// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "LevelEditorViewport.h"
#include "EditorDragTools.h"

class FCanvas;
class UModel;

/**
 * Draws a box in the current viewport and when the mouse button is released,
 * it selects/unselects everything inside of it.
 */
class FDragTool_ActorBoxSelect: public FDragTool
{
public:
    explicit FDragTool_ActorBoxSelect(FLevelEditorViewportClient* InLevelViewportClient)
        : FDragTool(InLevelViewportClient->GetModeTools()), LevelViewportClient(InLevelViewportClient)
    {}

    /**
     * Starts a mouse drag behavior.  The start location is snapped to the editor constraints if bUseSnapping is true.
     *
     * @param	InViewportClient	The viewport client in which the drag event occurred.
     * @param	InStart				Where the mouse was when the drag started.
     */
    virtual void StartDrag(FEditorViewportClient* InViewportClient, const FVector& InStart, const FVector2D& InStartScreen) override;

    /* Updates the drag tool's end location with the specified delta.  The end location is
     * snapped to the editor constraints if bUseSnapping is true.
     *
     * @param	InDelta		A delta of mouse movement.
     */
    virtual void AddDelta(const FVector& InDelta) override;

    /**
     * Ends a mouse drag behavior (the user has let go of the mouse button).
     */
    virtual void EndDrag() override;
    virtual void Render(const FSceneView* View, FCanvas* Canvas) override;

private:
    /**
     * Calculates a box to check actors against
     *
     * @param OutBox	The created box.
     */
    void CalculateBox(FBox& OutBox);

    /**
     * Returns true if the passed in Actor intersects with the provided box
     *
     * @param InActor				The actor to check
     * @param InBox					The box to check against
     * @param bUseStrictSelection	true if the actor must be entirely within the frustum
     */
    bool IntersectsBox(AActor& InActor, const FBox& InBox, bool bUseStrictSelection);

    /**
     * Returns true if the provided BSP node intersects with the provided frustum
     *
     * @param InModel				The model containing BSP nodes to check
     * @param NodeIndex				The index to a BSP node in the model.  This node is used for the bounds check.
     * @param InFrustum				The frustum to check against.
     * @param bUseStrictSelection	true if the node must be entirely within the frustum
     */
    bool IntersectsBox(const UModel& InModel, int32 NodeIndex, const FBox& InBox, bool bUseStrictSelection) const;

    /** Adds a hover effect to the passed in actor */
    void AddHoverEffect(AActor& InActor);

    /** Adds a hover effect to the passed in bsp surface */
    void AddHoverEffect(UModel& InModel, int32 SurfIndex);

    /** Removes a hover effect from the passed in actor */
    void RemoveHoverEffect(AActor& InActor);

    /** Removes a hover effect from the passed in bsp surface */
    void RemoveHoverEffect(UModel& InModel, int32 SurfIndex);

    /** List of BSP models to check for selection */
    TArray<UModel*> ModelsToCheck;

    FLevelEditorViewportClient* LevelViewportClient;
};