Add ExtendedStatsBucket aggregatoin (#1756)

See PR: #1756

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added `Elastica\Reindex->setQuery(Elastica\Query\AbstractQuery $query): void` [#1752](https://github.com/ruflin/Elastica/pull/1752)
 * Added constants `PIPELINE`, `REFRESH_TRUE`, `REFRESH_FALSE`, `REFRESH_WAIT_FOR`, `SLICES` and `SLICES_AUTO` to `Elastica\Reindex` [#1752](https://github.com/ruflin/Elastica/pull/1752)
 * Added `Elastica\Pipeline->getId(): ?string` [#1752](https://github.com/ruflin/Elastica/pull/1752)
+* Added `Elastica\Aggregation\ExtendedStatsBucket` aggregation [#1756](https://github.com/ruflin/Elastica/pull/1756)
 
 ### Changed
 - Updated PHP coding standards to adhere to PSR-12 [#1760](https://github.com/ruflin/Elastica/pull/1760)

src/Aggregation/ExtendedStatsBucket.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Elastica\Aggregation;
+
+/**
+ * Implements a Extended Stats Bucket Aggregation.
+ *
+ * @see https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-pipeline-extended-stats-bucket-aggregation.html
+ */
+class ExtendedStatsBucket extends AbstractAggregation
+{
+    public function __construct(string $name, string $bucketsPath)
+    {
+        parent::__construct($name);
+        $this->setBucketsPath($bucketsPath);
+    }
+
+    public function setBucketsPath(string $bucketsPath): self
+    {
+        return $this->setParam('buckets_path', $bucketsPath);
+    }
+
+    public function setGapPolicy(string $gapPolicy): self
+    {
+        return $this->setParam('gap_policy', $gapPolicy);
+    }
+
+    public function setFormat(string $format): self
+    {
+        return $this->setParam('format', $format);
+    }
+
+    public function setSigma(int $sigma): self
+    {
+        return $this->setParam('sigma', $sigma);
+    }
+}

tests/Aggregation/ExtendedStatsBucketTest.php

@@ -0,0 +1,84 @@
+<?php
+
+namespace Elastica\Test\Aggregation;
+
+use Elastica\Aggregation\ExtendedStatsBucket;
+use Elastica\Aggregation\Histogram;
+use Elastica\Aggregation\Max;
+use Elastica\Document;
+use Elastica\Index;
+use Elastica\Query;
+
+/**
+ * @internal
+ */
+class ExtendedStatsBucketTest extends BaseAggregationTest
+{
+    /**
+     * @group functional
+     */
+    public function testExtendedStatBucketAggregation(): void
+    {
+        $bucketScriptAggregation = new ExtendedStatsBucket('result', 'age_groups>max_weight');
+
+        $histogramAggregation = new Histogram('age_groups', 'age', 10);
+
+        $histogramAggregation->addAggregation((new Max('max_weight'))->setField('weight'));
+
+        $query = Query::create([])
+            ->addAggregation($histogramAggregation)
+            ->addAggregation($bucketScriptAggregation)
+        ;
+
+        $results = $this->_getIndexForTest()->search($query)->getAggregation('result');
+
+        $this->assertEquals(3, $results['count']);
+        $this->assertEquals(50, $results['min']);
+        $this->assertEquals(70, $results['max']);
+        $this->assertEquals(60, $results['avg']);
+        $this->assertEquals(180, $results['sum']);
+        $this->assertEquals(11000, $results['sum_of_squares']);
+        $this->assertEquals(66.66666666666667, $results['variance']);
+        $this->assertEquals(8.16496580927726, $results['std_deviation']);
+        $this->assertEquals(['upper' => 76.32993161855453, 'lower' => 43.670068381445475], $results['std_deviation_bounds']);
+    }
+
+    /**
+     * @group unit
+     */
+    public function testOverrideBucketsPathThroughSetters(): void
+    {
+        $serialDiffAgg = new ExtendedStatsBucket('bucket_part', 'foobar');
+
+        $serialDiffAgg
+            ->setBucketsPath('age_groups>max_weight')
+            ->setFormat('test_format')
+            ->setGapPolicy(10)
+        ;
+
+        $expected = [
+            'extended_stats_bucket' => [
+                'buckets_path' => 'age_groups>max_weight',
+                'format' => 'test_format',
+                'gap_policy' => 10,
+            ],
+        ];
+
+        $this->assertEquals($expected, $serialDiffAgg->toArray());
+    }
+
+    private function _getIndexForTest(): Index
+    {
+        $index = $this->_createIndex();
+
+        $index->addDocuments([
+            Document::create(['weight' => 60, 'height' => 180, 'age' => 25]),
+            Document::create(['weight' => 70, 'height' => 156, 'age' => 32]),
+            Document::create(['weight' => 50, 'height' => 155, 'age' => 45]),
+        ]);
+
+        $index->refresh();
+
+        return $index;
+    }
+}