/*
    * 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.db.jpa;
  
  import java.util.Map;
  
  import javax.persistence.Inheritance;
  import javax.persistence.InheritanceType;
  import javax.persistence.MappedSuperclass;
  import javax.persistence.Transient;
  
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.Marker;
  import org.apache.logging.log4j.ThreadContext;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.message.Message;
  
  /**
   * <p>
   * Users of the JPA appender MUST extend this class, using JPA annotations on the concrete class and all of its
   * accessor methods (as needed) to map them to the proper table and columns. Accessors you do not want persisted should
   * be annotated with {@link Transient @Transient}. All accessors should call {@link #getWrappedEvent()} and delegate the
   * call to the underlying event. Users may want to instead extend {@link BasicLogEventEntity}, which takes care of all
   * of this for you.
   * </p>
   * <p>
   * The concrete class must have two constructors: a public no-arg constructor to convince the JPA provider that it's a
   * valid entity, and a public constructor that takes a single {@link LogEvent event} and passes it to the parent class
   * with {@link #AbstractLogEventWrapperEntity(LogEvent) super(event)}. Furthermore, the concrete class must be annotated
   * {@link javax.persistence.Entity @Entity} and {@link javax.persistence.Table @Table} and must implement a fully
   * mutable ID property annotated with {@link javax.persistence.Id @Id} and
   * {@link javax.persistence.GeneratedValue @GeneratedValue} to tell the JPA provider how to calculate an ID for new
   * events.
   * </p>
   * <p>
   * Many of the return types of {@link LogEvent} methods (e.g., {@link StackTraceElement}, {@link Message},
   * {@link Marker}, {@link Throwable}, 
   * {@link org.apache.logging.log4j.ThreadContext.ContextStack ThreadContext.ContextStack}, and 
   * {@link Map Map&lt;String, String&gt}) will not be recognized by the JPA provider. In conjunction with 
   * {@link javax.persistence.Convert @Convert}, you can use the converters in the 
   * {@link org.apache.logging.log4j.core.appender.db.jpa.converter} package to convert these types to database columns.
   * If you want to retrieve log events from the database, you can create a true POJO entity and also use these 
   * converters for extracting persisted values.<br>
   * </p>
   * <p>
   * The mutator methods in this class not specified in {@link LogEvent} are no-op methods, implemented to satisfy the JPA
   * requirement that accessor methods have matching mutator methods. If you create additional accessor methods, you must
   * likewise create matching no-op mutator methods.
   * </p>
   *
   * @see BasicLogEventEntity
   */
  @MappedSuperclass
  @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
  public abstract class AbstractLogEventWrapperEntity implements LogEvent {
      private static final long serialVersionUID = 1L;
  
      private final LogEvent wrappedEvent;
  
      /**
       * Instantiates this base class. All concrete implementations must have a constructor matching this constructor's
       * signature. The no-argument constructor is required for a standards-compliant JPA provider to accept this as an
       * entity.
       */
      @SuppressWarnings("unused")
      protected AbstractLogEventWrapperEntity() {
          this(new NullLogEvent());
      }
  
      /**
       * Instantiates this base class. All concrete implementations must have a constructor matching this constructor's
       * signature. This constructor is used for wrapping this entity around a logged event.
       *
       * @param wrappedEvent The underlying event from which information is obtained.
       */
      protected AbstractLogEventWrapperEntity(final LogEvent wrappedEvent) {
          if (wrappedEvent == null) {
              throw new IllegalArgumentException("The wrapped event cannot be null.");
          }
          this.wrappedEvent = wrappedEvent;
      }
  
      /**
       * All eventual accessor methods must call this method and delegate the method call to the underlying wrapped event.
       * Annotated {@link Transient} so as not to be included in the persisted entity.
      *
      * @return The underlying event from which information is obtained.
      */
     @Transient
     protected final LogEvent getWrappedEvent() {
         return this.wrappedEvent;
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param level Ignored.
      */
     @SuppressWarnings("unused")
     public void setLevel(final Level level) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param loggerName Ignored.
      */
     @SuppressWarnings("unused")
     public void setLoggerName(final String loggerName) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param source Ignored.
      */
     @SuppressWarnings("unused")
     public void setSource(final StackTraceElement source) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param message Ignored.
      */
     @SuppressWarnings("unused")
     public void setMessage(final Message message) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param marker Ignored.
      */
     @SuppressWarnings("unused")
     public void setMarker(final Marker marker) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param threadName Ignored.
      */
     @SuppressWarnings("unused")
     public void setThreadName(final String threadName) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param millis Ignored.
      */
     @SuppressWarnings("unused")
     public void setMillis(final long millis) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param throwable Ignored.
      */
     @SuppressWarnings("unused")
     public void setThrown(final Throwable throwable) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param contextMap Ignored.
      */
     @SuppressWarnings("unused")
     public void setContextMap(final Map<String, String> contextMap) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param contextStack Ignored.
      */
     @SuppressWarnings("unused")
     public void setContextStack(final ThreadContext.ContextStack contextStack) {
         // this entity is write-only
     }
 
     /**
      * A no-op mutator to satisfy JPA requirements, as this entity is write-only.
      *
      * @param fqcn Ignored.
      */
     @SuppressWarnings("unused")
     public void setFQCN(final String fqcn) {
         // this entity is write-only
     }
 
     /**
      * Indicates whether the source of the logging request is required downstream. Annotated
      * {@link Transient @Transient} so as to not be included in the persisted entity.
      *
      * @return whether the source of the logging request is required downstream.
      */
     @Override
     @Transient
     public final boolean isIncludeLocation() {
         return this.getWrappedEvent().isIncludeLocation();
     }
 
     @Override
     public final void setIncludeLocation(final boolean locationRequired) {
         this.getWrappedEvent().setIncludeLocation(locationRequired);
     }
 
     /**
      * Indicates whether this event is the last one in a batch. Annotated {@link Transient @Transient} so as to not be
      * included in the persisted entity.
      *
      * @return whether this event is the last one in a batch.
      */
     @Override
     @Transient
     public final boolean isEndOfBatch() {
         return this.getWrappedEvent().isEndOfBatch();
     }
 
     @Override
     public final void setEndOfBatch(final boolean endOfBatch) {
         this.getWrappedEvent().setEndOfBatch(endOfBatch);
     }
 
     /**
      * A no-op log event class to prevent {@code NullPointerException}s. O/RMs tend to create instances of entities in
      * order to "play around" with them.
      */
     private static class NullLogEvent implements LogEvent {
         private static final long serialVersionUID = 1L;
 
         @Override
         public Level getLevel() {
             return null;
         }
 
         @Override
         public String getLoggerName() {
             return null;
         }
 
         @Override
         public StackTraceElement getSource() {
             return null;
         }
 
         @Override
         public Message getMessage() {
             return null;
         }
 
         @Override
         public Marker getMarker() {
             return null;
         }
 
         @Override
         public String getThreadName() {
             return null;
         }
 
         @Override
         public long getMillis() {
             return 0;
         }
 
         @Override
         public Throwable getThrown() {
             return null;
         }
 
         @Override
         public Map<String, String> getContextMap() {
             return null;
         }
 
         @Override
         public ThreadContext.ContextStack getContextStack() {
             return null;
         }
 
         @Override
         public String getFQCN() {
             return null;
         }
 
         @Override
         public boolean isIncludeLocation() {
             return false;
         }
 
         @Override
         public void setIncludeLocation(final boolean locationRequired) {
 
         }
 
         @Override
         public boolean isEndOfBatch() {
             return false;
         }
 
         @Override
         public void setEndOfBatch(final boolean endOfBatch) {
 
         }
     }
 }