Added BucketSelector aggregation

CHANGELOG.md

@@ -9,6 +9,7 @@ All notable changes to this project will be documented in this file based on the
 
 ### Added
 
+* Added `BucketSelector` aggregation [#1554](https://github.com/ruflin/Elastica/pull/1554)
 * Added `DerivativeAggregation` [#1553](https://github.com/ruflin/Elastica/pull/1553)
 
 ### Improvements
@@ -54,6 +55,7 @@ All notable changes to this project will be documented in this file based on the
       "number_of_significant_value_digits" : 3
     }
   ```
+
 * Never implemented the method *Missing* on [`Aggregation\Percentiles`](https://www.elastic.co/guide/en/elasticsearch/reference/6.4/search-aggregations-metrics-percentile-aggregation.html) [#1532](https://github.com/ruflin/Elastica/pull/1532)
 
 ## [6.0.2](https://github.com/ruflin/Elastica/compare/6.0.1...6.0.2)

lib/Elastica/Aggregation/BucketSelector.php

@@ -0,0 +1,52 @@
+<?php
+namespace Elastica\Aggregation;
+
+/**
+ * Class BucketSelector.
+ * @link https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-pipeline-bucket-selector-aggregation.html
+ */
+class BucketSelector extends AbstractSimpleAggregation
+{
+    /**
+     * @param string      $name
+     * @param array|null  $bucketsPath
+     * @param string|null $script
+     */
+    public function __construct(string $name, array $bucketsPath = null, string $script = null)
+    {
+        parent::__construct($name);
+
+        if ($bucketsPath !== null) {
+            $this->setBucketsPath($bucketsPath);
+        }
+
+        if ($script !== null) {
+            $this->setScript($script);
+        }
+    }
+
+    /**
+     * Set the buckets_path for this aggregation.
+     *
+     * @param array $bucketsPath
+     *
+     * @return $this
+     */
+    public function setBucketsPath($bucketsPath)
+    {
+        return $this->setParam('buckets_path', $bucketsPath);
+    }
+
+    /**
+     * Set the gap policy for this aggregation.
+     *
+     * @param string $gapPolicy
+     *
+     * @return $this
+     */
+    public function setGapPolicy(string $gapPolicy = 'skip')
+    {
+        return $this->setParam('gap_policy', $gapPolicy);
+    }
+}
+

test/Elastica/Aggregation/BucketSelectorTest.php

@@ -0,0 +1,90 @@
+<?php
+namespace Elastica\Test\Aggregation;
+
+use Elastica\Aggregation\BucketSelector;
+use Elastica\Aggregation\DateHistogram;
+use Elastica\Aggregation\Max;
+use Elastica\Document;
+use Elastica\Query;
+
+class BucketSelectorTest extends BaseAggregationTest
+{
+    protected function _getIndexForTest()
+    {
+        $index = $this->_createIndex();
+
+        $index->getType('test')->addDocuments([
+            new Document(1, ['date' => '2018-12-01', 'value' => 1]),
+            new Document(2, ['date' => '2018-12-02', 'value' => 2]),
+            new Document(3, ['date' => '2018-12-03', 'value' => 5]),
+            new Document(4, ['date' => '2018-12-04', 'value' => 4]),
+            new Document(5, ['date' => '2018-12-05', 'value' => 6]),
+            new Document(6, ['date' => '2018-12-06', 'value' => 9]),
+            new Document(7, ['date' => '2018-12-07', 'value' => 11]),
+            new Document(8, ['date' => '2018-12-08', 'value' => 4]),
+            new Document(9, ['date' => '2018-12-09', 'value' => 7]),
+            new Document(10, ['date' => '2018-12-10', 'value' => 4]),
+        ]);
+
+        $index->refresh();
+
+        return $index;
+    }
+
+    /**
+     * @group unit
+     */
+    public function testToArray()
+    {
+        $expected = [
+            'max' => [
+                'field' => 'value',
+            ],
+            'aggs' => [
+                'selector_agg' => [
+                    'bucket_selector' => [
+                        'buckets_path' => ['max' => 'max_agg'],
+                        'script' => 'params.max > 5',
+                    ],
+                ],
+            ],
+        ];
+
+        $maxAgg = new Max('max_agg');
+        $maxAgg->setField('value');
+
+        $selectorAgg = new BucketSelector('selector_agg', ['max' => 'max_agg'], 'params.max > 5');
+        $maxAgg->addAggregation($selectorAgg);
+
+        $this->assertEquals($expected, $maxAgg->toArray());
+    }
+
+    /**
+     * @group functional
+     */
+    public function testMaxAggregation()
+    {
+        $index = $this->_getIndexForTest();
+
+        $dateHistogramAgg = new DateHistogram('histogram_agg', 'date', 'day');
+        $dateHistogramAgg->setFormat('yyyy-MM-dd');
+
+        $maxAgg = new Max('max_agg');
+        $maxAgg->setField('value');
+        $dateHistogramAgg->addAggregation($maxAgg);
+
+        $bucketAgg = new BucketSelector('selector_agg', ['max' => 'max_agg'], 'params.max > 5');
+        $dateHistogramAgg->addAggregation($bucketAgg);
+
+        $query = new Query();
+        $query->addAggregation($dateHistogramAgg);
+
+        $dateHistogramAggResult = $index->search($query)->getAggregation('histogram_agg')['buckets'];
+
+        $this->assertEquals(4, count($dateHistogramAggResult));
+        $this->assertEquals(6, $dateHistogramAggResult[0]['max_agg']['value']);
+        $this->assertEquals(9, $dateHistogramAggResult[1]['max_agg']['value']);
+        $this->assertEquals(11, $dateHistogramAggResult[2]['max_agg']['value']);
+        $this->assertEquals(7, $dateHistogramAggResult[3]['max_agg']['value']);
+    }
+}