package org.gwtbootstrap3.client.ui.base.mixin;

/*
 * #%L
 * GwtBootstrap3
 * %%
 * Copyright (C) 2013 GwtBootstrap3
 * %%
 * 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%
 */

import java.util.List;

import org.gwtbootstrap3.client.ui.base.HasDataTarget;
import org.gwtbootstrap3.client.ui.constants.Attributes;

import com.google.gwt.dom.client.Document;
import com.google.gwt.user.client.ui.UIObject;
import com.google.gwt.user.client.ui.Widget;

/**
 * @author Sven Jacobs
 */
public class DataTargetMixin<T extends UIObject & HasDataTarget> extends AbstractMixin implements HasDataTarget {

    public DataTargetMixin(final T uiObject) {
        super(uiObject);
    }

    @Override
    public void setDataTargetWidget(final Widget widget) {
        final String id = Document.get().createUniqueId();
        widget.getElement().setId(id);
        this.setDataTarget("#" + id);
    }

    @Override
    public void setDataTargetWidgets(final List<Widget> widgets) {
        final String styleName = Document.get().createUniqueId();
        for (final Widget widget : widgets) {
            widget.addStyleName(styleName);
        }
        this.setDataTarget("." + styleName);
    }

    @Override
    public void setDataTarget(final String dataTarget) {
        if (dataTarget != null) {
            uiObject.getElement().setAttribute(Attributes.DATA_TARGET, dataTarget);
        } else {
            uiObject.getElement().removeAttribute(Attributes.DATA_TARGET);
        }
    }

    @Override
    public String getDataTarget() {
        return uiObject.getElement().getAttribute(Attributes.DATA_TARGET);
    }
}

package org.gwtbootstrap3.client.ui.base.mixin;

/*
 * #%L
 * GwtBootstrap3
 * %%
 * Copyright (C) 2013 GwtBootstrap3
 * %%
 * 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%
 */

import java.util.List;

import org.gwtbootstrap3.client.ui.base.HasDataTarget;
import org.gwtbootstrap3.client.ui.constants.Attributes;

import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.user.client.ui.UIObject;
import com.google.gwt.user.client.ui.Widget;

/**
 * @author Sven Jacobs
 */
public class DataTargetMixin<T extends UIObject & HasDataTarget> extends AbstractMixin implements HasDataTarget {

    /**
     * Ensures the given element has a non-empty id.
     *
     * @param element The element being examined.
     * @see Document#createUniqueId()
     */
    public static void ensureId(final Element element) {
        final String id = element.getId();
        if (id == null || id.isEmpty()) {
            element.setId(Document.get().createUniqueId());
        }
    }

    public DataTargetMixin(final T uiObject) {
        super(uiObject);
    }

    @Override
    public void setDataTargetWidget(final Widget widget) {
        final Element element = widget.getElement();
        ensureId(element);
        this.setDataTarget("#" + element.getId());
    }

    @Override
    public void setDataTargetWidgets(final List<Widget> widgets) {
        final String styleName = Document.get().createUniqueId();
        for (final Widget widget : widgets) {
            widget.addStyleName(styleName);
        }
        this.setDataTarget("." + styleName);
    }

    @Override
    public void setDataTarget(final String dataTarget) {
        if (dataTarget != null) {
            uiObject.getElement().setAttribute(Attributes.DATA_TARGET, dataTarget);
        } else {
            uiObject.getElement().removeAttribute(Attributes.DATA_TARGET);
        }
    }

    @Override
    public String getDataTarget() {
        return uiObject.getElement().getAttribute(Attributes.DATA_TARGET);
    }
}

Introduce DataTargetMixin.ensureId() and use in DataTargetMixin.setDataTargetWidget().