#include <gtest/gtest.h>

#include "Viewport/SceneViewportCameraController.h"

#include <XCEngine/Components/GameObject.h>

#include <cmath>

namespace {

bool NearlyEqual(float lhs, float rhs, float epsilon = 1e-4f) {
    return std::abs(lhs - rhs) <= epsilon;
}

bool NearlyEqual(const XCEngine::Math::Vector3& lhs, const XCEngine::Math::Vector3& rhs, float epsilon = 1e-4f) {
    return NearlyEqual(lhs.x, rhs.x, epsilon) &&
           NearlyEqual(lhs.y, rhs.y, epsilon) &&
           NearlyEqual(lhs.z, rhs.z, epsilon);
}

} // namespace

using XCEngine::Components::GameObject;
using XCEngine::Editor::SceneViewportCameraController;
using XCEngine::Editor::SceneViewportCameraInputState;
using XCEngine::Math::Vector3;

TEST(SceneViewportCameraController_Test, ApplyToMatchesComputedPositionAndForward) {
    SceneViewportCameraController controller;
    controller.Reset();
    controller.Focus(Vector3(2.0f, 1.0f, -3.0f));

    GameObject cameraObject("EditorCamera");
    controller.ApplyTo(*cameraObject.GetTransform());

    EXPECT_TRUE(NearlyEqual(cameraObject.GetTransform()->GetPosition(), controller.GetPosition()));
    EXPECT_TRUE(NearlyEqual(
        cameraObject.GetTransform()->GetForward().Normalized(),
        controller.GetForward(),
        1e-3f));
    EXPECT_GT(Vector3::Dot(cameraObject.GetTransform()->GetUp().Normalized(), Vector3::Up()), 0.0f);
}

TEST(SceneViewportCameraController_Test, ApplyInputUpdatesOrbitPanAndZoomState) {
    SceneViewportCameraController controller;
    controller.Reset();

    const float initialDistance = controller.GetDistance();
    const float initialYaw = controller.GetYawDegrees();
    const float initialPitch = controller.GetPitchDegrees();
    const Vector3 initialFocus = controller.GetFocalPoint();

    SceneViewportCameraInputState input = {};
    input.viewportHeight = 720.0f;
    input.zoomDelta = 1.0f;
    input.orbitDeltaX = 20.0f;
    input.orbitDeltaY = -15.0f;
    input.panDeltaX = 16.0f;
    input.panDeltaY = -10.0f;
    controller.ApplyInput(input);

    EXPECT_LT(controller.GetDistance(), initialDistance);
    EXPECT_NE(controller.GetYawDegrees(), initialYaw);
    EXPECT_NE(controller.GetPitchDegrees(), initialPitch);
    EXPECT_FALSE(NearlyEqual(controller.GetFocalPoint(), initialFocus));
}

TEST(SceneViewportCameraController_Test, FocusMovesPivotWithoutChangingDistance) {
    SceneViewportCameraController controller;
    controller.Reset();

    const float initialDistance = controller.GetDistance();
    const Vector3 target(5.0f, -2.0f, 7.5f);
    controller.Focus(target);

    EXPECT_TRUE(NearlyEqual(controller.GetFocalPoint(), target));
    EXPECT_FLOAT_EQ(controller.GetDistance(), initialDistance);
}