/*
 * 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;
    }

}