Codec provider for BigInt

modules/kernel/src/main/scala/mongo4cats/bson/Document.scala

@@ -111,8 +111,8 @@ final private class ListMapDocument(
         doc.toMap.forall { case (k, v) =>
           (v, fields.get(k)) match {
             case (BsonValue.BBinary(bin1), Some(BsonValue.BBinary(bin2))) => bin1.sameElements(bin2)
-            case (bv1, Some(bv2))                                     => bv1 == bv2
-            case _                                                    => false
+            case (bv1, Some(bv2))                                         => bv1 == bv2
+            case _                                                        => false
           }
         }
       case _ => false

modules/kernel/src/main/scala/mongo4cats/codecs/BigIntCodecProvider.scala

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2020 Kirill5k
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package mongo4cats.codecs
+
+import mongo4cats.Clazz
+import org.bson.codecs.configuration.CodecProvider
+import org.bson.codecs.{Codec, DecoderContext, EncoderContext}
+import org.bson.types.Decimal128
+import org.bson.{BsonInvalidOperationException, BsonReader, BsonType, BsonWriter}
+
+private object BigIntCodec extends Codec[BigInt] {
+
+  override def encode(writer: BsonWriter, bd: BigInt, encoderContext: EncoderContext): Unit =
+    writer.writeDecimal128(new Decimal128(BigDecimal(bd).bigDecimal))
+
+  override def getEncoderClass: Class[BigInt] = Clazz.tag[BigInt]
+
+  override def decode(reader: BsonReader, decoderContext: DecoderContext): BigInt =
+    reader.getCurrentBsonType match {
+      case BsonType.DECIMAL128 => reader.readDecimal128().bigDecimalValue().toBigInteger
+      case otherType           => throw new BsonInvalidOperationException(s"Unexpected bson type $otherType when reading BigInt")
+    }
+}
+
+object BigIntCodecProvider extends CodecProvider {
+  override def get[T](clazz: Class[T], registry: CodecRegistry): Codec[T] =
+    if (classOf[BigDecimal].isAssignableFrom(clazz)) BigIntCodec.asInstanceOf[Codec[T]] else null
+}

modules/kernel/src/main/scala/mongo4cats/codecs/package.scala

@@ -29,6 +29,7 @@ package object codecs {
       from(BsonValueCodecProvider),
       MongoClientSettings.getDefaultCodecRegistry,
       from(BigDecimalCodecProvider),
+      from(BigIntCodecProvider),
       from(OptionCodecProvider),
       from(MapCodecProvider),
       from(IterableCodecProvider)