/*
 * #%L
 * GwtMaterial
 * %%
 * Copyright (C) 2015 - 2017 GwtMaterialDesign
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
package gwt.material.design.client.ui;

import com.google.gwt.dom.client.OptionElement;
import gwt.material.design.client.base.AllowBlankKeyFactory;
import gwt.material.design.client.ui.html.Option;

//@formatter:off

/**
 * <p>Material ListBox is another dropdown component that will set / get the value depends on the selected index
 * <h3>UiBinder Usage:</h3>
 * <p>
 * <pre>
 * {@code
 *    <m:MaterialListBox ui:field="lstBox" />
 * }
 * </pre>
 * <h3>Java Usage:</h3>
 * <p>
 * <pre>
 * {@code
 *     // functions
 *    lstBox.setSelectedIndex(2);
 *    lstBox.getSelectedIndex();
 *    lstBox.addValueChangeHandler(handler);
 * }
 * </pre>
 * </p>
 *
 * @author kevzlou7979
 * @author Ben Dol
 * @see <a href="http://gwtmaterialdesign.github.io/gwt-material-demo/#listbox">Material ListBox</a>
 * @see <a href="https://material.io/guidelines/components/menus.html">Material Design Specification</a>
 */
//@formatter:on
public class MaterialListBox extends MaterialListValueBox<String> {

    public void add(Option option) {
        getSelectElement().add(OptionElement.as(option.getElement()), null);
        values.add(option.getValue());
    }

    @Override
    public String getValue() {
        String value = super.getValue();
        if (value == null) {
            return AllowBlankKeyFactory.BLANK_VALUE_TEXT;
        } else {
            return value;
        }
    }

    @Override
    public void setValue(String value) {
        if (AllowBlankKeyFactory.BLANK_VALUE_TEXT.equals(value)) {
            super.setValue(null);
        } else {
            super.setValue(value);
        }
    }

}