package com.worldturner.commons.wicket.googleanalytics;

import org.apache.wicket.Component;
import org.apache.wicket.MarkupContainer;
import org.apache.wicket.Page;
import org.apache.wicket.markup.html.panel.Panel;
import org.apache.wicket.model.AbstractReadOnlyModel;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.Model;

/**
 * An implementation of IModel<String> that returns the class name of a component as its object. It will look up that
 * class name each time it is asked for it, and it can be different each time. It will query a MarkupContainer to find a
 * child component with a certain component id, and return the class name of that component. Any wicket component that
 * can hold other components is a MarkupContainer, including {@link Panel} and {@link Page}.
 * <p/>
 * By using models to resolve both the markup container and the component id, there is a lot of flexibility and the
 * decision to ask which container for which comnponent id can be dynamically made just before the value of this model
 * is needed.
 * 
 * @author Erwin Bolwidt (ebolwidt@worldturner.nl)
 */
public class ComponentClassNameModel extends AbstractReadOnlyModel<String> {

    /**
     * A model that, when queried, will return the markup container that will be asked for a child component.
     */
    private IModel<MarkupContainer> containerModel;

    /**
     * A model that, when queried, will return the component id of the child within the markup container, that we are
     * interested in.
     */
    private IModel<String> componentIdModel;

    /**
     * Constructor.
     * 
     * @param container
     *            The markup container that will be asked for a child component.
     * @param componentId
     *            The component id of the child within the markup container, that we are interested in.
     */
    public ComponentClassNameModel(MarkupContainer container, String componentId) {
        this(new Model<MarkupContainer>(container), new Model<String>(componentId));
    }

    /**
     * Constructor.
     * 
     * @param container
     *            A model that, when queried, will return the markup container that will be asked for a child component.
     * @param componentId
     *            A model that, when queried, will return the component id of the child within the markup container,
     *            that we are interested in.
     */
    public ComponentClassNameModel(IModel<MarkupContainer> containerModel, IModel<String> componentIdModel) {
        this.containerModel = containerModel;
        this.componentIdModel = componentIdModel;
    }

    @Override
    public void detach() {
        super.detach();
        if (containerModel != null) {
            containerModel.detach();
        }
        if (componentIdModel != null) {
            componentIdModel.detach();
        }
    }

    @Override
    public String getObject() {
        MarkupContainer container = containerModel.getObject();
        String componentId = componentIdModel.getObject();
        if (container == null || componentId == null) {
            return null;
        }
        Component component = container.get(componentId);
        if (component == null) {
            return null;
        } else {
            return component.getClass().getName();
        }
    }
}