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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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package org.apache.juneau.html;

import org.apache.juneau.html.annotation.*;
import org.apache.juneau.svl.*;

/**
 * HTML widget variable resolver.
 *
 * <p>
 * The format for this var is <js>"$W{widgetName}"</js>.
 *
 * <p>
 * Widgets are simple class that produce some sort of string based on a passed-in HTTP request.
 *
 * <p>
 * They're registered via the following mechanisms:
 * <ul>
 * 	<li>{@link HtmlDocConfig#widgets() @HtmlDocConfig(widgets)}
 * </ul>
 *
 * <ul class='seealso'>
 * 	<li class='link'>{@doc jrs.HtmlWidgets}
 * 	<li class='link'>{@doc jm.HtmlDetails}
 * 	<li class='extlink'>{@source}
 * </ul>
 */
public class HtmlWidgetVar extends SimpleVar {

	/**
	 * The name of this variable.
	 */
	public static final String NAME = "W";

	/**
	 * Constructor.
	 */
	public HtmlWidgetVar() {
		super(NAME);
	}

	@Override /* Parameter */
	public String resolve(VarResolverSession session, String key) throws Exception {
		HtmlWidgetMap m = session.getBean(HtmlWidgetMap.class).orElseThrow(RuntimeException::new);

		HtmlWidget w = m.get(key);
		if (w == null)
			return "unknown-widget-"+key;

		return w.getHtml(session);
	}

	@Override
	public boolean canResolve(VarResolverSession session) {
		return session.getBean(HtmlWidgetMap.class).isPresent();
	}
}