/**
* Customised version of {@link org.hibernate.type.MaterializedNClobType} that forces use of NCLOB_BINDING (setNClob)
* so that unicode characters can be persisted in a JPA field text field (with database column type nclob).
* The original version used NClobTypeDescriptor.DEFAULT which ends up using streams (hibernate.jdbc.use_streams_for_binary) not setNClob,
* and the stream handling uses setCharacterStream (where it should use setNCharacterStream).
* The original version also has a bug in the StringDescriptor that would always shortcut at Clob (rather than NClob) type.
*
*/
public class MaterializedNClobType extends AbstractSingleColumnStandardBasicType<String> {
    public static final MaterializedNClobType INSTANCE = new MaterializedNClobType();

    // This code contains the fix for STREAM_BINDING (i.e. use setNCharacterStream)
    public MaterializedNClobType() {
        super ( STREAM_BINDING, StringTypeDescriptor.INSTANCE );
    }

    public String getName() {
        return "materialized_nclob";
    }

    public static final NClobTypeDescriptor STREAM_BINDING =
            new NClobTypeDescriptor() {
                @Override
                public <X> BasicBinder<X> getNClobBinder(final JavaTypeDescriptor<X> javaTypeDescriptor) {
                    return new BasicBinder< X>( javaTypeDescriptor, this ) {
                        @Override
                        protected void doBind(PreparedStatement st, X value, int index, WrapperOptions options)
                                throws SQLException {
                            final CharacterStream characterStream = javaTypeDescriptor.unwrap( value, CharacterStream. class, options );
                            st.setNCharacterStream( index, characterStream.asReader(), characterStream.getLength() );
                        }
                    };
                }
            };

    // This code contains the fix for NCLOB_BINDING (i.e. return an NCLOB not a CLOB)
    public MaterializedNClobType() {
        super( NClobTypeDescriptor.NCLOB_BINDING, StringNClobTypeDescriptor.INSTANCE );
    }

    public static class StringNClobTypeDescriptor extends StringTypeDescriptor {
        public static StringNClobTypeDescriptor INSTANCE = new StringNClobTypeDescriptor();
        @Override
        public <X> X unwrap(String value, Class<X> type, WrapperOptions options) {
            if ( value == null ) {
                return null;
            }
            if ( DataHelper.isNClob(type) ) {
                return (X) options.getLobCreator().createNClob( value );
            }

            throw unknownUnwrap( type );
        }
    }
}