feat: optimized aggregation pipeline to use indexes when possible

Author: jmarkerink

core/src/main/java/de/bwaldvogel/mongo/backend/aggregation/Aggregation.java

@@ -189,7 +189,11 @@ public static Aggregation fromPipeline(List<Document> pipeline, DatabaseResolver
     }
 
     private List<Document> runStages() {
-        return runStages(collection.queryAllAsStream());
+        return stages.stream()
+            .filter(stage -> stage instanceof MatchStage)
+            .findFirst()
+            .map(match -> runStages(collection.handleQueryAsStream(((MatchStage) match).getQuery())))
+            .orElseGet(() -> runStages(collection.queryAllAsStream()));
     }
 
     public List<Document> runStages(Stream<Document> stream) {

core/src/main/java/de/bwaldvogel/mongo/backend/aggregation/stage/MatchStage.java

@@ -24,4 +24,8 @@ public String name() {
     public Stream<Document> apply(Stream<Document> stream) {
         return stream.filter(document -> queryMatcher.matches(document, query));
     }
+
+    public Document getQuery() {
+        return query;
+    }
 }