integration/Source/Integration/AnimQueue.h

#pragma once

#include "CoreMinimal.h"
#include "StringDecoder.h"
#include "Containers/Deque.h"

////////////////////////////////////////////////
//
// This is copied over from Luprex source.  Not ideal.
//
////////////////////////////////////////////////

enum class ElxAnimValueType {
	STRING,
	NUMBER,
	BOOLEAN,
	XYZ,
	INVALID
};

////////////////////////////////////////////////
//
// Playback Modes
//
// There are three different ways to play an animation:
//
// 1. Start Animation.  This is the normal way to play an animation.
// 
// 2. Warp to Final.  Skip the actual animation, and jump
//    instantaneously to the final state of the animation.
// 
// 3. Blend to Final.  Skip the actual animation, and blend
//    smoothly to the final state of the animation.  If the current
//    state is very far from the final state, then maybe jump instantaneously
//    instead.
//
////////////////////////////////////////////////

enum class ElxAnimPlaybackMode {
	START_ANIMATION,
	WARP_TO_FINAL,
	BLEND_TO_FINAL,
	INVALID,
};

////////////////////////////////////////////////
//
// An single animation step.
// 
// The body consists of a sequence of FlxAnimField
// records.  The body is encoded, to read the
// FlxAnimField records you need an FlxAnimStepDecoder.
// This comes in two versions: the string version,
// and the string_view version.
//
////////////////////////////////////////////////

struct FlxAnimStep {
	uint64 Hash;
	std::string_view Body;

	FlxAnimStep() : Hash(0), Body("") {}
	FlxAnimStep(uint64 h, std::string_view b) : Hash(h), Body(b) {}
};

struct FlxAnimStoredStep {
	uint64 Hash;
	std::string Body;

	FlxAnimStoredStep() : Hash(0), Body("") {}
	FlxAnimStoredStep(uint64 h, std::string_view b) : Hash(h), Body(b) {}
};

////////////////////////////////////////////////
//
// A single animation field.
// 
// A field consists of a variable name,
// a persistent flag, a type, and some fields
// to hold the values.
//
// If the value is boolean, it is stored in
// X, as either 1 or 0.   If the value is double,
// it is stored in X.
// 
////////////////////////////////////////////////

struct FlxAnimField {
	std::string_view Name;
	bool Persistent;
	ElxAnimValueType Type;
	double X, Y, Z;
	std::string_view S;
};

////////////////////////////////////////////////
//
// An Animation Queue Decoder.
//
// This acts a lot like a stream reader,
// it reads one AnimEntry at a time from
// the animation queue until you reach
// 'end-of-file'.
//
////////////////////////////////////////////////

class FlxAnimQueueDecoder {
private:
	FlxStringDecoder Decoder;

public:
	// Initialize the FlxAnimQueueDecoder with the encoded animation queue.
	//
	FlxAnimQueueDecoder(std::string_view s) : Decoder(s) {}

	// Return true if the parser has reached the end of the string.
	//
	bool AtEOF() { return Decoder.at_eof(); }

	// Read one animation step.
	// 
	FlxAnimStep ReadStep();

	// Convert an AnimQueue to an FString.
	//
	static FString DebugString(std::string_view s);
};

////////////////////////////////////////////////
//
// An Animation Step Decoder.
//
// This acts a lot like a stream reader,
// it reads one FlxAnimField at a time from
// the animation queue until you reach
// 'end-of-file'.
//
////////////////////////////////////////////////

class FlxAnimStepDecoder {
private:
	FlxStringDecoder Decoder;

public:
	// Initialize the FlxAnimStepDecoder from the FlxAnimStep.
	// 
	FlxAnimStepDecoder(const FlxAnimStep &step) : Decoder(step.Body) {}
	FlxAnimStepDecoder(const FlxAnimStoredStep& step) : Decoder(step.Body) {}

	// Return true if the parser has reached the end of the string.
	//
	bool AtEOF() { return Decoder.at_eof(); }

	// Read one field.
	// 
	FlxAnimField ReadField();

	// Convert an AnimStep to an FString.
	//
	static FString DebugString(const FlxAnimStep &step);
};

////////////////////////////////////////////////
//
// FlxAnimTracker
//
// This class monitors the animation queue for a single
// tangible.  It can identify when a new animation has
// appeared on the animation queue, and when animations have
// been removed from the animation queue.  It also
// keeps track of which animations have been started.
// 
////////////////////////////////////////////////

class FlxAnimTracker {
public:
	// Our own copy of the animation queue.  We only
	// store the hashes, not the steps.  The First element
	// of the queue is the oldest item.
	//
	TDeque<FlxAnimStoredStep> AQ;

	// The sequence number of the first item in AQ.
	//
	int32 FirstSeqno;

	// Map from hash to sequence number.
	//
	TMap<uint64, int32> HashToSeqno;

	// The sequence number of the first unstarted animation.
	//
	int32 UnstartedSeqno;

	// Indicates whether the unstarted animation should be played or otherwise.
	// 
	ElxAnimPlaybackMode PlaybackMode;
	
	// Array of recently-aborted hash values.
	//
	TArray<uint64> AbortedHashes;

public:
	// Construct a tracker.
	//
	// Initially, the tracker is in the empty (Clear) state.
	//
	FlxAnimTracker();

	// Update from the specified animation queue.
	//
	// After the update is done, AQ will be a copy
	// of the animation queue that is passed in.
	//
	void Update(std::string_view encqueue);

	// Fetch the aborted hash values.
	//
	// This gets the array of aborted hashes and clears
	// the stored array.
	//
	TArray<uint64> GetAborted();

	// Get the next unstarted animation step.
	//
	// Get the next animation step.  Returns the next step and the
	// playback mode.  If the playback mode is INVALID then there is
	// no next step to play
	//
	ElxAnimPlaybackMode GetNextStep(FlxAnimStoredStep& step);

	// Declare that an animation has been started.
	//
	// After starting an animation, you should call this.
	//
	void StartedStep(uint64 Hash);
};