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


#include "WaveSubsystem.h"

#include "Kismet/GameplayStatics.h"

void UWaveSubsystem::Init(const TArray<UWave*> InWaves, const int32 CurrWave = 0)
{
	CurrentWave = CurrWave;
	Waves = InWaves;
}

int32 UWaveSubsystem::SpawnWave(const float InVerticalSpacing, const float InHorizontalOffset, const int InNumRows)
{
	NumRows = InNumRows;
	HorizontalOffset = InHorizontalOffset;
	VerticalSpacing = InVerticalSpacing;
	SpawnQueue = Waves[CurrentWave]->GetUnits();
	const auto NumUnits = SpawnQueue.Num(); 
	CurrentColumn = 0;
	
	TArray<AActor*> SpawnPoints;
	UGameplayStatics::GetAllActorsWithTag(GetWorld(), "EnemySpawn", SpawnPoints);
	SpawnPoint = SpawnPoints[0];
	
	SpawnUnits();
	GetWorld()->GetTimerManager().SetTimer(
		SpawnTimerHandle,
		this,
		&UWaveSubsystem::SpawnUnits,
		0.5f,
		true);

	CurrentWave++;
	return NumUnits;
}

void UWaveSubsystem::SpawnUnits()
{
	for(auto i = 0; i < NumRows; i++)
	{
		if(i + LastSpawnIndex >= SpawnQueue.Num())
		{
			GetWorld()->GetTimerManager().ClearTimer(SpawnTimerHandle);
			LastSpawnIndex += i;
			return;
		}

		FActorSpawnParameters SpawnActorParameters = {};
		SpawnActorParameters.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AdjustIfPossibleButAlwaysSpawn;

		FVector Location = SpawnPoint->GetActorLocation() + FVector(i * -VerticalSpacing, -HorizontalOffset * CurrentColumn, 300);
		FRotator Rotation = FRotator(0,-90.0f, 0);
		AActor* NewEnemy = GetWorld()->SpawnActor(SpawnQueue[i + LastSpawnIndex]->GetCharacterClass(), &Location, &Rotation, SpawnActorParameters);
		
		if(NewEnemy != nullptr)
		{
			NewEnemy->Tags.Add(TEXT("enemy"));
			USkeletalMeshComponent* Mesh = NewEnemy->FindComponentByClass<USkeletalMeshComponent>();
			Mesh->SetCollisionObjectType(ECC_GameTraceChannel2);
		}

		FHitResult Hit;
		FVector TraceStart = NewEnemy->GetActorLocation();
		FVector TraceEnd = -NewEnemy->GetActorUpVector() * 10000.0f;
		FCollisionQueryParams QueryParams;
		QueryParams.AddIgnoredActor(NewEnemy);

		NewEnemy->GetWorld()->LineTraceSingleByChannel(Hit, TraceStart, TraceEnd, ECC_WorldStatic, QueryParams);
		if(Hit.bBlockingHit)
		{
			NewEnemy->SetActorLocation(Hit.Location, true, nullptr, ETeleportType::ResetPhysics);
		}
	}

	LastSpawnIndex += NumRows;
}