/*

 * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package jdk.jfr;

import java.lang.annotation.Annotation;

import java.util.Collections;

import java.util.List;

import java.util.Objects;

import jdk.jfr.internal.AnnotationConstruct;

import jdk.jfr.internal.Type;

/**

 * Describes an event setting.

 *

 * @since 9

 */

public final class SettingDescriptor {

    private final AnnotationConstruct annotationConstruct;

    private final Type type;

    private final String name;

    private final String defaultValue;

    // package private, invoked by jdk.internal.

    SettingDescriptor(Type type, String name, String defaultValue, List<AnnotationElement> annotations) {

        Objects.requireNonNull(annotations);

        this.name = Objects.requireNonNull(name, "Name of value descriptor can't be null");

        this.type = Objects.requireNonNull(type);

        this.annotationConstruct = new AnnotationConstruct(annotations);

        this.defaultValue = Objects.requireNonNull(defaultValue);

    }

    // package private

    void setAnnotations(List<AnnotationElement> as) {

        annotationConstruct.setAnnotationElements(as);

    }

    /**

     * Returns the name of the setting (for example, {@code "threshold"}).

     *

     * @return the name, not {@code null}

     */

    public String getName() {

        return name;

    }

    /**

     * Returns a human-readable name that describes the setting (for example,

     * {@code "Threshold"}).

     * <p>

     * If the setting lacks a label, the label for the type that is associated with this

     * setting is returned, or {@code null} if doesn't exist

     *

     * @return a human-readable name, or {@code null} if doesn't exist

     */

    public String getLabel() {

        String label = annotationConstruct.getLabel();

        if (label == null) {

            label = type.getLabel();

        }

        return label;

    }

    /**

     * Returns a sentence that describes the setting (for example

     * {@code "Record event with duration

     * above or equal to threshold"}).

     * <p>

     * If the setting lacks a description, the description for the type that is

     * associated with this setting is returned, or {@code null} if doesn't exist.

     *

     * @return the description, or {@code null} if doesn't exist

     */

    public String getDescription() {

        String description = annotationConstruct.getDescription();

        if (description == null) {

            description = type.getDescription();

        }

        return description;

    }

    /**

     * Returns a textual identifier that specifies how a value that is represented by

     * this {@code SettingDescriptor} object is interpreted or formatted.

     * <p>

     * For example, if the setting descriptor represents a percentage, then

     * {@code "jdk.jfr.Percentage"} hints to a client that a value of "0.5"

     * is formatted as "50%".

     * <p>

     * The JDK provides the following predefined content types:

     * <ul>

     * <li>jdk.jfr.Percentage</li>

     * <li>jdk.jfr.Timespan</li>

     * <li>jdk.jfr.Timestamp</li>

     * <li>jdk.jfr.Frequency</li>

     * <li>jdk.jfr.Flag</li>

     * <li>jdk.jfr.MemoryAddress</li>

     * <li>jdk.jfr.DataAmount</li>

     * <li>jdk.jfr.NetworkAddress</li>

     * </ul>

     * <p>

     * User-defined content types can be created by using {@link ContentType}.

     * <p>

     * If the setting lacks a content type, the content type for the type

     * that is associated with this setting is returned, or {@code null} if not

     * available.

     *

     * @return the content type, or {@code null} if doesn't exist

     *

     * @see ContentType

     */

    public String getContentType() {

        for (AnnotationElement anno : getAnnotationElements()) {

            for (AnnotationElement meta : anno.getAnnotationElements()) {

                if (meta.getTypeName().equals(ContentType.class.getName())) {

                    return anno.getTypeName();

                }

            }

        }

        for (AnnotationElement anno : type.getAnnotationElements()) {

            for (AnnotationElement meta : anno.getAnnotationElements()) {

                if (meta.getTypeName().equals(ContentType.class.getName())) {

                    return anno.getTypeName();

                }

            }

        }

        return null;

    }

    /**

     * Returns the fully qualified class name of the type that is associated with this

     * setting descriptor.

     *

     * @return the type name, not {@code null}

     *

     * @see SettingDescriptor#getTypeId()

     */

    public String getTypeName() {

        return type.getName();

    }

    /**

     * Returns a unique ID for the type in the Java Virtual Machine (JVM).

     * <p>

     * The ID might not be the same between JVM instances.

     *

     * @return the type ID, not negative

     */

    public long getTypeId() {

        return type.getId();

    }

    /**

     * Returns the first annotation for the specified type if an annotation

     * element with the same name is available, {@code null} otherwise.

     *

     * @param <A> the type of the annotation to query for and return if available

     * @param annotationType the Class object that corresponds to the annotation

     *        type, not {@code null}

     * @return this element's annotation for the specified annotation type if

     *         available, {@code null} otherwise

     */

    public <A extends Annotation> A getAnnotation(Class<A> annotationType) {

        Objects.requireNonNull(annotationType);

        return annotationConstruct.getAnnotation(annotationType);

    }

    /**

     * Returns an immutable list of annotation elements for this value

     * descriptor.

     *

     * @return a list of annotations, not {@code null}

     */

    public List<AnnotationElement> getAnnotationElements() {

        return Collections.unmodifiableList(annotationConstruct.getUnmodifiableAnnotationElements());

    }

    /**

     * Returns the default value for this setting descriptor.

     *

     * @return the default value, not {@code null}

     */

    public String getDefaultValue() {

        return defaultValue;

    }

    // package private

    Type getType() {

        return type;

    }

}