/*

  * #%L

  * BatchedInsertCountingCallback.java - mongodb-async-driver - Allanbank Consulting, Inc.

  * %%

  * Copyright (C) 2011 - 2014 Allanbank Consulting, Inc.

  * %%

  * 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.

  * #L%

  */

 package com.allanbank.mongodb.client.callback;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.IdentityHashMap;

 import java.util.List;

 import java.util.Map;

 import com.allanbank.mongodb.Callback;

 import com.allanbank.mongodb.bson.Document;

 import com.allanbank.mongodb.bson.builder.BuilderFactory;

 import com.allanbank.mongodb.builder.BatchedWrite;

 import com.allanbank.mongodb.builder.write.WriteOperation;

 import com.allanbank.mongodb.client.message.Reply;

 import com.allanbank.mongodb.error.BatchedWriteException;

 /**

  * BatchedInsertCountingCallback is designed to work with the

  * {@link BatchedWriteCallback}. This callback can be used as the callback for a

  * series of individual writes and will coalesce the results into a single

  * result based on a an expected number of callbacks.

  * <p>

  * The class does not track the input {@code n} value and instead always returns

  * an N value based on the expected count. That limits the utility of this class

  * to inserts.

  * </p>

  * 

  * @api.no This class is <b>NOT</b> part of the drivers API. This class may be

  *         mutated in incompatible ways between any two releases of the driver.

  * @copyright 2014, Allanbank Consulting, Inc., All Rights Reserved

  */

 public class BatchedInsertCountingCallback implements Callback<Reply> {

     /** The count of the number of callbacks received so far. */

     private int myCount = 0;

     /** The failed operations. */

     private Map<WriteOperation, Throwable> myErrors;

     /** The expected number of callbacks. */

     private final int myExpectedCount;

     /**

      * The count of the number of failure ({@link #exception(Throwable)})

      * callbacks received so far.

      */

     private int myFailureCount = 0;

     /** The callback to notify with the final results once we receive them all. */

     private final Callback<Reply> myForwardCallback;

     /** The last batched write that failed. */

     private BatchedWrite myLastWrite;

     /** The skipped operations. */

     private List<WriteOperation> mySkipped;

     /**

      * Creates a new CountingCallback.

      * 

      * @param forwardCallback

      *            The callback to notify with the final results once we receive

      *            them all.

      * @param expectedCount

      *            The expected number of callbacks.

      */

     public BatchedInsertCountingCallback(final Callback<Reply> forwardCallback,

             final int expectedCount) {

         myForwardCallback = forwardCallback;

         myExpectedCount = expectedCount;

         myCount = 0;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to increment the count and when the max is reached forward the

      * final results.

      * </p>

      */

     @Override

     public void callback(final Reply result) {

         boolean publish;

         synchronized (this) {

             myCount += 1;

             publish = (myCount == myExpectedCount);

         }

         if (publish) {

             publish();

         }

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to record the exception details.

      * </p>

      */

     @Override

     public void exception(final Throwable thrown) {

         boolean publish;

         synchronized (this) {

             myFailureCount += 1;

             myCount += 1;

             publish = (myCount == myExpectedCount);

             if (mySkipped == null) {

                 mySkipped = new ArrayList<WriteOperation>();

                 myErrors = new IdentityHashMap<WriteOperation, Throwable>();

             }

             if (thrown instanceof BatchedWriteException) {

                 final BatchedWriteException errors = (BatchedWriteException) thrown;

                 myLastWrite = errors.getWrite();

                 mySkipped.addAll(errors.getSkipped());

                 myErrors.putAll(errors.getErrors());

             }

         }

         if (publish) {

             publish();

         }

     }

     /**

      * Publishes the final results to {@link #myForwardCallback}.

      */

     private void publish() {

         Reply reply = null;

         BatchedWriteException error = null;

         synchronized (this) {

             if (myFailureCount == 0) {

                 final Document doc = BuilderFactory.start().add("ok", 1)

                         .add("n", myExpectedCount).build();

                 reply = new Reply(0, 0, 0, Collections.singletonList(doc),

                         false, false, false, false);

             }

             else {

                 error = new BatchedWriteException(myLastWrite,

                         (myExpectedCount - myFailureCount), mySkipped, myErrors);

             }

         }

         // Reply outside the lock.

         if (reply != null) {

             myForwardCallback.callback(reply);

         }

         else {

             myForwardCallback.exception(error);

         }

     }

 }