/** A data structure that provides counterexample information when a graph is
    tested to see if it is a lattice.

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 All rights reserved.
 Permission is hereby granted, without written agreement and without
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 */
package ptolemy.graph;

///////////////////////////////////////////////////////////////////
//// NonLatticeCounterExample

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

import ptolemy.graph.CPO.BoundType;

/**
A data structure that provides counterexample information when a graph is
tested to see if it is a lattice. If a graph is not a lattice, it could be
because a set of nodes have no least upper or greatest lower bound, or because
the graph has a cycle.

@author Charles Shelton
@version $Id: NonLatticeCounterExample.java 70398 2014-10-22 23:44:32Z cxh $
@since Ptolemy II 10.0
@Pt.ProposedRating Red (cshelton)
@Pt.AcceptedRating Red (cshelton)
 */
public class NonLatticeCounterExample {

    /** Construct a NonLatticeCounterExample object with the given example
     *  type.
     *  @param exampleType The given example type for this counterexample.
     */
    public NonLatticeCounterExample(ExampleType exampleType) {
        _exampleType = exampleType;
        _nodeList = new ArrayList();
    }

    /** Construct a NonLatticeCounterExample object with the given example
     *  type and list of nodes in the graph.
     *  @param exampleType The given example type for this counterexample.
     *  @param nodeList The list of node weights for this counterexample.
     */
    public NonLatticeCounterExample(ExampleType exampleType, List nodeList) {
        _exampleType = exampleType;
        _nodeList = new ArrayList(nodeList);
    }

    /** Construct a NonLatticeCounterExample object for a graph with a cycle.
     *  @param node The weight of one of the nodes in the graph that is on the
     *   cycle path.
     */
    public NonLatticeCounterExample(Object node) {
        _exampleType = GraphExampleType.GRAPHCYCLE;
        _nodeList = new ArrayList();
        _nodeList.add(node);
    }

    /** Construct a NonLatticeCounterExample object for a pair of nodes that
     *  have either no least upper or greatest lower bound.
     *  @param bound The bound type for this counter example.
     *  @param node1 The first node weight.
     *  @param node2 The second node weight.
     */
    public NonLatticeCounterExample(BoundType bound, Object node1, Object node2) {
        _exampleType = getExampleTypeFromBoundType(bound);
        _nodeList = new ArrayList();
        _nodeList.add(node1);
        _nodeList.add(node2);
    }

    ///////////////////////////////////////////////////////////////////
    ////                         public methods                    ////

    /** Return the example type for this NonLatticeCounterExample.
     *  @return Either LEASTUPPER, GREATESTLOWER, or GRAPHCYCLE.
     */
    public ExampleType getExampleType() {
        return _exampleType;
    }

    /** Return the list of node weights in the graph associated with this
     *  counter example.
     *  @return The list of node weights.
     */
    public List getNodeList() {
        return _nodeList;
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private methods                   ////

    /** Return the correct example type given the CPO bound type (LEASTUPPER or
     *  GREATESTLOWER).
     *  @param boundType The given CPO bound type.
     *  @return The example type for the given bound type.
     */
    private ExampleType getExampleTypeFromBoundType(BoundType boundType) {
        switch (boundType) {
        case LEASTUPPER:
            return GraphExampleType.LEASTUPPER;
        case GREATESTLOWER:
            return GraphExampleType.GREATESTLOWER;
        default:
            return null;
        }
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private variables                 ////

    /** The example type for this NonLatticeCounterExample. */
    private ExampleType _exampleType;

    /** The list of nodes associated with this NonLatticeCounterExample. */
    private List _nodeList;

    ///////////////////////////////////////////////////////////////////
    ////                         public inner classes              ////

    /** Marker interface for the counter example type. This allows
     *  us to create other enumerations of counter example types in
     *  subclasses. In particular, this is needed for the ontologies
     *  package classes ptolemy.data.ontologies.lattice.ProductLatticeOntology
     *  ProductLatticeOntology and
     *  ptolemy.data.ontologies.lattice.ProductLatticeCPO ProductLatticeCPO.
     *  When a product lattice is not a lattice, the reason is because one of
     *  its component lattices is not a lattice. This is only relevant for
     *  product lattice ontologies.
     */
    public interface ExampleType {
    }

    /** An enumeration type to represent the types of counterexamples
     *  that can be found when checking to see if a graph is a lattice.
     */
    public static enum GraphExampleType implements ExampleType {
        /** Represents a counterexample where some nodes have no greatest lower bound. */
        GREATESTLOWER,

        /** Represents a counterexample where some nodes have no least upper bound. */
        LEASTUPPER,

        /** Represents a counterexample where the graph has a cycle. */
        GRAPHCYCLE
    }
}