pstlab / PLATINUm

@TemporalFacadeConfiguration(

		// default network type 

		network = TemporalNetworkType.STNU,

		// default temporal reasoner

		solver = TemporalSolverType.APSP

)

public class TemporalFacade extends FrameworkObject implements QueryManager<TemporalQuery>

{

	@TemporalNetworkPlaceholder

	protected TemporalNetwork tn;										// temporal network

	@TemporalSolverPlaceholder

	protected TemporalSolver<TimePointQuery> solver;					// time point reasoner

	protected Set<TemporalInterval> intervals;							// set of created temporal intervals

	protected TemporalQueryFactory qf;									// temporal query factory

	protected TemporalConstraintFactory cf;	 							// temporal constraint factory

	// static information

	private static final AtomicInteger ID_COUNTER = new AtomicInteger(0);

	/**

	 * 

	 */

	protected TemporalFacade() {

		super();

		// get query factory instance

		this.qf = new TemporalQueryFactory();

		this.cf = new TemporalConstraintFactory();

		this.intervals = new HashSet<>();

		// reset atomic id counter if needed

		ID_COUNTER.set(0);

	}

	/**

	 * 

	 * @return

	 */

	public long getOrigin() {

		return this.tn.getOrigin();

	}

	/**

	 * 

	 * @return

	 */

	public long getHorizon() {

		return this.tn.getHorizon();

	}

	/**

	 * Create a flexible time point

	 * 

	 * @return

	 * @throws TimePointCreationException

	 */

	public synchronized TimePoint createTimePoint() 

			throws TimePointCreationException 

	{

		// time point to create

		TimePoint point = null;

		try {

			// create a time point

			point = this.tn.addTimePoint();

		} catch (InconsistentDistanceConstraintException ex) {

			throw new TimePointCreationException(ex.getMessage());

		}

		// get time point

		return point;

	}

	/**

	 * Create a scheduled time point

	 * 

	 * @param at

	 * @return

	 * @throws TimePointCreationException

	 */

	public synchronized TimePoint createTimePoint(long at) 

			throws TimePointCreationException {

		// time point to create

		TimePoint point = null;

		try {

			// create a fixed time point

			point = this.tn.addTimePoint(at);

		} catch (InconsistentTpValueException | InconsistentDistanceConstraintException  ex) {

			throw new TimePointCreationException(ex.getMessage());

		}

		// get time point

		return point;

	}

	/**

	 * Create a flexible time point within the specified bound

	 * 

	 * @param bounds

	 * @return

	 * @throws TimePointCreationException

	 */

	public synchronized TimePoint createTimePoint(long[] bounds) 

			throws TimePointCreationException {

		// time point to create

		TimePoint point = null;

		try {

			// create a time point within bound

			point = this.tn.addTimePoint(bounds[0], bounds[1]);

		} catch (InconsistentDistanceConstraintException | InconsistentTpValueException ex) {

			throw new TimePointCreationException(ex.getMessage());

		}

		// get created time point

		return point;

	}

	/**

	 * Create a controllable temporal interval

	 * 

	 * @return

	 * @throws TemporalIntervalCreationException

	 */

	public synchronized TemporalInterval createTemporalInterval(boolean controllable) 

			throws TemporalIntervalCreationException {

		// create temporal interval

		return this.createTemporalInterval(new long[] {this.getOrigin(), this.getHorizon()}, 

				new long[] {this.getOrigin(), this.getHorizon()}, 

				new long[] {1, this.getHorizon()}, 

				controllable);		

	}

	/**

	 * Create a flexible interval with duration within the specified bound

	 * 

	 * @param duration

	 * @return

	 * @throws TemporalIntervalCreationException

	 */

	public synchronized TemporalInterval createTemporalInterval(long[] duration, boolean controllable) 

			throws TemporalIntervalCreationException 

	{

		// create temporal interval

		return this.createTemporalInterval(new long[] {this.getOrigin(), this.getHorizon()}, 

				new long[] {this.getOrigin(), this.getHorizon()}, 

				duration, 

				controllable);

	}

	/**

	 * 

	 * @param end

	 * @param duration

	 * @param controllable

	 * @return

	 * @throws TemporalIntervalCreationException

	 */

	public synchronized TemporalInterval createTemporalInterval(long[] end, long[] duration, boolean controllable) 

			throws TemporalIntervalCreationException 

	{

		// create temporal interval

		return this.createTemporalInterval(new long[] {this.getOrigin(), this.getHorizon()}, 

				end, 

				duration, 

				controllable);

	}

	/**

	 * 

	 * @param end

	 * @param duration

	 * @param controllable

	 * @return

	 * @throws TemporalIntervalCreationException

	 */

	public synchronized TemporalInterval createTemporalInterval(long[] start, long[] end, long[] duration, boolean controllable) 

			throws TemporalIntervalCreationException {

		// interval's start time

		TimePoint s = null;

		try {

			// create flexible start time

			s = this.tn.addTimePoint(start[0], start[1]);

		} catch (InconsistentDistanceConstraintException | InconsistentTpValueException ex) {

			// throw exception

			throw new InconsistentIntervalStartTimeException(ex.getMessage());

		}

		// interval's end time

		TimePoint e = null;

		try {

			// create flexible end time

			e = this.tn.addTimePoint(end[0], end[1]);

		} catch (InconsistentDistanceConstraintException | InconsistentTpValueException ex) {

			// delete start time

			this.tn.removeTimePoint(s);

			throw new InconsistentIntervaEndTimeException(ex.getMessage());

		}

		// interval's duration

		TimePointDistanceConstraint d = null;

		try {

			// create distance constraint

			d = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

			d.setReference(s);

			d.setTarget(e);

			d.setDistanceLowerBound(Math.max(1, duration[0]));

			d.setDistanceUpperBound(Math.min(duration[1], this.getHorizon()));

			d.setControllable(controllable);

			// propagate distance constraint

			this.tn.addDistanceConstraint(d);

		} catch (InconsistentDistanceConstraintException ex) {

			// remove start and end time points

			this.tn.removeTimePoint(s);

			this.tn.removeTimePoint(e);

			// throw exception

			throw new InconsistentIntervalDurationException(ex.getMessage());

		}

		// create temporal interval 

		TemporalInterval interval = new TemporalInterval(ID_COUNTER.getAndIncrement(), d);

		// record interval

		this.intervals.add(interval);

		// get created interval

		return interval;

	}

	/**

	 * 

	 * Remove a temporal interval from the temporal data-based. 

	 * 

	 * The method removes the time points of the interval and all related time point distance constraints from the underlying temporal network

	 * 

	 * @param i

	 */

	public synchronized void deleteTemporalInterval(TemporalInterval i) {

		// list of time points to remove

		List<TimePoint> list = new ArrayList<>();

		// get start time

		list.add(i.getStartTime());

		// get end time

		list.add(i.getEndTime());

		// the network will automatically remove all constraints concerning the two time points

		this.tn.removeTimePoints(list);

		// remove interval 

		this.intervals.remove(i);

	}

	/**

	 * Check the temporal consistency of the temporal information as well as the 

	 * pseudo-controllability property of the STNU.

	 * 

	 * 

	 */

	public synchronized void verify() 

			throws ConsistencyCheckException {

		// check temporal network consistency

		if (!this.solver.isValid()) {

			throw new TemporalConsistencyException("The STNU is not valid!\nCheck propagated temporal constraints...\n");

		}

		// check also if the network is valid

		if (!this.isPseudoControllable()) {

			throw new PseudoControllabilityException("The STNU is not pseudo-controllable!\nCheck constraints on uncontrollable intervals...\n");

		}

	}

	/**

	 * 

	 * @throws TemporalConsistencyException

	 */

	public synchronized void verifyTemporalConsistency() 

			throws TemporalConsistencyException {

		// check temporal network consistency

		if (!this.solver.isValid()) {

			throw new TemporalConsistencyException("The STNU is not valid!\nCheck propagated temporal constraints...\n");

		}

	}

	/**

	 * 

	 * @throws PseudoControllabilityException

	 */

	public synchronized void verifyPseudocontrollability() 

			throws PseudoControllabilityException {

		// check also if the network is valid

		if (!this.isPseudoControllable()) {

			throw new PseudoControllabilityException("The STNU is not pseudo-controllable!\nCheck constraints on uncontrollable intervals...\n");

		}

	}

	/**

	 * 

	 * @param type

	 * @return

	 */

	public synchronized <T extends TemporalQuery> T createTemporalQuery(TemporalQueryType type) {

		// query instance

		T query = this.qf.create(type);

		// get created instance

		return query;

	}

	/**

	 * 

	 * @param type

	 * @return

	 */

	public synchronized <T extends TemporalConstraint> T createTemporalConstraint(TemporalConstraintType type) {

		// create constraint

		T cons = this.cf.create(type);

		// get created constraint

		return cons;

	}

	/**

	 * 

	 */

	@Override

	public synchronized void process(TemporalQuery query) 

	{

		// check query type

		switch (query.getType()) 

		{

			// check distance between intervals

			case INTERVAL_DISTANCE : 

			{

				// get query

				IntervalDistanceQuery dQuery = (IntervalDistanceQuery) query;

				// get intervals

				TemporalInterval a = dQuery.getSource();

				TemporalInterval b = dQuery.getTarget();

				// create time point query

				TimePointDistanceQuery tpQuery = this.qf.create(TemporalQueryType.TP_DISTANCE);

				// set source and target

				tpQuery.setSource(a.getEndTime());

				tpQuery.setTarget(b.getStartTime());

				// process query

				this.solver.process(tpQuery);

				// set bounds

				dQuery.setDistanceLowerBound(tpQuery.getDistanceLowerBound());

				dQuery.setDistanceUpperBOund(tpQuery.getDistanceUpperBound());

			}

			break;

			// check overlapping intervals

			case INTERVAL_OVERLAP :

			{

				// get query

				IntervalOverlapQuery overlap = (IntervalOverlapQuery) query;

				// get intervals

				TemporalInterval a = overlap.getReference();

				TemporalInterval b = overlap.getTarget();

				// check the distance between the time point of A and the start time point of B

				TimePointDistanceQuery eAsB = this.qf.create(TemporalQueryType.TP_DISTANCE);

				eAsB.setSource(a.getEndTime());

				eAsB.setTarget(b.getStartTime());

				// process query

				this.process(eAsB);

				// check computed bounds

				long dmin = eAsB.getDistanceLowerBound();

				long dmax = eAsB.getDistanceUpperBound();

				// check if can overlap

				boolean o1 = !((dmin <= 0 && dmax <= 0) || (dmin >= 0 && dmax >= 0));

				// get intervals

				a = overlap.getTarget();

				b = overlap.getReference();

				// check the distance between the time point of A and the start time point of B

				TimePointDistanceQuery eBsA = this.qf.create(TemporalQueryType.TP_DISTANCE);

				eBsA.setSource(a.getEndTime());

				eBsA.setTarget(b.getStartTime());

				// process query

				this.process(eBsA);

				// check computed bounds

				dmin = eBsA.getDistanceLowerBound();

				dmax = eBsA.getDistanceUpperBound();

				// check if can overlap

				boolean o2 = !((dmin <= 0 && dmax <= 0) || (dmin >= 0 && dmax >= 0));

				// set result

				overlap.setCanOverlap(o1 || o2);

				// print logging message

				debug("[" + this.getClass().getName() + "] Processing query INTERVAL_OVERLAP:\n"

						+ "- Temporal Interval (A): " + a + "\n"

						+ "- Temporal Interval (B): " + b + "\n"

						+ "- Computed (flexible) distance: [dmin= " + dmin + ", dmax= " + dmax +"]\n"

						+ "- Answer to query: " + overlap.canOverlap());

			}

			break;

			// check interval schedule 

			case INTERVAL_SCHEDULE : 

			{

				// get query

				IntervalScheduleQuery scheduleQuery = (IntervalScheduleQuery) query;

				// get interval

				TemporalInterval i = scheduleQuery.getInterval();

				// create time point bound query

				TimePointScheduleQuery sQuery = this.qf.create(TemporalQueryType.TP_SCHEDULE);

				// set point 

				sQuery.setTimePoint(i.getStartTime());

				// check start schedule

				this.solver.process(sQuery);

				// process end time

				TimePointScheduleQuery eQuery = this.qf.create(TemporalQueryType.TP_SCHEDULE);

				// set point

				eQuery.setTimePoint(i.getEndTime());

				// check end schedule

				this.solver.process(eQuery);

				// check time point distance

				TimePointDistanceQuery dQuery= this.qf.create(TemporalQueryType.TP_DISTANCE);

				// set points

				dQuery.setSource(i.getStartTime());

				dQuery.setTarget(i.getEndTime());

				// process query

				this.solver.process(dQuery);

				// set interval duration

				i.setDurationLowerBound(dQuery.getDistanceLowerBound());

				i.setDurationUpperBound(dQuery.getDistanceUpperBound());

			}

			break;

			// check if squeezed interval

			case INTERVAL_PSEUDO_CONTROLLABILITY : 

			{

				// get query

				IntervalPseudoControllabilityQuery pseudoQuery = (IntervalPseudoControllabilityQuery) query;

				// get temporal interval

				TemporalInterval i = pseudoQuery.getInterval();

				// check the schedule

				IntervalScheduleQuery squery = this.qf.create(TemporalQueryType.INTERVAL_SCHEDULE);

				squery.setInterval(i);

				this.process(squery);

				// check if pseudo-controllability condition

				pseudoQuery.setPseudoControllable(i.getDurationLowerBound() == i.getNominalDurationLowerBound() && 

						i.getDurationUpperBound() == i.getNominalDurationUpperBound());

			}

			break;

			// time point queries

			case TP_SCHEDULE :

			case TP_DISTANCE : 

			case TP_DISTANCE_TO_HORIZON : {

				// propagate time point query to the reasoner

				this.solver.process((TimePointQuery) query);

			}

			break;

		}

	}

	/**

	 * This method propagates an interval constraint to the underlying temporal network.

	 * 

	 * When propagating constraints no contingent link can be affected or overwritten. Thus,

	 * the method throws an exception if a contingent link is affected by the propagated 

	 * constraint.

	 * 

	 * @param constraint

	 * @throws Exception

	 */

	public synchronized void propagate(TemporalConstraint constraint) 

			throws TemporalConstraintPropagationException 

	{

		try 

		{

			// check temporal constraint type

			switch (constraint.getType()) 

			{

				// create BEFORE constraint into the temporal network

				case BEFORE : 

				{

					// get constraint

					BeforeIntervalConstraint before = (BeforeIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = new TimePointDistanceConstraint[] { 

						this.doPropagateBeforeConstraint(before)

					};

					// set propagated constraint

					before.setPropagatedConstraints(c);

				}

				break;

				// create AFTER constraint into the temporal network

				case AFTER : 

				{

					AfterIntervalConstraint after = (AfterIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = new TimePointDistanceConstraint[] {

						this.doPropagateAfterConstraint(after)

					};

					// set propagated constraint

					after.setPropagatedConstraints(c);

				}

				break;

				// create MEETS constraint into the temporal network

				case MEETS : 

				{

					// get constraint

					MeetsIntervalConstraint meets = (MeetsIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = new TimePointDistanceConstraint[] { 

							this.doPropagateMeetsConstraint(meets)	

					};

					// set propagated constraints

					meets.setPropagatedConstraints(c);

				}

				break;

				// create MET-BY constraint into the temporal network

				case MET_BY : 

				{

					// get constraint

					MetByIntervalConstraint metby = (MetByIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = new TimePointDistanceConstraint[] {

							this.doPropagateMetByConstraint(metby)

					};

					// set propagated constraints

					metby.setPropagatedConstraints(c);

				}

				break;

				// create CONTAINS constraint into the temporal network

				case CONTAINS : 

				{

					// get constraint

					ContainsIntervalConstraint contains = (ContainsIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = this.doPropagateContainsConstraint(contains);

					// set propagated constraints

					contains.setPropagatedConstraints(c);

				}

				break;

				// create DURING constraint into the temporal network

				case DURING : 

				{

					// get constraint

					DuringIntervalConstraint during = (DuringIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = this.doPropagateDuringConstraint(during);

					// set propagated constraints

					during.setPropagatedConstraints(c);

				}

				break;

				// create STARTS-DURING constraint into the network

				case STARTS_DURING : 

				{

					// get constraint

					StartsDuringIntervalConstraint sdc = (StartsDuringIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = this.doPropagateStartsDuringConstraint(sdc);

					// set propagated constraints

					sdc.setPropagatedConstraints(c);

				}

				break;

				// create ENDS-DURING constraint into the network

				case ENDS_DURING : 

				{

					// get constraint

					EndsDuringIntervalConstraint edc = (EndsDuringIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = this.doPropagateEndsDuringConstraint(edc);

					// set propagated constraints

					edc.setPropagatedConstraints(c);

				}

				break;

				// create EQUALS constraint into the temporal network

				case EQUALS : 

				{

					// get constraint

					EqualsIntervalConstraint equals = (EqualsIntervalConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint[] c = this.doPropagateEqualsConstraint(equals);

					// set propagated constraint

					equals.setPropagatedConstraints(c);

				}

				break;

				// set the duration of a temporal interval

				case FIX_INTERVAL_DURATION : 

				{

					// get constraint

					FixIntervalDurationConstraint fix = (FixIntervalDurationConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint c = this.doPropagateFixIntervalDurationConstraint(fix);

					// set propagate constraints

					fix.setPropagatedConstraints(new TimePointDistanceConstraint[] {c});

				}

				break;

				// schedule a time point at a given time

				case FIX_TIME_POINT :

				{

					// get constraint

					FixTimePointConstraint fix = (FixTimePointConstraint) constraint;

					// propagate constraint

					TimePointDistanceConstraint c = this.doPropagateFixTimePointConstraint(fix);

					// set propagated constraint

					fix.setPropagatedConstraints(new TimePointDistanceConstraint[] {c});

				}

				break;

				// set a distance constraint between two time points

				case TIME_POINT_DISTANCE :

				{

					// get constraint

					TimePointDistanceConstraint cons = (TimePointDistanceConstraint) constraint;

					// directly propagate distance constraint to the temporal network

					this.tn.addDistanceConstraint(cons);

				}

				break;

				default : { 

				}

			}

		}

		catch (InconsistentDistanceConstraintException ex) {

			throw new TemporalConstraintPropagationException(ex.getMessage());

		}

	}

	/**

	 * 

	 * @param constraint

	 * @throws Exception

	 */

	public synchronized void retract(TemporalConstraint constraint) {

		// retract propagated constraints

		TimePointDistanceConstraint[] toRetract = constraint.getPropagatedConstraints();

		// verify whether some constraints have been propagated

		if (toRetract != null) {

			// remove propagated distance constraints

			this.tn.removeDistanceConstraint(Arrays.asList(toRetract));

			// clear data structure

			constraint.clear();

		}

	}

	/**

	 * 

	 */

	@Override

	public String toString() {

		return "\nTemporal Network:\n"

				+ "" + this.tn.toString() + "\n"

				+ "--------------\n"

				+ "Solver:\n"

				+ "" + this.solver.toString() + "\n\n";

	}

	/**

	 * 

	 * @param equals

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint[] doPropagateEqualsConstraint(EqualsIntervalConstraint equals) 

			throws InconsistentDistanceConstraintException {

		// create distance constraint 

		TimePointDistanceConstraint c1 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		// set constraint data

		c1.setReference(equals.getReference().getStartTime());

		c1.setTarget(equals.getTarget().getStartTime());

		c1.setDistanceLowerBound(0);

		c1.setDistanceUpperBound(0);

		c1.setControllable(true);

		// create distance constraint

		TimePointDistanceConstraint c2 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		// set constraint data

		c2.setReference(equals.getReference().getEndTime());

		c2.setTarget(equals.getTarget().getEndTime());

		c2.setDistanceLowerBound(0);

		c2.setDistanceUpperBound(0);

		c2.setControllable(true);

		// add constraints

		this.tn.addDistanceConstraint(new TimePointDistanceConstraint[] {c1, c2});

		// get added distance constraints

		return new TimePointDistanceConstraint[] {c1, c2};

	}

	/**

	 * 

	 * @param contains

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint[] doPropagateContainsConstraint(ContainsIntervalConstraint contains) 

			throws InconsistentDistanceConstraintException {

		// create distance constraint

		TimePointDistanceConstraint c1 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		// set data

		c1.setReference(contains.getReference().getStartTime());

		c1.setTarget(contains.getTarget().getStartTime());

		c1.setDistanceLowerBound(contains.getFirstBound()[0]);

		c1.setDistanceUpperBound(contains.getFirstBound()[1]);

		c1.setControllable(true);

		// create distance constraint

		TimePointDistanceConstraint c2 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		// set data

		c2.setReference(contains.getTarget().getEndTime());

		c2.setTarget(contains.getReference().getEndTime());

		c2.setDistanceLowerBound(contains.getSecondBound()[0]);

		c2.setDistanceUpperBound(contains.getSecondBound()[1]);

		c2.setControllable(true);

		// add constraints

		this.tn.addDistanceConstraint(new TimePointDistanceConstraint[] {c1, c2});

		// get added constraints

		return new TimePointDistanceConstraint[] {c1, c2};

	}

	/**

	 * 

	 * @param during

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint[] doPropagateDuringConstraint(DuringIntervalConstraint during) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c1 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c1.setReference(during.getTarget().getStartTime());

		c1.setTarget(during.getReference().getStartTime());

		c1.setDistanceLowerBound(during.getFirstBound()[0]);

		c1.setDistanceUpperBound(during.getFirstBound()[1]);

		c1.setControllable(true);

		// create constraint

		TimePointDistanceConstraint c2 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c2.setReference(during.getReference().getEndTime());

		c2.setTarget(during.getTarget().getEndTime());

		c2.setDistanceLowerBound(during.getSecondBound()[0]);

		c2.setDistanceUpperBound(during.getSecondBound()[1]);

		c2.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(new TimePointDistanceConstraint[] {c1, c2});

		// get added constraints

		return new TimePointDistanceConstraint[] {c1, c2};

	}

	/**

	 * 

	 * @param edc

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint[] doPropagateEndsDuringConstraint(EndsDuringIntervalConstraint edc) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c1 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c1.setReference(edc.getTarget().getStartTime());

		c1.setTarget(edc.getReference().getEndTime());

		c1.setDistanceLowerBound(edc.getFirstTimeBound()[0]);

		c1.setDistanceUpperBound(edc.getFirstTimeBound()[1]);

		c1.setControllable(true);

		// create constraint

		TimePointDistanceConstraint c2 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c2.setReference(edc.getReference().getEndTime());

		c2.setTarget(edc.getTarget().getEndTime());

		c2.setDistanceLowerBound(edc.getSecondTimeBound()[0]);

		c2.setDistanceUpperBound(edc.getSecondTimeBound()[1]);

		c2.setControllable(true);

		// add constraint 

		this.tn.addDistanceConstraint(new TimePointDistanceConstraint[] {c1, c2});

		// propagate constraints

		return new TimePointDistanceConstraint[] {c1, c2};

	}

	/**

	 * 

	 * @param sdc

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint[] doPropagateStartsDuringConstraint(StartsDuringIntervalConstraint sdc) 

			throws InconsistentDistanceConstraintException 

	{

		// create constraint

		TimePointDistanceConstraint c1 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c1.setReference(sdc.getTarget().getStartTime());

		c1.setTarget(sdc.getReference().getStartTime());

		c1.setDistanceLowerBound(sdc.getFirstTimeBound()[0]);

		c1.setDistanceUpperBound(sdc.getFirstTimeBound()[1]);

		c1.setControllable(true);

		// create constraint

		TimePointDistanceConstraint c2 = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE); 

		c2.setReference(sdc.getReference().getStartTime());

		c2.setTarget(sdc.getTarget().getEndTime());

		c2.setDistanceLowerBound(sdc.getSecondTimeBound()[0]);

		c2.setDistanceUpperBound(sdc.getSecondTimeBound()[1]);

		c2.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(new TimePointDistanceConstraint[] {c1, c2});

		// propagate constraints

		return new TimePointDistanceConstraint[] {c1, c2};

	}

	/**

	 * 

	 * @param before

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint doPropagateBeforeConstraint(BeforeIntervalConstraint before)

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c.setReference(before.getReference().getEndTime());

		c.setTarget(before.getTarget().getStartTime());

		c.setDistanceLowerBound(before.getLowerBound());

		c.setDistanceUpperBound(before.getUpperBound());

		c.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(c);

		// get propagated constraint

		return c;

	}

	/**

	 * 

	 * @param meets

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint doPropagateMeetsConstraint(MeetsIntervalConstraint meets) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c.setReference(meets.getReference().getEndTime());

		c.setTarget(meets.getTarget().getStartTime());

		c.setDistanceLowerBound(0);

		c.setDistanceUpperBound(0);

		c.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(c);

		// get propagated constraint

		return c;

	}

	/**

	 * 

	 * @param after

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint doPropagateAfterConstraint(AfterIntervalConstraint after) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c.setReference(after.getTarget().getEndTime());

		c.setTarget(after.getReference().getStartTime());

		c.setDistanceLowerBound(after.getLowerBound());

		c.setDistanceUpperBound(after.getUpperBound());

		c.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(c);

		// get propagated constraint

		return c;

	}

	/**

	 * 

	 * @param metby

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint doPropagateMetByConstraint(MetByIntervalConstraint metby) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c.setReference(metby.getTarget().getEndTime());

		c.setTarget(metby.getReference().getStartTime());

		c.setDistanceLowerBound(0);

		c.setDistanceUpperBound(0);

		c.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(c);

		// get propagated constraint

		return c;

	}

	/**

	 * 

	 * @param fix

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint doPropagateFixTimePointConstraint(FixTimePointConstraint fix) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c.setReference(this.tn.getOriginTimePoint());

		c.setTarget(fix.getReference());

		c.setDistanceLowerBound(fix.getTime());

		c.setDistanceUpperBound(fix.getTime());

		c.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(c);

		// get propagated constraint

		return c;

	}

	/**

	 * 

	 * @param reference

	 * @param duration

	 * @return

	 * @throws InconsistentDistanceConstraintException

	 */

	protected TimePointDistanceConstraint doPropagateFixIntervalDurationConstraint(FixIntervalDurationConstraint fix) 

			throws InconsistentDistanceConstraintException {

		// create constraint

		TimePointDistanceConstraint c = this.cf.create(TemporalConstraintType.TIME_POINT_DISTANCE);

		c.setReference(fix.getReference().getStartTime());

		c.setTarget(fix.getReference().getEndTime());

		c.setDistanceLowerBound(fix.getDuration());

		c.setDistanceUpperBound(fix.getDuration());

		c.setControllable(true);

		// add constraint

		this.tn.addDistanceConstraint(c);

		// get propagated constraint

		return c;

	}

	/**

	 * This method checks if the STNU is pseudo-controllable. 

	 * 

	 *	This procedure checks if contingent links have been "squeezed"

	 *	so, the STNU is pseudo-controllable if no assumption has been 

	 *	made on the duration of uncontrollable constraints (i.e. contingent

	 *	links).

	 *

	 * @return

	 */

	private boolean isPseudoControllable() {

		// hypothesis

		boolean pseudoControllable = true;

		// get constraints

		for (TimePointDistanceConstraint constraint : this.tn.getContingentConstraints()) {

			// check contingent constraints

			if (!constraint.isControllable()) {

				// create query

				TimePointDistanceQuery query = this.qf.create(TemporalQueryType.TP_DISTANCE);

				query.setSource(constraint.getReference());

				query.setTarget(constraint.getTarget());

				// process query

				this.solver.process(query);

				// get actual bounds

				long dmin = query.getDistanceLowerBound();

				long dmax = query.getDistanceUpperBound();

				// check duration

				pseudoControllable = !(dmin > constraint.getDistanceLowerBound() || dmax < constraint.getDistanceUpperBound());

			}