#include "ScriptedAnimation.h"

////////////////////////////////////////////////////////////
//
// Routines to calculate the current state of an FlxScriptedAnimation.
//
////////////////////////////////////////////////////////////


double FlxScriptedAnimation::CalculateFade(double Offset, double Fade)
{
    if (Offset < 0.0)
    {
        return 0.0;
    }
    if (Fade > 0.001)
    {
        return FMath::Min(Offset / Fade, 1.0);
    }
    return 1.0;
}

double FlxScriptedAnimation::UnclampedElapsedTime(double CurrentTime) const
{
    return CurrentTime - StartTime;
}

double FlxScriptedAnimation::UnclampedTimeLeft(double CurrentTime) const
{
    return EndTime - CurrentTime;
}

double FlxScriptedAnimation::ClampedElapsedTime(double CurrentTime) const
{
    return FMath::Max(0.0, CurrentTime - StartTime);
}

double FlxScriptedAnimation::ClampedTimeLeft(double CurrentTime) const
{
    return FMath::Max(0.0, EndTime - CurrentTime);
}

double FlxScriptedAnimation::CalcFadeInAlpha(double CurrentTime) const
{
    return CalculateFade(UnclampedElapsedTime(CurrentTime), FadeInDuration);
}

double FlxScriptedAnimation::CalcFadeOutAlpha(double CurrentTime) const
{
    return CalculateFade(UnclampedTimeLeft(CurrentTime), FadeOutDuration);
}

double FlxScriptedAnimation::CalcFadeInOutAlpha(double CurrentTime) const
{
    return FMath::Min(CalcFadeInAlpha(CurrentTime), CalcFadeOutAlpha(CurrentTime));
}

void FlxScriptedAnimation::InitiateFadeOut(double CurrentTime, double AllowedFade)
{
    // We only need to truncate if we aren't already fading out,
    // or if the in-progress fadeout isn't sufficiently fast.
    //
    double FadeOutAlpha = CalcFadeOutAlpha(CurrentTime);
    if ((FadeOutAlpha >= 1.0) || (FadeOutDuration > AllowedFade))
    {
        double CurrentAlpha = FMath::Min(CalcFadeInAlpha(CurrentTime), FadeOutAlpha);
        double NewFadeOutDuration = FMath::Min(AllowedFade, FadeOutDuration);
        double NewTimeLeft = NewFadeOutDuration * CurrentAlpha;
        EndTime = CurrentTime + NewTimeLeft;
        FadeOutDuration = NewFadeOutDuration;
    }
}

void UlxScriptedAnimations::Keep(int n)
{
	if (n < 0) n = 0;
	if (Animations.Num() > n)
	{
		Animations.SetNum(n);
	}
}

void UlxScriptedAnimations::AddAnimation(
    UObject* WorldContextObject, UAnimSequenceBase* Sequence, double FadeInTime, double FadeOutTime, int64 AqHash)
{
	check(KeepCount >= 1);
	FlxScriptedAnimation Result;

	// Get World Time
	UWorld* World = GEngine->GetWorldFromContextObjectChecked(WorldContextObject);
	double WorldTime = World ? World->GetTimeSeconds() : 0.0;

    // Get the animation Length.
    double Length = (Sequence ? static_cast<double>(Sequence->GetPlayLength()) : 0.0);

	// Fill the static setup fields
	Result.Sequence          = Sequence;
	Result.AqHash            = AqHash;
	Result.FadeInDuration    = FadeInTime;
	Result.FadeOutDuration   = FadeOutTime;
	Result.StartTime         = WorldTime;
	Result.EndTime           = WorldTime + Length;

	Keep(KeepCount - 1);
	Animations.Insert(Result, 0);
}

void UlxScriptedAnimations::FadeGarbage(TArray<int32> Hashes, double CurrentTime)
{
    for (int i = 0; i < Animations.Num(); i++)
    {
        FlxScriptedAnimation &Anim = Animations[i];
        if ((Anim.AqHash != 0) && (!Hashes.Contains(Anim.AqHash)))
        {
            Anim.InitiateFadeOut(CurrentTime, 0.2);
        }
    }
}

void UlxScriptedAnimationLibrary::ScriptedAnimationEvaluatorData(const UlxScriptedAnimations *Animations, double CurrentTime,
		UAnimSequenceBase *&Sequence0, float &ExplicitTime0,
		UAnimSequenceBase *&Sequence1, float &ExplicitTime1,
		UAnimSequenceBase *&Sequence2, float &ExplicitTime2,
		float &BaseAlpha, float &Sequence0Alpha, float &Sequence1Alpha, float &Sequence2Alpha) 
{
	Sequence0 = nullptr;
	Sequence1 = nullptr;
	Sequence2 = nullptr;
	ExplicitTime0 = 0.0;
	ExplicitTime1 = 0.0;
	ExplicitTime2 = 0.0;
	BaseAlpha = 0.0;
	Sequence0Alpha = 0.0;
	Sequence1Alpha = 0.0;
	Sequence2Alpha = 0.0;
	
	if (Animations != nullptr)
	{
		const TArray<FlxScriptedAnimation> &Anims = Animations->GetAnimations();
		if (Anims.Num() > 0)
		{
            const FlxScriptedAnimation &Anim = Anims[0];
			Sequence0 = Anim.Sequence;
			ExplicitTime0 = Anim.ClampedElapsedTime(CurrentTime);
			Sequence0Alpha = Anim.CalcFadeInOutAlpha(CurrentTime);
		}
		if (Anims.Num() > 1)
		{
            const FlxScriptedAnimation &Anim = Anims[1];
			Sequence1 = Anim.Sequence;
			ExplicitTime1 = Anim.ClampedElapsedTime(CurrentTime);
			Sequence1Alpha = Anim.CalcFadeInOutAlpha(CurrentTime);
		}
		if (Anims.Num() > 2)
		{
            const FlxScriptedAnimation &Anim = Anims[2];
			Sequence2 = Anim.Sequence;
			ExplicitTime2 = Anim.ClampedElapsedTime(CurrentTime);
			Sequence2Alpha = Anim.CalcFadeInOutAlpha(CurrentTime);
		}
	}

	double AlphaTotal = Sequence0Alpha + Sequence1Alpha + Sequence2Alpha;
	if (AlphaTotal > 1.0)
	{
		double Scale = 1.0 / AlphaTotal;
		Sequence0Alpha *= Scale;
		Sequence1Alpha *= Scale;
		Sequence2Alpha *= Scale;
		BaseAlpha = 0.0;
	}
	else
	{
		BaseAlpha = 1.0 - AlphaTotal;
	}
}