// This software is released into the Public Domain. See copying.txt for details.
package org.openstreetmap.osmosis.apidb.v0_6.impl;
import org.openstreetmap.osmosis.core.container.v0_6.ChangeContainer;
import org.openstreetmap.osmosis.core.container.v0_6.EntityContainer;
import org.openstreetmap.osmosis.core.container.v0_6.EntityContainerFactory;
import org.openstreetmap.osmosis.core.domain.v0_6.Entity;
import org.openstreetmap.osmosis.core.lifecycle.ReleasableIterator;
import org.openstreetmap.osmosis.core.task.common.ChangeAction;
/**
* Creates change records based on the data provided by an underlying entity history iterator.
*
* @param <T>
* The type of entity provided by this iterator.
*/
public class ChangeReader<T extends Entity> implements ReleasableIterator<ChangeContainer> {
private ReleasableIterator<EntityHistory<T>> source;
private EntityContainerFactory<T> containerFactory;
/**
* Creates a new instance.
*
* @param source
* The entity history source.
* @param containerFactory
* The factory for wrapping entity objects into containers.
*/
public ChangeReader(ReleasableIterator<EntityHistory<T>> source, EntityContainerFactory<T> containerFactory) {
this.source = source;
this.containerFactory = containerFactory;
}
/**
* {@inheritDoc}
*/
@Override
public boolean hasNext() {
return source.hasNext();
}
/**
* {@inheritDoc}
*/
@Override
public ChangeContainer next() {
EntityHistory<T> entityHistory;
T entity;
EntityContainer entityContainer;
boolean createdPreviously;
// Get the entity from the underlying source.
entityHistory = source.next();
entity = entityHistory.getEntity();
// Wrap the entity in a container.
entityContainer = containerFactory.createContainer(entity);
// This is only a create if the version is 1.
createdPreviously = (entityHistory.getEntity().getVersion() > 1);
// The entity has been modified if it is visible and was created previously.
// It is a create if it is visible and was NOT created previously.
// It is a delete if it is NOT visible and was created previously.
// No action if it is NOT visible and was NOT created previously.
if (entityHistory.isVisible() && createdPreviously) {
return new ChangeContainer(entityContainer, ChangeAction.Modify);
} else if (entityHistory.isVisible() && !createdPreviously) {
return new ChangeContainer(entityContainer, ChangeAction.Create);
} else if (!entityHistory.isVisible() && createdPreviously) {
return new ChangeContainer(entityContainer, ChangeAction.Delete);
} else {
// This is an unusual case in that an initial version has been marked as not visible.
// The production database contains many examples of this, presumably due to the original
// TIGER import not being deleted properly.
return new ChangeContainer(entityContainer, ChangeAction.Delete);
}
}
/**
* {@inheritDoc}
*/
@Override
public void remove() {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
*/
@Override
public void release() {
source.release();
}
}