#include <gtest/gtest.h>

#include <XCEngine/Components/BoxColliderComponent.h>
#include <XCEngine/Components/CapsuleColliderComponent.h>
#include <XCEngine/Components/GameObject.h>
#include <XCEngine/Components/RigidbodyComponent.h>
#include <XCEngine/Components/SphereColliderComponent.h>
#include <XCEngine/Physics/PhysicsWorld.h>
#include <XCEngine/Scene/Scene.h>

namespace {

TEST(PhysicsWorld_Test, DefaultWorldStartsUninitialized) {
    XCEngine::Physics::PhysicsWorld world;

    EXPECT_FALSE(world.IsInitialized());
    EXPECT_EQ(world.GetNativeActorCount(), 0u);
    EXPECT_EQ(world.GetNativeShapeCount(), 0u);
}

TEST(PhysicsWorld_Test, InitializeStoresCreateInfoWithoutMarkingWorldReadyYet) {
    XCEngine::Components::Scene scene("PhysicsScene");
    XCEngine::Physics::PhysicsWorld world;
    XCEngine::Physics::PhysicsWorldCreateInfo createInfo;
    createInfo.scene = &scene;
    createInfo.gravity = XCEngine::Math::Vector3(0.0f, -3.5f, 0.0f);

    const bool expectedInitialized = XCEngine::Physics::PhysicsWorld::IsPhysXAvailable();

    EXPECT_EQ(world.Initialize(createInfo), expectedInitialized);
    EXPECT_EQ(world.IsInitialized(), expectedInitialized);
    EXPECT_EQ(world.GetCreateInfo().scene, &scene);
    EXPECT_EQ(world.GetCreateInfo().gravity, XCEngine::Math::Vector3(0.0f, -3.5f, 0.0f));
}

TEST(PhysicsWorld_Test, StepWithoutInitializationIsNoOp) {
    XCEngine::Physics::PhysicsWorld world;

    world.Step(0.016f);

    EXPECT_FALSE(world.IsInitialized());
}

TEST(PhysicsWorld_Test, InitializeBuildsNativeActorsFromSceneComponents) {
    using namespace XCEngine::Components;

    Scene scene("PhysicsScene");
    GameObject* ground = scene.CreateGameObject("Ground");
    ground->AddComponent<BoxColliderComponent>();

    GameObject* player = scene.CreateGameObject("Player");
    player->AddComponent<RigidbodyComponent>();
    player->AddComponent<SphereColliderComponent>();

    GameObject* childTrigger = scene.CreateGameObject("ChildTrigger", player);
    childTrigger->AddComponent<CapsuleColliderComponent>();

    XCEngine::Physics::PhysicsWorld world;
    XCEngine::Physics::PhysicsWorldCreateInfo createInfo = {};
    createInfo.scene = &scene;

    const bool expectedInitialized = XCEngine::Physics::PhysicsWorld::IsPhysXAvailable();
    ASSERT_EQ(world.Initialize(createInfo), expectedInitialized);
    EXPECT_EQ(world.GetTrackedRigidbodyCount(), 1u);
    EXPECT_EQ(world.GetTrackedColliderCount(), 3u);

    if (!expectedInitialized) {
        EXPECT_EQ(world.GetNativeActorCount(), 0u);
        EXPECT_EQ(world.GetNativeShapeCount(), 0u);
        return;
    }

    EXPECT_EQ(world.GetNativeActorCount(), 2u);
    EXPECT_EQ(world.GetNativeShapeCount(), 3u);
}

TEST(PhysicsWorld_Test, ComponentChangesRebuildNativeActorOwnership) {
    using namespace XCEngine::Components;

    Scene scene("PhysicsScene");
    GameObject* player = scene.CreateGameObject("Player");
    player->AddComponent<RigidbodyComponent>();
    SphereColliderComponent* playerSphere = player->AddComponent<SphereColliderComponent>();
    BoxColliderComponent* playerBox = player->AddComponent<BoxColliderComponent>();

    GameObject* child = scene.CreateGameObject("Child", player);
    child->AddComponent<CapsuleColliderComponent>();

    XCEngine::Physics::PhysicsWorld world;
    XCEngine::Physics::PhysicsWorldCreateInfo createInfo = {};
    createInfo.scene = &scene;

    const bool expectedInitialized = XCEngine::Physics::PhysicsWorld::IsPhysXAvailable();
    ASSERT_EQ(world.Initialize(createInfo), expectedInitialized);

    EXPECT_EQ(world.GetTrackedRigidbodyCount(), 1u);
    EXPECT_EQ(world.GetTrackedColliderCount(), 3u);

    if (!expectedInitialized) {
        return;
    }

    EXPECT_EQ(world.GetNativeActorCount(), 1u);
    EXPECT_EQ(world.GetNativeShapeCount(), 3u);

    ASSERT_TRUE(player->RemoveComponent(playerBox));
    EXPECT_EQ(world.GetTrackedRigidbodyCount(), 1u);
    EXPECT_EQ(world.GetTrackedColliderCount(), 2u);
    EXPECT_EQ(world.GetNativeActorCount(), 1u);
    EXPECT_EQ(world.GetNativeShapeCount(), 2u);

    child->AddComponent<RigidbodyComponent>();
    EXPECT_EQ(world.GetTrackedRigidbodyCount(), 2u);
    EXPECT_EQ(world.GetTrackedColliderCount(), 2u);
    EXPECT_EQ(world.GetNativeActorCount(), 2u);
    EXPECT_EQ(world.GetNativeShapeCount(), 2u);

    scene.DestroyGameObject(player);
    EXPECT_EQ(world.GetTrackedRigidbodyCount(), 0u);
    EXPECT_EQ(world.GetTrackedColliderCount(), 0u);
    EXPECT_EQ(world.GetNativeActorCount(), 0u);
    EXPECT_EQ(world.GetNativeShapeCount(), 0u);

    (void)playerSphere;
}

TEST(PhysicsWorld_Test, DynamicSimulationWritesBackTransform) {
    using namespace XCEngine::Components;

    if (!XCEngine::Physics::PhysicsWorld::IsPhysXAvailable()) {
        GTEST_SKIP() << "PhysX backend is not available in this build.";
    }

    Scene scene("PhysicsScene");

    GameObject* ground = scene.CreateGameObject("Ground");
    ground->GetTransform()->SetPosition(XCEngine::Math::Vector3(0.0f, -0.5f, 0.0f));
    BoxColliderComponent* groundCollider = ground->AddComponent<BoxColliderComponent>();
    groundCollider->SetSize(XCEngine::Math::Vector3(20.0f, 1.0f, 20.0f));

    GameObject* ball = scene.CreateGameObject("Ball");
    ball->GetTransform()->SetPosition(XCEngine::Math::Vector3(0.0f, 4.0f, 0.0f));
    RigidbodyComponent* rigidbody = ball->AddComponent<RigidbodyComponent>();
    rigidbody->SetBodyType(XCEngine::Physics::PhysicsBodyType::Dynamic);
    rigidbody->SetMass(1.0f);
    rigidbody->SetUseGravity(true);
    SphereColliderComponent* sphere = ball->AddComponent<SphereColliderComponent>();
    sphere->SetRadius(0.5f);

    XCEngine::Physics::PhysicsWorld world;
    XCEngine::Physics::PhysicsWorldCreateInfo createInfo = {};
    createInfo.scene = &scene;
    ASSERT_TRUE(world.Initialize(createInfo));

    const float initialY = ball->GetTransform()->GetPosition().y;
    for (int index = 0; index < 30; ++index) {
        world.Step(1.0f / 60.0f);
    }

    EXPECT_LT(ball->GetTransform()->GetPosition().y, initialY - 0.1f);
}

} // namespace