/*

  * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH

  *

  * Licensed 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 de.smartics.properties.api.config.domain;

 import java.util.ArrayList;

 import java.util.List;

 /**

  * Helper to parse dependencies from a property value. A dependency is a place

  * holder that is to be resolved to resolve the property's value.

  */

 final class DependenciesParser

 {

   // ********************************* Fields *********************************

   // --- constants ------------------------------------------------------------

   // --- members --------------------------------------------------------------

   // ****************************** Initializer *******************************

   // ****************************** Constructors ******************************

   // ****************************** Inner Classes *****************************

   // ********************************* Methods ********************************

   // --- init -----------------------------------------------------------------

   // --- get&set --------------------------------------------------------------

   // --- business -------------------------------------------------------------

   /**

    * Returns the names of properties this property depends on. May be

    * <code>null</code>, if this property does not refer to other properties.

    *

    * @param value the value to parse, may be <code>null</code>.

    * @return the names of properties this property depends on.

    */

   List<String> getDependencies(final String value)

   {

     final List<String> dependencies = new ArrayList<String>();

     if (value != null)

     {

       final int length = value.length();

       for (int i = 0; i < length; i++)

       {

         final char c = value.charAt(i);

         if (c == '$' && i < length - 1 && value.charAt(i + 1) == '{')

         {

           // CHECKSTYLE:OFF

           i = readKey(dependencies, value, i + 1);

           // CHECKSTYLE:ON

         }

       }

     }

     return dependencies;

   }

   private static int readKey(final List<String> dependencies,

       final String value, final int index)

   {

     final int length = value.length() - 1;

     final StringBuilder keyBuffer = new StringBuilder(64);

     int i = index;

     char n = value.charAt(++i);

     while (n != '}' && i < length)

     {

       keyBuffer.append(n);

       n = value.charAt(++i);

     }

     final String key = keyBuffer.toString();

     dependencies.add(key);

     return i;

   }

   // --- object basics --------------------------------------------------------

 }