mgt/extensions/device/organization/api/DeviceOrganizationMgtService.java

@@ -346,14 +346,14 @@ public interface DeviceOrganizationMgtService {
     Response getDeviceOrganizationLeafs(
             @ApiParam(
                     name = "offset",
-                    value = "The starting pagination index for the complete list of qualified items",
+                    value = "leaf node offset",
                     required = false,
                     defaultValue = "0")
             @DefaultValue("0") @QueryParam("offset")
             int offset,
             @ApiParam(
                     name = "limit",
-                    value = "Provide how many policy details you require from the starting pagination index/offset.",
+                    value = "leaf node limit",
                     required = false,
                     defaultValue = "5")
             @DefaultValue("20") @QueryParam("limit")
@@ -369,8 +369,8 @@ public interface DeviceOrganizationMgtService {
     @ApiOperation(
             produces = MediaType.APPLICATION_JSON,
             httpMethod = "GET",
-            value = "Retrieve leaf Device Organizations",
-            notes = "Get a list of leaf device organizations.",
+            value = "Retrieve root Device Organizations",
+            notes = "Get a list of root device organizations.",
             tags = "Device Organization Management",
             extensions = {
                     @Extension(properties = {
@@ -414,19 +414,97 @@ public interface DeviceOrganizationMgtService {
     Response getDeviceOrganizationRoots(
             @ApiParam(
                     name = "offset",
-                    value = "The starting pagination index for the complete list of qualified items",
+                    value = "root node offset",
                     required = false,
                     defaultValue = "0")
             @DefaultValue("0") @QueryParam("offset")
             int offset,
             @ApiParam(
                     name = "limit",
-                    value = "Provide how many policy details you require from the starting pagination index/offset.",
+                    value = "root node limit",
                     required = false,
-                    defaultValue = "5")
+                    defaultValue = "20")
             @DefaultValue("20") @QueryParam("limit")
             int limit);
 
+    /**
+     * Retrieves a list of root device organizations.
+     *
+     * @return A response containing a list of root device organizations.
+     */
+    @GET
+    @Path("roots-children")
+    @ApiOperation(
+            produces = MediaType.APPLICATION_JSON,
+            httpMethod = "GET",
+            value = "Retrieve children for root Device Organizations",
+            notes = "Get a list of children for root device organizations.",
+            tags = "Device Organization Management",
+            extensions = {
+                    @Extension(properties = {
+                            @ExtensionProperty(name = SCOPE, value = "dm:device-org:view")
+                    })
+            }
+    )
+    @ApiResponses(
+            value = {
+                    @ApiResponse(
+                            code = 200,
+                            message = "OK. \n Successfully fetched the all devices.",
+                            responseHeaders = {
+                                    @ResponseHeader(
+                                            name = "Content-Type",
+                                            description = "The content type of the body"),
+                                    @ResponseHeader(
+                                            name = "ETag",
+                                            description = "Entity Tag of the response resource.\n" +
+                                                    "Used by caches, or in conditional requests."),
+                                    @ResponseHeader(
+                                            name = "Last-Modified",
+                                            description =
+                                                    "Date and time the resource was last modified.\n" +
+                                                            "Used by caches, or in conditional requests."),
+                            }
+                    ),
+                    @ApiResponse(
+                            code = 400,
+                            message =
+                                    "Bad Request. \n"),
+                    @ApiResponse(
+                            code = 406,
+                            message = "Not Acceptable.\n The requested media type is not supported"),
+                    @ApiResponse(
+                            code = 500,
+                            message = "Internal Server Error. \n Server error occurred while fetching the " +
+                                    "list of supported device types.",
+                            response = ErrorResponse.class)
+            })
+    Response getDeviceOrganizationChildrenForRoots(
+            @ApiParam(
+                    name = "offset",
+                    value = "root offset",
+                    required = false,
+                    defaultValue = "0")
+            @DefaultValue("0") @QueryParam("offset")
+            int offset,
+            @ApiParam(
+                    name = "limit",
+                    value = "root limit.",
+                    required = false,
+                    defaultValue = "20")
+            @DefaultValue("20") @QueryParam("limit")
+            int limit,
+            @ApiParam(
+                    name= "maxDepth",
+                    value = "The maximum depth of child nodes to retrieve for each root.",
+                    required = true) @QueryParam("maxDepth")
+            int maxDepth,
+            @ApiParam(
+                    name= "includeDevice",
+                    value = "Indicates whether to include device information in the retrieved child nodes.",
+                    required = true) @QueryParam("includeDevice")
+            boolean includeDevice);
+
     /**
      * Retrieves a specific device organization by its organization ID.
      *

components/device-mgt-extensions/io.entgra.device.mgt.core.device.mgt.extensions.device.organization.api/src/main/java/io/entgra/device/mgt/core/device/mgt/extensions/device/organization/api/DeviceOrganizationMgtServiceImpl.java

@@ -24,6 +24,7 @@ import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.api.u
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceNodeResult;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceOrganization;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.PaginationRequest;
+import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.RootChildrenRequest;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.exception.DeviceOrganizationMgtPluginException;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.spi.DeviceOrganizationService;
 import org.apache.commons.logging.Log;
@@ -154,6 +155,29 @@ public class DeviceOrganizationMgtServiceImpl implements DeviceOrganizationMgtSe
         }
     }
 
+    @GET
+    @Path("roots-children")
+    @Override
+    public Response getDeviceOrganizationChildrenForRoots(
+            @DefaultValue("0") @QueryParam("offset") int offset,
+            @DefaultValue("20") @QueryParam("limit") int limit,
+            @QueryParam("maxDepth") int maxDepth,
+            @QueryParam("includeDevice") boolean includeDevice) {
+        RequestValidationUtil.validatePaginationParameters(offset, limit);
+        try {
+            DeviceOrganizationService deviceOrganizationService = DeviceOrgAPIUtils.getDeviceOrganizationService();
+            RootChildrenRequest request = new RootChildrenRequest(offset, limit);
+            request.setMaxDepth(maxDepth);
+            request.setIncludeDevice(includeDevice);
+            List<DeviceNodeResult> nodeResultList  = deviceOrganizationService.getAllDeviceOrganizationsForRoots(request);
+            return Response.status(Response.Status.OK).entity(nodeResultList).build();
+        } catch (DeviceOrganizationMgtPluginException e) {
+            String errorMessage = "get children for root organizations failed";
+            log.error(errorMessage);
+            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity(errorMessage).build();
+        }
+    }
+
     @GET
     @Override
     @Path("{organizationId}")

components/device-mgt-extensions/io.entgra.device.mgt.core.device.mgt.extensions.device.organization/src/main/java/io/entgra/device/mgt/core/device/mgt/extensions/device/organization/dto/RootChildrenRequest.java

@@ -0,0 +1,27 @@
+package io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto;
+
+public class RootChildrenRequest extends PaginationRequest{
+
+    int maxDepth;
+    boolean includeDevice;
+
+    public RootChildrenRequest(int start, int limit) {
+        super(start, limit);
+    }
+
+    public int getMaxDepth() {
+        return maxDepth;
+    }
+
+    public void setMaxDepth(int maxDepth) {
+        this.maxDepth = maxDepth;
+    }
+
+    public boolean isIncludeDevice() {
+        return includeDevice;
+    }
+
+    public void setIncludeDevice(boolean includeDevice) {
+        this.includeDevice = includeDevice;
+    }
+}

components/device-mgt-extensions/io.entgra.device.mgt.core.device.mgt.extensions.device.organization/src/main/java/io/entgra/device/mgt/core/device/mgt/extensions/device/organization/impl/DeviceOrganizationServiceImpl.java

@@ -20,10 +20,7 @@ package io.entgra.device.mgt.core.device.mgt.extensions.device.organization.impl
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dao.DeviceOrganizationDAO;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dao.DeviceOrganizationDAOFactory;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dao.util.ConnectionManagerUtil;
-import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.AdditionResult;
-import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceNodeResult;
-import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceOrganization;
-import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.PaginationRequest;
+import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.*;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.exception.BadRequestException;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.exception.DBConnectionException;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.exception.DeviceOrganizationMgtDAOException;
@@ -34,6 +31,7 @@ import org.apache.commons.logging.LogFactory;
 import org.wso2.carbon.context.PrivilegedCarbonContext;
 
 import java.sql.Connection;
+import java.util.ArrayList;
 import java.util.List;
 
 public class DeviceOrganizationServiceImpl implements DeviceOrganizationService {
@@ -164,6 +162,32 @@ public class DeviceOrganizationServiceImpl implements DeviceOrganizationService
         }
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public List<DeviceNodeResult> getAllDeviceOrganizationsForRoots(RootChildrenRequest request) throws DeviceOrganizationMgtPluginException {
+        List<DeviceNodeResult> allDeviceOrganizations = new ArrayList<>();
+
+        try {
+            // Get all root device organizations
+            PaginationRequest paginationRequest = new PaginationRequest(request.getOffSet(), request.getLimit());
+            List<DeviceOrganization> roots = getDeviceOrganizationRoots(paginationRequest);
+
+            // Iterate over each root and fetch its children
+            for (DeviceOrganization root : roots) {
+                DeviceNodeResult childrenResult = getChildrenOfDeviceNode(root.getDeviceId(), request.getMaxDepth(), request.isIncludeDevice());
+                allDeviceOrganizations.add(childrenResult);
+            }
+            return allDeviceOrganizations;
+        } catch (Exception e) {
+            String msg = "Error occurred while retrieving all device organizations for roots.";
+            log.error(msg);
+            throw new DeviceOrganizationMgtPluginException(msg, e);
+        }
+    }
+
+
     /**
      * {@inheritDoc}
      */

components/device-mgt-extensions/io.entgra.device.mgt.core.device.mgt.extensions.device.organization/src/main/java/io/entgra/device/mgt/core/device/mgt/extensions/device/organization/spi/DeviceOrganizationService.java

@@ -20,6 +20,7 @@ package io.entgra.device.mgt.core.device.mgt.extensions.device.organization.spi;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceNodeResult;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceOrganization;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.PaginationRequest;
+import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.RootChildrenRequest;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.exception.DeviceOrganizationMgtPluginException;
 
 import java.util.List;
@@ -71,6 +72,15 @@ public interface DeviceOrganizationService {
      */
     List<DeviceOrganization> getAllDeviceOrganizations() throws DeviceOrganizationMgtPluginException;
 
+    /**
+     * Retrieves a list of all device organizations for roots.
+     * @param request
+     * @return
+     * @throws DeviceOrganizationMgtPluginException
+     */
+    List<DeviceNodeResult> getAllDeviceOrganizationsForRoots(RootChildrenRequest request)
+            throws DeviceOrganizationMgtPluginException;
+
     /**
      * Retrieves device Organization Leafs
      *

components/device-mgt-extensions/io.entgra.device.mgt.core.device.mgt.extensions.device.organization/src/test/java/io/entgra/device/mgt/core/device/mgt/extensions/device/organization/ServiceTest.java

@@ -22,6 +22,7 @@ import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dao.D
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceNodeResult;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.DeviceOrganization;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.PaginationRequest;
+import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.dto.RootChildrenRequest;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.exception.DeviceOrganizationMgtPluginException;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.impl.DeviceOrganizationServiceImpl;
 import io.entgra.device.mgt.core.device.mgt.extensions.device.organization.mock.BaseDeviceOrganizationTest;
@@ -285,6 +286,21 @@ public class ServiceTest extends BaseDeviceOrganizationTest {
         Assert.assertFalse(organizations.isEmpty(), "List of organizations should not be empty");
     }
 
+    @Test(dependsOnMethods = "testAddDeviceOrganizationWithNullParent")
+    public void testGetAllOrganizationsForRoots() throws DeviceOrganizationMgtPluginException {
+
+        int offSet = 0;
+        int limit = 100;
+        boolean includeDevice = true;
+        int maxDepth =100;
+        RootChildrenRequest request = new RootChildrenRequest(offSet, limit);
+        request.setMaxDepth(maxDepth);
+        request.setIncludeDevice(includeDevice);
+        List<DeviceNodeResult> nodeResultList = deviceOrganizationService.getAllDeviceOrganizationsForRoots(request);
+        Assert.assertNotNull(nodeResultList, "Cannot be null");
+        Assert.assertFalse(nodeResultList.isEmpty(), "List of node result should not be empty");
+    }
+
     @Test(dependsOnMethods = "testAddDeviceOrganizationWithNullParent")
     public void testGetRootOrganizations() throws DeviceOrganizationMgtPluginException {
         int offset = 0;