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 * Version: EPL 1.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.eclipse.org/legal/epl-v10.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2001-2011 The JRuby Community (and contribs)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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package org.jruby.util.log;

import java.lang.reflect.Constructor;
import org.jruby.util.cli.Options;

public class LoggerFactory {

    static final String LOGGER_CLASS = Options.LOGGER_CLASS.load();
    static final String BACKUP_LOGGER_CLASS = "org.jruby.util.log.StandardErrorLogger";

    static final Constructor<? extends Logger> LOGGER; // (Class)
    static final Constructor<? extends Logger> LOGGER_OLD; // (String)

    static {
        LOGGER = resolveLoggerConstructor(LOGGER_CLASS, Class.class, true);
        // due backwards compatibility (if someone implemented the Logger iface)
        if ( LOGGER == null ) {
            LOGGER_OLD = resolveLoggerConstructor(LOGGER_CLASS, String.class, false);
        }
        else {
            LOGGER_OLD = resolveLoggerConstructor(LOGGER_CLASS, String.class, true);
        }
    }

    static Constructor<? extends Logger> resolveLoggerConstructor(
        final String className, final Class<?> paramType, boolean allowNoSuchMethod) {
        Constructor<? extends Logger> loggerCtor;
        final Object param = paramType == String.class ?
                LoggerFactory.class.getSimpleName() : LoggerFactory.class;
        try {
            @SuppressWarnings("unchecked")
            Class<? extends Logger> klass = (Class<? extends Logger>) Class.forName(className);
            loggerCtor = klass.getDeclaredConstructor(paramType);
            loggerCtor.newInstance(param); // check its working
        }
        catch (Exception ex) {
            if ( allowNoSuchMethod && ex instanceof NoSuchMethodException ) {
                return null;
            }
            try {
                @SuppressWarnings("unchecked")
                Class<? extends Logger> klass = (Class<? extends Logger>) Class.forName(BACKUP_LOGGER_CLASS);
                loggerCtor = klass.getDeclaredConstructor(paramType);
                Logger log = loggerCtor.newInstance(param);
                // log failure to load passeed -Djruby.logger.class :
                log.info("failed to create logger \"" + className + "\", using \"" + BACKUP_LOGGER_CLASS + "\"");
            }
            catch (Exception e2) {
                throw new IllegalStateException("unable to instantiate any logger", ex);
            }
        }
        return loggerCtor;
    }

    public static Logger getLogger(Class<?> loggerClass) {
        if ( LOGGER == null ) {
            return getLogger(loggerClass.getName());
        }
        try {
            return LOGGER.newInstance(loggerClass);
        }
        catch (Exception ex) {
            return getLoggerFallback(loggerClass, ex);
        }
    }

    /**
     * @deprecated prefer using {@link #getLogger(java.lang.Class)} if possible
     */
    public static Logger getLogger(String loggerName) {
        try {
            return LOGGER_OLD.newInstance(loggerName);
        }
        catch (Exception ex) {
            return getLoggerFallback(loggerName, ex);
        }
    }

    private static Logger getLoggerFallback(final String loggerName, final Exception ex) {
        Throwable rootCause = ex;
        // unwrap reflection exception wrappers
        while (rootCause.getCause() != null) {
            rootCause = rootCause.getCause();
        }

        if (rootCause instanceof SecurityException) {
            return new StandardErrorLogger(loggerName);
        }

        throw new IllegalStateException("unable to instantiate logger", ex);
    }

    private static Logger getLoggerFallback(final Class loggerClass, final Exception ex) {
        Throwable rootCause = ex;
        // unwrap reflection exception wrappers
        while (rootCause.getCause() != null) {
            rootCause = rootCause.getCause();
        }

        if (rootCause instanceof SecurityException) {
            return new StandardErrorLogger(loggerClass);
        }

        throw new IllegalStateException("unable to instantiate logger", ex);
    }

}
