// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "Math/Range.h"
#include "Misc/Guid.h"
#include "Containers/ArrayView.h"
#include "Curves/KeyHandle.h"

#include "Templates/SharedPointer.h"
#include "Misc/Optional.h"
#include "IKeyArea.h"
#include "Misc/FrameRate.h"

namespace UE
{
namespace Sequencer
{
class FChannelModel;
}
}

/** Simple structure that caches the sorted key times for a given key area */
struct FSequencerCachedKeys
{
	FSequencerCachedKeys(TSharedPtr<UE::Sequencer::FChannelModel> InChannel)
		: WeakChannel(InChannel)
	{}

	/**
	 * Update this cache to store key times and handles from the specified key area
	 * @return true if this cache was updated, false if it was already up to date
	 */
	bool Update(FFrameRate SourceResolution);

	/** Get an view of the cached array for keys that fall within the specified range */
	void GetKeysInRange(const TRange<double>& Range, TArrayView<const double>* OutTimes, TArrayView<const FFrameNumber>* OutKeyFrames, TArrayView<const FKeyHandle>* OutHandles) const;

	/** Get the key area this cache was generated for, or nullptr if the cache has never been updated */
	TSharedPtr<UE::Sequencer::FChannelModel> GetChannel() const
	{
		return WeakChannel.Pin();
	}

private:
	/** Cached key information */
	TArray<double> CachedKeyTimes;
	TArray<FFrameNumber> CachedKeyFrames;
	TArray<FKeyHandle> CachedKeyHandles;

	/** The guid with which the above array was generated */
	FGuid CachedSignature;

	/** The tick resolution of the sequence that this cache was generated with */
	FFrameRate CachedTickResolution;

	/** The key area this cache is for */
	TWeakPtr<UE::Sequencer::FChannelModel> WeakChannel;
};