#include "PlayerControllerBase.h"
#include "Common.h"
#include "Tangible.h"
#include "TangibleManager.h"
#include "Blueprint/UserWidget.h"
#include "Components/InputComponent.h"
#include "Engine/GameInstance.h"
#include "Engine/GameViewportClient.h"
#include "Engine/LevelScriptActor.h"
#include "Engine/LocalPlayer.h"
#include "Framework/Application/SlateApplication.h"
#include "Framework/Application/SlateUser.h"
#include "Kismet/GameplayStatics.h"
#include "Widgets/SViewport.h"

AlxPlayerControllerBase *AlxPlayerControllerBase::FromContext(const UObject *Context)
{
	APlayerController *PC = Context->GetWorld()->GetFirstPlayerController();
	AlxPlayerControllerBase *Result = Cast<AlxPlayerControllerBase>(PC);
	if (Result == nullptr)
	{
		UE_LOG(LogLuprexIntegration, Fatal, TEXT("Not currently using a Luprex Player Controller."));
	}
	return Result;
}

const FHitResult &AlxPlayerControllerBase::GetLookAt(const UObject *Context)
{
	return FromContext(Context)->CurrentLookAt;
}

const AActor *AlxPlayerControllerBase::GetLookAtActor(const UObject *Context)
{
	return FromContext(Context)->CurrentLookAt.GetActor();
}

void AlxPlayerControllerBase::SetLookAt(const UObject *Context, const FHitResult &HitResult)
{
	AlxPlayerControllerBase *PC = FromContext(Context);
	if (PC->CurrentLookAt.HitObjectHandle != HitResult.HitObjectHandle)
	{
		PC->MustCallLookAtChanged = true;
	}
	PC->CurrentLookAt = HitResult;
}

void AlxPlayerControllerBase::SetLookAtChanged(const UObject *Context)
{
	AlxPlayerControllerBase *PC = FromContext(Context);
	PC->MustCallLookAtChanged = true;
}

FVector2D AlxPlayerControllerBase::GetLookAtPixel(const UObject *Context)
{
	AlxPlayerControllerBase *PC = FromContext(Context);
	FVector2D ScreenPosition;
	if (!UGameplayStatics::ProjectWorldToScreen(PC, PC->CurrentLookAt.Location, ScreenPosition, false))
	{
		return FVector2D();
	}
	return ScreenPosition;
}

void AlxPlayerControllerBase::BeginPlay()
{
	Super::BeginPlay();
	if (FSlateApplication::IsInitialized())
	{
		FocusChangingHandle = FSlateApplication::Get().OnFocusChanging().AddUObject(
			this, &AlxPlayerControllerBase::HandleFocusChanging);
	}
}

void AlxPlayerControllerBase::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
	if (FocusChangingHandle.IsValid() && FSlateApplication::IsInitialized())
	{
		FSlateApplication::Get().OnFocusChanging().Remove(FocusChangingHandle);
		FocusChangingHandle.Reset();
	}
	Super::EndPlay(EndPlayReason);
}

void AlxPlayerControllerBase::HandleFocusChanging(
	const FFocusEvent &FocusEvent,
	const FWeakWidgetPath &OldPath,
	const TSharedPtr<SWidget> &OldFocusedWidget,
	const FWidgetPath &NewPath,
	const TSharedPtr<SWidget> &NewFocusedWidget)
{
	UE_LOG(LogLuprexIntegration, Display,
		TEXT("Focus changing: '%s' -> '%s' (cause: %s)"),
		OldFocusedWidget.IsValid() ? *OldFocusedWidget->GetTypeAsString() : TEXT("<none>"),
		NewFocusedWidget.IsValid() ? *NewFocusedWidget->GetTypeAsString() : TEXT("<none>"),
		*UEnum::GetValueAsString(FocusEvent.GetCause()));
}

UInputComponent* AlxPlayerControllerBase::GetWidgetInputComponent(UUserWidget *Widget)
{
	if (!IsValid(Widget)) return nullptr;

	// Cache the FProperty on first call. FProperties are owned by
	// the native UUserWidget UClass, which lives for the process
	// lifetime, so the pointer stays valid without us needing to
	// root anything against GC. Static local init is thread-safe.
	static FObjectProperty *InputComponentProp = FindFProperty<FObjectProperty>(
		UUserWidget::StaticClass(), TEXT("InputComponent"));
	check(InputComponentProp);
	
	UObject *Value = InputComponentProp->GetObjectPropertyValue_InContainer(Widget);
	return Cast<UInputComponent>(Value);
}

void AlxPlayerControllerBase::WidgetRequestInputMode(UUserWidget *Widget, bool ShowPointer, bool BlockInput, UWidget *Focus, bool EnableInputComponent)
{
	if (!IsValid(Widget))
	{
		UE_LOG(LogLuprexIntegration, Error, TEXT("WidgetRequestInputMode called with an invalid widget."));
		return;
	}
	APlayerController *OwningPC = Widget->GetOwningPlayer();
	AlxPlayerControllerBase *PC = Cast<AlxPlayerControllerBase>(OwningPC);
	if (PC == nullptr)
	{
		UE_LOG(LogLuprexIntegration, Error,
			TEXT("WidgetRequestInputMode: widget '%s' owning player is not an AlxPlayerControllerBase (got %s)."),
			*Widget->GetName(), *GetNameSafe(OwningPC));
		return;
	}
	FlxInputModeRequest Req;
	Req.Widget = Widget;
	Req.Focus = Focus;
	Req.ShowPointer = ShowPointer;
	Req.BlockInput = BlockInput;
	Req.EnableInputComponent = EnableInputComponent;
	PC->InputModeRequests.Request(Req);
}

void AlxPlayerControllerBase::PushInputComponent(UInputComponent* InInputComponent)
{
	if (InInputComponent)
	{
		// Widgets don't go on the current input stack. Instead, they're
		// tracked in InputModeRequests, where the PlayerController can arbitrate
		// focus, pointer visibility, and input blocking across them.
		if (UUserWidget *Widget = Cast<UUserWidget>(InInputComponent->GetOuter()))
		{
			InputModeRequests.SetEnableInputComponent(Widget, true);
			return;
		}
		CurrentInputStack.RemoveSingle(InInputComponent);
		CurrentInputStack.Add(InInputComponent);
	}
}

bool AlxPlayerControllerBase::PopInputComponent(UInputComponent* InInputComponent)
{
	if (InInputComponent)
	{
		if (UUserWidget *Widget = Cast<UUserWidget>(InInputComponent->GetOuter()))
		{
			InputModeRequests.SetEnableInputComponent(Widget, false);
			InInputComponent->ClearBindingValues();
			return true;
		}
		if (CurrentInputStack.RemoveSingle(InInputComponent) > 0)
		{
			InInputComponent->ClearBindingValues();
			return true;
		}
	}
	return false;
}

void AlxPlayerControllerBase::BuildInputStack(TArray<UInputComponent*>& InputStack)
{
	// Controlled pawn gets last dibs on the input stack
	APawn* ControlledPawn = GetPawnOrSpectator();
	if (ControlledPawn)
	{
		if (ControlledPawn->InputEnabled())
		{
			// Get the explicit input component that is created upon Pawn possession. This one gets last dibs.
			if (ControlledPawn->InputComponent)
			{
				InputStack.Push(ControlledPawn->InputComponent);
			}

			// See if there is another InputComponent that was added to the Pawn's components array (possibly by script).
			for (UActorComponent* ActorComponent : ControlledPawn->GetComponents())
			{
				UInputComponent* PawnInputComponent = Cast<UInputComponent>(ActorComponent);
				if (PawnInputComponent && PawnInputComponent != ControlledPawn->InputComponent)
				{
					InputStack.Push(PawnInputComponent);
				}
			}
		}
	}

	// LevelScriptActors are put on the stack next
	for (ULevel* Level : GetWorld()->GetLevels())
	{
		ALevelScriptActor* ScriptActor = Level->GetLevelScriptActor();
		if (ScriptActor)
		{
			if (ScriptActor->InputEnabled() && ScriptActor->InputComponent)
			{
				InputStack.Push(ScriptActor->InputComponent);
			}
		}
	}

	if (InputEnabled())
	{
		InputStack.Push(InputComponent);
	}

	// The current input stack is unlikely to have anything,
	// given that we've moved widgets to their own mechanism.
	// But, if there's anything here, sort it and push it.
	if (!CurrentInputStack.IsEmpty())
	{
		TArray<UInputComponent*, TInlineAllocator<20>> Pushed;
		for (int32 Idx = 0; Idx < CurrentInputStack.Num(); ++Idx)
		{
			UInputComponent* IC = CurrentInputStack[Idx].Get();
			if (IsValid(IC)) Pushed.Add(IC);
			else CurrentInputStack.RemoveAt(Idx--);
		}

		Pushed.StableSort([](const UInputComponent& A, const UInputComponent& B)
		{
			if (A.bBlockInput != B.bBlockInput) return !A.bBlockInput;
			return A.Priority < B.Priority;
		});

		InputStack.Append(Pushed);
	}

	// Push the widget input components from InputModeRequests. Requests
	// are ordered high-priority first; the input stack is processed
	// from top (last index) down, so we push back-to-front: low
	// priority first, high priority last (ending up on top).
	const TArray<FlxInputModeRequest> &Requests = InputModeRequests.GetRequests();
	for (int32 Idx = Requests.Num() - 1; Idx >= 0; --Idx)
	{
		const FlxInputModeRequest &Req = Requests[Idx];
		if (!Req.EnableInputComponent) continue;
		UUserWidget *Widget = Req.Widget;
		if (!Widget->IsInViewport()) continue;
		if (UInputComponent *IC = GetWidgetInputComponent(Widget))
		{
			IC->bBlockInput = Req.BlockInput;
			InputStack.Push(IC);
		}
	}
}

void AlxPlayerControllerBase::UpdateInputMode()
{
	InputModeRequests.GarbageCollect();

	// Get all the various objects we need to be able to manipulate
	// the input mode.
	UGameViewportClient *GameViewportClient = GetWorld()->GetGameViewport();
	ULocalPlayer *LocalPlayer = Cast<ULocalPlayer>(Player);
	if (GameViewportClient == nullptr || LocalPlayer == nullptr) return;
	TSharedPtr<SViewport> ViewportWidget = GameViewportClient->GetGameViewportWidget();
	if (!ViewportWidget.IsValid()) return;
	TSharedRef<SViewport> ViewportWidgetRef = ViewportWidget.ToSharedRef();
	FReply &SlateOperations = LocalPlayer->GetSlateOperations();
	TSharedPtr<FSlateUser> SlateUser = LocalPlayer->GetSlateUser();
	if (!SlateUser.IsValid()) return;

	// The first active entry in InputModeRequests dictates the
	// pointer / capture / focus state. If there are no requests at all,
	// fall back to a static default-constructed request.
	static const FlxInputModeRequest EmptyRequest;
	const FlxInputModeRequest *Top = &EmptyRequest;
	for (const FlxInputModeRequest &Req : InputModeRequests.GetRequests())
	{
		if (Req.Widget->IsInViewport()) { Top = &Req; break; }
	}

	SetShowMouseCursor(Top->ShowPointer);

	if (Top->ShowPointer)
	{
		// Only release capture if the viewport is currently holding it
		// (e.g. we just came from GameOnly). A blanket ReleaseMouseCapture
		// every tick would yank capture away from widgets mid-gesture
		// (scrollbar drags, slider drags, etc.).
		if (SlateUser->DoesWidgetHaveAnyCapture(ViewportWidget))
		{
			SlateOperations.ReleaseMouseCapture();
		}
		SlateOperations.ReleaseMouseLock();
		GameViewportClient->SetMouseLockMode(EMouseLockMode::DoNotLock);
		GameViewportClient->SetHideCursorDuringCapture(false);
		GameViewportClient->SetMouseCaptureMode(EMouseCaptureMode::CaptureDuringMouseDown);
	}
	else
	{
		// Also captures the mouse to the viewport.
		SlateOperations.UseHighPrecisionMouseMovement(ViewportWidgetRef);
		SlateOperations.LockMouseToWidget(ViewportWidgetRef);
		GameViewportClient->SetMouseLockMode(EMouseLockMode::LockOnCapture);
		GameViewportClient->SetMouseCaptureMode(EMouseCaptureMode::CapturePermanently);
	}

	GameViewportClient->SetIgnoreInput(false);

	// How we handle focus depends on whether we're showing the pointer.
	// In pointer mode, we set focus to the desired state just once,
	// and then we let the pointer control it from there on.  In
	// no-pointer mode, we set focus to the desired state and
	// keep putting it back forever.
	//
	// If the user clicks the mouse on a focusable widget, the
	// viewport client notifies us of that fact.  We then focus the
	// widget if possible.
	// 
	if ((!Top->ShowPointer) || (LastRequestGrantedFocus != Top->SequenceNumber))
	{
		if (Top->Focus)
		{
			if (TSharedPtr<SWidget> SlateFocus = Top->Focus->GetCachedWidget())
			{
				SlateOperations.SetUserFocus(SlateFocus.ToSharedRef());
				LastRequestGrantedFocus = Top->SequenceNumber;
			}
		}
		else
		{
			SlateOperations.SetUserFocus(ViewportWidgetRef);
			LastRequestGrantedFocus = Top->SequenceNumber;
		}
	}
	else if (TSharedPtr<SWidget> ClickedWidget = ClickToFocusTarget.Pin())
	{
		SlateOperations.SetUserFocus(ClickedWidget.ToSharedRef());
	}
	ClickToFocusTarget.Reset();
}

void AlxPlayerControllerBase::ClickToFocus(TSharedRef<SWidget> Widget)
{
	ClickToFocusTarget = Widget.ToWeakPtr();
}

void AlxPlayerControllerBase::UpdateLookAt()
{
	UlxTangibleManager *TM = GetGameInstance()->GetSubsystem<UlxTangibleManager>();
	if (TM == nullptr) return;
	UlxTangible *Possessed = TM->GetPossessedTangible();
	if (Possessed == nullptr) return;
	APawn *Pawn = GetPawn();
	if (Pawn == nullptr) return;
	if (Possessed->GetActor() != Cast<AActor>(Pawn)) return;
	if (PlayerCameraManager == nullptr) return;

	CalculateLookAt();

	if (MustCallLookAtChanged)
	{
		MustCallLookAtChanged = false;
		LookAtChanged();
	}
}