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

#pragma once

#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "GameFramework/Actor.h"
#include "Engine/Blueprint.h"
#include "PreviewScene.h"
#include "TickableEditorObject.h"
#include "Animation/SkeletalMeshActor.h"
#include "ThumbnailHelpers.generated.h"

class FSceneViewFamily;
class USceneThumbnailInfo;

class UNREALED_API FThumbnailPreviewScene: public FPreviewScene
    , public FTickableEditorObject
{
public:
    /** Constructor */
    FThumbnailPreviewScene();

    /** Allocates then adds an FSceneView to the ViewFamily. */
    void GetView(FSceneViewFamily* ViewFamily, int32 X, int32 Y, uint32 SizeX, uint32 SizeY) const;

    /* Begin FTickableEditorObject */
    virtual void Tick(float DeltaTime) override;
    virtual ETickableTickType GetTickableTickType() const override { return ETickableTickType::Always; }
    virtual TStatId GetStatId() const override;
    /* End FTickableEditorObject */

protected:
    /** Helper function to get the bounds offset to display an asset */
    float GetBoundsZOffset(const FBoxSphereBounds& Bounds) const;

    /**
     * Gets parameters to create a view matrix to be used by GetView(). Implemented in children classes.
     * @param InFOVDegrees  The FOV used to display the thumbnail. Often used to calculate the output parameters.
     * @param OutOrigin	 The origin of the orbit view. Typically the center of the bounds of the target object.
     * @param OutOrbitPitch The pitch of the orbit cam around the object.
     * @param OutOrbitYaw	 The yaw of the orbit cam around the object.
     * @param OutOrbitZoom  The camera distance from the object.
     */
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const = 0;
};

class UNREALED_API FParticleSystemThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor/Destructor */
    FParticleSystemThumbnailScene();
    virtual ~FParticleSystemThumbnailScene();

    /** Sets the particle system to use in the next GetView() */
    void SetParticleSystem(class UParticleSystem* ParticleSystem);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

protected:
    /** The particle system component used to display all particle system thumbnails */
    class UParticleSystemComponent* PartComponent;

    /** The FXSystem used to render all thumbnail particle systems */
    class FFXSystemInterface* ThumbnailFXSystem;
};

class UNREALED_API FMaterialThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FMaterialThumbnailScene();

    /** Sets the material to use in the next GetView() */
    void SetMaterialInterface(class UMaterialInterface* InMaterial);

    bool ShouldSetSeparateTranslucency(class UMaterialInterface* InMaterial) const;

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

protected:
    /** The static mesh actor used to display all material thumbnails */
    class AStaticMeshActor* PreviewActor;
    /** Material being used for something that only makes sense to visualize as a plane (UI, particle sprites)*/
    bool bForcePlaneThumbnail;
};

class UNREALED_API FSkeletalMeshThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FSkeletalMeshThumbnailScene();

    /** Sets the skeletal mesh to use in the next GetView() */
    void SetSkeletalMesh(class USkeletalMesh* InSkeletalMesh);

    /** Returns the preview actor within the scene */
    class ASkeletalMeshActor* GetPreviewActor() { return PreviewActor; }

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

private:
    /** The skeletal mesh actor used to display all skeletal mesh thumbnails */
    class ASkeletalMeshActor* PreviewActor;
};

class UNREALED_API FStaticMeshThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FStaticMeshThumbnailScene();

    /** Sets the static mesh to use in the next GetView() */
    void SetStaticMesh(class UStaticMesh* StaticMesh);

    /** Sets override materials for the static mesh  */
    void SetOverrideMaterials(const TArray<class UMaterialInterface*>& OverrideMaterials);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

private:
    /** The static mesh actor used to display all static mesh thumbnails */
    class AStaticMeshActor* PreviewActor;
};

UCLASS(ClassGroup = ISkeletalMeshes, ComponentWrapperClass, ConversionRoot, meta = (ChildCanTick))
class AAnimationThumbnailSkeletalMeshActor: public ASkeletalMeshActor
{
    GENERATED_UCLASS_BODY()
};

class UNREALED_API FAnimationSequenceThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FAnimationSequenceThumbnailScene();

    /** Sets the animation to use in the next GetView() */
    bool SetAnimation(class UAnimSequenceBase* InAnimation);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

    // Clean up the children of this component
    void CleanupComponentChildren(USceneComponent* Component);

private:
    /** The skeletal mesh actor used to display all animation thumbnails */
    class AAnimationThumbnailSkeletalMeshActor* PreviewActor;

    /** Animation we are generating the thumbnail for */
    class UAnimSequenceBase* PreviewAnimation;
};

class UNREALED_API FBlendSpaceThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FBlendSpaceThumbnailScene();

    /** Sets the animation to use in the next GetView() */
    bool SetBlendSpace(class UBlendSpaceBase* InBlendSpace);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

    // Clean up the children of this component
    void CleanupComponentChildren(USceneComponent* Component);

private:
    /** The skeletal mesh actor used to display all animation thumbnails */
    class AAnimationThumbnailSkeletalMeshActor* PreviewActor;

    /** Animation we are generating the thumbnail for */
    class UBlendSpaceBase* PreviewAnimation;
};

class UNREALED_API FAnimBlueprintThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FAnimBlueprintThumbnailScene();

    /** Sets the animation blueprint to use in the next GetView() */
    bool SetAnimBlueprint(class UAnimBlueprint* InBlueprint);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

    // Clean up the children of this component
    void CleanupComponentChildren(USceneComponent* Component);

private:
    /** The skeletal mesh actor used to display all animation thumbnails */
    class ASkeletalMeshActor* PreviewActor;

    /** Animation Blueprint we are generating the thumbnail for */
    class UAnimBlueprint* PreviewBlueprint;
};

class UNREALED_API FPhysicsAssetThumbnailScene: public FThumbnailPreviewScene
{
public:
    /** Constructor */
    FPhysicsAssetThumbnailScene();

    /** Sets the skeletal mesh to use in the next GetView() */
    void SetPhysicsAsset(class UPhysicsAsset* InPhysicsAsset);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

private:
    /** The skeletal mesh actor used to display all physics asset thumbnails */
    class ASkeletalMeshActor* PreviewActor;
};

class UActorComponent;

class UNREALED_API FClassActorThumbnailScene: public FThumbnailPreviewScene
{
public:
    FClassActorThumbnailScene();

    /** Returns true if this component can be visualized */
    static bool IsValidComponentForVisualization(UActorComponent* Component);

protected:
    // FThumbnailPreviewScene implementation
    virtual void GetViewMatrixParameters(const float InFOVDegrees, FVector& OutOrigin, float& OutOrbitPitch, float& OutOrbitYaw, float& OutOrbitZoom) const override;

    /** Sets the object (class or blueprint) used in the next GetView() */
    void SpawnPreviewActor(class UClass* Obj);

    /** Get the scene thumbnail info to use for the object currently being rendered */
    virtual USceneThumbnailInfo* GetSceneThumbnailInfo(const float TargetDistance) const = 0;

    FBoxSphereBounds GetPreviewActorBounds() const;

private:
    /** Clears out any stale actors in this scene if PreviewActor enters a stale state */
    void ClearStaleActors();

    int32 NumStartingActors;
    TWeakObjectPtr<class AActor> PreviewActor;
};

class UNREALED_API FBlueprintThumbnailScene: public FClassActorThumbnailScene
{
public:
    /** Constructor/Destructor */
    FBlueprintThumbnailScene();

    /** Sets the static mesh to use in the next GetView() */
    void SetBlueprint(class UBlueprint* Blueprint);

    /** Refreshes components for the specified blueprint */
    void BlueprintChanged(class UBlueprint* Blueprint);

protected:
    /** Get the scene thumbnail info to use for the object currently being rendered */
    virtual USceneThumbnailInfo* GetSceneThumbnailInfo(const float TargetDistance) const override;

private:
    /** The blueprint that is currently being rendered. NULL when not rendering. */
    TWeakObjectPtr<class UBlueprint> CurrentBlueprint;
};

class UNREALED_API FClassThumbnailScene: public FClassActorThumbnailScene
{
public:
    /** Constructor/Destructor */
    FClassThumbnailScene();

    /** Sets the class use in the next GetView() */
    void SetClass(class UClass* Class);

protected:
    /** Get the scene thumbnail info to use for the object currently being rendered */
    virtual USceneThumbnailInfo* GetSceneThumbnailInfo(const float TargetDistance) const override;

private:
    /** The class that is currently being rendered. NULL when not rendering. */
    UClass* CurrentClass;
};

/** Handles instancing thumbnail scenes for Class and Blueprint types (use the class or generated class as the key). */
template <typename ThumbnailSceneType, int32 MaxNumScenes>
class TClassInstanceThumbnailScene
{
public:
    /** Constructor */
    TClassInstanceThumbnailScene()
    {
        InstancedThumbnailScenes.Reserve(MaxNumScenes);
    }

    /** Find an existing thumbnail scene instance for this class type. */
    TSharedPtr<ThumbnailSceneType> FindThumbnailScene(const UClass* InClass) const
    {
        check(InClass);
        const FName ClassName = InClass->GetFName();

        return InstancedThumbnailScenes.FindRef(ClassName);
    }

    /** Find or create a thumbnail scene instance for this class type. */
    TSharedRef<ThumbnailSceneType> EnsureThumbnailScene(const UClass* InClass)
    {
        check(InClass);
        const FName ClassName                                 = InClass->GetFName();

        TSharedPtr<ThumbnailSceneType> ExistingThumbnailScene = InstancedThumbnailScenes.FindRef(ClassName);
        if (!ExistingThumbnailScene.IsValid())
        {
            if (InstancedThumbnailScenes.Num() >= MaxNumScenes)
            {
                InstancedThumbnailScenes.Reset();
                // Will hitch but is better than a crash
                CollectGarbage(GARBAGE_COLLECTION_KEEPFLAGS);
            }

            ExistingThumbnailScene = MakeShareable(new ThumbnailSceneType());
            InstancedThumbnailScenes.Add(ClassName, ExistingThumbnailScene);
        }

        return ExistingThumbnailScene.ToSharedRef();
    }

    /** Clears all thumbnail scenes */
    void Clear()
    {
        InstancedThumbnailScenes.Reset();
    }

private:
    /**
     * Mapping between the class type and its thumbnail scene.
     * @note This uses the class name rather than the class pointer to avoid leaving behind stale class instances as Blueprints are re-compiled.
     */
    TMap<FName, TSharedPtr<ThumbnailSceneType>> InstancedThumbnailScenes;
};