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package org.semanticweb.elk.reasoner.saturation.rules.subsumers;

/*
 * #%L
 * ELK Reasoner
 * $Id:$
 * $HeadURL:$
 * %%
 * Copyright (C) 2011 - 2013 Department of Computer Science, University of Oxford
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import java.util.ArrayList;
import java.util.List;

import org.semanticweb.elk.owl.interfaces.ElkAxiom;
import org.semanticweb.elk.reasoner.indexing.model.IndexedClassExpression;
import org.semanticweb.elk.reasoner.indexing.model.IndexedClassExpressionList;
import org.semanticweb.elk.reasoner.indexing.model.ModifiableIndexedClassExpression;
import org.semanticweb.elk.reasoner.indexing.model.ModifiableIndexedDisjointClassesAxiom;
import org.semanticweb.elk.reasoner.indexing.model.ModifiableOntologyIndex;
import org.semanticweb.elk.reasoner.saturation.conclusions.model.DisjointSubsumer;
import org.semanticweb.elk.reasoner.saturation.context.ContextPremises;
import org.semanticweb.elk.reasoner.saturation.inferences.DisjointSubsumerFromSubsumer;
import org.semanticweb.elk.reasoner.saturation.rules.ClassInferenceProducer;
import org.semanticweb.elk.util.collections.chains.Chain;
import org.semanticweb.elk.util.collections.chains.Matcher;
import org.semanticweb.elk.util.collections.chains.ReferenceFactory;
import org.semanticweb.elk.util.collections.chains.SimpleTypeBasedMatcher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A {@link ChainableSubsumerRule} producing {@link DisjointSubsumer} when
 * processing an {@link IndexedClassExpression} that is present in an
 * {@link IndexedClassExpressionList} of this {@link DisjointSubsumer} exactly
 * once.
 * 
 * @author Pavel Klinov
 * 
 *         [email protected]
 * @author "Yevgeny Kazakov"
 */
public class DisjointSubsumerFromMemberRule
		extends
			AbstractChainableSubsumerRule {

	// logger for events
	private static final Logger LOGGER_ = LoggerFactory
			.getLogger(DisjointSubsumerFromMemberRule.class);

	public static final String NAME = "DisjointClasses Introduction";

	/**
	 * A list of {@link IndexedClassExpressionList}s; each representing disjoint
	 * {@link IndexedClassExpression}s
	 */
	private final List disjointMembers_;

	/**
	 * The positions at which the {@link IndexedClassExpression} for which the
	 * {@link DisjointSubsumerFromMemberRule} is registered, appears in the
	 * respective {@link IndexedClassExpressionList} of
	 * {@link #disjointMembers_}
	 */
	private final List positions_;

	/**
	 * The {@link ElkAxiom} that are responsible for the respective
	 * {@link IndexedClassExpressionList} of disjoint
	 * {@link IndexedClassExpression}s
	 * 
	 */
	private final List reasons_;

	private DisjointSubsumerFromMemberRule(ChainableSubsumerRule tail) {
		super(tail);
		this.disjointMembers_ = new ArrayList(1);
		this.positions_ = new ArrayList(1);
		this.reasons_ = new ArrayList(1);
	}

	private DisjointSubsumerFromMemberRule(
			ModifiableIndexedDisjointClassesAxiom axiom, int position,
			ElkAxiom reason) {
		this((ChainableSubsumerRule) null);
		disjointMembers_.add(axiom.getMembers());
		positions_.add(position);
		reasons_.add(reason);
	}

	public static boolean addRulesFor(
			ModifiableIndexedDisjointClassesAxiom axiom,
			ModifiableOntologyIndex index, ElkAxiom reason) {
		boolean success = true;
		int added = 0;
		List members = axiom
				.getMembers().getElements();
		for (int pos = 0; pos < members.size(); pos++) {
			ModifiableIndexedClassExpression ice = members.get(pos);
			if (index.add(ice,
					new DisjointSubsumerFromMemberRule(axiom, pos, reason))) {
				added++;
			} else {
				success = false;
				break;
			}
		}
		if (success)
			return true;
		// else revert the changes made
		for (int pos = 0; pos < members.size(); pos++) {
			ModifiableIndexedClassExpression ice = members.get(pos);
			if (added == 0)
				break;
			// else
			added--;
			index.remove(ice,
					new DisjointSubsumerFromMemberRule(axiom, pos, reason));
		}
		return false;
	}

	public static boolean removeRulesFor(
			ModifiableIndexedDisjointClassesAxiom axiom,
			ModifiableOntologyIndex index, ElkAxiom reason) {
		boolean success = true;
		int removed = 0;
		List members = axiom
				.getMembers().getElements();
		for (int pos = 0; pos < members.size(); pos++) {
			ModifiableIndexedClassExpression ice = members.get(pos);
			if (index.remove(ice,
					new DisjointSubsumerFromMemberRule(axiom, pos, reason))) {
				removed++;
			} else {
				success = false;
				break;
			}
		}
		if (success)
			return true;
		// else revert the changes made
		for (int pos = 0; pos < members.size(); pos++) {
			ModifiableIndexedClassExpression ice = members.get(pos);
			if (removed == 0)
				break;
			// else
			removed--;
			index.add(ice,
					new DisjointSubsumerFromMemberRule(axiom, pos, reason));
		}
		return false;
	}

	@Deprecated
	public List getDisjointnessAxioms() {
		return disjointMembers_;
	}

	@Override
	public String toString() {
		return NAME;
	}

	@Override
	public void accept(LinkedSubsumerRuleVisitor visitor,
			IndexedClassExpression premise, ContextPremises premises,
			ClassInferenceProducer producer) {
		visitor.visit(this, premise, premises, producer);
	}

	@Override
	public void apply(IndexedClassExpression member, ContextPremises premises,
			ClassInferenceProducer producer) {
		for (int i = 0; i < disjointMembers_.size(); i++) {
			producer.produce(new DisjointSubsumerFromSubsumer(
					premises.getRoot(), disjointMembers_.get(i),
					positions_.get(i), reasons_.get(i)));
		}
	}

	@Override
	public boolean isTracingRule() {
		return true;
	}

	@Override
	public boolean addTo(Chain ruleChain) {
		if (isEmpty())
			return true;
		DisjointSubsumerFromMemberRule rule = ruleChain.getCreate(MATCHER_,
				FACTORY_);
		boolean success = true;
		int added = 0;
		for (int i = 0; i < disjointMembers_.size(); i++) {
			IndexedClassExpressionList disjoint = disjointMembers_.get(i);
			int position = positions_.get(i);
			ElkAxiom reason = reasons_.get(i);
			if (LOGGER_.isTraceEnabled()) {
				LOGGER_.trace("{}: adding to {} reason: {}", disjoint, NAME,
						reason);
			}
			if (rule.disjointMembers_.add(disjoint)) {
				rule.positions_.add(position);
				rule.reasons_.add(reason);
				added++;
			} else {
				success = false;
				break;
			}
		}
		if (success) {
			return true;
		}
		// else revert all changes
		for (int i = 0; i < disjointMembers_.size(); i++) {
			if (added == 0)
				break;
			added--;
			IndexedClassExpressionList axiom = disjointMembers_.get(i);
			ElkAxiom reason = reasons_.get(i);
			if (LOGGER_.isTraceEnabled()) {
				LOGGER_.trace("{}: removing from {} reason: {}", axiom, NAME,
						reason);
			}
			int j = rule.indexOf(axiom, reason);
			rule.disjointMembers_.remove(j);
			rule.positions_.remove(j);
			rule.reasons_.remove(j);
		}
		return false;
	}

	@Override
	public boolean removeFrom(Chain ruleChain) {
		if (isEmpty())
			return true;
		DisjointSubsumerFromMemberRule rule = ruleChain.find(MATCHER_);
		if (rule == null)
			return false;
		// else
		boolean success = true;
		int removed = 0;
		for (int i = 0; i < disjointMembers_.size(); i++) {
			IndexedClassExpressionList axiom = disjointMembers_.get(i);
			ElkAxiom reason = reasons_.get(i);
			if (LOGGER_.isTraceEnabled()) {
				LOGGER_.trace("{}: removing from {} reason: {}", axiom, NAME,
						reason);
			}
			int j = rule.indexOf(axiom, reason);
			if (j >= 0) {
				rule.disjointMembers_.remove(j);
				rule.positions_.remove(j);
				rule.reasons_.remove(j);
				removed++;
			} else {
				success = false;
				break;
			}
		}
		if (success) {
			if (rule.isEmpty()) {
				ruleChain.remove(MATCHER_);
				LOGGER_.trace("{}: removed ", NAME);
			}
			return true;
		}
		// else revert all changes
		for (int i = 0; i < disjointMembers_.size(); i++) {
			if (removed == 0)
				break;
			removed--;
			IndexedClassExpressionList axiom = disjointMembers_.get(i);
			int position = positions_.get(i);
			ElkAxiom reason = reasons_.get(i);
			if (LOGGER_.isTraceEnabled()) {
				LOGGER_.trace("{}: adding to {} reason: {} [revert]", axiom,
						NAME, reason);
			}
			rule.disjointMembers_.add(axiom);
			rule.positions_.add(position);
			rule.reasons_.add(reason);
		}
		return false;
	}

	private int indexOf(IndexedClassExpressionList disjoint, ElkAxiom reason) {
		for (int i = 0; i < disjointMembers_.size(); i++) {
			if (disjointMembers_.get(i).equals(disjoint)
					&& reasons_.get(i).equals(reason))
				return i;
		}
		// else not found
		return -1;
	}

	private boolean isEmpty() {
		return disjointMembers_.isEmpty();
	}

	private static Matcher MATCHER_ = new SimpleTypeBasedMatcher(
			DisjointSubsumerFromMemberRule.class);

	private static ReferenceFactory FACTORY_ = new ReferenceFactory() {
		@Override
		public DisjointSubsumerFromMemberRule create(
				ChainableSubsumerRule tail) {
			return new DisjointSubsumerFromMemberRule(tail);
		}
	};
}