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/*
========================================================================
SchemaCrawler
http://www.schemacrawler.com
Copyright (c) 2000-2020, Sualeh Fatehi .
All rights reserved.
------------------------------------------------------------------------

SchemaCrawler is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SchemaCrawler and the accompanying materials are made available under
the terms of the Eclipse Public License v1.0, GNU General Public License
v3 or GNU Lesser General Public License v3.

You may elect to redistribute this code under any of these licenses.

The Eclipse Public License is available at:
http://www.eclipse.org/legal/epl-v10.html

The GNU General Public License v3 and the GNU Lesser General Public
License v3 are available at:
http://www.gnu.org/licenses/

========================================================================
*/

package schemacrawler.crawl;


import static java.util.Objects.requireNonNull;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.SortedSet;
import java.util.TreeSet;

import schemacrawler.schema.BaseForeignKey;
import schemacrawler.schema.Column;
import schemacrawler.schema.ColumnReference;
import schemacrawler.schema.NamedObject;
import us.fatehi.utility.CompareUtility;

/**
 * Represents a foreign-key mapping to a primary key in another table.
 *
 * @author Sualeh Fatehi
 */
public final class WeakAssociation
  implements BaseForeignKey
{

  private static final long serialVersionUID = -5164664131926303038L;

  private final String name;
  private final SortedSet columnReferences =
    new TreeSet<>();

  public WeakAssociation(final String name)
  {
    this.name = requireNonNull(name, "No name provided");
  }

  /**
   * {@inheritDoc}
   * 
   * Note: Since foreign keys are not always explicitly named in databases, the
   * sorting routine orders the foreign keys by the names of the columns in the
   * foreign keys.
   * 
   */
  @Override
  public int compareTo(final NamedObject obj)
  {
    if (obj == null)
    {
      return -1;
    }

    final BaseForeignKey other = (BaseForeignKey) obj;
    final List thisColumnReferences =
      getColumnReferences();
    final List otherColumnReferences =
      other.getColumnReferences();

    return CompareUtility.compareLists(thisColumnReferences,
                                       otherColumnReferences);
  }

  @Override
  public List getColumnReferences()
  {
    return new ArrayList<>(columnReferences);
  }

  @Override
  public String getFullName()
  {
    return getName();
  }

  @Override
  public String getName()
  {
    return name;
  }

  @Override
  public List toUniqueLookupKey()
  {
    return Arrays.asList(getName());
  }

  @Override
  public int hashCode()
  {
    return Objects.hash(columnReferences);
  }

  @Override
  public boolean equals(final Object obj)
  {
    if (this == obj)
    {
      return true;
    }
    if (obj == null)
    {
      return false;
    }
    if (!(obj instanceof WeakAssociation))
    {
      return false;
    }
    final WeakAssociation other = (WeakAssociation) obj;
    return Objects.equals(columnReferences, other.columnReferences);
  }

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

  @Override
  public Iterator iterator()
  {
    return columnReferences.iterator();
  }

  void addColumnReference(final Column pkColumn, final Column fkColumn)
  {
    columnReferences.add(new WeakAssociationColumnReference(pkColumn,
                                                            fkColumn));
  }

}