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This project is about configuration of applications and about parameterization of Objects. This library offers annotations (and annotation processors), parsers, typing, observing changes, serialization, cloning and more when working with settings and/or object parameters. Settings and its features can be declared using an xml format. The library offers syntax support for settings and parameters in a loosely coupled manner. You are not restricted to built in syntax, you can provide your own. At runtime this library tracks keys for which a default is used because they are not found in settings. Also it tracks unused keys. You can stack features for settings such as caching, preparing keys and values, readonlyness, threadsafety, helpsupport, reading / parsing from input. You can easily develop your own features for settings.

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/*
 * Copyright 2015 VectorPrint.
 *
 * 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 com.vectorprint.configuration.binding.settings;

/*
 * #%L
 * Config
 * %%
 * Copyright (C) 2015 - 2016 VectorPrint
 * %%
 * 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.
 * #L%
 */

import java.util.ArrayList;
import java.util.List;
import java.util.ServiceLoader;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Singleton provider of {@link EnhancedMapBindingFactory} instances. This class uses spi ({@link ServiceLoader#load(java.lang.Class)
 * }) to find instances of {@link EnhancedMapBindingFactory} and of {@link SettingsFactoryValidator}. Every factory found is validated by all validators found,
 * the first valid factory is returned.
 *
 * @author Eduard Drenth at VectorPrint.nl
 */
public class SettingsBindingService {
   
   private static final Logger LOGGER = Logger.getLogger(SettingsBindingService.class.getName());

   private final ServiceLoader factories;
   private final ServiceLoader validators;

   private SettingsBindingService() {
      factories = ServiceLoader.load(EnhancedMapBindingFactory.class);
      validators = ServiceLoader.load(SettingsFactoryValidator.class);
   }

   private static final SettingsBindingService instance = new SettingsBindingService();

   public static SettingsBindingService getInstance() {
      return instance;
   }

   /**
    * Return the first implementation of {@link EnhancedMapBindingFactory} found that is valid according to all
    * {@link SettingsFactoryValidator}s, or return null. When no validator is published return the first {@link EnhancedMapBindingFactory} found.
    *
    * @return
    */
   public EnhancedMapBindingFactory getFactory() {
      for (EnhancedMapBindingFactory f : factories) {
         if (isValid(f)) {
            return f;
         }
      }
      return null;
   }
   
   public boolean isValid(EnhancedMapBindingFactory f ) {
         boolean ok = true;
         boolean noValidatorFound = true;
         for (SettingsFactoryValidator validator : validators) {
            noValidatorFound = false;
            if (!validator.isValid(f)) {
               if (LOGGER.isLoggable(Level.FINE)) {
                  LOGGER.fine(String.format("%s does not pass validation by %s", f.getClass().getName(), validator.getClass().getName()));
               }
               ok = false;
               break;
            }
         }
         return ok||noValidatorFound;
   }

   /**
    * 
    * @return a list of factories found through SPI
    */
   public List> getFactoriesKnown() {
      List> l = new ArrayList<>();
      for (EnhancedMapBindingFactory f : factories) {
         l.add(f.getClass());
      }
      return l;
   }

   /**
    * 
    * @return a list of valid factories found through SPI
    */
   public List> getValidFactories() {
      List> l = new ArrayList<>();
      for (EnhancedMapBindingFactory f : factories) {
         if (isValid(f)) {
            l.add(f.getClass());
         }
      }
      return l;
   }

   /**
    * 
    * @return a list of validators found through SPI
    */
   public List> getValidatorsKnown() {
      List> l = new ArrayList<>();
      for (SettingsFactoryValidator f : validators) {
         l.add(f.getClass());
      }
      return l;
   }
}