XCEngine/editor/src/Viewport/SceneViewportRotateGizmo.h

#pragma once

#include "IViewportHostService.h"

#include <XCEngine/Core/Math/Color.h>
#include <XCEngine/Core/Math/Plane.h>
#include <XCEngine/Core/Math/Quaternion.h>
#include <XCEngine/Core/Math/Vector2.h>
#include <XCEngine/Core/Math/Vector3.h>

#include <array>
#include <cstdint>
#include <vector>

namespace XCEngine {
namespace Components {
class GameObject;
} // namespace Components

namespace Editor {

class IUndoManager;

enum class SceneViewportRotateGizmoAxis : uint8_t {
    None = 0,
    X,
    Y,
    Z,
    View
};

constexpr size_t kSceneViewportRotateGizmoSegmentCount = 96;
constexpr size_t kSceneViewportRotateGizmoAngleFillPointCount = kSceneViewportRotateGizmoSegmentCount + 1;

struct SceneViewportRotateGizmoSegmentDrawData {
    Math::Vector2 start = Math::Vector2::Zero();
    Math::Vector2 end = Math::Vector2::Zero();
    float startAngle = 0.0f;
    float endAngle = 0.0f;
    bool visible = false;
    bool frontFacing = true;
};

struct SceneViewportRotateGizmoHandleDrawData {
    SceneViewportRotateGizmoAxis axis = SceneViewportRotateGizmoAxis::None;
    std::array<SceneViewportRotateGizmoSegmentDrawData, kSceneViewportRotateGizmoSegmentCount> segments = {};
    Math::Color color = Math::Color::White();
    bool visible = false;
    bool hovered = false;
    bool active = false;
};

struct SceneViewportRotateGizmoAngleFillDrawData {
    SceneViewportRotateGizmoAxis axis = SceneViewportRotateGizmoAxis::None;
    Math::Vector2 pivot = Math::Vector2::Zero();
    std::array<Math::Vector2, kSceneViewportRotateGizmoAngleFillPointCount> arcPoints = {};
    size_t arcPointCount = 0;
    Math::Color fillColor = Math::Color::White();
    Math::Color outlineColor = Math::Color::White();
    bool visible = false;
};

struct SceneViewportRotateGizmoDrawData {
    bool visible = false;
    Math::Vector2 pivot = Math::Vector2::Zero();
    std::array<SceneViewportRotateGizmoHandleDrawData, 4> handles = {};
    SceneViewportRotateGizmoAngleFillDrawData angleFill = {};
};

struct SceneViewportRotateGizmoContext {
    SceneViewportOverlayData overlay = {};
    Math::Vector2 viewportSize = Math::Vector2::Zero();
    Math::Vector2 mousePosition = Math::Vector2::Zero();
    Components::GameObject* selectedObject = nullptr;
    std::vector<Components::GameObject*> selectedObjects = {};
    Math::Vector3 pivotWorldPosition = Math::Vector3::Zero();
    Math::Quaternion axisOrientation = Math::Quaternion::Identity();
    bool localSpace = false;
    bool rotateAroundSharedPivot = false;
};

struct SceneViewportRotateGizmoHitResult {
    SceneViewportRotateGizmoAxis axis = SceneViewportRotateGizmoAxis::None;
    float distanceSq = Math::FLOAT_MAX;

    bool HasHit() const {
        return axis != SceneViewportRotateGizmoAxis::None;
    }
};

class SceneViewportRotateGizmo {
public:
    void Update(const SceneViewportRotateGizmoContext& context);
    bool TryBeginDrag(const SceneViewportRotateGizmoContext& context, IUndoManager& undoManager);
    void UpdateDrag(const SceneViewportRotateGizmoContext& context);
    void EndDrag(IUndoManager& undoManager);
    void CancelDrag(IUndoManager* undoManager = nullptr);

    bool IsHoveringHandle() const;
    bool IsActive() const;
    uint64_t GetActiveEntityId() const;
    const SceneViewportRotateGizmoDrawData& GetDrawData() const;
    SceneViewportRotateGizmoHitResult EvaluateHit(const Math::Vector2& mousePosition) const;
    void SetHoveredHandle(SceneViewportRotateGizmoAxis axis);

private:
    void BuildDrawData(const SceneViewportRotateGizmoContext& context);
    void RefreshHandleState();
    bool TryGetClosestRingAngle(
        SceneViewportRotateGizmoAxis axis,
        const Math::Vector2& mousePosition,
        bool allowBackFacing,
        float& outAngle) const;

    SceneViewportRotateGizmoDrawData m_drawData = {};
    SceneViewportRotateGizmoAxis m_hoveredAxis = SceneViewportRotateGizmoAxis::None;
    SceneViewportRotateGizmoAxis m_activeAxis = SceneViewportRotateGizmoAxis::None;
    uint64_t m_activeEntityId = 0;
    bool m_screenSpaceDrag = false;
    bool m_localSpace = false;
    bool m_rotateAroundSharedPivot = false;
    Math::Vector3 m_activeWorldAxis = Math::Vector3::Zero();
    Math::Plane m_dragPlane = {};
    float m_dragStartRingAngle = 0.0f;
    float m_dragCurrentDeltaRadians = 0.0f;
    Math::Vector3 m_dragStartPivotWorldPosition = Math::Vector3::Zero();
    std::vector<Components::GameObject*> m_dragObjects = {};
    std::vector<Math::Vector3> m_dragStartWorldPositions = {};
    std::vector<Math::Quaternion> m_dragStartWorldRotations = {};
};

} // namespace Editor
} // namespace XCEngine