/*
    * 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.spi.config.support;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.Properties;
  
  import org.apache.commons.lang.ObjectUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import de.smartics.properties.api.config.domain.ConfigurationException;
  import de.smartics.properties.api.config.domain.DuplicatePropertyException;
  import de.smartics.properties.api.config.domain.Property;
  import de.smartics.properties.api.config.domain.PropertyLocation;
  import de.smartics.properties.api.config.domain.PropertyProvider;
  import de.smartics.properties.api.config.domain.key.ConfigurationKey;
  
  /**
   * Provides properties from multiple sources for a given configuration.
   */
  class MultiSourceProperties implements Serializable
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    /**
     * The class version identifier.
     * <p>
     * The value of this constant is {@value}.
     * </p>
     */
    private static final long serialVersionUID = 1L;
  
    /**
     * Reference to the logger for this class.
     */
    private static final Logger LOG = LoggerFactory
        .getLogger(MultiSourceProperties.class);
  
    // --- members --------------------------------------------------------------
  
    /**
     * The key to the configuration the properties are added to.
     *
     * @serial
     */
    private final ConfigurationKey<?> configurationKey;
  
    /**
     * The exceptions encountered during merging properties. May be
     * <code>null</code> if no exceptions are to be collected.
     *
     * @serial
     */
    private final List<ConfigurationException> exceptions;
  
    /**
     * Maps the source of the properties to the properties instance.
     *
     * @serial
     */
    private final Map<PropertyLocation, PropertyProvider> propertiesMap =
        new LinkedHashMap<PropertyLocation, PropertyProvider>();
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Convenience constructor with an empty exceptions list.
     *
     * @param configurationKey the key to the configuration the properties are
     *          added to.
     */
    MultiSourceProperties(final ConfigurationKey<?> configurationKey)
    {
     this(configurationKey, new ArrayList<ConfigurationException>());
   }
 
   /**
    * Default constructor.
    *
    * @param configurationKey the key to the configuration the properties are
    *          added to.
    * @param exceptions the exceptions encountered during merging properties.
    */
   MultiSourceProperties(final ConfigurationKey<?> configurationKey,
       final List<ConfigurationException> exceptions)
   {
     this.configurationKey = configurationKey;
     this.exceptions = exceptions;
   }
 
   // ****************************** Inner Classes *****************************
 
   // ********************************* Methods ********************************
 
   // --- init -----------------------------------------------------------------
 
   // --- get&set --------------------------------------------------------------
 
   /**
    * Returns the key to the configuration the properties are added to.
    *
    * @return the key to the configuration the properties are added to.
    */
   public ConfigurationKey<?> getConfigurationKey()
   {
     return configurationKey;
   }
 
   /**
    * Returns the exceptions encountered during merging properties. May be
    * <code>null</code> if no exceptions are to be collected.
    *
    * @return the exceptions encountered during merging properties.
    */
   public List<ConfigurationException> getExceptions()
   {
     if (exceptions != null)
     {
       return exceptions;
     }
     else
     {
       return Collections.emptyList();
     }
   }
 
   // --- business -------------------------------------------------------------
 
   void add(final PropertyLocation source, final Properties properties)
   {
     if (propertiesMap.containsKey(source))
     {
       LOG.warn("Properties from '{}' already added.", source);
       return;
     }
 
     for (final Iterator<Object> i = properties.keySet().iterator(); i.hasNext();)
     {
       final Object key = i.next();
       final Object value = properties.get(key);
       if (contains(source, key, value))
       {
         LOG.info("Duplicate property '{}' of '{}' removed.", key, source);
         i.remove();
       }
     }
 
     final PropertiesPropertyProvider provider =
         new PropertiesPropertyProvider(configurationKey, source, properties);
     propertiesMap.put(source, provider);
   }
 
   void addProviders(final Collection<PropertyProvider> providers)
   {
     for (final PropertyProvider provider : providers)
     {
       if (configurationKey.equals(provider.getConfigurationKey()))
       {
         addProvider(provider);
       }
     }
   }
 
   void addProvider(final PropertyProvider provider)
   {
     final PropertyLocation source = provider.getSourceId();
     if (propertiesMap.containsKey(source))
     {
       LOG.warn("Properties from '{}' already added.", source);
       return;
     }
 
     propertiesMap.put(source, provider);
   }
 
   private boolean contains(final PropertyLocation newSource, final Object key,
       final Object newValue)
   {
     boolean contains = false;
     for (final Map.Entry<PropertyLocation, PropertyProvider> entry : propertiesMap
         .entrySet())
     {
       final PropertyLocation currentSource = entry.getKey();
       final PropertyProvider currentProperties = entry.getValue();
 
       final String name = ObjectUtils.toString(key, null);
       if (currentProperties.containsKey(name))
       {
         final Property property = currentProperties.getProperty(name);
         final String currentValue =
             property != null ? property.getValue() : null;
         final String currentValueString =
             ObjectUtils.toString(currentValue, null);
         final String newValueString = ObjectUtils.toString(newValue, null);
         if (!ObjectUtils.equals(currentValueString, newValueString))
         {
           if (exceptions != null)
           {
             addException(newSource, currentSource, name, currentValueString,
                 newValueString);
           }
           else
           {
             warnDuplicateWithDifferentValue(newSource, newValue, currentSource,
                 name, currentValue);
           }
         }
         else
         {
           warnDuplicateWithSameValue(name, currentSource, newSource,
               currentValue);
         }
 
         contains = true;
       }
     }
 
     return contains;
   }
 
   private void addException(final PropertyLocation newSource,
       final PropertyLocation currentSource, final String name,
       final String currentValueString, final String newValueString)
   {
     final DuplicatePropertyException e =
         new DuplicatePropertyException(configurationKey,
             new Property(currentSource, ObjectUtils.toString(name, null),
                 currentValueString), new Property(newSource,
                 ObjectUtils.toString(name, null), newValueString));
     exceptions.add(e);
   }
 
   private void warnDuplicateWithDifferentValue(
       final PropertyLocation newSource, final Object newValue,
       final PropertyLocation currentSource, final String name,
       final String currentValue)
   {
     LOG.warn("Duplicate key '{}' with new value '{}' in\n  '{}'."
              + "\nAlready found in\n  '{}'\nwith value '{}' (active).",
         new Object[] { name, newValue, newSource, currentSource, currentValue });
   }
 
   private void warnDuplicateWithSameValue(final String name,
       final PropertyLocation currentSource, final PropertyLocation newSource,
       final Object commonValue)
   {
     LOG.warn("Duplicate key '{}' with same value '{}' in\n   '{}'\n and in\n"
              + "   '{}'.", new Object[] { name, commonValue, currentSource,
                                          newSource });
   }
 
   Property getValue(final String key)
   {
     return getValue(key, false);
   }
 
   Property getValue(final String key, final boolean excludeLazies)
   {
     final List<Property> properties = new LinkedList<Property>();
     for (final Map.Entry<PropertyLocation, PropertyProvider> entry : propertiesMap
         .entrySet())
     {
       final PropertyProvider currentProperties = entry.getValue();
 
       if(excludeLazies && currentProperties.isLazy())
       {
         continue;
       }
 
       if (currentProperties.containsKey(key))
       {
         final Property property = currentProperties.getProperty(key);
         properties.add(property);
       }
     }
 
     if (properties.isEmpty())
     {
       return null;
     }
     else if (properties.size() == 1)
     {
       return properties.get(0);
     }
     else
     {
       LOG.warn("Duplicate key '{}' in\n  {}.", new Object[] { key, properties });
       return properties.get(0);
     }
   }
   // --- object basics --------------------------------------------------------
 
   /**
    * Returns the string representation of the object.
    *
    * @return the string representation of the object.
    */
   @Override
   public String toString()
   {
     final StringBuilder buffer = new StringBuilder();
 
     buffer.append(configurationKey).append('=');
 
     for (final PropertyLocation source : propertiesMap.keySet())
     {
       buffer.append(' ').append(source);
     }
 
     if (exceptions != null)
     {
       buffer.append("Exceptions:");
       for (final Exception e : exceptions)
       {
         buffer.append('\n').append(e.getMessage());
       }
     }
 
     return buffer.toString();
   }
 }