/*
    * 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.Serializable;
  
  /**
   * The StructuredData identifier.
   */
  public class StructuredDataId implements Serializable {
  
      private static final String AT = "@";
  
      /**
       * RFC 5424 Time Quality.
       */
      public static final StructuredDataId TIME_QUALITY = new StructuredDataId("timeQuality", null,
          new String[]{"tzKnown", "isSynced", "syncAccuracy"});
  
      /**
       * RFC 5424 Origin.
       */
      public static final StructuredDataId ORIGIN = new StructuredDataId("origin", null,
          new String[]{"ip", "enterpriseId", "software", "swVersion"});
  
      /**
       * RFC 5424 Meta.
       */
      public static final StructuredDataId META = new StructuredDataId("meta", null,
          new String[]{"sequenceId", "sysUpTime", "language"});
  
      /**
       * Reserved enterprise number.
       */
      public static final int RESERVED = -1;
  
      private static final long serialVersionUID = 9031746276396249990L;
      private static final int MAX_LENGTH = 32;
  
      private final String name;
      private final int enterpriseNumber;
      private final String[] required;
      private final String[] optional;
  
  
      protected StructuredDataId(final String name, final String[] required, final String[] optional) {
          int index = -1;
          if (name != null) {
              if (name.length() > MAX_LENGTH) {
                  throw new IllegalArgumentException(String.format("Length of id %s exceeds maximum of %d characters",
                          name, MAX_LENGTH));
              }
              index = name.indexOf(AT);
          }
  
          if (index > 0) {
              this.name = name.substring(0, index);
              this.enterpriseNumber = Integer.parseInt(name.substring(index + 1));
          } else {
              this.name = name;
              this.enterpriseNumber = RESERVED;
          }
          this.required = required;
          this.optional = optional;
      }
  
      /**
       * A Constructor that helps conformance to RFC 5424.
       *
       * @param name             The name portion of the id.
       * @param enterpriseNumber The enterprise number.
       * @param required         The list of keys that are required for this id.
       * @param optional         The list of keys that are optional for this id.
       */
      public StructuredDataId(final String name, final int enterpriseNumber, final String[] required,
                              final String[] optional) {
          if (name == null) {
              throw new IllegalArgumentException("No structured id name was supplied");
          }
          if (name.contains(AT)) {
              throw new IllegalArgumentException("Structured id name cannot contain an '" + AT + '\'');
          }
          if (enterpriseNumber <= 0) {
              throw new IllegalArgumentException("No enterprise number was supplied");
          }
         this.name = name;
         this.enterpriseNumber = enterpriseNumber;
         final String id = enterpriseNumber < 0 ? name : name + AT + enterpriseNumber;
         if (id.length() > MAX_LENGTH) {
             throw new IllegalArgumentException("Length of id exceeds maximum of 32 characters: " + id);
         }
         this.required = required;
         this.optional = optional;
     }
 
     /**
      * Creates an id using another id to supply default values.
      * @param id The original StructuredDataId.
      * @return the new StructuredDataId.
      */
     public StructuredDataId makeId(final StructuredDataId id) {
         if (id == null) {
             return this;
         }
         return makeId(id.getName(), id.getEnterpriseNumber());
     }
 
     /**
      * Creates an id based on the current id.
      * @param defaultId The default id to use if this StructuredDataId doesn't have a name.
      * @param enterpriseNumber The enterprise number.
      * @return a StructuredDataId.
      */
     public StructuredDataId makeId(final String defaultId, final int enterpriseNumber) {
         String id;
         String[] req;
         String[] opt;
         if (enterpriseNumber <= 0) {
             return this;
         }
         if (this.name != null) {
             id = this.name;
             req = this.required;
             opt = this.optional;
         } else {
             id = defaultId;
             req = null;
             opt = null;
         }
 
         return new StructuredDataId(id, enterpriseNumber, req, opt);
     }
 
     /**
      * Returns a list of required keys.
      * @return a List of required keys or null if none have been provided.
      */
     public String[] getRequired() {
         return required;
     }
 
     /**
      * Returns a list of optional keys.
      * @return a List of optional keys or null if none have been provided.
      */
     public String[] getOptional() {
         return optional;
     }
 
     /**
      * Returns the StructuredDataId name.
      * @return the StructuredDataId name.
      */
     public String getName() {
         return name;
     }
 
     /**
      * Returns the enterprise number.
      * @return the enterprise number.
      */
     public int getEnterpriseNumber() {
         return enterpriseNumber;
     }
 
     /**
      * Indicates if the id is reserved.
      * @return true if the id uses the reserved enterprise number, false otherwise.
      */
     public boolean isReserved() {
         return enterpriseNumber <= 0;
     }
 
     @Override
     public String toString() {
         return isReserved() ? name : name + AT + enterpriseNumber;
     }
 }