// Copyright IHY. Vertical Partition Streaming plugin.
//
// In-world coordinator. One per streamed level (auto-spawned by the volume at
// BeginPlay, or placed manually). Determines the tracked player's current cell,
// drives the runtime subsystem at the configured interval, and hosts the debug
// component. Keep this lightweight: the heavy lifting is in the subsystem.
#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "VerticalPartitionTypes.h"
#include "VerticalPartitionManager.generated.h"

class UVerticalPartitionDescriptor;
class UVerticalPartitionDebugComponent;
class AVerticalPartitionVolume;

UCLASS()
class VERTICALPARTITION_API AVerticalPartitionManager : public AActor
{
	GENERATED_BODY()

public:
	AVerticalPartitionManager();

	/** Descriptor to stream. If unset, the manager searches the level for a volume. */
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="VerticalPartition")
	TSoftObjectPtr<UVerticalPartitionDescriptor> Descriptor;

	/** Optional explicit volume (otherwise the first one found is used). */
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="VerticalPartition")
	TObjectPtr<AVerticalPartitionVolume> Volume;

	/** Pawn whose position drives streaming. Defaults to local player pawn each tick. */
	UPROPERTY(BlueprintReadWrite, Category="VerticalPartition")
	TWeakObjectPtr<APawn> TrackedPawn;

	UPROPERTY(VisibleAnywhere, Category="VerticalPartition")
	TObjectPtr<UVerticalPartitionDebugComponent> DebugComponent;

	virtual void BeginPlay() override;
	virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
	virtual void Tick(float DeltaSeconds) override;

	/** Snap streaming to the tracked pawn immediately (checkpoint / teleport). */
	UFUNCTION(BlueprintCallable, Category="VerticalPartition")
	void RequestSnap() { bSnapNextUpdate = true; }

	/** Teleport the tracked pawn to the centre of a Z cell (debug). */
	UFUNCTION(BlueprintCallable, Category="VerticalPartition")
	void TeleportToCell(int32 Z);

private:
	float UpdateAccumulator = 0.f;
	bool bSnapNextUpdate = true;            // snap on the first update
	bool bHavePrevPos = false;
	FVector PrevTrackedPos = FVector::ZeroVector;
	FVector SmoothedVelocity = FVector::ZeroVector;

	APawn* ResolveTrackedPawn();
	bool BuildContext(struct FVerticalStreamingContext& OutCtx, float DeltaSeconds, bool& bOutTeleport);
};