From 3feff56791b635abbfc9f5e097195a9130d72577 Mon Sep 17 00:00:00 2001
From: Abhishek Kumar Gupta <abhishekguptaatweb17@gmail.com>
Date: Wed, 12 Jun 2024 17:50:12 +0530
Subject: [PATCH] update the codec for big decimal (#663) (#687)

* update the codec for big decimal (#663)

refer the codec defintion in zio-bson repo :
zio/zio-bson/src/main/scala/zio/bson/BsonCodec.scala#L80

* add test case for BigDecimal's codec (#663)
---
 .../zio/schema/codec/BsonSchemaCodec.scala    |  2 +-
 .../schema/codec/BsonSchemaCodecSpec.scala    | 21 +++++++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/zio-schema-bson/src/main/scala/zio/schema/codec/BsonSchemaCodec.scala b/zio-schema-bson/src/main/scala/zio/schema/codec/BsonSchemaCodec.scala
index 2531f4f97..bf3298813 100644
--- a/zio-schema-bson/src/main/scala/zio/schema/codec/BsonSchemaCodec.scala
+++ b/zio-schema-bson/src/main/scala/zio/schema/codec/BsonSchemaCodec.scala
@@ -412,7 +412,7 @@ object BsonSchemaCodec {
         case StandardType.BinaryType     => BsonCodec.byteIterable[Chunk].asInstanceOf[BsonCodec[A]]
         case StandardType.CharType       => BsonCodec.char.asInstanceOf[BsonCodec[A]]
         case StandardType.BigIntegerType => BsonCodec.bigInteger.asInstanceOf[BsonCodec[A]]
-        case StandardType.BigDecimalType => BsonCodec.bigDecimal.asInstanceOf[BsonCodec[A]]
+        case StandardType.BigDecimalType => BsonCodec.javaBigDecimal.asInstanceOf[BsonCodec[A]]
         case StandardType.UUIDType       => BsonCodec.uuid.asInstanceOf[BsonCodec[A]]
         case StandardType.DayOfWeekType =>
           BsonCodec.dayOfWeek.asInstanceOf[BsonCodec[A]] // BsonCodec[java.time.DayOfWeek]
diff --git a/zio-schema-bson/src/test/scala/zio/schema/codec/BsonSchemaCodecSpec.scala b/zio-schema-bson/src/test/scala/zio/schema/codec/BsonSchemaCodecSpec.scala
index 0ee22827b..941dc1450 100644
--- a/zio-schema-bson/src/test/scala/zio/schema/codec/BsonSchemaCodecSpec.scala
+++ b/zio-schema-bson/src/test/scala/zio/schema/codec/BsonSchemaCodecSpec.scala
@@ -2,12 +2,12 @@ package zio.schema.codec
 
 import scala.reflect.{ ClassTag, classTag }
 
-import org.bson._
 import org.bson.codecs.configuration.CodecRegistry
 import org.bson.codecs.{ Codec => BCodec, DecoderContext, EncoderContext }
 import org.bson.conversions.Bson
 import org.bson.io.BasicOutputBuffer
-import org.bson.types.ObjectId
+import org.bson.types.{ Decimal128, ObjectId }
+import org.bson.{ BsonDecimal128, _ }
 
 import zio.bson.BsonBuilder._
 import zio.bson._
@@ -24,6 +24,13 @@ object BsonSchemaCodecSpec extends ZIOSpecDefault {
     implicit lazy val codec: BsonCodec[SimpleClass] = BsonSchemaCodec.bsonCodec(schema)
   }
 
+  case class BigDecimalClass(value: BigDecimal)
+
+  object BigDecimalClass {
+    implicit val schema: Schema[BigDecimalClass]        = DeriveSchema.gen
+    implicit lazy val codec: BsonCodec[BigDecimalClass] = BsonSchemaCodec.bsonCodec(schema)
+  }
+
   sealed trait Tree
 
   object Tree {
@@ -79,6 +86,10 @@ object BsonSchemaCodecSpec extends ZIOSpecDefault {
       } yield Customer(id, name, age, friends)
   }
 
+  // Custom generator for BigDecimal values with rounding to ensure exact representation as Decimal128
+  def genRoundedBigDecimal(scale: Int): Gen[Any, BigDecimal] =
+    Gen.double.map(d => BigDecimal(d).setScale(scale, BigDecimal.RoundingMode.HALF_UP))
+
   def spec: Spec[TestEnvironment with Scope, Any] = suite("BsonSchemaCodecSpec")(
     suite("round trip")(
       roundTripTest("SimpleClass")(
@@ -107,6 +118,12 @@ object BsonSchemaCodecSpec extends ZIOSpecDefault {
             Customer.example.invitedFriends.map(_.value.toBsonValue): _*
           )
         )
+      ),
+      roundTripTest("BigDecimalClass")(
+        // 14 decimal places in the assert value below
+        genRoundedBigDecimal(14).map(BigDecimalClass(_)),
+        BigDecimalClass(BigDecimal("279.00000000000000")),
+        doc("value" -> new BsonDecimal128(Decimal128.parse("279.00000000000000")))
       )
     ),
     suite("configuration")(