/**
    * Copyright 2005-2016 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.krad.data.provider.impl;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.kuali.rice.krad.data.metadata.DataObjectMetadata;
  import org.kuali.rice.krad.data.provider.MetadataProvider;
  
  /**
   * Superclass for all metadata providers which contain the basic operations and data structure.
   *
   * <p>All each subclass needs to implement is the initializeMetadata method.</p>
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public abstract class MetadataProviderBase implements MetadataProvider {
  
      /**
       * The map of types to metadata.
       */
  	protected ConcurrentHashMap<Class<?>, DataObjectMetadata> masterMetadataMap =
              new ConcurrentHashMap<Class<?>, DataObjectMetadata>();
  
  	/**
  	 * Performs the initialization of the provider with the given set of types.
  	 *
       * <p>
  	 * If the list is null or empty, the provider is expected to discover the types via other means, or do nothing if
       * the types cannot be discovered.
       * </p>
  	 */
  	protected abstract void initializeMetadata(Collection<Class<?>> types);
  
      /**
       * {@inheritDoc}
       */
  	@Override
  	public boolean handles(Class<?> type) {
  		if (type == null) {
  			return false;
  		}
  		if (masterMetadataMap.isEmpty()) {
  			initializeMetadata(null);
  		}
  		return masterMetadataMap.containsKey(type);
  	}
  
      /**
       * {@inheritDoc}
       */
  	@Override
  	public Collection<Class<?>> getSupportedTypes() {
  		if (masterMetadataMap.isEmpty()) {
  			initializeMetadata(null);
  		}
  		return masterMetadataMap.keySet();
  	}
  
      /**
       * {@inheritDoc}
       */
  	@Override
  	public Map<Class<?>, DataObjectMetadata> provideMetadata() {
  		return provideMetadataForTypes(null);
  	}
  
      /**
       * {@inheritDoc}
       */
  	@Override
  	public Map<Class<?>, DataObjectMetadata> provideMetadataForTypes(Collection<Class<?>> types) {
  		if (masterMetadataMap.isEmpty()) {
  			initializeMetadata(types);
  			return Collections.unmodifiableMap(masterMetadataMap);
  		} else if (types == null || types.isEmpty()) {
  			return Collections.unmodifiableMap(masterMetadataMap);
  		} else {
  			HashMap<Class<?>, DataObjectMetadata> subMap = new HashMap<Class<?>, DataObjectMetadata>();
  
  			for (Class<?> key : masterMetadataMap.keySet()) {
  				if (types.contains(key)) {
 					subMap.put(key, masterMetadataMap.get(key));
 				}
 			}
 			return subMap;
 		}
 	}
 
     /**
      * {@inheritDoc}
      */
 	@Override
 	public DataObjectMetadata getMetadataForType(Class<?> dataObjectType) throws IllegalArgumentException {
 		if (dataObjectType == null) {
 			throw new IllegalArgumentException("getMetadataForType: NULL passed for the dataObjectType");
 		}
 		if (masterMetadataMap.isEmpty()) {
 			initializeMetadata(null);
 		}
 		return masterMetadataMap.get(dataObjectType);
 	}
 
     /**
      * Determines whether the given class can be persisted.
      *
      * @param clazz the class to check for persistability.
      * @return true if the class is persistable, false otherwise.
      */
     protected boolean isClassPersistable(Class<?> clazz) {
         if (masterMetadataMap.isEmpty()) {
 			initializeMetadata(null);
         }
         return masterMetadataMap.containsKey(clazz);
     }
 
 	/**
 	 * {@inheritDoc}
      *
      * By default, providers are assumed to be able to pull the list of annotated types from somewhere.
 	 */
 	@Override
 	public boolean requiresListOfExistingTypes() {
 		return false;
 	}
 }