#include <gtest/gtest.h>

#include <XCEngine/Core/Math/Quaternion.h>

#include "Core/EditorContext.h"
#include "Managers/SceneManager.h"
#include "Viewport/SceneViewportMath.h"
#include "Viewport/SceneViewportScaleGizmo.h"

namespace XCEngine::Editor {
namespace {

float HandleLength(const SceneViewportScaleGizmoAxisHandleDrawData& handle) {
    return (handle.end - handle.start).Magnitude();
}

Math::Vector2 HandleDirection(const SceneViewportScaleGizmoAxisHandleDrawData& handle) {
    return (handle.end - handle.start).Normalized();
}

const SceneViewportScaleGizmoAxisHandleDrawData* FindAxisHandle(
    const SceneViewportScaleGizmoDrawData& drawData,
    SceneViewportScaleGizmoHandle handleKind) {
    for (const SceneViewportScaleGizmoAxisHandleDrawData& handle : drawData.axisHandles) {
        if (handle.handle == handleKind) {
            return &handle;
        }
    }

    return nullptr;
}

class SceneViewportScaleGizmoTest : public ::testing::Test {
protected:
    void SetUp() override {
        m_context.GetSceneManager().NewScene("Scale Gizmo Test Scene");
    }

    static SceneViewportOverlayData MakeOverlay() {
        SceneViewportOverlayData overlay = {};
        overlay.valid = true;
        overlay.cameraPosition = Math::Vector3(0.0f, 0.0f, -5.0f);
        overlay.cameraForward = Math::Vector3::Forward();
        overlay.cameraRight = Math::Vector3::Right();
        overlay.cameraUp = Math::Vector3::Up();
        overlay.verticalFovDegrees = 60.0f;
        overlay.nearClipPlane = 0.03f;
        overlay.farClipPlane = 2000.0f;
        return overlay;
    }

    static SceneViewportOverlayData MakeIsometricOverlay() {
        SceneViewportOverlayData overlay = {};
        overlay.valid = true;
        overlay.cameraPosition = Math::Vector3(-5.0f, 5.0f, -5.0f);
        overlay.cameraForward = (Math::Vector3::Zero() - overlay.cameraPosition).Normalized();
        overlay.cameraRight = Math::Vector3::Cross(Math::Vector3::Up(), overlay.cameraForward).Normalized();
        overlay.cameraUp = Math::Vector3::Cross(overlay.cameraForward, overlay.cameraRight).Normalized();
        overlay.verticalFovDegrees = 60.0f;
        overlay.nearClipPlane = 0.03f;
        overlay.farClipPlane = 2000.0f;
        return overlay;
    }

    static SceneViewportScaleGizmoContext MakeContext(
        Components::GameObject* selectedObject,
        const Math::Vector2& mousePosition) {
        SceneViewportScaleGizmoContext context = {};
        context.overlay = MakeOverlay();
        context.viewportSize = Math::Vector2(800.0f, 600.0f);
        context.mousePosition = mousePosition;
        context.selectedObject = selectedObject;
        return context;
    }

    static SceneViewportScaleGizmoContext MakeContext(
        Components::GameObject* selectedObject,
        const Math::Vector2& mousePosition,
        const SceneViewportOverlayData& overlay) {
        SceneViewportScaleGizmoContext context = {};
        context.overlay = overlay;
        context.viewportSize = Math::Vector2(800.0f, 600.0f);
        context.mousePosition = mousePosition;
        context.selectedObject = selectedObject;
        return context;
    }

    SceneManager& GetSceneManager() {
        return dynamic_cast<SceneManager&>(m_context.GetSceneManager());
    }

    EditorContext m_context;
};

TEST_F(SceneViewportScaleGizmoTest, UpdateHighlightsXAxisWhenMouseIsNearXAxisHandle) {
    Components::GameObject* target = GetSceneManager().CreateEntity("Target");
    ASSERT_NE(target, nullptr);

    SceneViewportScaleGizmo gizmo;
    gizmo.Update(MakeContext(target, Math::Vector2(400.0f, 300.0f)));

    ASSERT_TRUE(gizmo.GetDrawData().visible);
    const SceneViewportScaleGizmoAxisHandleDrawData* xHandle =
        FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X);
    ASSERT_NE(xHandle, nullptr);
    ASSERT_TRUE(xHandle->visible);

    gizmo.Update(MakeContext(target, xHandle->capCenter));

    EXPECT_TRUE(gizmo.IsHoveringHandle());
    EXPECT_TRUE(FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X)->hovered);
}

TEST_F(SceneViewportScaleGizmoTest, DraggingXAxisOnChildWithScaledParentChangesOnlyLocalXScale) {
    Components::GameObject* parent = GetSceneManager().CreateEntity("Parent");
    ASSERT_NE(parent, nullptr);
    parent->GetTransform()->SetLocalScale(Math::Vector3(0.5f, 2.0f, 1.5f));
    parent->GetTransform()->SetLocalRotation(Math::Quaternion::FromAxisAngle(Math::Vector3::Up(), Math::PI * 0.25f));

    Components::GameObject* target = GetSceneManager().CreateEntity("Target", parent);
    ASSERT_NE(target, nullptr);
    target->GetTransform()->SetLocalScale(Math::Vector3(1.0f, 2.0f, 3.0f));

    const SceneViewportOverlayData overlay = MakeIsometricOverlay();
    SceneViewportScaleGizmo gizmo;
    gizmo.Update(MakeContext(target, Math::Vector2(400.0f, 300.0f), overlay));

    const SceneViewportScaleGizmoAxisHandleDrawData* xHandle =
        FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X);
    ASSERT_NE(xHandle, nullptr);
    ASSERT_TRUE(xHandle->visible);

    const Math::Vector2 startMouse = xHandle->capCenter;
    const Math::Vector2 dragMouse = startMouse + HandleDirection(*xHandle) * 48.0f;
    const auto startContext = MakeContext(target, startMouse, overlay);
    gizmo.Update(startContext);
    ASSERT_TRUE(gizmo.TryBeginDrag(startContext, m_context.GetUndoManager()));

    const auto dragContext = MakeContext(target, dragMouse, overlay);
    gizmo.Update(dragContext);
    gizmo.UpdateDrag(dragContext);
    gizmo.EndDrag(m_context.GetUndoManager());

    const Math::Vector3 localScale = target->GetTransform()->GetLocalScale();
    EXPECT_GT(localScale.x, 1.1f);
    EXPECT_NEAR(localScale.y, 2.0f, 1e-4f);
    EXPECT_NEAR(localScale.z, 3.0f, 1e-4f);
}

TEST_F(SceneViewportScaleGizmoTest, DraggingXAxisTemporarilyChangesHandleLengthAndResetsAfterRelease) {
    Components::GameObject* target = GetSceneManager().CreateEntity("Target");
    ASSERT_NE(target, nullptr);

    const SceneViewportOverlayData overlay = MakeIsometricOverlay();
    SceneViewportScaleGizmo gizmo;
    gizmo.Update(MakeContext(target, Math::Vector2(400.0f, 300.0f), overlay));

    const SceneViewportScaleGizmoAxisHandleDrawData* xInitial =
        FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X);
    ASSERT_NE(xInitial, nullptr);
    ASSERT_TRUE(xInitial->visible);
    const float initialLength = HandleLength(*xInitial);

    const Math::Vector2 startMouse = xInitial->capCenter;
    const Math::Vector2 dragMouse = startMouse + HandleDirection(*xInitial) * 48.0f;
    const auto startContext = MakeContext(target, startMouse, overlay);
    gizmo.Update(startContext);
    ASSERT_TRUE(gizmo.TryBeginDrag(startContext, m_context.GetUndoManager()));

    const auto dragContext = MakeContext(target, dragMouse, overlay);
    gizmo.Update(dragContext);
    gizmo.UpdateDrag(dragContext);
    gizmo.Update(dragContext);

    const SceneViewportScaleGizmoAxisHandleDrawData* xDuring =
        FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X);
    ASSERT_NE(xDuring, nullptr);
    EXPECT_GT(HandleLength(*xDuring), initialLength + 6.0f);

    gizmo.EndDrag(m_context.GetUndoManager());
    gizmo.Update(dragContext);

    const SceneViewportScaleGizmoAxisHandleDrawData* xAfter =
        FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X);
    ASSERT_NE(xAfter, nullptr);
    EXPECT_NEAR(HandleLength(*xAfter), initialLength, 1.0f);
}

TEST_F(SceneViewportScaleGizmoTest, DraggingCenterHandleScalesUniformlyAndCreatesUndoStep) {
    Components::GameObject* target = GetSceneManager().CreateEntity("Target");
    ASSERT_NE(target, nullptr);
    const uint64_t targetId = target->GetID();

    SceneViewportScaleGizmo gizmo;
    const SceneViewportOverlayData overlay = MakeIsometricOverlay();
    gizmo.Update(MakeContext(target, Math::Vector2(400.0f, 300.0f), overlay));

    ASSERT_TRUE(gizmo.GetDrawData().centerHandle.visible);
    const Math::Vector2 startMouse = gizmo.GetDrawData().centerHandle.center;
    const auto startContext = MakeContext(target, startMouse, overlay);
    gizmo.Update(startContext);
    ASSERT_TRUE(gizmo.TryBeginDrag(startContext, m_context.GetUndoManager()));

    const auto dragContext = MakeContext(target, startMouse + Math::Vector2(28.0f, -28.0f), overlay);
    gizmo.Update(dragContext);
    gizmo.UpdateDrag(dragContext);
    gizmo.EndDrag(m_context.GetUndoManager());

    const Math::Vector3 localScale = target->GetTransform()->GetLocalScale();
    EXPECT_GT(localScale.x, 1.1f);
    EXPECT_NEAR(localScale.x, localScale.y, 1e-4f);
    EXPECT_NEAR(localScale.y, localScale.z, 1e-4f);
    EXPECT_TRUE(m_context.GetUndoManager().CanUndo());

    m_context.GetUndoManager().Undo();
    Components::GameObject* restoredTarget = GetSceneManager().GetEntity(targetId);
    ASSERT_NE(restoredTarget, nullptr);
    EXPECT_NEAR(restoredTarget->GetTransform()->GetLocalScale().x, 1.0f, 1e-4f);
    EXPECT_NEAR(restoredTarget->GetTransform()->GetLocalScale().y, 1.0f, 1e-4f);
    EXPECT_NEAR(restoredTarget->GetTransform()->GetLocalScale().z, 1.0f, 1e-4f);
}

TEST_F(SceneViewportScaleGizmoTest, RotatedObjectPlacesXAxisHandleAlongProjectedLocalRight) {
    Components::GameObject* target = GetSceneManager().CreateEntity("Target");
    ASSERT_NE(target, nullptr);
    target->GetTransform()->SetLocalRotation(Math::Quaternion::FromAxisAngle(Math::Vector3::Up(), Math::PI * 0.33f));

    const SceneViewportOverlayData overlay = MakeIsometricOverlay();
    SceneViewportScaleGizmo gizmo;
    gizmo.Update(MakeContext(target, Math::Vector2(400.0f, 300.0f), overlay));

    const SceneViewportScaleGizmoAxisHandleDrawData* xHandle =
        FindAxisHandle(gizmo.GetDrawData(), SceneViewportScaleGizmoHandle::X);
    ASSERT_NE(xHandle, nullptr);
    ASSERT_TRUE(xHandle->visible);

    Math::Vector2 expectedDirection = Math::Vector2::Zero();
    ASSERT_TRUE(ProjectSceneViewportAxisDirectionAtPoint(
        overlay,
        800.0f,
        600.0f,
        target->GetTransform()->GetPosition(),
        target->GetTransform()->GetRight(),
        expectedDirection));

    EXPECT_GT(Math::Vector2::Dot(HandleDirection(*xHandle), expectedDirection), 0.99f);
}

} // namespace
} // namespace XCEngine::Editor