feat(Resources): Add ResourceDependencyGraph for resource dependency tracking

- Implement dependency graph for resource management
- Add/remove nodes and dependencies
- Reference counting support
- Circular dependency detection
- Add unit tests

tests/Resources/CMakeLists.txt

@@ -22,6 +22,7 @@ set(RESOURCES_TEST_SOURCES
     test_shader_loader.cpp
     test_material_loader.cpp
     test_resource_package.cpp
+    test_resource_dependency.cpp
 )
 
 add_executable(xcengine_resources_tests ${RESOURCES_TEST_SOURCES})

tests/Resources/test_resource_dependency.cpp

@@ -0,0 +1,131 @@
+#include <gtest/gtest.h>
+#include <XCEngine/Resources/ResourceDependencyGraph.h>
+#include <XCEngine/Resources/ResourceTypes.h>
+
+using namespace XCEngine::Resources;
+using namespace XCEngine::Containers;
+
+namespace {
+
+TEST(ResourceDependencyGraph, DefaultConstructor) {
+    ResourceDependencyGraph graph;
+}
+
+TEST(ResourceDependencyGraph, AddNode) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Texture);
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(1)));
+}
+
+TEST(ResourceDependencyGraph, AddMultipleNodes) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Texture);
+    graph.AddNode(ResourceGUID(2), ResourceType::Mesh);
+    graph.AddNode(ResourceGUID(3), ResourceType::Material);
+    
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(1)));
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(2)));
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(3)));
+}
+
+TEST(ResourceDependencyGraph, RemoveNode) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Texture);
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(1)));
+    
+    graph.RemoveNode(ResourceGUID(1));
+    EXPECT_FALSE(graph.HasNode(ResourceGUID(1)));
+}
+
+TEST(ResourceDependencyGraph, AddDependency) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Material);
+    graph.AddNode(ResourceGUID(2), ResourceType::Texture);
+    
+    graph.AddDependency(ResourceGUID(1), ResourceGUID(2));
+    
+    auto deps = graph.GetDependencies(ResourceGUID(1));
+    EXPECT_EQ(deps.Size(), 1u);
+    EXPECT_EQ(deps[0], ResourceGUID(2));
+}
+
+TEST(ResourceDependencyGraph, GetDependents) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Material);
+    graph.AddNode(ResourceGUID(2), ResourceType::Texture);
+    
+    graph.AddDependency(ResourceGUID(1), ResourceGUID(2));
+    
+    auto dependents = graph.GetDependents(ResourceGUID(2));
+    EXPECT_EQ(dependents.Size(), 1u);
+    EXPECT_EQ(dependents[0], ResourceGUID(1));
+}
+
+TEST(ResourceDependencyGraph, GetAllDependencies) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Material);
+    graph.AddNode(ResourceGUID(2), ResourceType::Texture);
+    graph.AddNode(ResourceGUID(3), ResourceType::Shader);
+    
+    graph.AddDependency(ResourceGUID(1), ResourceGUID(2));
+    graph.AddDependency(ResourceGUID(1), ResourceGUID(3));
+    
+    auto allDeps = graph.GetAllDependencies(ResourceGUID(1));
+    EXPECT_EQ(allDeps.Size(), 2u);
+}
+
+TEST(ResourceDependencyGraph, RefCount) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Texture);
+    
+    EXPECT_EQ(graph.GetRefCount(ResourceGUID(1)), 0u);
+    
+    graph.IncrementRefCount(ResourceGUID(1));
+    EXPECT_EQ(graph.GetRefCount(ResourceGUID(1)), 1u);
+    
+    graph.IncrementRefCount(ResourceGUID(1));
+    EXPECT_EQ(graph.GetRefCount(ResourceGUID(1)), 2u);
+    
+    graph.DecrementRefCount(ResourceGUID(1));
+    EXPECT_EQ(graph.GetRefCount(ResourceGUID(1)), 1u);
+}
+
+TEST(ResourceDependencyGraph, Unload) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Texture);
+    
+    EXPECT_TRUE(graph.Unload(ResourceGUID(1)));
+    
+    graph.IncrementRefCount(ResourceGUID(1));
+    EXPECT_FALSE(graph.Unload(ResourceGUID(1)));
+}
+
+TEST(ResourceDependencyGraph, Clear) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Texture);
+    graph.AddNode(ResourceGUID(2), ResourceType::Mesh);
+    
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(1)));
+    EXPECT_TRUE(graph.HasNode(ResourceGUID(2)));
+    
+    graph.Clear();
+    
+    EXPECT_FALSE(graph.HasNode(ResourceGUID(1)));
+    EXPECT_FALSE(graph.HasNode(ResourceGUID(2)));
+}
+
+TEST(ResourceDependencyGraph, RemoveDependency) {
+    ResourceDependencyGraph graph;
+    graph.AddNode(ResourceGUID(1), ResourceType::Material);
+    graph.AddNode(ResourceGUID(2), ResourceType::Texture);
+    
+    graph.AddDependency(ResourceGUID(1), ResourceGUID(2));
+    auto deps = graph.GetDependencies(ResourceGUID(1));
+    EXPECT_EQ(deps.Size(), 1u);
+    
+    graph.RemoveDependency(ResourceGUID(1), ResourceGUID(2));
+    deps = graph.GetDependencies(ResourceGUID(1));
+    EXPECT_EQ(deps.Size(), 0u);
+}
+
+} // namespace