/**
    * Copyright (C) 2010-14 pvmanager developers. See COPYRIGHT.TXT
    * All rights reserved. Use is subject to license terms. See LICENSE.TXT
    */
   package org.epics.pvmanager.jca;
   
   import org.epics.pvmanager.DataSourceTypeAdapter;
   import gov.aps.jca.Channel;
   import gov.aps.jca.dbr.DBR;
  import gov.aps.jca.dbr.DBRType;
  import org.epics.pvmanager.ValueCache;
  
  /**
   * Type adapter for JCA data source. Will match a channel based on the value
   * type provided and the array flag. Will match the cache based on the type class.
   *
   * @author carcassi
   */
  public abstract class JCATypeAdapter implements DataSourceTypeAdapter<JCAConnectionPayload, JCAMessagePayload> {
  
      private final Class<?> typeClass;
      private final DBRType epicsValueType;
      private final DBRType epicsMetaType;
      private final Boolean array;
  
      /**
       * Creates a new type adapter.
       * 
       * @param typeClass the java type this adapter will create
       * @param epicsValueType the epics type used for the monitor
       * @param epicsMetaType the epics type for the get at connection time; null if no metadata is needed
       * @param array true whether this will require an array type
       */
      public JCATypeAdapter(Class<?> typeClass, DBRType epicsValueType, DBRType epicsMetaType, Boolean array) {
          this.typeClass = typeClass;
          this.epicsValueType = epicsValueType;
          this.epicsMetaType = epicsMetaType;
          this.array = array;
      }
  
      @Override
      public int match(ValueCache<?> cache, JCAConnectionPayload connPayload) {
          Channel channel = connPayload.getChannel();
          
          // If the generated type can't be put in the cache, no match
          if (!cache.getType().isAssignableFrom(typeClass))
              return 0;
          
          // If the type of the channel does not match, no match
          if (!dbrTypeMatch(epicsValueType, connPayload.getFieldType()))
              return 0;
          
          // If processes array, but count is 1, no match
          if (array != null &&array && channel.getElementCount() == 1)
              return 0;
          
          // If processes scalar, but the count is not 1, no match
          if (array != null && !array && channel.getElementCount() != 1)
              return 0;
          
          // Everything matches
          return 1;
      }
      
      private static boolean dbrTypeMatch(DBRType aType, DBRType anotherType) {
          if (aType.getClass() == null && anotherType.getClass() != null) {
              return false;
          }
          if (aType.getClass() != null && anotherType.getClass() == null) {
              return false;
          }
          return aType.isBYTE() && anotherType.isBYTE() ||
                  aType.isDOUBLE() && anotherType.isDOUBLE() ||
                  aType.isENUM() && anotherType.isENUM() ||
                  aType.isFLOAT() && anotherType.isFLOAT() ||
                  aType.isINT() && anotherType.isINT() ||
                  aType.isSHORT() && anotherType.isSHORT() ||
                  aType.isSTRING() && anotherType.isSTRING();
      }
  
      @Override
      public Object getSubscriptionParameter(ValueCache cache, JCAConnectionPayload connPayload) {
          throw new UnsupportedOperationException("Not implemented: JCAChannelHandler is multiplexed, will not use this method");
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public boolean updateCache(ValueCache cache, JCAConnectionPayload connPayload, JCAMessagePayload message) {
          Channel channel = connPayload.getChannel();
          
          // If metadata is required and not present, no update
          if (epicsMetaType != null && message.getMetadata() == null)
              return false;
          
          // If value is not present, no update
          if (message.getEvent() == null)
              return false;
          
          Object value = createValue(message.getEvent().getDBR(), message.getMetadata(), connPayload);
         cache.writeValue(value);
         return true;
     }
 
     /**
      * Given the value and the (optional) metadata, will create the new value.
      * 
      * @param value the value taken from the monitor
      * @param metadata the value taken as metadata
      * @param connPayload the connection payload
      * @return the new value
      */
     public abstract Object createValue(DBR value, DBR metadata, JCAConnectionPayload connPayload);
     
 }