/*
    * 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;
  
  import java.io.Serializable;
  import java.util.Collection;
  import java.util.Locale;
  import java.util.Objects;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  import org.apache.logging.log4j.spi.StandardLevel;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * Levels used for identifying the severity of an event. Levels are organized from most specific to least:
   * <ul>
   * <li>{@link #OFF} (most specific, no logging)</li>
   * <li>{@link #FATAL} (most specific, little data)</li>
   * <li>{@link #ERROR}</li>
   * <li>{@link #WARN}</li>
   * <li>{@link #INFO}</li>
   * <li>{@link #DEBUG}</li>
   * <li>{@link #TRACE} (least specific, a lot of data)</li>
   * <li>{@link #ALL} (least specific, all data)</li>
   * </ul>
   *
   * Typically, configuring a level in a filter or on a logger will cause logging events of that level and those that are
   * more specific to pass through the filter. A special level, {@link #ALL}, is guaranteed to capture all levels when
   * used in logging configurations.
   */
  public final class Level implements Comparable<Level>, Serializable {
  
      /**
       * No events will be logged.
       */
      public static final Level OFF;
  
      /**
       * A severe error that will prevent the application from continuing.
       */
      public static final Level FATAL;
  
      /**
       * An error in the application, possibly recoverable.
       */
      public static final Level ERROR;
  
      /**
       * An event that might possible lead to an error.
       */
      public static final Level WARN;
  
      /**
       * An event for informational purposes.
       */
      public static final Level INFO;
  
      /**
       * A general debugging event.
       */
      public static final Level DEBUG;
  
      /**
       * A fine-grained debug message, typically capturing the flow through the application.
       */
      public static final Level TRACE;
  
      /**
       * All events should be logged.
       */
      public static final Level ALL;
  
      /**
       * @since 2.1
       */
      public static final String CATEGORY = "Level";
  
      private static final ConcurrentMap<String, Level> LEVELS = new ConcurrentHashMap<>(); // SUPPRESS CHECKSTYLE
  
      private static final long serialVersionUID = 1581082L;
  
      static {
          OFF = new Level("OFF", StandardLevel.OFF.intLevel());
          FATAL = new Level("FATAL", StandardLevel.FATAL.intLevel());
         ERROR = new Level("ERROR", StandardLevel.ERROR.intLevel());
         WARN = new Level("WARN", StandardLevel.WARN.intLevel());
         INFO = new Level("INFO", StandardLevel.INFO.intLevel());
         DEBUG = new Level("DEBUG", StandardLevel.DEBUG.intLevel());
         TRACE = new Level("TRACE", StandardLevel.TRACE.intLevel());
         ALL = new Level("ALL", StandardLevel.ALL.intLevel());
     }
 
     private final String name;
     private final int intLevel;
     private final StandardLevel standardLevel;
 
     private Level(final String name, final int intLevel) {
         if (Strings.isEmpty(name)) {
             throw new IllegalArgumentException("Illegal null or empty Level name.");
         }
         if (intLevel < 0) {
             throw new IllegalArgumentException("Illegal Level int less than zero.");
         }
         this.name = name;
         this.intLevel = intLevel;
         this.standardLevel = StandardLevel.getStandardLevel(intLevel);
         if (LEVELS.putIfAbsent(name, this) != null) {
             throw new IllegalStateException("Level " + name + " has already been defined.");
         }
     }
 
     /**
      * Gets the integral value of this Level.
      *
      * @return the value of this Level.
      */
     public int intLevel() {
         return this.intLevel;
     }
 
     /**
      * Gets the standard Level values as an enum.
      *
      * @return an enum of the standard Levels.
      */
     public StandardLevel getStandardLevel() {
         return standardLevel;
     }
 
     /**
      * Compares this level against the levels passed as arguments and returns true if this level is in between the given
      * levels.
      *
      * @param minLevel The minimum level to test.
      * @param maxLevel The maximum level to test.
      * @return True true if this level is in between the given levels
      * @since 2.4
      */
     public boolean isInRange(final Level minLevel, final Level maxLevel) {
         return this.intLevel >= minLevel.intLevel && this.intLevel <= maxLevel.intLevel;
     }
 
     /**
      * Compares this level against the level passed as an argument and returns true if this level is the same or is less
      * specific.
      * <p>
      * Concretely, {@link #ALL} is less specific than {@link #TRACE}, which is less specific than {@link #DEBUG}, which
      * is less specific than {@link #INFO}, which is less specific than {@link #WARN}, which is less specific than
      * {@link #ERROR}, which is less specific than {@link #FATAL}, and finally {@link #OFF}, which is the most specific
      * standard level.
      * </p>
      *
      * @param level
      *            The level to test.
      * @return True if this level Level is less specific or the same as the given Level.
      */
     public boolean isLessSpecificThan(final Level level) {
         return this.intLevel >= level.intLevel;
     }
 
     /**
      * Compares this level against the level passed as an argument and returns true if this level is the same or is more
      * specific.
      * <p>
      * Concretely, {@link #FATAL} is more specific than {@link #ERROR}, which is more specific than {@link #WARN},
      * etc., until {@link #TRACE}, and finally {@link #ALL}, which is the least specific standard level.
      * The most specific level is {@link #OFF}.
      * </p>
      *
      * @param level The level to test.
      * @return True if this level Level is more specific or the same as the given Level.
      */
     public boolean isMoreSpecificThan(final Level level) {
         return this.intLevel <= level.intLevel;
     }
 
     @Override
     @SuppressWarnings("CloneDoesntCallSuperClone")
     // CHECKSTYLE:OFF
     public Level clone() throws CloneNotSupportedException {
         throw new CloneNotSupportedException();
     }
     // CHECKSTYLE:ON
 
     @Override
     public int compareTo(final Level other) {
         return intLevel < other.intLevel ? -1 : (intLevel > other.intLevel ? 1 : 0);
     }
 
     @Override
     public boolean equals(final Object other) {
         return other instanceof Level && other == this;
     }
 
     public Class<Level> getDeclaringClass() {
         return Level.class;
     }
 
     @Override
     public int hashCode() {
         return this.name.hashCode();
     }
 
     /**
      * Gets the symbolic name of this Level. Equivalent to calling {@link #toString()}.
      *
      * @return the name of this Level.
      */
     public String name() {
         return this.name;
     }
 
     @Override
     public String toString() {
         return this.name;
     }
 
     /**
      * Retrieves an existing Level or creates on if it didn't previously exist.
      *
      * @param name The name of the level.
      * @param intValue The integer value for the Level. If the level was previously created this value is ignored.
      * @return The Level.
      * @throws java.lang.IllegalArgumentException if the name is null or intValue is less than zero.
      */
     public static Level forName(final String name, final int intValue) {
         final Level level = LEVELS.get(name);
         if (level != null) {
             return level;
         }
         try {
             return new Level(name, intValue);
         } catch (final IllegalStateException ex) {
             // The level was added by something else so just return that one.
             return LEVELS.get(name);
         }
     }
 
     /**
      * Return the Level associated with the name or null if the Level cannot be found.
      *
      * @param name The name of the Level.
      * @return The Level or null.
      */
     public static Level getLevel(final String name) {
         return LEVELS.get(name);
     }
 
     /**
      * Converts the string passed as argument to a level. If the conversion fails, then this method returns
      * {@link #DEBUG}.
      *
      * @param sArg The name of the desired Level.
      * @return The Level associated with the String.
      */
     public static Level toLevel(final String sArg) {
         return toLevel(sArg, Level.DEBUG);
     }
 
     /**
      * Converts the string passed as argument to a level. If the conversion fails, then this method returns the value of
      * <code>defaultLevel</code>.
      *
      * @param name The name of the desired Level.
      * @param defaultLevel The Level to use if the String is invalid.
      * @return The Level associated with the String.
      */
     public static Level toLevel(final String name, final Level defaultLevel) {
         if (name == null) {
             return defaultLevel;
         }
         final Level level = LEVELS.get(toUpperCase(name));
         return level == null ? defaultLevel : level;
     }
 
     private static String toUpperCase(final String name) {
         return name.toUpperCase(Locale.ENGLISH);
     }
 
     /**
      * Return an array of all the Levels that have been registered.
      *
      * @return An array of Levels.
      */
     public static Level[] values() {
         final Collection<Level> values = Level.LEVELS.values();
         return values.toArray(new Level[values.size()]);
     }
 
     /**
      * Return the Level associated with the name.
      *
      * @param name The name of the Level to return.
      * @return The Level.
      * @throws java.lang.NullPointerException if the Level name is {@code null}.
      * @throws java.lang.IllegalArgumentException if the Level name is not registered.
      */
     public static Level valueOf(final String name) {
         Objects.requireNonNull(name, "No level name given.");
         final String levelName = toUpperCase(name);
         final Level level = LEVELS.get(levelName);
         if (level != null) {
             return level;
         }
         throw new IllegalArgumentException("Unknown level constant [" + levelName + "].");
     }
 
     /**
      * Returns the enum constant of the specified enum type with the specified name. The name must match exactly an
      * identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
      *
      * @param enumType the {@code Class} object of the enum type from which to return a constant
      * @param name the name of the constant to return
      * @param <T> The enum type whose constant is to be returned
      * @return the enum constant of the specified enum type with the specified name
      * @throws java.lang.IllegalArgumentException if the specified enum type has no constant with the specified name, or
      *             the specified class object does not represent an enum type
      * @throws java.lang.NullPointerException if {@code enumType} or {@code name} are {@code null}
      * @see java.lang.Enum#valueOf(Class, String)
      */
     public static <T extends Enum<T>> T valueOf(final Class<T> enumType, final String name) {
         return Enum.valueOf(enumType, name);
     }
 
     // for deserialization
     protected Object readResolve() {
         return Level.valueOf(this.name);
     }
 }