//
// This class implements the layout calculatations for a radial
// menu.
//

#pragma once

#include "CoreMinimal.h"
#include "RadialMenu.generated.h"


USTRUCT(BlueprintType)
struct FRadialMenuItem
{
    GENERATED_BODY()

    FVector2D Point1 = {0,0};
    FVector2D Point2 = {0,0};
    FVector2D Point3 = {0,0};
    bool RightSide = false;
};

UCLASS(BlueprintType)
class URadialMenu : public UObject
{
    GENERATED_BODY()

public:
    UFUNCTION(BlueprintCallable)
    void Configure(int32 NItems, float ItemHeight, float InnerRadius, float MinSpoke, float Spread);

    UFUNCTION(BlueprintCallable)
    int32 LeftNum() const { return NumLeft; }

    UFUNCTION(BlueprintCallable)
    int32 RightNum() const { return NumRight; }

    UFUNCTION(BlueprintCallable)
    const TArray<FRadialMenuItem> GetItems() const { return Items; }


private:
    using View = TArrayView<FRadialMenuItem>;

    // Give the unit vector for the selected spoke. NSide is
    // the number of spokes on the side of the wheel that
    // we're calculating, and NTotal is the total number of
    // spokes on both sides. The spokes on a given side are
    // organized top-to-bottom, and the angle between the
    // spokes is always equal to (1/NTotal) of the circle.
    FVector2D SpokeVector(int32 I, int32 NSide, int32 NTotal);

    // Populate Point1 and Point2, these are the
    // endpoints of the spoke segment.  Spokes are
    // designed to always be long enough to make room
    // for MinSpoke, but also to make enough room to
    // keep the menu items from overlapping.
    void CalculateSpokes(View V, float ItemHeight, float InnerRadius, float MinSpoke);
    
    // Search for the widest spoke, and return its X coordinate.
    double WidestSpoke(View V);

    // Populate Point3, this is the endpoint of the spread
    // line that goes horizontal.
    void CalculateSpread(View V, double Offset);

    // Flip everything in the specified view horizontally.
    void FlipHorizontal(View V);

    // The array of items.
    TArray<FRadialMenuItem> Items;

    // Number of items on the left, and on the right.
    int32 NumLeft = 0;
    int32 NumRight = 0;
};