From 1b45e88b191923b1b1454ccd282dcb7333b23223 Mon Sep 17 00:00:00 2001
From: Benko Balog <benko.balog-ext@commercetools.com>
Date: Fri, 13 Oct 2023 16:22:12 +0200
Subject: [PATCH] deriveMongoFormat now skips generating instances that already
 exist

---
 .../mongo/generic/MongoFormatMacros.scala     | 13 +++++-
 .../mongo/generic/SumTypesDerivingSpec.scala  | 43 +++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/mongo/mongo-derivation/src/main/scala/io/sphere/mongo/generic/MongoFormatMacros.scala b/mongo/mongo-derivation/src/main/scala/io/sphere/mongo/generic/MongoFormatMacros.scala
index 0390ecd6..571146bb 100644
--- a/mongo/mongo-derivation/src/main/scala/io/sphere/mongo/generic/MongoFormatMacros.scala
+++ b/mongo/mongo-derivation/src/main/scala/io/sphere/mongo/generic/MongoFormatMacros.scala
@@ -107,6 +107,7 @@ private[generic] object MongoFormatMacros {
         )
       else {
         val subtypes = collectKnownSubtypes(c)(symbol)
+        val subtypesWithNoFormatter = subtypes.filterNot(mongoFormatExists(c))
         val idents = Ident(symbol.name) :: subtypes.map { s =>
           if (s.isModuleClass) New(TypeTree(s.asClass.toType)) else Ident(s.name)
         }.toList
@@ -114,7 +115,7 @@ private[generic] object MongoFormatMacros {
         if (idents.size == 1)
           c.abort(c.enclosingPosition, "Subtypes not found.")
         else {
-          val instanceDefs = subtypes.zipWithIndex.collect {
+          val instanceDefs = subtypesWithNoFormatter.zipWithIndex.collect {
             case (symbol, i) if symbol.isClass && symbol.asClass.isCaseClass =>
               if (symbol.asClass.typeParams.nonEmpty) {
                 c.abort(
@@ -152,4 +153,14 @@ private[generic] object MongoFormatMacros {
       }
     }
   }
+
+  private def mongoFormatExists(c: blackbox.Context)(s: c.universe.Symbol) = {
+    val typeName = s.asType.toType
+    try {
+      c.typecheck(c.parse(s"implicitly[MongoFormat[$typeName]]"))
+      true
+    } catch {
+      case _: Throwable => false
+    }
+  }
 }
diff --git a/mongo/mongo-derivation/src/test/scala/io/sphere/mongo/generic/SumTypesDerivingSpec.scala b/mongo/mongo-derivation/src/test/scala/io/sphere/mongo/generic/SumTypesDerivingSpec.scala
index 37c8ce9e..c919647a 100644
--- a/mongo/mongo-derivation/src/test/scala/io/sphere/mongo/generic/SumTypesDerivingSpec.scala
+++ b/mongo/mongo-derivation/src/test/scala/io/sphere/mongo/generic/SumTypesDerivingSpec.scala
@@ -6,6 +6,7 @@ import org.scalatest.wordspec.AnyWordSpec
 import io.sphere.mongo.MongoUtils.dbObj
 import io.sphere.mongo.format.DefaultMongoFormats._
 import io.sphere.mongo.format.MongoFormat
+import org.bson.BSONObject
 import org.scalatest.Assertion
 
 class SumTypesDerivingSpec extends AnyWordSpec with Matchers {
@@ -73,6 +74,22 @@ class SumTypesDerivingSpec extends AnyWordSpec with Matchers {
 
       check(Color9.format, Color9.Custom("2356"), dbObj("type" -> "Custom", "rgb" -> "2356"))
     }
+
+    "Formatters could be overridden for objects" in {
+      check(Color10.format, Color10.Red, dbObj("type" -> "Red", "extraField" -> "panda"))
+
+      check(Color10.format, Color10.Custom("2356"), dbObj("type" -> "Custom", "rgb" -> "2356"))
+    }
+
+    "Formatters could be overridden for classes" in {
+      check(Color11.format, Color11.Red, dbObj("type" -> "Red"))
+
+      check(
+        Color11.format,
+        Color11.Custom("2356"),
+        dbObj("type" -> "Custom", "rgb" -> "2356", "extraField" -> "panda"))
+    }
+
   }
 }
 
@@ -171,4 +188,30 @@ object SumTypesDerivingSpec {
     val format = deriveMongoFormat[Color9]
   }
 
+  sealed trait Color10
+  object Color10 {
+    case object Red extends Color10
+    case class Custom(rgb: String) extends Color10
+
+    implicit val redFormatter: MongoFormat[Red.type] = new MongoFormat[Red.type] {
+      override def toMongoValue(a: Red.type): Any = dbObj("type" -> "Red", "extraField" -> "panda")
+      override def fromMongoValue(any: Any): Red.type = Red
+    }
+    val format = deriveMongoFormat[Color10]
+  }
+
+  sealed trait Color11
+  object Color11 {
+    case object Red extends Color11
+    case class Custom(rgb: String) extends Color11
+
+    implicit val customFormatter: MongoFormat[Custom] = new MongoFormat[Custom] {
+      override def toMongoValue(a: Custom): Any =
+        dbObj("type" -> "Custom", "rgb" -> a.rgb, "extraField" -> "panda")
+      override def fromMongoValue(any: Any): Custom =
+        Custom(any.asInstanceOf[BSONObject].get("rgb").asInstanceOf[String])
+    }
+    val format = deriveMongoFormat[Color11]
+  }
+
 }