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

////////////////////////////////////////////////////////////
//
// FlxInputModeRequest
//
// A widget's declaration of interest in input events.
//
//   Widget:      The widget that wants to receive events.
//   Focus:       The widget that should receive keyboard focus
//                while this request is active.
//   ShowPointer: If true, the mouse pointer should be
//                visible when this widget has control.
//   BlockInput:  If true, input actions should be blocked from
//                reaching lower-priority consumers (e.g. the pawn).
//
////////////////////////////////////////////////////////////

USTRUCT(BlueprintType)
struct FlxInputModeRequest
{
	GENERATED_BODY()

	FlxInputModeRequest() = default;
	FlxInputModeRequest(UUserWidget *InWidget, UWidget *InFocus, bool InShowPointer, bool InBlockInput)
		: Widget(InWidget), Focus(InFocus), ShowPointer(InShowPointer), BlockInput(InBlockInput) {}

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

	// True if this request wants any high-priority resource:
	// keyboard focus, the mouse pointer, or input blocking.
	bool IsHighPrio() const { return Focus != nullptr || ShowPointer || BlockInput; }

	UPROPERTY(BlueprintReadWrite)
	UUserWidget* Widget = nullptr;

	UPROPERTY(BlueprintReadWrite)
	UWidget* Focus = nullptr;

	UPROPERTY(BlueprintReadWrite)
	bool ShowPointer = false;

	UPROPERTY(BlueprintReadWrite)
	bool BlockInput = false;
};

USTRUCT()
struct FlxInputModeRequests
{
	GENERATED_BODY()

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

	UPROPERTY()
	bool Dirty = true;

public:
	using View = TArrayView<FlxInputModeRequest>;

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

	// Sanity check a request to see if it is reasonable.
	static bool SanityCheck(const FlxInputModeRequest &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 FlxInputModeRequest &NewRequest);

	// Ensure the specified widget has a request in the array.
	// If it isn't already present, register a low-priority request for it.
	void EnsureWidget(UUserWidget *Widget);

	// 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; }
};