add reverse nested agg

Author: fedorf4

src/Aggregating/Bucket/ReverseNestedAggregation.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace Ensi\LaravelElasticQuery\Aggregating\Bucket;
+
+use Ensi\LaravelElasticQuery\Aggregating\AggregationCollection;
+use Ensi\LaravelElasticQuery\Contracts\Aggregation;
+use Webmozart\Assert\Assert;
+
+class ReverseNestedAggregation implements Aggregation
+{
+    public function __construct(
+        private string $name, 
+        private AggregationCollection $children
+    ) {
+        Assert::stringNotEmpty(trim($name));
+    }
+
+    public function name(): string
+    {
+        return $this->name;
+    }
+
+    public function toDSL(): array
+    {
+        return [$this->name => [
+            'reverse_nested' => new \stdClass(),
+            'aggs' => $this->children->toDSL(),
+        ]];
+    }
+
+    public function parseResults(array $response): array
+    {
+        return $this->children
+            ->parseResults($response[$this->name] ?? [])
+            ->all();
+    }
+}

src/Concerns/ConstructsAggregations.php

@@ -7,6 +7,7 @@
 use Ensi\LaravelElasticQuery\Aggregating\Bucket\FilterAggregation;
 use Ensi\LaravelElasticQuery\Aggregating\Bucket\FiltersAggregation;
 use Ensi\LaravelElasticQuery\Aggregating\Bucket\NestedAggregation;
+use Ensi\LaravelElasticQuery\Aggregating\Bucket\ReverseNestedAggregation;
 use Ensi\LaravelElasticQuery\Aggregating\Bucket\TermsAggregation;
 use Ensi\LaravelElasticQuery\Aggregating\CompositeAggregationBuilder;
 use Ensi\LaravelElasticQuery\Aggregating\FiltersCollection;
@@ -132,6 +133,21 @@ public function nested(string $path, Closure $callback): static
         return $this;
     }
 
+    public function reverseNested(string $name, Closure $callback): static
+    {
+        $builder = $this->createCompositeBuilder("{$name}_builder");
+        
+        /** @var AggregationCollection $aggs */
+        $aggs = tap($builder, $callback)->build();
+        
+        if (!$aggs->isEmpty()) {
+            $reverseNested = new ReverseNestedAggregation($name, $aggs);
+            $this->aggregations->merge(AggregationCollection::fromAggregation($reverseNested));
+        }
+        
+        return $this;
+    }
+
     protected function name(): string
     {
         return '';

src/Contracts/AggregationsBuilder.php

@@ -28,4 +28,6 @@ public function count(string $path, string $field): static;
     public function script(string $name, string $aggregationType, string $source, array $params = [], string $lang = ScriptLang::PAINLESS): static;
 
     public function nested(string $path, Closure $callback): static;
+
+    public function reverseNested(string $name, Closure $callback): static
 }

tests/IntegrationTests/AggregationQueryIntegrationTest.php

@@ -2,6 +2,7 @@
 
 use Ensi\LaravelElasticQuery\Aggregating\AggregationCollection;
 use Ensi\LaravelElasticQuery\Aggregating\Bucket;
+use Ensi\LaravelElasticQuery\Aggregating\BucketCollection;
 use Ensi\LaravelElasticQuery\Aggregating\FiltersCollection;
 use Ensi\LaravelElasticQuery\Aggregating\Metrics\MinMaxScoreAggregation;
 use Ensi\LaravelElasticQuery\Aggregating\Metrics\ScriptAggregation;
@@ -262,3 +263,26 @@
         $scores,
     );
 });
+
+test('reverse nested aggregation query', function () {
+    /** @var IntegrationTestCase $this */
+
+    $results = ProductsIndex::aggregate()
+        ->nested('offers', function ($builder) {
+            $builder->terms('offer_prices', 'offers.price', 5)
+                ->reverseNested('root_stats', function ($reverseBuilder) {
+                    $reverseBuilder->cardinality('unique_products', 'product_id')
+                        ->count('total_products', 'product_id');
+                });
+        })
+        ->get();
+
+    $prices = $results->get('offer_prices');
+    
+    expect($prices)->toBeInstanceOf(BucketCollection::class);
+    
+    foreach ($prices as $bucket) {
+        expect($bucket->getCompositeValue('unique_products'))->toBeGreaterThan(0);
+        expect($bucket->getCompositeValue('total_products'))->toBeGreaterThan(0);
+    }
+});