////////////////////////////////////////////////////////////
//
// InputEvents.h
//
// Custom input event dispatching system. Uses Unreal's
// built-in input modes (GameOnly / UIOnly) with an
// enhanced input component for GameOnly mode hotkeys.
//
////////////////////////////////////////////////////////////

#pragma once

#include "CoreMinimal.h"
#include "InputCoreTypes.h"
#include "Blueprint/UserWidget.h"
#include "InputEvents.generated.h"

////////////////////////////////////////////////////////////
//
// FlxEventRequest
//
// A widget's declaration of interest in input events.
//
//   Widget:      The widget that wants to receive events.
//   UseUIOnly: If true, activating this request puts
//                the system into UIOnly mode.
//   ShowPointer: If true, the mouse pointer should be
//                visible when this widget has control.
//   Hotkeys:     Keys that go to this widget when the
//                player is in GameOnly mode.
//
////////////////////////////////////////////////////////////

USTRUCT(BlueprintType)
struct FlxEventRequest
{
	GENERATED_BODY()

	FlxEventRequest() = default;
	FlxEventRequest(UUserWidget *InWidget, bool InUseUIOnly, bool InShowPointer, const TArray<FKey> &InHotkeys)
		: Widget(InWidget), UseUIOnly(InUseUIOnly), ShowPointer(InShowPointer), Hotkeys(InHotkeys) {}

	bool operator == (const FlxEventRequest &Other) const;

	UPROPERTY(BlueprintReadWrite)
	UUserWidget* Widget = nullptr;

	UPROPERTY(BlueprintReadWrite)
	bool UseUIOnly = false;

	UPROPERTY(BlueprintReadWrite)
	bool ShowPointer = false;

	UPROPERTY(BlueprintReadWrite)
	TArray<FKey> Hotkeys;
};

USTRUCT()
struct FlxEventRequests
{
	GENERATED_BODY()

private:
	UPROPERTY()
	// High priority requests are always before low-priority.
	// Otherwise, these are in order of most recent first.
	TArray<FlxEventRequest> Requests;

	UPROPERTY()
	bool Dirty = true;

public:
	enum class InputMode { UIOnly, GameOnly };

	using View = TArrayView<FlxEventRequest>;

	// Get the requests array.
	const TArray<FlxEventRequest> &GetRequests() const { return Requests; }

	// Sanity check a request to see if it is reasonable.
	static bool SanityCheck(const FlxEventRequest &Request);
	
	// Divide Requests into a high-priority slice and a low-priority slice.
	void SplitHighLow(View &High, View &Low); 

	// Apply a request.  Replaces any previous request by the same widget.
	void Request(const FlxEventRequest &NewRequest);

	// Remove all requests by the specified widget.
	void Remove(UUserWidget *Widget);

	// Remove any requests by dead widgets or widgets with no parents.
	void GarbageCollect();

	// Return true if the requests have changed since the last ClearDirty.
	bool IsDirty() { return Dirty; }

	// Clear the dirty flag.
	void ClearDirty() { Dirty = false; }

	// Set the dirty flag.
	void SetDirty() { Dirty = true; }

	// Get the currently-requested mode.
	InputMode GetRequestedMode() const;
};