/*

 * Copyright (c) 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.internal.net.http.common;

import java.util.Objects;

import java.util.ResourceBundle;

import java.util.function.Supplier;

/**

 * An internal {@code System.Logger} that is used for internal

 * debugging purposes in the {@link java.net.http} module.

 * <p>

 * Though not enforced, this interface is designed for emitting

 * debug messages with Level.DEBUG, when system assertions are

 * turned on.

 * <p>

 * It defines {@code log} methods that default to {@code Level.DEBUG}

 * and always return {@code true}, so that they can be called in

 * assert statements like:

 * <pre>{@code assert debug.log("some %s with %d %s", message(), one(), params());}</pre>

 *

 * @implSpec

 * This interface is implemented by loggers returned by

 * {@link Utils#getDebugLogger(Supplier, boolean)},

 * {@link Utils#getWebSocketLogger(Supplier, boolean)}and

 * {@link Utils#getHpackLogger(Supplier, boolean)}.

 * It is not designed to be implemented by any other

 * loggers. Do not use outside of this module.

 */

public interface Logger extends System.Logger {

    /**

     * Tells whether this logger is on.

     * @implSpec The default implementation for this method calls

     * {@code this.isLoggable(Level.DEBUG);}

     */

    public default boolean isOn() {

        return isLoggable(Level.DEBUG);

    }

    /**

     * Logs a message.

     *

     * @implSpec The default implementation for this method calls

     * {@code this.log(Level.DEBUG, msg);}

     *

     * @param msg the string message (or a key in the message catalog, if

     * this logger is a {@link

     * System.LoggerFinder#getLocalizedLogger(java.lang.String,

     * java.util.ResourceBundle, java.lang.Module) localized logger});

     * can be {@code null}.

     *

     * @return Always return true.

     */

    public default boolean log(String msg) {

        log(Level.DEBUG, msg);

        return true;

    }

    /**

     * Logs a lazily supplied message.

     *

     * @implSpec The default implementation for this method calls

     * {@code this.log(Level.DEBUG, msgSupplier);}

     *

     * @param msgSupplier a supplier function that produces a message.

     *

     * @throws NullPointerException if {@code msgSupplier} is {@code null}.

     *

     * @return Always return true.

     */

    public default boolean log(Supplier<String> msgSupplier) {

        log(Level.DEBUG, msgSupplier);

        return true;

    }

    /**

     * Logs a message produced from the given object.

     *

     * @implSpec The default implementation for this method calls

     * {@code this.log(Level.DEBUG, obj);}

     *

     * @param obj the object to log.

     *

     * @throws NullPointerException if {@code obj} is {@code null}.

     *

     * @return Always return true.

     */

    public default boolean log(Object obj) {

        log(Level.DEBUG,  obj);

        return true;

    }

    /**

     * Logs a message associated with a given throwable.

     *

     * @implSpec The default implementation for this method calls

     * {@code this.log(Level.DEBUG, msg, thrown);}

     *

     * @param msg the string message (or a key in the message catalog, if

     * this logger is a {@link

     * System.LoggerFinder#getLocalizedLogger(java.lang.String,

     * java.util.ResourceBundle, java.lang.Module) localized logger});

     * can be {@code null}.

     * @param thrown a {@code Throwable} associated with the log message;

     *        can be {@code null}.

     *

     * @return Always return true.

     */

    public default boolean log(String msg, Throwable thrown) {

        this.log(Level.DEBUG, msg, thrown);

        return true;

    }

    /**

     * Logs a lazily supplied message associated with a given throwable.

     *

     * @implSpec The default implementation for this method calls

     * {@code this.log(Level.DEBUG, msgSupplier, thrown);}

     *

     * @param msgSupplier a supplier function that produces a message.

     * @param thrown a {@code Throwable} associated with log message;

     *               can be {@code null}.

     *

     * @throws NullPointerException if {@code msgSupplier} is {@code null}.

     *

     * @return Always return true.

     */

    public default boolean log(Supplier<String> msgSupplier, Throwable thrown) {

        log(Level.DEBUG, msgSupplier, thrown);

        return true;

    }

    /**

     * Logs a message with an optional list of parameters.

     *

     * @implSpec The default implementation for this method calls

     * {@code this.log(Level.DEBUG, format, params);}

     *

     * @param format the string message format in

     * {@link String#format(String, Object...)} or {@link

     * java.text.MessageFormat} format, (or a key in the message

     * catalog, if this logger is a {@link

     * System.LoggerFinder#getLocalizedLogger(java.lang.String,

     * java.util.ResourceBundle, java.lang.Module) localized logger});

     * can be {@code null}.

     * @param params an optional list of parameters to the message (may be

     * none).

     *

     * @return Always return true.

     */

    public default boolean log(String format, Object... params) {

        log(Level.DEBUG, format, params);

        return true;

    }

}