/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF 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 org.apache.logging.log4j.core.appender;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.PrintStream;
  import java.io.Serializable;
  import java.io.UnsupportedEncodingException;
  import java.lang.reflect.Constructor;
  import java.nio.charset.Charset;
  
  import org.apache.logging.log4j.core.Filter;
  import org.apache.logging.log4j.core.Layout;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginElement;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.helpers.Booleans;
  import org.apache.logging.log4j.core.helpers.Loader;
  import org.apache.logging.log4j.core.layout.PatternLayout;
  import org.apache.logging.log4j.util.PropertiesUtil;
  
  /**
   * ConsoleAppender appends log events to <code>System.out</code> or
   * <code>System.err</code> using a layout specified by the user. The
   * default target is <code>System.out</code>.
   * @doubt accessing System.out or .err as a byte stream instead of a writer
   *    bypasses the JVM's knowledge of the proper encoding. (RG) Encoding
   * is handled within the Layout. Typically, a Layout will generate a String
   * and then call getBytes which may use a configured encoding or the system
   * default. OTOH, a Writer cannot print byte streams.
   */
  @Plugin(name = "Console", category = "Core", elementType = "appender", printObject = true)
  public final class ConsoleAppender extends AbstractOutputStreamAppender {
  
      private static final String JANSI_CLASS = "org.fusesource.jansi.WindowsAnsiOutputStream";
      private static ConsoleManagerFactory factory = new ConsoleManagerFactory();
  
      /**
       * Enumeration of console destinations.
       */
      public enum Target {
          /** Standard output. */
          SYSTEM_OUT,
          /** Standard error output. */
          SYSTEM_ERR
      }
  
      private ConsoleAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
                              final OutputStreamManager manager,
                              final boolean ignoreExceptions) {
          super(name, layout, filter, ignoreExceptions, true, manager);
      }
  
      /**
       * Create a Console Appender.
       * @param layout The layout to use (required).
       * @param filter The Filter or null.
       * @param t The target ("SYSTEM_OUT" or "SYSTEM_ERR"). The default is "SYSTEM_OUT".
       * @param follow If true will follow changes to the underlying output stream.
       * @param name The name of the Appender (required).
       * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
       *               they are propagated to the caller.
       * @return The ConsoleAppender.
       */
      @PluginFactory
      public static ConsoleAppender createAppender(
              @PluginElement("Layout") Layout<? extends Serializable> layout,
              @PluginElement("Filters") final Filter filter,
              @PluginAttribute("target") final String t,
              @PluginAttribute("name") final String name,
              @PluginAttribute("follow") final String follow,
              @PluginAttribute("ignoreExceptions") final String ignore) {
          if (name == null) {
              LOGGER.error("No name provided for ConsoleAppender");
              return null;
          }
          if (layout == null) {
              layout = PatternLayout.createLayout(null, null, null, null, null);
          }
          final boolean isFollow = Boolean.parseBoolean(follow);
          final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
          final Target target = t == null ? Target.SYSTEM_OUT : Target.valueOf(t);
          return new ConsoleAppender(name, layout, filter, getManager(isFollow, target, layout), ignoreExceptions);
     }
 
     private static OutputStreamManager getManager(final boolean follow, final Target target, final Layout<? extends Serializable> layout) {
         final String type = target.name();
         final OutputStream os = getOutputStream(follow, target);
         return OutputStreamManager.getManager(target.name() + "." + follow, new FactoryData(os, type, layout), factory);
     }
 
     private static OutputStream getOutputStream(final boolean follow, final Target target) {
         final String enc = Charset.defaultCharset().name();
         PrintStream printStream = null;
         try {
             printStream = target == Target.SYSTEM_OUT ?
             follow ? new PrintStream(new SystemOutStream(), true, enc) : System.out :
             follow ? new PrintStream(new SystemErrStream(), true, enc) : System.err;
         } catch (final UnsupportedEncodingException ex) { // should never happen
             throw new IllegalStateException("Unsupported default encoding " + enc, ex);
         }
         final PropertiesUtil propsUtil = PropertiesUtil.getProperties();
         if (!propsUtil.getStringProperty("os.name").startsWith("Windows") ||
             propsUtil.getBooleanProperty("log4j.skipJansi")) {
             return printStream;
         }
         try {
             final ClassLoader loader = Loader.getClassLoader();
             // We type the parameter as a wildcard to avoid a hard reference to Jansi.
             final Class<?> clazz = loader.loadClass(JANSI_CLASS);
             final Constructor<?> constructor = clazz.getConstructor(OutputStream.class);
             return (OutputStream) constructor.newInstance(printStream);
         } catch (final ClassNotFoundException cnfe) {
             LOGGER.debug("Jansi is not installed, cannot find {}", JANSI_CLASS);
         } catch (final NoSuchMethodException nsme) {
             LOGGER.warn("{} is missing the proper constructor", JANSI_CLASS);
         } catch (final Exception ex) {
             LOGGER.warn("Unable to instantiate {}", JANSI_CLASS);
         }
         return printStream;
     }
 
     /**
      * An implementation of OutputStream that redirects to the current System.err.
      */
     private static class SystemErrStream extends OutputStream {
         public SystemErrStream() {
         }
 
         @Override
         public void close() {
             // do not close sys err!
         }
 
         @Override
         public void flush() {
             System.err.flush();
         }
 
         @Override
         public void write(final byte[] b) throws IOException {
             System.err.write(b);
         }
 
         @Override
         public void write(final byte[] b, final int off, final int len)
             throws IOException {
             System.err.write(b, off, len);
         }
 
         @Override
         public void write(final int b) {
             System.err.write(b);
         }
     }
 
     /**
      * An implementation of OutputStream that redirects to the current System.out.
      */
     private static class SystemOutStream extends OutputStream {
         public SystemOutStream() {
         }
 
         @Override
         public void close() {
             // do not close sys out!
         }
 
         @Override
         public void flush() {
             System.out.flush();
         }
 
         @Override
         public void write(final byte[] b) throws IOException {
             System.out.write(b);
         }
 
         @Override
         public void write(final byte[] b, final int off, final int len)
             throws IOException {
             System.out.write(b, off, len);
         }
 
         @Override
         public void write(final int b) throws IOException {
             System.out.write(b);
         }
     }
 
     /**
      * Data to pass to factory method.
      */
     private static class FactoryData {
         private final OutputStream os;
         private final String type;
         private final Layout<? extends Serializable> layout;
 
         /**
          * Constructor.
          * @param os The OutputStream.
          * @param type The name of the target.
          * @param layout A Serializable layout
          */
         public FactoryData(final OutputStream os, final String type, final Layout<? extends Serializable> layout) {
             this.os = os;
             this.type = type;
             this.layout = layout;
         }
     }
 
     /**
      * Factory to create the Appender.
      */
     private static class ConsoleManagerFactory implements ManagerFactory<OutputStreamManager, FactoryData> {
 
         /**
          * Create an OutputStreamManager.
          * @param name The name of the entity to manage.
          * @param data The data required to create the entity.
          * @return The OutputStreamManager
          */
         @Override
         public OutputStreamManager createManager(final String name, final FactoryData data) {
             return new OutputStreamManager(data.os, data.type, data.layout);
         }
     }
 
 }