/*
    * 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.config;
  
  import java.util.Objects;
  
  import org.apache.logging.log4j.Logger;
  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.PluginFactory;
  import org.apache.logging.log4j.core.config.plugins.PluginValue;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * Represents a key/value pair in the configuration.
   */
  @Plugin(name = "property", category = Node.CATEGORY, printObject = true)
  public final class Property {
  
      /**
       * @since 2.11.2
       */
      public static final Property[] EMPTY_ARRAY = new Property[0];
  
      private static final Logger LOGGER = StatusLogger.getLogger();
  
      private final String name;
      private final String value;
      private final boolean valueNeedsLookup;
  
      private Property(final String name, final String value) {
          this.name = name;
          this.value = value;
          this.valueNeedsLookup = value != null && value.contains("${");
      }
  
      /**
       * Returns the property name.
       * @return the property name.
       */
      public String getName() {
          return name;
      }
  
      /**
       * Returns the property value.
       * @return the value of the property.
       */
      public String getValue() {
          return Objects.toString(value, Strings.EMPTY); // LOG4J2-1313 null would be same as Property not existing
      }
  
      /**
       * Returns {@code true} if the value contains a substitutable property that requires a lookup to be resolved.
       * @return {@code true} if the value contains {@code "${"}, {@code false} otherwise
       */
      public boolean isValueNeedsLookup() {
          return valueNeedsLookup;
      }
  
      /**
       * Creates a Property.
       *
       * @param name The key.
       * @param value The value.
       * @return A Property.
       */
      @PluginFactory
      public static Property createProperty(
              @PluginAttribute("name") final String name,
              @PluginValue("value") final String value) {
          if (name == null) {
              LOGGER.error("Property name cannot be null");
          }
          return new Property(name, value);
      }
  
      @Override
      public String toString() {
          return name + '=' + getValue();
      }
  }