#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);
}

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

    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* target = scene.CreateGameObject("Target");
    target->GetTransform()->SetPosition(XCEngine::Math::Vector3(0.0f, 2.0f, 0.0f));
    SphereColliderComponent* sphereCollider = target->AddComponent<SphereColliderComponent>();
    sphereCollider->SetRadius(0.5f);

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

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

    XCEngine::Physics::RaycastHit hit;
    const bool result = world.Raycast(
        XCEngine::Math::Vector3(0.0f, 5.0f, 0.0f),
        XCEngine::Math::Vector3::Down(),
        10.0f,
        hit);

    if (!expectedInitialized) {
        EXPECT_FALSE(result);
        EXPECT_EQ(hit.gameObject, nullptr);
        return;
    }

    ASSERT_TRUE(result);
    EXPECT_EQ(hit.gameObject, target);
    EXPECT_NEAR(hit.distance, 2.5f, 0.02f);
    EXPECT_NEAR(hit.point.x, 0.0f, 0.001f);
    EXPECT_NEAR(hit.point.y, 2.5f, 0.02f);
    EXPECT_NEAR(hit.point.z, 0.0f, 0.001f);
    EXPECT_NEAR(hit.normal.x, 0.0f, 0.001f);
    EXPECT_NEAR(hit.normal.y, 1.0f, 0.02f);
    EXPECT_NEAR(hit.normal.z, 0.0f, 0.001f);
    EXPECT_FALSE(hit.isTrigger);
}

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

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

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

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

    XCEngine::Physics::RaycastHit hit;
    hit.gameObject = target;
    hit.point = XCEngine::Math::Vector3::One();
    hit.normal = XCEngine::Math::Vector3::Up();
    hit.distance = 123.0f;
    hit.isTrigger = true;

    const bool result = world.Raycast(
        XCEngine::Math::Vector3(0.0f, 5.0f, 0.0f),
        XCEngine::Math::Vector3::Up(),
        10.0f,
        hit);

    EXPECT_FALSE(result);
    EXPECT_EQ(hit.gameObject, nullptr);
    EXPECT_EQ(hit.point, XCEngine::Math::Vector3::Zero());
    EXPECT_EQ(hit.normal, XCEngine::Math::Vector3::Zero());
    EXPECT_FLOAT_EQ(hit.distance, 0.0f);
    EXPECT_FALSE(hit.isTrigger);
}

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

    Scene scene("PhysicsScene");
    GameObject* trigger = scene.CreateGameObject("Trigger");
    SphereColliderComponent* sphereCollider = trigger->AddComponent<SphereColliderComponent>();
    sphereCollider->SetRadius(1.0f);
    sphereCollider->SetTrigger(true);

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

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

    XCEngine::Physics::RaycastHit hit;
    const bool result = world.Raycast(
        XCEngine::Math::Vector3(0.0f, 0.0f, -5.0f),
        XCEngine::Math::Vector3::Forward(),
        10.0f,
        hit);

    if (!expectedInitialized) {
        EXPECT_FALSE(result);
        EXPECT_EQ(hit.gameObject, nullptr);
        return;
    }

    ASSERT_TRUE(result);
    EXPECT_EQ(hit.gameObject, trigger);
    EXPECT_NEAR(hit.distance, 4.0f, 0.02f);
    EXPECT_TRUE(hit.isTrigger);
    EXPECT_NEAR(hit.normal.x, 0.0f, 0.001f);
    EXPECT_NEAR(hit.normal.y, 0.0f, 0.001f);
    EXPECT_NEAR(hit.normal.z, -1.0f, 0.02f);
}

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

    Scene scene("PhysicsScene");
    GameObject* target = scene.CreateGameObject("Target");
    BoxColliderComponent* boxCollider = target->AddComponent<BoxColliderComponent>();
    boxCollider->SetSize(XCEngine::Math::Vector3(1.0f, 1.0f, 1.0f));

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

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

    XCEngine::Physics::RaycastHit hit;
    EXPECT_FALSE(world.Raycast(
        XCEngine::Math::Vector3(0.0f, 1.5f, -5.0f),
        XCEngine::Math::Vector3::Forward(),
        10.0f,
        hit));

    boxCollider->SetSize(XCEngine::Math::Vector3(1.0f, 4.0f, 1.0f));

    const bool result = world.Raycast(
        XCEngine::Math::Vector3(0.0f, 1.5f, -5.0f),
        XCEngine::Math::Vector3::Forward(),
        10.0f,
        hit);

    if (!expectedInitialized) {
        EXPECT_FALSE(result);
        EXPECT_EQ(hit.gameObject, nullptr);
        return;
    }

    ASSERT_TRUE(result);
    EXPECT_EQ(hit.gameObject, target);
    EXPECT_NEAR(hit.distance, 4.5f, 0.02f);
}

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

    Scene scene("PhysicsScene");
    GameObject* target = scene.CreateGameObject("Target");
    SphereColliderComponent* sphereCollider = target->AddComponent<SphereColliderComponent>();
    sphereCollider->SetRadius(1.0f);

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

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

    sphereCollider->SetTrigger(true);

    XCEngine::Physics::RaycastHit hit;
    const bool result = world.Raycast(
        XCEngine::Math::Vector3(0.0f, 0.0f, -5.0f),
        XCEngine::Math::Vector3::Forward(),
        10.0f,
        hit);

    if (!expectedInitialized) {
        EXPECT_FALSE(result);
        EXPECT_EQ(hit.gameObject, nullptr);
        return;
    }

    ASSERT_TRUE(result);
    EXPECT_EQ(hit.gameObject, target);
    EXPECT_TRUE(hit.isTrigger);
}

TEST(PhysicsWorld_Test, RuntimeBodyTypeChangesRebuildActorAndEnableSimulation) {
    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* body = scene.CreateGameObject("Body");
    body->GetTransform()->SetPosition(XCEngine::Math::Vector3(0.0f, 4.0f, 0.0f));
    RigidbodyComponent* rigidbody = body->AddComponent<RigidbodyComponent>();
    rigidbody->SetBodyType(XCEngine::Physics::PhysicsBodyType::Static);
    SphereColliderComponent* sphereCollider = body->AddComponent<SphereColliderComponent>();
    sphereCollider->SetRadius(0.5f);

    XCEngine::Physics::PhysicsWorld world;
    XCEngine::Physics::PhysicsWorldCreateInfo createInfo = {};
    createInfo.scene = &scene;
    ASSERT_TRUE(world.Initialize(createInfo));
    ASSERT_EQ(world.GetNativeActorCount(), 2u);

    const float initialY = body->GetTransform()->GetPosition().y;
    world.Step(1.0f / 60.0f);
    EXPECT_NEAR(body->GetTransform()->GetPosition().y, initialY, 0.001f);

    rigidbody->SetBodyType(XCEngine::Physics::PhysicsBodyType::Dynamic);
    world.Step(1.0f / 60.0f);
    EXPECT_EQ(world.GetNativeActorCount(), 2u);

    for (int index = 0; index < 30; ++index) {
        world.Step(1.0f / 60.0f);
    }

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

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

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

    Scene scene("PhysicsScene");
    GameObject* body = scene.CreateGameObject("Body");
    body->GetTransform()->SetPosition(XCEngine::Math::Vector3(0.0f, 1.0f, 0.0f));
    RigidbodyComponent* rigidbody = body->AddComponent<RigidbodyComponent>();
    rigidbody->SetBodyType(XCEngine::Physics::PhysicsBodyType::Dynamic);
    rigidbody->SetUseGravity(false);
    rigidbody->SetLinearVelocity(XCEngine::Math::Vector3(0.0f, 2.0f, 0.0f));
    SphereColliderComponent* sphereCollider = body->AddComponent<SphereColliderComponent>();
    sphereCollider->SetRadius(0.5f);

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

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

    EXPECT_GT(body->GetTransform()->GetPosition().y, initialY + 0.9f);
    EXPECT_NEAR(rigidbody->GetLinearVelocity().y, 2.0f, 0.02f);
}

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

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

    Scene scene("PhysicsScene");
    GameObject* body = scene.CreateGameObject("Body");
    body->GetTransform()->SetPosition(XCEngine::Math::Vector3(0.0f, 1.0f, 0.0f));
    RigidbodyComponent* rigidbody = body->AddComponent<RigidbodyComponent>();
    rigidbody->SetBodyType(XCEngine::Physics::PhysicsBodyType::Dynamic);
    rigidbody->SetUseGravity(false);
    rigidbody->SetMass(1.0f);
    SphereColliderComponent* sphereCollider = body->AddComponent<SphereColliderComponent>();
    sphereCollider->SetRadius(0.5f);

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

    const float initialY = body->GetTransform()->GetPosition().y;
    rigidbody->AddForce(
        XCEngine::Math::Vector3(0.0f, 3.0f, 0.0f),
        XCEngine::Physics::PhysicsForceMode::Impulse);

    for (int index = 0; index < 10; ++index) {
        world.Step(1.0f / 60.0f);
    }

    EXPECT_GT(body->GetTransform()->GetPosition().y, initialY + 0.35f);
    EXPECT_NEAR(rigidbody->GetLinearVelocity().y, 3.0f, 0.02f);
}

} // namespace