/**
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2017 Yegor Bugayenko
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package org.takes.rs.xe;

import java.lang.management.ManagementFactory;
import lombok.EqualsAndHashCode;
import org.xembly.Directive;
import org.xembly.Directives;

/**
 * Xembly source to create SLA attribute with server load average.
 *
 * <p>Add this Xembly source to your page like this:
 *
 * <pre> new RsXembly(
 *   new XsStylesheet("/xsl/home.xsl"),
 *   new XsAppend(
 *     "page",
 *     new XsSLA()
 *   )
 * )</pre>
 *
 * <p>And expect this attribute in the XML:
 *
 * <pre><?xml version="1.0"?>
 * <?xml-stylesheet href="/xsl/home.xsl" type="text/xsl"?>
 * <page sla="1.908"/>
 * </pre>
 *
 * <p>The class is immutable and thread-safe.
 *
 * @author Yegor Bugayenko (yegor256@gmail.com)
 * @version $Id: 1a40c1cb3fd24efffbfc74b306a46d1d485c66e4 $
 * @since 0.3
 */
@EqualsAndHashCode(callSuper = true)
public final class XeSla extends XeWrap {

    /**
     * Ctor.
     */
    public XeSla() {
        this("sla");
    }

    /**
     * Ctor.
     * @param attr Attribute name
     */
    public XeSla(final CharSequence attr) {
        super(
            new XeSource() {
                @Override
                public Iterable<Directive> toXembly() {
                    return new Directives().attr(
                        attr.toString(),
                        String.format(
                            "%.3f",
                            ManagementFactory.getOperatingSystemMXBean()
                                .getSystemLoadAverage()
                        )
                    );
                }
            }
        );
    }

}