[BUGFIX] Explain is not rendred with Apache Solr 8.2

Add's a testcase and the recursive lookup in the rootline for a node with a given fieldname.

Fixes: #7

Author: timohund

Classes/Domain/Result/Explanation/Parser.php

@@ -84,6 +84,7 @@ protected function parseChildNodes($contextContent, \ArrayObject $collection, $p
 		preg_match_all('~((?<=^)|(?<=\n))(?<token>[0-9].*?\n)((?=[0-9])|(?=$))~s',$contextContent,$matches);
 
 		if( array_key_exists('token',$matches)) {
+
 			foreach($matches['token'] as $tokenKey => $tokenContent) {
 				$nodeParts		= explode(PHP_EOL,$tokenContent);
 				$nodeContent	= trim(array_shift($nodeParts));
@@ -107,8 +108,6 @@ protected function parseChildNodes($contextContent, \ArrayObject $collection, $p
 				}
 			}
 		}
-
-		$collection;
 	}
 
 	/**
@@ -175,7 +174,6 @@ protected function getQueryAttribute($content) {
 	protected function getFieldNameFromNodeName($nodeName) {
 		$result 	= '';
 		$matches 	= array();
-
         if (mb_strpos($nodeName,'weight(Synonym(') !== false ) {
             preg_match('~weight\(Synonym\((?<fieldname>[^\):]*)~', $nodeName, $matches);
         } elseif(mb_strpos($nodeName,'weight(') !== false ){

Classes/Domain/Result/Explanation/Visitors/SummarizeFieldImpacts.php

@@ -11,7 +11,7 @@
 class SummarizeFieldImpacts implements ExplainNodeVisitorInterface {
 
 	/**
-	 * @var float
+	 * @var array
 	 */
 	protected $sums = array();
 
@@ -22,8 +22,7 @@ class SummarizeFieldImpacts implements ExplainNodeVisitorInterface {
 	public function visit(Explain $node) {
 		if($node->getNodeType() == $node::NODE_TYPE_LEAF) {
 			if($node->getParent() != null) {
-				$fieldName = $node->getParent()->getFieldName();
-
+				$fieldName = $this->getClosestFieldName($node);
                 if(trim($fieldName) === '') {
                     return;
                 }
@@ -38,6 +37,25 @@ public function visit(Explain $node) {
 		}
 	}
 
+    /**
+     * Returns the closest fieldname in the parent root line and and empty string when none is present.
+     *
+     * @param $node
+     * @return string
+     */
+	protected function getClosestFieldName($node) {
+        while(!is_null($node->getParent())) {
+            $parent = $node->getParent();
+            if ($parent->getFieldName() !== '') {
+                return $parent->getFieldName();
+            }
+
+            $node = $parent;
+        }
+
+        return '';
+    }
+
 	/**
 	 * Returns the fieldnames that have been relevant during the explain.
 	 *

Tests/Domain/Result/Explanation/ExplainServiceTestCase.php

@@ -62,4 +62,24 @@ public function testCanParseSynonymeNodes() {
 
         $this->assertEquals($expectedResult, $result);
     }
+
+    /**
+     * @test
+     */
+    public function testCanParse82Response() {
+        $content 	= $this->getFixtureContent('8.2.001.txt');
+        $result 	= ExplainService::getFieldImpactsFromRawContent(
+            $content,
+            'foo',
+            'bar'
+        );
+
+        $expectedResult = [
+            'content' => 85.44380986095436,
+            'tagsH2H3' => 4.056216176545581,
+            'title' => 10.499972051284612
+        ];
+
+        $this->assertEquals($expectedResult, $result);
+    }
 }

Tests/Domain/Result/Explanation/Fixtures/8.2.001.txt

@@ -0,0 +1,38 @@
+44.474316 = sum of:
+  44.474316 = max plus 0.5 times others of:
+    3.6079488 = weight(tagsH2H3:page in 45) [SchemaSimilarity], result of:
+      3.6079488 = score(freq=1.0), product of:
+        3.0 = boost
+        1.6405284 = idf, computed as log(1 + (N - n + 0.5) / (n + 0.5)) from:
+          9 = n, number of documents containing term
+          48 = N, total number of documents with field
+        0.73308676 = tf, computed as freq / (freq + k1 * (1 - b + b * dl / avgdl)) from:
+          1.0 = freq, occurrences of term within document
+          1.2 = k1, term saturation parameter
+          0.75 = b, length normalization parameter
+          1.0 = dl, length of field
+          14.041667 = avgdl, average length of field
+    9.3395815 = weight(title:page in 45) [SchemaSimilarity], result of:
+      9.3395815 = score(freq=1.0), product of:
+        5.0 = boost
+        3.2884018 = idf, computed as log(1 + (N - n + 0.5) / (n + 0.5)) from:
+          2 = n, number of documents containing term
+          66 = N, total number of documents with field
+        0.56803167 = tf, computed as freq / (freq + k1 * (1 - b + b * dl / avgdl)) from:
+          1.0 = freq, occurrences of term within document
+          1.2 = k1, term saturation parameter
+          0.75 = b, length normalization parameter
+          1.0 = dl, length of field
+          1.9545455 = avgdl, average length of field
+    38.00055 = weight(content:page in 45) [SchemaSimilarity], result of:
+      38.00055 = score(freq=4.0), product of:
+        40.0 = boost
+        1.0761395 = idf, computed as log(1 + (N - n + 0.5) / (n + 0.5)) from:
+          22 = n, number of documents containing term
+          65 = N, total number of documents with field
+        0.882798 = tf, computed as freq / (freq + k1 * (1 - b + b * dl / avgdl)) from:
+          4.0 = freq, occurrences of term within document
+          1.2 = k1, term saturation parameter
+          0.75 = b, length normalization parameter
+          72.0 = dl, length of field (approximate)
+          280.46155 = avgdl, average length of field