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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package jdk.jfr;

import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Path;
import java.text.ParseException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import jdk.jfr.internal.JVMSupport;
import jdk.jfr.internal.jfc.JFC;

/**
 * A collection of settings and metadata describing the configuration.
 * <p>
 * The following example shows how the {@code Configuration} class can be used
 * to list available configurations and how to pass a configuration object to a
 * {@code Recording}.
 * {@snippet class = "Snippets" region = "ConfigurationxsOverview"}
 *
 * @since 9
 */
public final class Configuration {
    private final Map<String, String> settings;
    private final String label;
    private final String description;
    private final String provider;
    private final String contents;
    private final String name;

    // package private
    Configuration(String name, String label, String description, String provider, Map<String, String> settings, String contents) {
        this.name = name;
        this.label = label;
        this.description = description;
        this.provider = provider;
        this.settings = settings;
        this.contents = contents;
    }

    /**
     * Returns the settings that specifies how a recording is configured.
     * <p>
     * Modifying the returned {@code Map} object doesn't change the
     * configuration.
     *
     * @return settings, not {@code null}
     */
    public Map<String, String> getSettings() {
        return new LinkedHashMap<String, String>(settings);
    }

    /**
     * Returns an identifying name (for example, {@code "default" or "profile")}.
     *
     * @return the name, or {@code null} if it doesn't exist
     */
    public String getName() {
        return this.name;
    }

    /**
     * Returns a human-readable name (for example, {@code "Continuous" or "Profiling"}}.
     *
     * @return the label, or {@code null} if it doesn't exist
     */
    public String getLabel() {
        return this.label;
    }

    /**
     * Returns a short sentence that describes the configuration (for example
     * {@code "Low
     * overhead configuration safe for continuous use in production
     * environments"})
     *
     * @return the description, or {@code null} if it doesn't exist
     */
    public String getDescription() {
        return description;
    }

    /**
     * Returns who created the configuration (for example {@code "OpenJDK"}).
     *
     * @return the provider, or {@code null} if it doesn't exist
     */
    public String getProvider() {
        return provider;
    }

    /**
     * Returns a textual representation of the configuration (for example, the
     * contents of a JFC file).
     *
     * @return contents, or {@code null} if it doesn't exist
     *
     * @see Configuration#getContents()
     */
    public String getContents() {
        return contents;
    }

    /**
     * Reads a configuration from a file.
     *
     * @param path the file that contains the configuration, not {@code null}
     * @return the read {@link Configuration}, not {@code null}
     * @throws ParseException if the file can't be parsed
     * @throws IOException if the file can't be read
     *
     * @see java.io.File#getPath()
     */
    public static Configuration create(Path path) throws IOException, ParseException {
        Objects.requireNonNull(path, "path");
        JVMSupport.ensureWithIOException();
        try (Reader reader = Files.newBufferedReader(path)) {
            return JFC.create(JFC.nameFromPath(path), reader);
        }
    }

    /**
     * Reads a configuration from a character stream.
     *
     * @param reader a {@code Reader} that provides the configuration contents, not
     *        {@code null}
     * @return a configuration, not {@code null}
     * @throws IOException if an I/O error occurs while trying to read contents
     *         from the {@code Reader}
     * @throws ParseException if the file can't be parsed
     */
    public static Configuration create(Reader reader) throws IOException, ParseException {
        Objects.requireNonNull(reader, "reader");
        JVMSupport.ensureWithIOException();
        return JFC.create(null, reader);
    }

    /**
     * Returns a predefined configuration.
     * <p>
     * See {@link Configuration#getConfigurations()} for available configuration
     * names.
     *
     * @param name the name of the configuration (for example, {@code "default"} or
     *        {@code "profile"})
     * @return a configuration, not {@code null}
     *
     * @throws IOException if a configuration with the given name does not
     *         exist, or if an I/O error occurs while reading the
     *         configuration file
     * @throws ParseException if the configuration file can't be parsed
     */
    public static Configuration getConfiguration(String name) throws IOException, ParseException {
        Objects.requireNonNull(name, "name");
        JVMSupport.ensureWithIOException();
        return JFC.getPredefined(name);
    }

    /**
     * Returns an immutable list of predefined configurations for this Java Virtual Machine (JVM).
     *
     * @return the list of predefined configurations, not {@code null}
     */
    public static List<Configuration> getConfigurations() {
        if (JVMSupport.isNotAvailable()) {
            return List.of();
        }
        return List.copyOf(JFC.getConfigurations());
    }
}