// Copyright 2009 The Apache Software Foundation

 //

 // 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.apache.tapestry5.internal.util;

 import org.apache.tapestry5.PrimaryKeyEncoder;

 import org.apache.tapestry5.ValueEncoder;

 import org.apache.tapestry5.ioc.services.Coercion;

 import org.apache.tapestry5.ioc.services.TypeCoercer;

 import org.apache.tapestry5.util.DefaultPrimaryKeyEncoder;

 import java.io.Serializable;

 /**

  * This is a key part of the plan to eliminate {@link org.apache.tapestry5.PrimaryKeyEncoder}.

  *

  * @since 5.1.0.0

  */

 @SuppressWarnings({ "unchecked" })

 public class PrimaryKeyEncoder2ValueEncoder implements Coercion<PrimaryKeyEncoder, ValueEncoder>

 {

     // The magic of proxies: a coercion within TypeCoercer can use TypeCoercer as part of its job!

     private final TypeCoercer coercer;

     public PrimaryKeyEncoder2ValueEncoder(TypeCoercer coercer)

     {

         this.coercer = coercer;

     }

     public ValueEncoder coerce(final PrimaryKeyEncoder input)

     {

         final Class keyType = input.getKeyType();

         if (keyType == null)

         {

             String message = String.format("Unable to extract primary key type from %s. " +

                     "This represents a change from Tapestry 5.0 to Tapestry 5.1.", input);

             if (input instanceof DefaultPrimaryKeyEncoder)

                 message +=

                         " Class DefaultPrimaryKeyEncoder now includes a constructor for specifying the key type. " +

                                 "You should change the code that instantiates the encoder.";

             else

                 message += " You should ensure that the getKeyType() method returns the correct Class.";

             throw new RuntimeException(message);

         }

         return new ValueEncoder()

         {

             public String toClient(Object value)

             {

                 Object key = input.toKey(value);

                 return coercer.coerce(key, String.class);

             }

             public Object toValue(String clientValue)

             {

                 Serializable key = (Serializable) coercer.coerce(clientValue, keyType);

                 return input.toValue(key);

             }

             @Override

             public String toString()

             {

                 return String.format("<ValueEncoder coercion wrapper around PrimaryKeyEncoder[%s]>",

                                      keyType.getName());

             }

         };

     }

 }