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   1 /**
   2  * Copyright (c) 2010-2020 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.persistence.dynamodb.internal;
  14
  15 import java.time.ZonedDateTime;
  16 import java.util.Collections;
  17
  18 import org.eclipse.jdt.annotation.NonNullByDefault;
  19 import org.eclipse.jdt.annotation.Nullable;
  20 import org.openhab.core.persistence.FilterCriteria;
  21 import org.openhab.core.persistence.FilterCriteria.Operator;
  22 import org.openhab.core.persistence.FilterCriteria.Ordering;
  23
  24 import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBQueryExpression;
  25 import com.amazonaws.services.dynamodbv2.model.AttributeValue;
  26 import com.amazonaws.services.dynamodbv2.model.ComparisonOperator;
  27 import com.amazonaws.services.dynamodbv2.model.Condition;
  28
  29 /**
  30  * Utility class
  31  *
  32  * @author Sami Salonen - Initial contribution
  33  */
  34 @NonNullByDefault
  35 public class DynamoDBQueryUtils {
  36     /**
  37      * Construct dynamodb query from filter
  38      *
  39      * @param filter
  40      * @return DynamoDBQueryExpression corresponding to the given FilterCriteria
  41      */
  42     public static DynamoDBQueryExpression<DynamoDBItem<?>> createQueryExpression(
  43             Class<? extends DynamoDBItem<?>> dtoClass, FilterCriteria filter) {
  44         DynamoDBItem<?> item = getDynamoDBHashKey(dtoClass, filter.getItemName());
  45         final DynamoDBQueryExpression<DynamoDBItem<?>> queryExpression = new DynamoDBQueryExpression<DynamoDBItem<?>>()
  46                 .withHashKeyValues(item).withScanIndexForward(filter.getOrdering() == Ordering.ASCENDING)
  47                 .withLimit(filter.getPageSize());
  48         maybeAddTimeFilter(queryExpression, filter);
  49         maybeAddStateFilter(filter, queryExpression);
  50         return queryExpression;
  51     }
  52
  53     private static DynamoDBItem<?> getDynamoDBHashKey(Class<? extends DynamoDBItem<?>> dtoClass, String itemName) {
  54         DynamoDBItem<?> item;
  55         try {
  56             item = dtoClass.newInstance();
  57         } catch (InstantiationException e) {
  58             throw new RuntimeException(e);
  59         } catch (IllegalAccessException e) {
  60             throw new RuntimeException(e);
  61         }
  62         item.setName(itemName);
  63         return item;
  64     }
  65
  66     private static void maybeAddStateFilter(FilterCriteria filter,
  67             final DynamoDBQueryExpression<DynamoDBItem<?>> queryExpression) {
  68         if (filter.getOperator() != null && filter.getState() != null) {
  69             // Convert filter's state to DynamoDBItem in order get suitable string representation for the state
  70             final DynamoDBItem<?> filterState = AbstractDynamoDBItem.fromState(filter.getItemName(), filter.getState(),
  71                     ZonedDateTime.now());
  72             queryExpression.setFilterExpression(String.format("%s %s :opstate", DynamoDBItem.ATTRIBUTE_NAME_ITEMSTATE,
  73                     operatorAsString(filter.getOperator())));
  74
  75             filterState.accept(new DynamoDBItemVisitor() {
  76
  77                 @Override
  78                 public void visit(DynamoDBStringItem dynamoStringItem) {
  79                     queryExpression.setExpressionAttributeValues(Collections.singletonMap(":opstate",
  80                             new AttributeValue().withS(dynamoStringItem.getState())));
  81                 }
  82
  83                 @Override
  84                 public void visit(DynamoDBBigDecimalItem dynamoBigDecimalItem) {
  85                     queryExpression.setExpressionAttributeValues(Collections.singletonMap(":opstate",
  86                             new AttributeValue().withN(dynamoBigDecimalItem.getState().toPlainString())));
  87                 }
  88             });
  89         }
  90     }
  91
  92     private static @Nullable Condition maybeAddTimeFilter(
  93             final DynamoDBQueryExpression<DynamoDBItem<?>> queryExpression, final FilterCriteria filter) {
  94         final Condition timeCondition = constructTimeCondition(filter);
  95         if (timeCondition != null) {
  96             queryExpression.setRangeKeyConditions(
  97                     Collections.singletonMap(DynamoDBItem.ATTRIBUTE_NAME_TIMEUTC, timeCondition));
  98         }
  99         return timeCondition;
 100     }
 101
 102     private static @Nullable Condition constructTimeCondition(FilterCriteria filter) {
 103         boolean hasBegin = filter.getBeginDate() != null;
 104         boolean hasEnd = filter.getEndDate() != null;
 105
 106         final Condition timeCondition;
 107         if (!hasBegin && !hasEnd) {
 108             timeCondition = null;
 109         } else if (hasBegin && !hasEnd) {
 110             timeCondition = new Condition().withComparisonOperator(ComparisonOperator.GE).withAttributeValueList(
 111                     new AttributeValue().withS(filter.getBeginDate().format(AbstractDynamoDBItem.DATEFORMATTER)));
 112         } else if (!hasBegin && hasEnd) {
 113             timeCondition = new Condition().withComparisonOperator(ComparisonOperator.LE).withAttributeValueList(
 114                     new AttributeValue().withS(filter.getEndDate().format(AbstractDynamoDBItem.DATEFORMATTER)));
 115         } else {
 116             timeCondition = new Condition().withComparisonOperator(ComparisonOperator.BETWEEN).withAttributeValueList(
 117                     new AttributeValue().withS(filter.getBeginDate().format(AbstractDynamoDBItem.DATEFORMATTER)),
 118                     new AttributeValue().withS(filter.getEndDate().format(AbstractDynamoDBItem.DATEFORMATTER)));
 119         }
 120         return timeCondition;
 121     }
 122
 123     /**
 124      * Convert op to string suitable for dynamodb filter expression
 125      *
 126      * @param op
 127      * @return string representation corresponding to the given the Operator
 128      */
 129     private static String operatorAsString(Operator op) {
 130         switch (op) {
 131             case EQ:
 132                 return "=";
 133             case NEQ:
 134                 return "<>";
 135             case LT:
 136                 return "<";
 137             case LTE:
 138                 return "<=";
 139             case GT:
 140                 return ">";
 141             case GTE:
 142                 return ">=";
 143
 144             default:
 145                 throw new IllegalStateException("Unknown operator " + op);
 146         }
 147     }
 148 }