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Vaadin 7 compatibility package for Vaadin 8
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/*
 * Copyright (C) 2000-2024 Vaadin Ltd
 *
 * This program is available under Vaadin Commercial License and Service Terms.
 *
 * See  for the full
 * license.
 */
package com.vaadin.v7.client.connectors;

import com.vaadin.client.ServerConnector;
import com.vaadin.client.communication.JsonDecoder;
import com.vaadin.client.extensions.AbstractExtensionConnector;
import com.vaadin.client.metadata.NoDataException;
import com.vaadin.client.metadata.Type;
import com.vaadin.client.metadata.TypeData;
import com.vaadin.client.metadata.TypeDataStore;
import com.vaadin.v7.client.renderers.Renderer;
import com.vaadin.v7.client.widgets.Grid.Column;

import elemental.json.JsonObject;
import elemental.json.JsonValue;

/**
 * An abstract base class for renderer connectors.
 *
 * @param 
 *            the presentation type of the renderer
 */
public abstract class AbstractRendererConnector
        extends AbstractExtensionConnector {

    private Renderer renderer = null;

    private final Type presentationType = TypeDataStore
            .getPresentationType(this.getClass());

    protected AbstractRendererConnector() {
        if (presentationType == null) {
            throw new IllegalStateException("No presentation type found for "
                    + getClass().getSimpleName()
                    + ". This may be caused by some unspecified problem in widgetset compilation.");
        }
    }

    /**
     * Returns the renderer associated with this renderer connector.
     * 
     * A subclass of AbstractRendererConnector should override this method as
     * shown below. The framework uses
     * {@link com.google.gwt.core.client.GWT#create(Class) GWT.create(Class)} to
     * create a renderer based on the return type of the overridden method, but
     * only if {@link #createRenderer()} is not overridden as well:
     *
     * 
     * public MyRenderer getRenderer() {
     *     return (MyRenderer) super.getRenderer();
     * }
     * 
     *
     * @return the renderer bound to this connector
     */
    public Renderer getRenderer() {
        if (renderer == null) {
            renderer = createRenderer();
        }
        return renderer;
    }

    /**
     * Creates a new Renderer instance associated with this renderer connector.
     * 
     * You should typically not override this method since the framework by
     * default generates an implementation that uses
     * {@link com.google.gwt.core.client.GWT#create(Class)} to create a renderer
     * of the same type as returned by the most specific override of
     * {@link #getRenderer()}. If you do override the method, you can't call
     * super.createRenderer() since the metadata needed for that
     * implementation is not generated if there's an override of the method.
     *
     * @return a new renderer to be used with this connector
     */
    protected Renderer createRenderer() {
        // TODO generate type data
        Type type = TypeData.getType(getClass());
        try {
            Type rendererType = type.getMethod("getRenderer").getReturnType();
            @SuppressWarnings("unchecked")
            Renderer instance = (Renderer) rendererType.createInstance();
            return instance;
        } catch (NoDataException e) {
            throw new IllegalStateException(
                    "Default implementation of createRenderer() does not work for "
                            + getClass().getSimpleName()
                            + ". This might be caused by explicitely using "
                            + "super.createRenderer() or some unspecified "
                            + "problem with the widgetset compilation.",
                    e);
        }
    }

    /**
     * Decodes the given JSON value into a value of type T so it can be passed
     * to the {@link #getRenderer() renderer}.
     *
     * @param value
     *            the value to decode
     * @return the decoded value of {@code value}
     */
    public T decode(JsonValue value) {
        @SuppressWarnings("unchecked")
        T decodedValue = (T) JsonDecoder.decodeValue(presentationType, value,
                null, getConnection());
        return decodedValue;
    }

    @Override
    @Deprecated
    protected void extend(ServerConnector target) {
        // NOOP
    }

    /**
     * Gets the row key for a row object.
     * 

     * In case this renderer wants be able to identify a row in such a way that
     * the server also understands it, the row key is used for that. Rows are
     * identified by unified keys between the client and the server.
     *
     * @param row
     *            the row object
     * @return the row key for the given row
     */
    protected String getRowKey(JsonObject row) {
        final ServerConnector parent = getParent();
        if (parent instanceof GridConnector) {
            return ((GridConnector) parent).getRowKey(row);
        } else {
            throw new IllegalStateException(
                    "Renderers can only be used " + "with a Grid.");
        }
    }

    /**
     * Gets the column id for a column.
     * 
     * In case this renderer wants be able to identify a column in such a way
     * that the server also understands it, the column id is used for that.
     * Columns are identified by unified ids between the client and the server.
     *
     * @param column
     *            the column object
     * @return the column id for the given column
     */
    protected String getColumnId(Column column) {
        final ServerConnector parent = getParent();
        if (parent instanceof GridConnector) {
            return ((GridConnector) parent).getColumnId(column);
        } else {
            throw new IllegalStateException(
                    "Renderers can only be used " + "with a Grid.");
        }
    }

}