/**

  * Copyright (c) 2014, stateful.co

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met: 1) Redistributions of source code must retain the above

  * copyright notice, this list of conditions and the following

  * disclaimer. 2) Redistributions in binary form must reproduce the above

  * copyright notice, this list of conditions and the following

  * disclaimer in the documentation and/or other materials provided

  * with the distribution. 3) Neither the name of the stateful.co nor

  * the names of its contributors may be used to endorse or promote

  * products derived from this software without specific prior written

  * permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT

  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL

  * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

  * OF THE POSSIBILITY OF SUCH DAMAGE.

  */

 package co.stateful.core;

 import co.stateful.spi.Counter;

 import co.stateful.spi.Counters;

 import com.amazonaws.services.dynamodbv2.model.AttributeValue;

 import com.google.common.base.Function;

 import com.google.common.base.Predicates;

 import com.google.common.collect.Iterables;

 import com.google.common.collect.Iterators;

 import com.jcabi.aspects.Cacheable;

 import com.jcabi.aspects.Immutable;

 import com.jcabi.aspects.Loggable;

 import com.jcabi.dynamo.Attributes;

 import com.jcabi.dynamo.Conditions;

 import com.jcabi.dynamo.Item;

 import com.jcabi.dynamo.QueryValve;

 import com.jcabi.dynamo.Table;

 import com.jcabi.urn.URN;

 import java.io.IOException;

 import java.util.concurrent.TimeUnit;

 import lombok.EqualsAndHashCode;

 import lombok.ToString;

 /**

  * Counters in DynamoDB.

  *

  * @author Yegor Bugayenko (yegor@tpc2.com)

  * @version $Id$

  */

 @Immutable

 @ToString

 @EqualsAndHashCode(of = "owner")

 @Loggable(Loggable.DEBUG)

 final class DyCounters implements Counters {

     /**

      * Table name.

      */

     public static final String TBL = "counters";

     /**

      * Hash.

      */

     public static final String HASH = "urn";

     /**

      * Range.

      */

     public static final String RANGE = "name";

     /**

      * Value attribute.

      */

     public static final String ATTR_VALUE = "value";

     /**

      * Dynamo table.

      */

     private final transient Table table;

     /**

      * Name of the user.

      */

     private final transient URN owner;

     /**

      * Ctor.

      * @param tbl Dynamo table

      * @param urn Owner of them

      */

     DyCounters(final Table tbl, final URN urn) {

         this.table = tbl;

         this.owner = urn;

     }

     @Override

     @Cacheable.FlushAfter

     public void create(final String name) throws IOException {

         this.table.put(

             new Attributes()

                 .with(DyCounters.HASH, this.owner)

                 .with(DyCounters.RANGE, name)

                 .with(DyCounters.ATTR_VALUE, new AttributeValue().withN("0"))

         );

     }

     @Override

     @Cacheable.FlushAfter

     public void delete(final String name) {

         Iterators.removeIf(

             this.table.frame()

                 .through(new QueryValve().withLimit(1))

                 .where(DyCounters.HASH, Conditions.equalTo(this.owner))

                 .where(DyCounters.RANGE, Conditions.equalTo(name))

                 .iterator(),

             Predicates.alwaysTrue()

         );

     }

     @Override

     @Cacheable(lifetime = 1, unit = TimeUnit.HOURS)

     public Counter get(final String name) {

         return new DyCounter(

             this.table.frame()

                 .through(new QueryValve().withLimit(1))

                 .where(DyCounters.HASH, Conditions.equalTo(this.owner))

                 .where(DyCounters.RANGE, Conditions.equalTo(name))

                 .iterator()

                 .next()

         );

     }

     @Override

     @Cacheable(lifetime = 1, unit = TimeUnit.HOURS)

     public Iterable<String> names() {

         return Iterables.transform(

             this.table.frame()

                 .through(new QueryValve())

                 .where(DyCounters.HASH, Conditions.equalTo(this.owner)),

             new Function<Item, String>() {

                 @Override

                 public String apply(final Item item) {

                     try {

                         return item.get(DyCounters.RANGE).getS();

                     } catch (final IOException ex) {

                         throw new IllegalStateException(ex);

                     }

                 }

             }

         );

     }

 }