/*
    * Copyright (C) 2010-2014 Hamburg Sud and the contributors.
    *
    * 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 org.aludratest.config;
  
  /**
   * Helper class for Preferences consumers which can be used to have getter methods which validate the existence of a configuration
   * property when trying to retrieve it. Clients can wrap an existing Preferences object with this class and use its methods. <br>
   * Queried child nodes are automatically wrapped and returned as ValidatingPreferencesWrapper.
   * 
   * @author falbrech
   * 
   */
  public final class ValidatingPreferencesWrapper implements Preferences {
  
      private Preferences delegate;
  
      /**
       * Creates a new ValidatingPreferencesWrapper object which wraps the given Preferences object.
       * 
       * @param delegate
       *            Preferences node to wrap.
       */
      public ValidatingPreferencesWrapper(Preferences delegate) {
          this.delegate = delegate;
      }
  
      /** Returns the String representation of the given configuration key's value. If the configuration key does not exist on this
       * Preferences node, or if its value is <code>null</code>, an {@link org.aludratest.exception.AutomationException} is thrown.
       * 
       * @param key Configuration key to retrieve the value of.
       * 
       * @return The value of the configuration key, as a String. */
      public String getRequiredStringValue(String key) {
          return assertNotNull(key, getStringValue(key));
      }
  
      /** Returns the int representation of the given configuration key's value. If the configuration key does not exist on this
       * Preferences node, or if its stored String value is <code>null</code>, an
       * {@link org.aludratest.exception.AutomationException} is thrown.
       * 
       * @param key Configuration key to retrieve the value of.
       * 
       * @return The value of the configuration key, as an int. */
      public int getRequiredIntValue(String key) {
          return assertNotNull(key, getIntValue(key));
      }
  
      /** Returns the double representation of the given configuration key's value. If the configuration key does not exist on this
       * Preferences node, or if its stored String value is <code>null</code>, an
       * {@link org.aludratest.exception.AutomationException} is thrown.
       * 
       * @param key Configuration key to retrieve the value of.
       * 
       * @return The value of the configuration key, as a double. */
      public double getRequiredDoubleValue(String key) {
          return assertNotNull(key, getDoubleValue(key));
      }
  
      /** Returns the float representation of the given configuration key's value. If the configuration key does not exist on this
       * Preferences node, or if its stored String value is <code>null</code>, an
       * {@link org.aludratest.exception.AutomationException} is thrown.
       * 
       * @param key Configuration key to retrieve the value of.
       * 
       * @return The value of the configuration key, as a float. */
      public float getRequiredFloatValue(String key) {
          return assertNotNull(key, getFloatValue(key));
      }
  
      /** Returns the boolean representation of the given configuration key's value. If the configuration key does not exist on this
       * Preferences node, or if its stored String value is <code>null</code>, an
       * {@link org.aludratest.exception.AutomationException} is thrown.
       * 
       * @param key Configuration key to retrieve the value of.
       * 
       * @return The value of the configuration key, as a boolean. */
      public boolean getRequiredBooleanValue(String key) {
          return assertNotNull(key, getBooleanValue(key));
      }
  
      /** Returns the char representation of the given configuration key's value. If the configuration key does not exist on this
       * Preferences node, or if its stored String value is <code>null</code>, an
       * {@link org.aludratest.exception.AutomationException} is thrown.
       * 
       * @param key Configuration key to retrieve the value of.
       * 
      * @return The value of the configuration key, as a char. */
     public char getRequiredCharValue(String key) {
         return assertNotNull(key, getCharValue(key));
     }
 
     @Override
     public String getStringValue(String key) {
         return delegate.getStringValue(key);
     }
 
     @Override
     public int getIntValue(String key) {
         return delegate.getIntValue(key);
     }
 
     @Override
     public boolean getBooleanValue(String key) {
         return delegate.getBooleanValue(key);
     }
 
     @Override
     public float getFloatValue(String key) {
         return delegate.getFloatValue(key);
     }
 
     @Override
     public double getDoubleValue(String key) {
         return delegate.getDoubleValue(key);
     }
 
     @Override
     public char getCharValue(String key) {
         return delegate.getCharValue(key);
     }
 
     @Override
     public String getStringValue(String key, String defaultValue) {
         return delegate.getStringValue(key, defaultValue);
     }
 
     @Override
     public int getIntValue(String key, int defaultValue) {
         return delegate.getIntValue(key, defaultValue);
     }
 
     @Override
     public boolean getBooleanValue(String key, boolean defaultValue) {
         return delegate.getBooleanValue(key, defaultValue);
     }
 
     @Override
     public float getFloatValue(String key, float defaultValue) {
         return delegate.getFloatValue(key, defaultValue);
     }
 
     @Override
     public double getDoubleValue(String key, double defaultValue) {
         return delegate.getDoubleValue(key, defaultValue);
     }
 
     @Override
     public char getCharValue(String key, char defaultValue) {
         return delegate.getCharValue(key, defaultValue);
     }
 
     @Override
     public String[] getKeyNames() {
         return delegate.getKeyNames();
     }
 
     @Override
     public ValidatingPreferencesWrapper getChildNode(String name) {
         return new ValidatingPreferencesWrapper(delegate.getChildNode(name));
     }
 
     @Override
     public String[] getChildNodeNames() {
         return delegate.getChildNodeNames();
     }
 
     /** Helper method which asserts that a property value is not null and not empty.
      * 
      * @param key the name of the property to check
      * @param value the property value to check
      * @return the value specified as parameter */
     private static <T> T assertNotNull(String key, T value) {
         if (value == null || "".equals(value)) {
             throw new ConfigurationException("Missing configuration property: " + key);
         }
         return value;
     }
 }