/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.util.internal.logging;


import org.slf4j.LoggerFactory;
import org.slf4j.helpers.NOPLoggerFactory;

import java.io.OutputStream;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;

/**
 * Logger factory which creates a <a href="http://www.slf4j.org/">SLF4J</a>
 * logger.
 */
public class Slf4JLoggerFactory extends InternalLoggerFactory {

    public Slf4JLoggerFactory() {
    }

    Slf4JLoggerFactory(boolean failIfNOP) {
        assert failIfNOP; // Should be always called with true.

        // SFL4J writes it error messages to System.err. Capture them so that the user does not see such a message on
        // the console during automatic detection.
        final StringBuffer buf = new StringBuffer();
        final PrintStream err = System.err;
        try {
            System.setErr(new PrintStream(new OutputStream() {
                @Override
                public void write(int b) {
                    buf.append((char) b);
                }
            }, true, "US-ASCII"));
        } catch (UnsupportedEncodingException e) {
            throw new Error(e);
        }

        try {
            if (LoggerFactory.getILoggerFactory() instanceof NOPLoggerFactory) {
                throw new NoClassDefFoundError(buf.toString());
            } else {
                err.print(buf);
                err.flush();
            }
        } finally {
            System.setErr(err);
        }
    }

    @Override
    public InternalLogger newInstance(String name) {
        return new Slf4JLogger(LoggerFactory.getLogger(name));
    }
}