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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.jclouds.ec2.binders;

import static com.google.common.base.Preconditions.checkArgument;

import javax.inject.Inject;
import javax.inject.Singleton;

import org.jclouds.http.HttpRequest;
import org.jclouds.rest.Binder;

/**
 * Binds the AvailabilityZone to a form parameter if set.
 * 
 * @author Adrian Cole
 */
@Singleton
public class IfNotNullBindAvailabilityZoneToFormParam implements Binder {
   private final String param;

   @Inject
   protected IfNotNullBindAvailabilityZoneToFormParam() {
      this("Placement.AvailabilityZone");
   }

   protected IfNotNullBindAvailabilityZoneToFormParam(String param) {
      this.param = param;
   }

   @SuppressWarnings("unchecked")
   @Override
   public  R bindToRequest(R request, Object input) {
      if (input != null) {
         checkArgument(input instanceof String, "this binder is only valid for String!");
         return (R) request.toBuilder().replaceFormParam(param, String.class.cast(input)).build();
      }
      return request;
   }

}