feat: add resource group entity, repository, and service

src/main/java/com/slotline/resource/ResourceGroup.java

@@ -0,0 +1,61 @@
+package com.slotline.resource;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+
+import java.time.Instant;
+
+@Entity
+@Table(name = "resource_group")
+public class ResourceGroup {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "organization_id", nullable = false)
+    private Long organizationId;
+
+    @Column(name = "parent_group_id")
+    private Long parentGroupId;
+
+    @Column(nullable = false, length = 128)
+    private String name;
+
+    @Column(name = "created_at", nullable = false)
+    private Instant createdAt;
+
+    protected ResourceGroup() {
+    }
+
+    public ResourceGroup(Long organizationId, Long parentGroupId, String name, Instant createdAt) {
+        this.organizationId = organizationId;
+        this.parentGroupId = parentGroupId;
+        this.name = name;
+        this.createdAt = createdAt;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public Long getOrganizationId() {
+        return organizationId;
+    }
+
+    public Long getParentGroupId() {
+        return parentGroupId;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public Instant getCreatedAt() {
+        return createdAt;
+    }
+}

src/main/java/com/slotline/resource/ResourceGroupRepository.java

@@ -0,0 +1,15 @@
+package com.slotline.resource;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface ResourceGroupRepository extends JpaRepository<ResourceGroup, Long> {
+
+    List<ResourceGroup> findByOrganizationIdOrderByCreatedAtAsc(Long organizationId);
+
+    List<ResourceGroup> findByParentGroupId(Long parentGroupId);
+
+    Optional<ResourceGroup> findByIdAndOrganizationId(Long id, Long organizationId);
+}

src/main/java/com/slotline/resource/ResourceGroupService.java

@@ -0,0 +1,63 @@
+package com.slotline.resource;
+
+import com.slotline.common.NotFoundException;
+import com.slotline.resource.dto.ResourceGroupRequest;
+import com.slotline.resource.dto.ResourceGroupResponse;
+import com.slotline.resource.dto.ResourceResponse;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.Instant;
+import java.util.List;
+
+@Service
+public class ResourceGroupService {
+
+    private final ResourceGroupRepository groups;
+    private final ResourceService resources;
+    private final ResourceRepository resourceRepository;
+
+    public ResourceGroupService(ResourceGroupRepository groups, ResourceService resources,
+                                ResourceRepository resourceRepository) {
+        this.groups = groups;
+        this.resources = resources;
+        this.resourceRepository = resourceRepository;
+    }
+
+    @Transactional
+    public ResourceGroupResponse create(Long organizationId, ResourceGroupRequest request) {
+        if (request.parentGroupId() != null) {
+            require(organizationId, request.parentGroupId());
+        }
+        ResourceGroup group = new ResourceGroup(organizationId, request.parentGroupId(), request.name(), Instant.now());
+        return ResourceGroupResponse.from(groups.save(group));
+    }
+
+    @Transactional(readOnly = true)
+    public List<ResourceGroupResponse> findAll(Long organizationId) {
+        return groups.findByOrganizationIdOrderByCreatedAtAsc(organizationId).stream()
+                .map(ResourceGroupResponse::from)
+                .toList();
+    }
+
+    @Transactional
+    public ResourceResponse assignResource(Long organizationId, Long groupId, Long resourceId) {
+        ResourceGroup group = require(organizationId, groupId);
+        Resource resource = resources.require(organizationId, resourceId);
+        resource.setGroupId(group.getId());
+        return ResourceResponse.from(resource);
+    }
+
+    @Transactional(readOnly = true)
+    public List<ResourceResponse> resourcesInGroup(Long organizationId, Long groupId) {
+        ResourceGroup group = require(organizationId, groupId);
+        return resourceRepository.findByGroupIdOrderByCreatedAtDesc(group.getId()).stream()
+                .map(ResourceResponse::from)
+                .toList();
+    }
+
+    private ResourceGroup require(Long organizationId, Long groupId) {
+        return groups.findByIdAndOrganizationId(groupId, organizationId)
+                .orElseThrow(() -> new NotFoundException("Resource group " + groupId + " not found"));
+    }
+}