// Fill out your copyright notice in the Description page of Project Settings.


#include "LagCompensationComponent.h"

#include "Blaster/Blaster.h"
#include "Blaster/Weapon/Weapon.h"
#include "Components/BoxComponent.h"
#include "Kismet/GameplayStatics.h"

ULagCompensationComponent::ULagCompensationComponent()
{
	PrimaryComponentTick.bCanEverTick = true;
}

FFramePackage ULagCompensationComponent::InterpBetweenFrames(const FFramePackage& OlderFrame, const FFramePackage& YoungerFrame, float HitTime)
{
	const float Distance = YoungerFrame.Time - OlderFrame.Time;
	const float InterpFraction = FMath::Clamp((HitTime - OlderFrame.Time) / Distance, 0.f, 1.f);

	FFramePackage InterpFramePackage;
	InterpFramePackage.Time = HitTime;

	for (auto& YoungerPair : YoungerFrame.HitBoxInfo)
	{
		const FName& BoxInfoName = YoungerPair.Key;
		const FBoxInformation& OlderBox = OlderFrame.HitBoxInfo[BoxInfoName];
		const FBoxInformation& YoungerBox = YoungerFrame.HitBoxInfo[BoxInfoName];

		FBoxInformation InterpBoxInfo;
		InterpBoxInfo.Location = FMath::VInterpTo(OlderBox.Location, YoungerBox.Location, 1.f, InterpFraction);
		InterpBoxInfo.Rotation = FMath::RInterpTo(OlderBox.Rotation, YoungerBox.Rotation, 1.f, InterpFraction);
		InterpBoxInfo.BoxExtent = YoungerBox.BoxExtent;

		InterpFramePackage.HitBoxInfo.Add(BoxInfoName, InterpBoxInfo);
	}
	
	return InterpFramePackage;
}

FServerSideRewindResult ULagCompensationComponent::ConfirmHit(const FFramePackage& Package, ABlasterCharacter* HitCharacter,
	const FVector_NetQuantize& TraceStart, const FVector_NetQuantize HitLocation)
{
	if (HitCharacter == nullptr) return FServerSideRewindResult();

	FFramePackage CurrentFrame;
	CacheBoxPositions(HitCharacter, CurrentFrame);
	MoveBoxes(HitCharacter, Package);
	EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::NoCollision);

	// Enable collision for the head first
	UBoxComponent* HeadBox = HitCharacter->HitCollisionBoxes[FName("head")];
	HeadBox->SetCollisionEnabled(ECollisionEnabled::QueryOnly);
	HeadBox->SetCollisionResponseToChannel(ECC_HitBox, ECR_Block);

	const FVector TraceEnd = TraceStart + (HitLocation - TraceStart) * 1.25f;
	if (UWorld* World = GetWorld())
	{
		FHitResult ConfirmHitResult;
		World->LineTraceSingleByChannel(
			ConfirmHitResult,
			TraceStart,
			TraceEnd,
			ECC_HitBox
		);
		if (ConfirmHitResult.bBlockingHit) // we hit the head, return early
		{
			ResetHitBoxes(HitCharacter, CurrentFrame);
			EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::QueryAndPhysics);
			return FServerSideRewindResult{ true, true };
		}
		
		// Didn't hit the head, check the rest of the boxes
		for (auto& HitBoxPair : HitCharacter->HitCollisionBoxes)
		{
			if (HitBoxPair.Value != nullptr)
			{
				HitBoxPair.Value->SetCollisionEnabled(ECollisionEnabled::QueryOnly);
				HitBoxPair.Value->SetCollisionResponseToChannel(ECC_HitBox, ECR_Block);
			}
		} 
		
		World->LineTraceSingleByChannel(
			ConfirmHitResult,
			TraceStart,
			TraceEnd,
			ECC_HitBox
		);

		if (ConfirmHitResult.bBlockingHit)
		{
			ResetHitBoxes(HitCharacter, CurrentFrame);
			EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::QueryAndPhysics);
			return FServerSideRewindResult{ true, false };
		}
	}

	ResetHitBoxes(HitCharacter, CurrentFrame);
	EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::QueryAndPhysics);
	return FServerSideRewindResult{ false, false };
}

FServerSideRewindResult ULagCompensationComponent::ProjectileConfirmHit(const FFramePackage& Package, ABlasterCharacter* HitCharacter, const FVector_NetQuantize& TraceStart,
	const FVector_NetQuantize100& InitialVelocity, float HitTime)
{
	FFramePackage CurrentFrame;
	CacheBoxPositions(HitCharacter, CurrentFrame);
	MoveBoxes(HitCharacter, Package);
	EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::NoCollision);

	// Enable collision for the head first
	UBoxComponent* HeadBox = HitCharacter->HitCollisionBoxes[FName("head")];
	HeadBox->SetCollisionEnabled(ECollisionEnabled::QueryOnly);
	HeadBox->SetCollisionResponseToChannel(ECC_HitBox, ECR_Block);

	FPredictProjectilePathParams PathParams;
	PathParams.bTraceWithCollision = true;
	PathParams.MaxSimTime = MaxRecordTime;
	PathParams.LaunchVelocity = InitialVelocity;
	PathParams.StartLocation = TraceStart;
	PathParams.SimFrequency = 15.f;
	PathParams.ProjectileRadius = 5.f;
	PathParams.TraceChannel = ECC_HitBox;
	PathParams.ActorsToIgnore.Add(GetOwner());
	
	FPredictProjectilePathResult PathResult;
	UGameplayStatics::PredictProjectilePath(this, PathParams, PathResult);

	if (PathResult.HitResult.bBlockingHit) // we hit the head, return early
	{
		ResetHitBoxes(HitCharacter, CurrentFrame);
		EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::QueryAndPhysics);
		return FServerSideRewindResult{ true, true };
	}

	// we didn't hit the head; check the rest of the boxes
	for (auto& HitBoxPair : HitCharacter->HitCollisionBoxes)
	{
		if (HitBoxPair.Value != nullptr)
		{
			HitBoxPair.Value->SetCollisionEnabled(ECollisionEnabled::QueryOnly);
			HitBoxPair.Value->SetCollisionResponseToChannel(ECC_HitBox, ECR_Block);
		}
	}
	
	UGameplayStatics::PredictProjectilePath(this, PathParams, PathResult);
	if (PathResult.HitResult.bBlockingHit)
	{
		ResetHitBoxes(HitCharacter, CurrentFrame);
		EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::QueryAndPhysics);
		return FServerSideRewindResult{ true, false };
	}
	
	ResetHitBoxes(HitCharacter, CurrentFrame);
	EnableCharacterMeshCollision(HitCharacter, ECollisionEnabled::QueryAndPhysics);
	return FServerSideRewindResult{ false, false };
}

FShotgunServerSideRewindResult ULagCompensationComponent::ShotgunConfirmHit(const TArray<FFramePackage>& FramePackages,
                                                                            const FVector_NetQuantize& TraceStart, const TArray<FVector_NetQuantize>& HitLocations)
{
	for (auto& Frame : FramePackages)
	{
		if (Frame.Character == nullptr) return FShotgunServerSideRewindResult();
	}
	
	FShotgunServerSideRewindResult ShotgunResult;

	TArray<FFramePackage> CurrentFrames;
	for (auto& Frame : FramePackages)
	{
		FFramePackage CurrentFrame;
		CurrentFrame.Character = Frame.Character;
		CacheBoxPositions(Frame.Character, CurrentFrame);
		MoveBoxes(Frame.Character, Frame);
		EnableCharacterMeshCollision(Frame.Character, ECollisionEnabled::NoCollision);
		CurrentFrames.Add(CurrentFrame);
	}

	for (auto& Frame : FramePackages)
	{
		// Enable collision for the head first
		UBoxComponent* HeadBox = Frame.Character->HitCollisionBoxes[FName("head")];
		HeadBox->SetCollisionEnabled(ECollisionEnabled::QueryOnly);
		HeadBox->SetCollisionResponseToChannel(ECC_HitBox, ECR_Block);
	}

	UWorld* World = GetWorld();
	
	// Check for headshots
	for (auto& HitLocation : HitLocations)
	{
		const FVector TraceEnd = TraceStart + (HitLocation - TraceStart) * 1.25f;
		if (World)
		{
			FHitResult ConfirmHitResult;
			World->LineTraceSingleByChannel(
				ConfirmHitResult,
				TraceStart,
				TraceEnd,
				ECC_HitBox
			);

			ABlasterCharacter* BlasterCharacter = Cast<ABlasterCharacter>(ConfirmHitResult.GetActor());
			if (BlasterCharacter)
			{
				if (ShotgunResult.Headshots.Contains(BlasterCharacter))
				{
					ShotgunResult.Headshots[BlasterCharacter]++;
				}
				else
				{
					ShotgunResult.Headshots.Emplace(BlasterCharacter, 1);
				}
			}
		}
	}

	// Enable collision for all boxes, then disable for head box
	for (auto& Frame : FramePackages)
	{
		for (auto& HitBoxPair : Frame.Character->HitCollisionBoxes)
		{
			if (HitBoxPair.Value != nullptr)
			{
				HitBoxPair.Value->SetCollisionEnabled(ECollisionEnabled::QueryOnly);
				HitBoxPair.Value->SetCollisionResponseToChannel(ECC_HitBox, ECR_Block);
			}
		}
		UBoxComponent* HeadBox = Frame.Character->HitCollisionBoxes[FName("head")];
		HeadBox->SetCollisionEnabled(ECollisionEnabled::NoCollision);
	}

	// Check for body shots
	for (auto& HitLocation : HitLocations)
	{
		const FVector TraceEnd = TraceStart + (HitLocation - TraceStart) * 1.25f;
		if (World)
		{
			FHitResult ConfirmHitResult;
			World->LineTraceSingleByChannel(
				ConfirmHitResult,
				TraceStart,
				TraceEnd,
				ECC_HitBox
			);

			ABlasterCharacter* BlasterCharacter = Cast<ABlasterCharacter>(ConfirmHitResult.GetActor());
			if (BlasterCharacter)
			{
				if (ShotgunResult.BodyShots.Contains(BlasterCharacter))
				{
					ShotgunResult.BodyShots[BlasterCharacter]++;
				}
				else
				{
					ShotgunResult.BodyShots.Emplace(BlasterCharacter, 1);
				}
			}
		}
	}

	for (auto& CurrentFrame : CurrentFrames)
	{
		ResetHitBoxes(CurrentFrame.Character, CurrentFrame);
		EnableCharacterMeshCollision(CurrentFrame.Character, ECollisionEnabled::QueryAndPhysics);
	}

	return ShotgunResult;
}

void ULagCompensationComponent::CacheBoxPositions(ABlasterCharacter* HitCharacter, FFramePackage& OutFramePackage)
{
	if (HitCharacter == nullptr) return;
	for (auto& HitBoxPair : HitCharacter->HitCollisionBoxes)
	{
		if (HitBoxPair.Value != nullptr)
		{
			FBoxInformation BoxInfo;
			BoxInfo.Location = HitBoxPair.Value->GetComponentLocation();
			BoxInfo.Rotation = HitBoxPair.Value->GetComponentRotation();
			BoxInfo.BoxExtent = HitBoxPair.Value->GetScaledBoxExtent();
			OutFramePackage.HitBoxInfo.Add(HitBoxPair.Key, BoxInfo);
		}
	}
}

void ULagCompensationComponent::MoveBoxes(ABlasterCharacter* HitCharacter, const FFramePackage& Package)
{
	if (HitCharacter == nullptr) return;
	for (auto& HitBoxPair : HitCharacter->HitCollisionBoxes)
	{
		if (HitBoxPair.Value != nullptr)
		{
			HitBoxPair.Value->SetWorldLocation(Package.HitBoxInfo[HitBoxPair.Key].Location);
			HitBoxPair.Value->SetWorldRotation(Package.HitBoxInfo[HitBoxPair.Key].Rotation);
			HitBoxPair.Value->SetBoxExtent(Package.HitBoxInfo[HitBoxPair.Key].BoxExtent);
		}
	}
}

void ULagCompensationComponent::ResetHitBoxes(ABlasterCharacter* HitCharacter, const FFramePackage& Package)
{
	if (HitCharacter == nullptr) return;
	for (auto& HitBoxPair : HitCharacter->HitCollisionBoxes)
	{
		if (HitBoxPair.Value != nullptr)
		{
			HitBoxPair.Value->SetWorldLocation(Package.HitBoxInfo[HitBoxPair.Key].Location);
			HitBoxPair.Value->SetWorldRotation(Package.HitBoxInfo[HitBoxPair.Key].Rotation);
			HitBoxPair.Value->SetBoxExtent(Package.HitBoxInfo[HitBoxPair.Key].BoxExtent);
			HitBoxPair.Value->SetCollisionEnabled(ECollisionEnabled::NoCollision);
		}
	}
}

void ULagCompensationComponent::ShowFramePackage(const FFramePackage& Package, const FColor Color)
{
	for (auto& BoxInfo : Package.HitBoxInfo)
	{
		DrawDebugBox(
			GetWorld(),
			BoxInfo.Value.Location,
			BoxInfo.Value.BoxExtent,
			FQuat(BoxInfo.Value.Rotation),
			Color,
			false,
			4.f
		);
	}
}

FServerSideRewindResult ULagCompensationComponent::ServerSideRewind(ABlasterCharacter* HitCharacter, const FVector_NetQuantize& TraceStart, const FVector_NetQuantize& HitLocation,
	float HitTime)
{
	const FFramePackage FrameToCheck = GetFrameToCheck(HitCharacter, HitTime);
	return ConfirmHit(FrameToCheck, HitCharacter, TraceStart, HitLocation);
}

FServerSideRewindResult ULagCompensationComponent::ProjectileServerSideRewind(ABlasterCharacter* HitCharacter, const FVector_NetQuantize& TraceStart,
	const FVector_NetQuantize100& InitialVelocity, float HitTime)
{
	const FFramePackage FrameToCheck = GetFrameToCheck(HitCharacter, HitTime);
	return ProjectileConfirmHit(FrameToCheck, HitCharacter, TraceStart, InitialVelocity, HitTime);
}

FShotgunServerSideRewindResult ULagCompensationComponent::ShotgunServerSideRewind(const TArray<ABlasterCharacter*>& HitCharacters,
                                                                                  const FVector_NetQuantize& TraceStart, const TArray<FVector_NetQuantize>& HitLocations, float HitTime)
{
	TArray<FFramePackage> FramesToCheck;
	for (ABlasterCharacter* HitCharacter : HitCharacters)
	{
		FramesToCheck.Add(GetFrameToCheck(HitCharacter, HitTime));
	}

	return ShotgunConfirmHit(FramesToCheck, TraceStart, HitLocations);
}

FFramePackage ULagCompensationComponent::GetFrameToCheck(ABlasterCharacter* HitCharacter, float HitTime)
{
	bool bReturn = HitCharacter == nullptr ||
		HitCharacter->GetLagCompensation() == nullptr ||
			HitCharacter->GetLagCompensation()->FrameHistory.GetHead() == nullptr ||
			HitCharacter->GetLagCompensation()->FrameHistory.GetTail() == nullptr;
	if (bReturn) FFramePackage();
	// Frame package that we check to verify a hit
	FFramePackage FrameToCheck;
	bool bShouldInterpolate = true;
	
	const TDoubleLinkedList<FFramePackage>& History = HitCharacter->GetLagCompensation()->FrameHistory;
	const float OldestHistoryTime = History.GetTail()->GetValue().Time;
	const float NewestHistoryTime = History.GetHead()->GetValue().Time;
	if (OldestHistoryTime > HitTime)
	{
		// Too far back, too laggy to do SSR
		FFramePackage();
	}
	if (OldestHistoryTime == HitTime)
	{
		FrameToCheck = History.GetTail()->GetValue();
		bShouldInterpolate = false;
	}
	if (NewestHistoryTime <= HitTime)
	{
		FrameToCheck = History.GetHead()->GetValue();
		bShouldInterpolate = false;
	}
	auto Younger = History.GetHead();
	auto Older = History.GetHead();
	while (Older->GetValue().Time > HitTime)
	{
		if (Older->GetNextNode() == nullptr) break;
		Older = Older->GetNextNode();
		if (Older->GetValue().Time > HitTime)
		{
			Younger = Older;
		}
	}
	if (Older->GetValue().Time == HitTime)
	{
		FrameToCheck = Older->GetValue();
		bShouldInterpolate = false;
	}
	if (bShouldInterpolate) // Why not just check if FrameToCheck == nullptr?
	{
		// Interpolate between Younger and Older
		FrameToCheck = InterpBetweenFrames(Older->GetValue(), Younger->GetValue(), HitTime);
	}
	FrameToCheck.Character = HitCharacter;
	
	return FrameToCheck;
}
void ULagCompensationComponent::ServerScoreRequest_Implementation(ABlasterCharacter* HitCharacter, const FVector_NetQuantize& TraceStart,
                                                                  const FVector_NetQuantize& HitLocation, float HitTime)
{
	const FServerSideRewindResult Confirm = ServerSideRewind(HitCharacter, TraceStart, HitLocation, HitTime);

	if (Character && HitCharacter && Character->GetEquippedWeapon() && Confirm.bHitConfirmed)
	{
		const float Damage = Confirm.bHeadShot ? Character->GetEquippedWeapon()->GetHeadShotDamage() : Character->GetEquippedWeapon()->GetDamage();
		
		UGameplayStatics::ApplyDamage(
			HitCharacter,
			Damage,
			Character->Controller,
			Character->GetEquippedWeapon(),
			UDamageType::StaticClass()
		);
	}
}

void ULagCompensationComponent::ProjectileServerScoreRequest_Implementation(ABlasterCharacter* HitCharacter, const FVector_NetQuantize& TraceStart,
	const FVector_NetQuantize100& InitialVelocity, float HitTime)
{
	const FServerSideRewindResult Confirm = ProjectileServerSideRewind(HitCharacter, TraceStart, InitialVelocity, HitTime);

	if (Character && HitCharacter && Character->GetEquippedWeapon() && Confirm.bHitConfirmed)
	{
		const float Damage = Confirm.bHeadShot ? Character->GetEquippedWeapon()->GetHeadShotDamage() : Character->GetEquippedWeapon()->GetDamage();

		UGameplayStatics::ApplyDamage(
			HitCharacter,
			Damage,
			Character->Controller,
			Character->GetEquippedWeapon(),
			UDamageType::StaticClass()
		);
	}
}

void ULagCompensationComponent::ShotgunServerScoreRequest_Implementation(const TArray<ABlasterCharacter*>& HitCharacters, const FVector_NetQuantize& TraceStart,
	const TArray<FVector_NetQuantize>& HitLocations, float HitTime)
{
	FShotgunServerSideRewindResult Confirm = ShotgunServerSideRewind(HitCharacters, TraceStart, HitLocations, HitTime);

	for (auto& HitCharacter : HitCharacters)
	{
		if (HitCharacter == nullptr || Character == nullptr || HitCharacter->GetEquippedWeapon() == nullptr) continue;
		float TotalDamage = 0.f;
		if (Confirm.Headshots.Contains(HitCharacter))
		{
			TotalDamage += Confirm.Headshots[HitCharacter] * Character->GetEquippedWeapon()->GetHeadShotDamage();
		}
		if (Confirm.BodyShots.Contains(HitCharacter))
		{
			TotalDamage += Confirm.BodyShots[HitCharacter] * Character->GetEquippedWeapon()->GetDamage();
		}

		UGameplayStatics::ApplyDamage(
			HitCharacter,
			TotalDamage,
			Character->Controller,
			Character->GetEquippedWeapon(),
			UDamageType::StaticClass()
		);
	}
}

void ULagCompensationComponent::EnableCharacterMeshCollision(ABlasterCharacter* HitCharacter, ECollisionEnabled::Type CollisionEnabled)
{
	if (HitCharacter && HitCharacter->GetMesh())
	{
		HitCharacter->GetMesh()->SetCollisionEnabled(CollisionEnabled);
	}
}

void ULagCompensationComponent::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

	SaveFramePackage();
}

void ULagCompensationComponent::SaveFramePackage()
{
	if (Character == nullptr || !Character->HasAuthority()) return;
	if (FrameHistory.Num() <= 1)
	{
		FFramePackage ThisFrame;
		SaveFramePackage(ThisFrame);
		FrameHistory.AddHead(ThisFrame);
	}
	else
	{
		float HistoryLength = FrameHistory.GetHead()->GetValue().Time - FrameHistory.GetTail()->GetValue().Time;
		while (HistoryLength > MaxRecordTime)
		{
			FrameHistory.RemoveNode(FrameHistory.GetTail());
			HistoryLength = FrameHistory.GetHead()->GetValue().Time - FrameHistory.GetTail()->GetValue().Time;
		}
		FFramePackage ThisFrame;
		SaveFramePackage(ThisFrame);
		FrameHistory.AddHead(ThisFrame);
	}
}

void ULagCompensationComponent::SaveFramePackage(FFramePackage& Package)
{
	Character = Character == nullptr ? Cast<ABlasterCharacter>(GetOwner()) : Character;
	if (Character)
	{
		Package.Time = GetWorld()->GetTimeSeconds();
		Package.Character = Character;
		for (auto& BoxPair : Character->HitCollisionBoxes)
		{
			FBoxInformation BoxInformation;
			BoxInformation.Location = BoxPair.Value->GetComponentLocation();
			BoxInformation.Rotation = BoxPair.Value->GetComponentRotation();
			BoxInformation.BoxExtent = BoxPair.Value->GetScaledBoxExtent();
			Package.HitBoxInfo.Add(BoxPair.Key, BoxInformation);
		}
	}
}