owlapi-version5/tools/src/main/java/uk/ac/manchester/cs/atomicdecomposition/Atom.java
package uk.ac.manchester.cs.atomicdecomposition;

import static org.semanticweb.owlapi.util.OWLAPIPreconditions.verifyNotNull;
import static org.semanticweb.owlapi.util.OWLAPIStreamUtils.add;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import javax.annotation.Nullable;
import org.semanticweb.owlapi.model.OWLAxiom;
import org.semanticweb.owlapi.model.OWLEntity;

/**
 * An atom in the atomic decomposition
 */
public class Atom {

    private final Collection<OWLAxiom> axioms;
    // XXX cache properly
    @Nullable
    private List<OWLEntity> signature;
    @Nullable
    private Collection<OWLEntity> label;
    private final int hashcode;

    /**
     * @param axioms build an atom out of a set of axioms
     */
    public Atom(Collection<OWLAxiom> axioms) {
        this.axioms = axioms;
        hashcode = this.axioms.hashCode();
    }

    /**
     * @param ax axiom
     * @return true if ax is in this atom
     */
    public boolean contains(OWLAxiom ax) {
        return axioms.contains(ax);
    }

    private void initSignature() {
        if (signature == null) {
            signature = new ArrayList<>();
            axioms.forEach(ax -> add(verifyNotNull(signature), ax.signature()));
        }
    }

    /**
     * @return signature for the atom
     */
    public Collection<OWLEntity> getSignature() {
        initSignature();
        return verifyNotNull(signature);
    }

    /**
     * @return axioms in the atom
     */
    public Collection<OWLAxiom> getAxioms() {
        return axioms;
    }

    /**
     * @return label for the atom
     */
    @Nullable
    public Collection<OWLEntity> getLabel() {
        return label;
    }

    /**
     * @param labelSignature the label for the atom
     */
    public void setLabel(Collection<OWLEntity> labelSignature) {
        label = labelSignature;
    }

    @Override
    public boolean equals(@Nullable Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (obj instanceof Atom) {
            return axioms.equals(((Atom) obj).axioms);
        }
        return false;
    }

    @Override
    public int hashCode() {
        return hashcode;
    }

    @Override
    public String toString() {
        return axioms.toString();
    }
}
