/*
    * 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.message;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import org.apache.logging.log4j.util.StringBuilderFormattable;
  
  /**
   * The simplest possible implementation of Message. It just returns the String given as the constructor argument.
   */
  public class SimpleMessage implements Message, StringBuilderFormattable, CharSequence {
      private static final long serialVersionUID = -8398002534962715992L;
  
      private String message;
      private transient CharSequence charSequence;
  
      /**
       * Basic constructor.
       */
      public SimpleMessage() {
          this(null);
      }
  
      /**
       * Constructor that includes the message.
       * @param message The String message.
       */
      public SimpleMessage(final String message) {
          this.message = message;
          this.charSequence = message;
      }
  
      /**
       * Constructor that includes the message.
       * @param charSequence The CharSequence message.
       */
      public SimpleMessage(final CharSequence charSequence) {
          // this.message = String.valueOf(charSequence); // postponed until getFormattedMessage
          this.charSequence = charSequence;
      }
  
      /**
       * Returns the message.
       * @return the message.
       */
      @Override
      public String getFormattedMessage() {
          if (message == null) {
              message = String.valueOf(charSequence);
          }
          return message;
      }
  
      @Override
      public void formatTo(final StringBuilder buffer) {
          if (message != null) {
              buffer.append(message);
          } else {
              buffer.append(charSequence);
          }
      }
  
      /**
       * Returns the message.
       * @return the message.
       */
      @Override
      public String getFormat() {
          return getFormattedMessage();
      }
  
      /**
       * Returns null since there are no parameters.
       * @return null.
       */
      @Override
      public Object[] getParameters() {
          return null;
      }
  
      @Override
      public boolean equals(final Object o) {
          if (this == o) {
             return true;
         }
         if (o == null || getClass() != o.getClass()) {
             return false;
         }
 
         final SimpleMessage that = (SimpleMessage) o;
 
         return !(charSequence != null ? !charSequence.equals(that.charSequence) : that.charSequence != null);
     }
 
     @Override
     public int hashCode() {
         return charSequence != null ? charSequence.hashCode() : 0;
     }
 
     @Override
     public String toString() {
         return getFormattedMessage();
     }
 
     /**
      * Always returns null.
      *
      * @return null
      */
     @Override
     public Throwable getThrowable() {
         return null;
     }
 
 
     // CharSequence impl
 
     @Override
     public int length() {
         return charSequence == null ? 0 : charSequence.length();
     }
 
     @Override
     public char charAt(final int index) {
         return charSequence.charAt(index);
     }
 
     @Override
     public CharSequence subSequence(final int start, final int end) {
         return charSequence.subSequence(start, end);
     }
 
 
     private void writeObject(final ObjectOutputStream out) throws IOException {
         getFormattedMessage(); // initialize the message:String field
         out.defaultWriteObject();
     }
 
     private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
         charSequence = message;
     }
 }