/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.collection.internal;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.loader.CollectionAliases;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.type.Type;

An unordered, unkeyed collection that can contain the same element
multiple times. The Java collections API, curiously, has no Bag.
Most developers seem to use Lists to represent bag semantics,
so Hibernate follows this practice.
Author:
Gavin King/**
 * An unordered, unkeyed collection that can contain the same element
 * multiple times. The Java collections API, curiously, has no <tt>Bag</tt>.
 * Most developers seem to use <tt>List</tt>s to represent bag semantics,
 * so Hibernate follows this practice.
 *
 * @author Gavin King
 */
public class PersistentBag extends AbstractPersistentCollection implements List {

	protected List bag;

	
Constructs a PersistentBag.  Needed for SOAP libraries, etc
/**
	 * Constructs a PersistentBag.  Needed for SOAP libraries, etc
	 */
	@SuppressWarnings("UnusedDeclaration")
	public PersistentBag() {
	}

	
Constructs a PersistentBag
Params:
session – The session/**
	 * Constructs a PersistentBag
	 *
	 * @param session The session
	 */
	public PersistentBag(SharedSessionContractImplementor session) {
		super( session );
	}

	
Constructs a PersistentBag
Params:
session – The session
coll – The base elements./**
	 * Constructs a PersistentBag
	 *
	 * @param session The session
	 * @param coll The base elements.
	 */
	@SuppressWarnings("unchecked")
	public PersistentBag(SharedSessionContractImplementor session, Collection coll) {
		super( session );
		if ( coll instanceof List ) {
			bag = (List) coll;
		}
		else {
			bag = new ArrayList();
			for ( Object element : coll ) {
				bag.add( element );
			}
		}
		setInitialized();
		setDirectlyAccessible( true );
	}

	@Override
	public boolean isWrapper(Object collection) {
		return bag==collection;
	}

	@Override
	public boolean empty() {
		return bag.isEmpty();
	}

	@Override
	public Iterator entries(CollectionPersister persister) {
		return bag.iterator();
	}

	@Override
	@SuppressWarnings("unchecked")
	public Object readFrom(ResultSet rs, CollectionPersister persister, CollectionAliases descriptor, Object owner)
			throws HibernateException, SQLException {
		// note that if we load this collection from a cartesian product
		// the multiplicity would be broken ... so use an idbag instead
		final Object element = persister.readElement( rs, owner, descriptor.getSuffixedElementAliases(), getSession() ) ;
		if ( element != null ) {
			bag.add( element );
		}
		return element;
	}

	@Override
	public void beforeInitialize(CollectionPersister persister, int anticipatedSize) {
		this.bag = (List) persister.getCollectionType().instantiate( anticipatedSize );
	}

	@Override
	public boolean equalsSnapshot(CollectionPersister persister) throws HibernateException {
		final Type elementType = persister.getElementType();
		final List sn = (List) getSnapshot();
		if ( sn.size() != bag.size() ) {
			return false;
		}
		for ( Object elt : bag ) {
			final boolean unequal = countOccurrences( elt, bag, elementType ) != countOccurrences( elt, sn, elementType );
			if ( unequal ) {
				return false;
			}
		}
		return true;
	}

	@Override
	public boolean isSnapshotEmpty(Serializable snapshot) {
		return ( (Collection) snapshot ).isEmpty();
	}

	private int countOccurrences(Object element, List list, Type elementType)
			throws HibernateException {
		final Iterator iter = list.iterator();
		int result = 0;
		while ( iter.hasNext() ) {
			if ( elementType.isSame( element, iter.next() ) ) {
				result++;
			}
		}
		return result;
	}

	@Override
	@SuppressWarnings("unchecked")
	public Serializable getSnapshot(CollectionPersister persister)
			throws HibernateException {
		final ArrayList clonedList = new ArrayList( bag.size() );
		for ( Object item : bag ) {
			clonedList.add( persister.getElementType().deepCopy( item, persister.getFactory() ) );
		}
		return clonedList;
	}

	@Override
	public Collection getOrphans(Serializable snapshot, String entityName) throws HibernateException {
		final List sn = (List) snapshot;
		return getOrphans( sn, bag, entityName, getSession() );
	}

	@Override
	public Serializable disassemble(CollectionPersister persister)
			throws HibernateException {
		final int length = bag.size();
		final Serializable[] result = new Serializable[length];
		for ( int i=0; i<length; i++ ) {
			result[i] = persister.getElementType().disassemble( bag.get( i ), getSession(), null );
		}
		return result;
	}

	@Override
	@SuppressWarnings("unchecked")
	public void initializeFromCache(CollectionPersister persister, Serializable disassembled, Object owner)
			throws HibernateException {
		final Serializable[] array = (Serializable[]) disassembled;
		final int size = array.length;
		beforeInitialize( persister, size );
		for ( Serializable item : array ) {
			final Object element = persister.getElementType().assemble( item, getSession(), owner );
			if ( element != null ) {
				bag.add( element );
			}
		}
	}

	@Override
	public boolean needsRecreate(CollectionPersister persister) {
		return !persister.isOneToMany();
	}


	// For a one-to-many, a <bag> is not really a bag;
	// it is *really* a set, since it can't contain the
	// same element twice. It could be considered a bug
	// in the mapping dtd that <bag> allows <one-to-many>.

	// Anyway, here we implement <set> semantics for a
	// <one-to-many> <bag>!

	@Override
	@SuppressWarnings("unchecked")
	public Iterator getDeletes(CollectionPersister persister, boolean indexIsFormula) throws HibernateException {
		final Type elementType = persister.getElementType();
		final ArrayList deletes = new ArrayList();
		final List sn = (List) getSnapshot();
		final Iterator olditer = sn.iterator();
		int i=0;
		while ( olditer.hasNext() ) {
			final Object old = olditer.next();
			final Iterator newiter = bag.iterator();
			boolean found = false;
			if ( bag.size()>i && elementType.isSame( old, bag.get( i++ ) ) ) {
			//a shortcut if its location didn't change!
				found = true;
			}
			else {
				//search for it
				//note that this code is incorrect for other than one-to-many
				while ( newiter.hasNext() ) {
					if ( elementType.isSame( old, newiter.next() ) ) {
						found = true;
						break;
					}
				}
			}
			if ( !found ) {
				deletes.add( old );
			}
		}
		return deletes.iterator();
	}

	@Override
	public boolean needsInserting(Object entry, int i, Type elemType) throws HibernateException {
		final List sn = (List) getSnapshot();
		if ( sn.size() > i && elemType.isSame( sn.get( i ), entry ) ) {
			//a shortcut if its location didn't change!
			return false;
		}
		else {
			//search for it
			//note that this code is incorrect for other than one-to-many
			for ( Object old : sn ) {
				if ( elemType.isSame( old, entry ) ) {
					return false;
				}
			}
			return true;
		}
	}

	@Override
	public boolean isRowUpdatePossible() {
		return false;
	}

	@Override
	public boolean needsUpdating(Object entry, int i, Type elemType) {
		return false;
	}

	@Override
	public int size() {
		return readSize() ? getCachedSize() : bag.size();
	}

	@Override
	public boolean isEmpty() {
		return readSize() ? getCachedSize()==0 : bag.isEmpty();
	}

	@Override
	public boolean contains(Object object) {
		final Boolean exists = readElementExistence( object );
		return exists == null ? bag.contains( object ) : exists;
	}

	@Override
	public Iterator iterator() {
		read();
		return new IteratorProxy( bag.iterator() );
	}

	@Override
	public Object[] toArray() {
		read();
		return bag.toArray();
	}

	@Override
	public Object[] toArray(Object[] a) {
		read();
		return bag.toArray( a );
	}

	@Override
	@SuppressWarnings("unchecked")
	public boolean add(Object object) {
		if ( !isOperationQueueEnabled() ) {
			write();
			return bag.add( object );
		}
		else {
			queueOperation( new SimpleAdd( object ) );
			return true;
		}
	}

	@Override
	public boolean remove(Object o) {
		initialize( true );
		if ( bag.remove( o ) ) {
			elementRemoved = true;
			dirty();
			return true;
		}
		else {
			return false;
		}
	}

	@Override
	@SuppressWarnings("unchecked")
	public boolean containsAll(Collection c) {
		read();
		return bag.containsAll( c );
	}

	@Override
	@SuppressWarnings("unchecked")
	public boolean addAll(Collection values) {
		if ( values.size()==0 ) {
			return false;
		}
		if ( !isOperationQueueEnabled() ) {
			write();
			return bag.addAll( values );
		}
		else {
			for ( Object value : values ) {
				queueOperation( new SimpleAdd( value ) );
			}
			return values.size()>0;
		}
	}

	@Override
	@SuppressWarnings("unchecked")
	public boolean removeAll(Collection c) {
		if ( c.size()>0 ) {
			initialize( true );
			if ( bag.removeAll( c ) ) {
				elementRemoved = true;
				dirty();
				return true;
			}
			else {
				return false;
			}
		}
		else {
			return false;
		}
	}

	@Override
	@SuppressWarnings("unchecked")
	public boolean retainAll(Collection c) {
		initialize( true );
		if ( bag.retainAll( c ) ) {
			dirty();
			return true;
		}
		else {
			return false;
		}
	}

	@Override
	@SuppressWarnings("unchecked")
	public void clear() {
		if ( isClearQueueEnabled() ) {
			queueOperation( new Clear() );
		}
		else {
			initialize( true );
			if ( ! bag.isEmpty() ) {
				bag.clear();
				dirty();
			}
		}
	}

	@Override
	public Object getIndex(Object entry, int i, CollectionPersister persister) {
		throw new UnsupportedOperationException("Bags don't have indexes");
	}

	@Override
	public Object getElement(Object entry) {
		return entry;
	}

	@Override
	public Object getSnapshotElement(Object entry, int i) {
		final List sn = (List) getSnapshot();
		return sn.get( i );
	}

	
Count how many times the given object occurs in the elements
Params:
o – The object to check
Returns:
The number of occurences./**
	 * Count how many times the given object occurs in the elements
	 *
	 * @param o The object to check
	 *
	 * @return The number of occurences.
	 */
	@SuppressWarnings("UnusedDeclaration")
	public int occurrences(Object o) {
		read();
		final Iterator itr = bag.iterator();
		int result = 0;
		while ( itr.hasNext() ) {
			if ( o.equals( itr.next() ) ) {
				result++;
			}
		}
		return result;
	}

	// List OPERATIONS:

	@Override
	@SuppressWarnings("unchecked")
	public void add(int i, Object o) {
		write();
		bag.add( i, o );
	}

	@Override
	@SuppressWarnings("unchecked")
	public boolean addAll(int i, Collection c) {
		if ( c.size() > 0 ) {
			write();
			return bag.addAll( i, c );
		}
		else {
			return false;
		}
	}

	@Override
	@SuppressWarnings("unchecked")
	public Object get(int i) {
		read();
		return bag.get( i );
	}

	@Override
	@SuppressWarnings("unchecked")
	public int indexOf(Object o) {
		read();
		return bag.indexOf( o );
	}

	@Override
	@SuppressWarnings("unchecked")
	public int lastIndexOf(Object o) {
		read();
		return bag.lastIndexOf( o );
	}

	@Override
	@SuppressWarnings("unchecked")
	public ListIterator listIterator() {
		read();
		return new ListIteratorProxy( bag.listIterator() );
	}

	@Override
	@SuppressWarnings("unchecked")
	public ListIterator listIterator(int i) {
		read();
		return new ListIteratorProxy( bag.listIterator( i ) );
	}

	@Override
	@SuppressWarnings("unchecked")
	public Object remove(int i) {
		write();
		return bag.remove( i );
	}

	@Override
	@SuppressWarnings("unchecked")
	public Object set(int i, Object o) {
		write();
		return bag.set( i, o );
	}

	@Override
	@SuppressWarnings("unchecked")
	public List subList(int start, int end) {
		read();
		return new ListProxy( bag.subList( start, end ) );
	}

	@Override
	public boolean entryExists(Object entry, int i) {
		return entry!=null;
	}

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

	
Bag does not respect the collection API and do an
JVM instance comparison to do the equals.
The semantic is broken not to have to initialize a
collection for a simple equals() operation.
See Also:

{@inheritDoc}/**
	 * Bag does not respect the collection API and do an
	 * JVM instance comparison to do the equals.
	 * The semantic is broken not to have to initialize a
	 * collection for a simple equals() operation.
	 * @see java.lang.Object#equals(java.lang.Object)
	 *
	 * {@inheritDoc}
	 */
	@Override
	public boolean equals(Object obj) {
		return super.equals( obj );
	}

	@Override
	public int hashCode() {
		return super.hashCode();
	}

	final class Clear implements DelayedOperation {
		@Override
		public void operate() {
			bag.clear();
		}

		@Override
		public Object getAddedInstance() {
			return null;
		}

		@Override
		public Object getOrphan() {
			throw new UnsupportedOperationException("queued clear cannot be used with orphan delete");
		}
	}

	final class SimpleAdd extends AbstractValueDelayedOperation {

		public SimpleAdd(Object addedValue) {
			super( addedValue, null );
		}

		@Override
		@SuppressWarnings("unchecked")
		public void operate() {
			bag.add( getAddedInstance() );
		}
	}
}