RP412/MUNGA/SIMULATE.h

#pragma once

#include "state.h"
#include "receiver.h"
#include "time.h"
#include "resource.h"
#include "hostid.h"

//##########################################################################
//###########################    Net clock    ##############################
//##########################################################################
//
// Aligning a peer's clock with ours, so a replicant is dead-reckoned from
// when its update was SENT rather than when it happened to arrive.
//
// Every update record carries the sender's own timestamp. The receiver
// used to throw it away and stamp lastUpdate with its own Now() - the
// original code says so: "HACK - should be based upon message->timeStamp".
// The dead reckoner then extrapolates over (lastPerformance - lastUpdate),
// so starting that clock at ARRIVAL rather than at SEND leaves every
// remote vehicle exactly one network latency behind where it should be.
// On the 1 ms arcade LAN that was invisible. Over Steam Datagram Relay it
// is a constant 50-150 ms of positional lag - a bias, not jitter.
//
// The timestamp cannot be used raw: two machines' clocks share no epoch,
// both being QueryPerformanceCounter since their own boot. So we estimate
// the offset per peer. Each arriving record gives
//
//     sample = ourNow - theirStamp = trueOffset + oneWayLatency
//
// and since latency is never negative, the SMALLEST sample seen is the
// closest to the true offset. Taking a minimum over a short rolling
// window tracks crystal drift and re-adapts when the route changes,
// instead of being pinned forever by one lucky packet.
//
// RP412NETCLOCK=0 turns the whole thing off and restores the arrival-time
// behaviour, so a test machine can A/B it without a rebuild.
//
void NetClock_BeginUpdate(HostID sender);	// around one message's records
void NetClock_EndUpdate();
void NetClock_Reset();						// forget every peer (new mission)

class Simulation__SharedData;
class Simulation__IndexData;
struct Simulation__IndexEntry;
class Simulation__AttributeIndexSet;
class MemoryStream;

//##########################################################################
//#################    Simulation::UpdateRecord    #########################
//##########################################################################

struct Simulation__UpdateRecord
{
public:
	size_t recordLength;
	Word subsystemID;
	Word recordID;
	Time timeStamp;
	Enumeration simulationState;
};

//##########################################################################
//#######################    Simulation    #################################
//##########################################################################

class Simulation:
	public Receiver
{
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Shared Data Support
//
public:
	typedef Simulation__SharedData SharedData;
	SharedData*
		GetSharedData();

	static Derivation *GetClassDerivations();

	static SharedData DefaultData;

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Construction and Destruction Support
//
protected:
	Simulation(
		ClassID class_ID,
		SharedData &shared_data
	);

public:
	~Simulation();

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Attribute Support
//
public:
	typedef Enumeration							AttributeID;
	typedef Simulation__IndexData				IndexData;
	typedef Simulation__IndexEntry			IndexEntry;
	typedef Simulation__AttributeIndexSet	AttributeIndexSet;
	typedef int Simulation::*AttributePointer;

	enum {
		AnyAttributeID = 0,
		SimulationStateAttributeID,
		NextAttributeID
	};

	static const AttributePointer NullAttribute;

	void*
		GetAttributePointer(AttributeID attribute);
	void*
		GetAttributePointer(const char* attribute_name);

private:
	static const IndexEntry AttributePointers[];

protected:
	//static AttributeIndexSet	AttributeIndex
	static AttributeIndexSet& GetAttributeIndex();

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Simulation Support
//
public:
	typedef void
		(Simulation::*Performance)(Scalar time_slice);
	typedef void
		(Simulation::*Encore)();
	typedef Simulation__UpdateRecord UpdateRecord;

	void
		SetPerformance(Performance performance)
			{Check(this); activePerformance = performance;}
	void
		Perform(Scalar time_slice)
			{
				Check(this);
				(this->*activePerformance)(time_slice);
			}

	virtual void
		PerformAndWatch(
			const Time& till,
			MemoryStream *update_stream
		);

	//
	// The two halves of PerformAndWatch, so an ENTITY can interleave its
	// subsystems' physics with its own, step by step, and still run the
	// watchers and the update stream once per frame. PerformTo advances
	// the simulation to the given time - in fixed steps when
	// RP412PHYSICSHZ names a rate, in one variable slice otherwise.
	//
	void
		PerformTo(const Time& till);
	void
		WatchAndWrite(MemoryStream *update_stream);

	//
	// Called by the entity interleave at the TOP of every fixed step,
	// before any subsystem adds its forces for that step. Per-frame set-up
	// work - clearing a force accumulator, deriving local velocity from
	// world state - belongs here when the fixed step is on, because "once
	// per frame" is a wall-clock cadence and the whole point is that wall
	// clock no longer reaches the physics. Default: nothing.
	//
	virtual void
		BeginStep();

	//
	// The fixed step in seconds, 0 when frame-coupled. Global on purpose:
	// a mixed-rate simulation would be a worse bug than either mode.
	//
	static Scalar
		FixedStep();

	void
		DoNothingOnce(Scalar time_slice);
	void
		DoNothing(Scalar time_slice);

	void
		SetLastPerformance(const Time& when)
			{Check(this); Check(&when); lastPerformance = when;}
	const Time&
		GetLastPerformance() const
			{Check(this); return lastPerformance;}
	void
		RequestEncore(Encore encore);

	virtual void
		ReadUpdateRecord(UpdateRecord *message);
	virtual void
		WriteUpdateRecord(
			UpdateRecord *message,
			int update_model
		);
	void
		WriteSimulationUpdate(MemoryStream *update_stream);

	enum {
		DefaultUpdateModelBit=0,
		NextUpdateModelBit
	};

	enum {
		DefaultUpdateModelFlag = 1<<DefaultUpdateModelBit
	};

	void
		ForceUpdate(Word model=DefaultUpdateModelFlag)
			{Check(this); updateModel |= model;}

protected:
	Time
		lastPerformance;
	Time
		lastUpdate;
	Word
		updateModel;

	Performance
		activePerformance;

//##########################################################################
// Flag Support
//
public:
	enum {
		DelayWatchersBit,
		DontExecuteBit,
		NextBit
	};
	enum {
		DelayWatchersFlag		= 1<<DelayWatchersBit,
		DontExecuteFlag		= 1<<DontExecuteBit
	};

	LWord simulationFlags;

	void
		SetWatcherDelay()
			{Check(this); simulationFlags |= DelayWatchersFlag;}
	void
		ClearWatcherDelay()
			{Check(this); simulationFlags &= ~DelayWatchersFlag;}
	Logical
		AreWatchersDelayed()
			{Check(this); return (simulationFlags & DelayWatchersFlag) != 0;}

	void
		NeverExecute()
			{Check(this); simulationFlags |= DontExecuteFlag;}
	void
		ExecuteOnUpdate()
			{Check(this); simulationFlags |= DontExecuteFlag;}
	void
		AlwaysExecute()
			{Check(this); simulationFlags &= ~DontExecuteFlag;}
	Logical
		IsReplicantExecutable()
			{
				Check(this);
				return
					(simulationFlags&DontExecuteFlag) == 0
					 || lastUpdate >= lastPerformance;
			}
	Logical
		IsNonReplicantExecutable()
			{Check(this); return (simulationFlags&DontExecuteFlag) == 0;}

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// State support
//
public:
	enum {
		DefaultState = 0,
		StateCount
	};

	unsigned
		GetSimulationState()
			{Check(this); return simulationState.GetState();}
	unsigned
		GetOldSimulationState()
			{Check(this); return simulationState.GetOldState();}
	void
		SetSimulationState(unsigned new_state)
			{Check(this); simulationState.SetState(new_state);}

	StateIndicator
		simulationState;

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Watcher Support
//
public:
	void
		AddAudioWatcher(Component *watcher)
			{Check(&audioWatcherSocket);audioWatcherSocket.Add(watcher);}
	void
		AddVideoWatcher(Component *watcher)
			{Check(&videoWatcherSocket);videoWatcherSocket.Add(watcher);}
	void
		AddGaugeWatcher(Component *watcher)
			{Check(&gaugeWatcherSocket);gaugeWatcherSocket.Add(watcher);}

	void
		AddEffectWatcher(Component *watcher)
		{Check(&effectWatcherSocket); effectWatcherSocket.Add(watcher);}

	void
		ExecuteWatchers();

private:
	SChainOf<Component*>
		audioWatcherSocket;
	SChainOf<Component*>
		videoWatcherSocket;
	SChainOf<Component*>
		gaugeWatcherSocket;
	SChainOf<Component*>
		effectWatcherSocket;

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Test Support
//
public:
	Logical
		TestInstance() const;
	static Logical
		TestClass();
};

//##########################################################################
//###################    Simulation::IndexEntry    #########################
//##########################################################################

struct Simulation__IndexEntry
{
	Enumeration
		entryID;
	const char *
		entryName;
	Simulation::AttributePointer
		entryAddress;
};

#define ATTRIBUTE_ENTRY(class,name,attribute)\
	{\
		class::name##AttributeID,\
		#name,\
		(Simulation::AttributePointer) &class::attribute\
	}

//##########################################################################
//#################    Simulation::AttributeIndexSet    ####################
//##########################################################################

class Simulation__AttributeIndexSet:
	public Receiver::InheritanceSet
{
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Construction and Destruction
//
public:
	Simulation__AttributeIndexSet(
		Simulation::AttributeID count,
		const Simulation::IndexEntry index_table[],
		const Simulation::AttributeIndexSet &inheritance
	)
		{Build(count, index_table, &inheritance);}

	Simulation__AttributeIndexSet(
		Simulation::AttributeID count,
		const Simulation::IndexEntry index_table[]
	)
		{Build(count, index_table, NULL);}

	Simulation__AttributeIndexSet()
		{attributeIndex = NULL; entryCount = 0;}

	~Simulation__AttributeIndexSet();

protected:
	void
		Build(
			Simulation::AttributeID count,
			const Simulation::IndexEntry index_table[],
			const Simulation::AttributeIndexSet *inheritance
		);

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// AttributeIndexSet Functionality
//
protected:
	Simulation::IndexEntry
		*attributeIndex;

public:
	Simulation::AttributePointer
		Find(Simulation::AttributeID attribute) const
			{
				Check(this);
           Verify(attribute > 0);
				if (attribute<=entryCount)
					return attributeIndex[attribute-1].entryAddress;
				else
					return Simulation::NullAttribute;
			}
	Simulation::AttributePointer
		Find(const char* attribute_name) const;
	const Simulation::IndexEntry*
		FindEntry(const char* attribute_name) const;

	static const Simulation::AttributeIndexSet
		NullSet;

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Test Support
//
public:
	static Logical
		TestClass();
};

//##########################################################################
//###################    Simulation::SharedData    #########################
//##########################################################################

class Simulation__SharedData:
	public Receiver::SharedData
{
public:
	Simulation__SharedData(
		Derivation* derivation,
		Receiver::MessageHandlerSet &message_handlers,
		Simulation::AttributeIndexSet &attribute_index,
		int state_count
	):
		Receiver::SharedData(derivation, message_handlers),
		activeAttributeIndex(&attribute_index),
		stateCount(state_count)
			{}

	Simulation::AttributeIndexSet*	activeAttributeIndex;
	int stateCount;
};

inline Simulation::SharedData*
	Simulation::GetSharedData()
		{return Cast_Object(SharedData*,sharedData);}