From 8ff945544c8f6bcd01f00451546d9e0f43fd5855 Mon Sep 17 00:00:00 2001
From: sksamuel <sam@sksamuel.com>
Date: Sun, 14 Apr 2024 19:58:23 -0500
Subject: [PATCH] Added maps support to encoders

---
 .../centurion/avro/encoders/Encoder.kt        |  1 +
 .../centurion/avro/encoders/collections.kt    | 14 ++++++--
 .../encoders/ReflectionRecordEncoderTest.kt   | 32 +++++++++++++++++++
 changelog.md                                  |  9 ++++++
 4 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 changelog.md

diff --git a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/Encoder.kt b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/Encoder.kt
index 6ba98f2..bcae856 100644
--- a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/Encoder.kt
+++ b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/Encoder.kt
@@ -40,6 +40,7 @@ fun interface Encoder<T> {
             BigDecimal::class -> BigDecimalStringEncoder
             Set::class -> GenericArraySetEncoder(encoderFor(type.arguments.first().type!!))
             List::class -> GenericArrayListEncoder(encoderFor(type.arguments.first().type!!))
+            Map::class -> MapEncoder(encoderFor(type.arguments[1].type!!))
             is KClass<*> -> if (classifier.java.isEnum) EnumEncoder<Enum<*>>() else error("Unsupported type $type")
             else -> error("Unsupported type $type")
          }
diff --git a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/collections.kt b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/collections.kt
index 3c77e82..94d1f46 100644
--- a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/collections.kt
+++ b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/encoders/collections.kt
@@ -1,6 +1,7 @@
 package com.sksamuel.centurion.avro.encoders
 
 import org.apache.avro.Schema
+import org.apache.avro.generic.GenericArray
 import org.apache.avro.generic.GenericData
 
 /**
@@ -29,9 +30,18 @@ class GenericArrayListEncoder<T>(private val encoder: Encoder<T>) : Encoder<List
  * An [Encoder] for Sets of [T] that encodes into an Avro [GenericArray].
  */
 class GenericArraySetEncoder<T>(private val encoder: Encoder<T>) : Encoder<Set<T>> {
-   override fun encode(schema: Schema, value: Set<T>): Any {
+   override fun encode(schema: Schema, value: Set<T>): GenericArray<Any> {
       require(schema.type == Schema.Type.ARRAY)
       val elements = value.map { encoder.encode(schema.elementType, it) }
-      return GenericData.Array<T>(elements.size, schema).also { it.addAll(elements as Collection<T>) }
+      val array = GenericData.get().newArray(null, elements.size, schema) as GenericArray<Any>
+      array.addAll(elements)
+      return array
+   }
+}
+
+class MapEncoder<T>(private val encoder: Encoder<T>) : Encoder<Map<String, T>> {
+   override fun encode(schema: Schema, value: Map<String, T>): Map<String, Any?> {
+      require(schema.type == Schema.Type.MAP)
+      return value.mapValues { encoder.encode(schema.valueType, it.value) }
    }
 }
diff --git a/centurion-avro/src/test/kotlin/com/sksamuel/centurion/avro/encoders/ReflectionRecordEncoderTest.kt b/centurion-avro/src/test/kotlin/com/sksamuel/centurion/avro/encoders/ReflectionRecordEncoderTest.kt
index 682e2af..c0b755b 100644
--- a/centurion-avro/src/test/kotlin/com/sksamuel/centurion/avro/encoders/ReflectionRecordEncoderTest.kt
+++ b/centurion-avro/src/test/kotlin/com/sksamuel/centurion/avro/encoders/ReflectionRecordEncoderTest.kt
@@ -91,6 +91,38 @@ class ReflectionRecordEncoderTest : FunSpec({
          Foo(listOf(1, 2), listOf(1L, null, 2L), listOf(Wine.Shiraz, Wine.Malbec))
       ) shouldBe expected
    }
+
+   test("maps") {
+      data class Foo(val map: Map<String, Int>)
+
+      val map = mapOf("a" to 1, "b" to 2)
+
+      val schema = SchemaBuilder.record("Foo").namespace(Foo::class.java.packageName)
+         .fields()
+         .name("map").type().map().values(SchemaBuilder.builder().intType()).noDefault()
+         .endRecord()
+
+      val record = GenericData.Record(schema)
+      record.put("map", map)
+
+      ReflectionRecordEncoder().encode(schema, Foo(map)) shouldBe record
+   }
+
+   test("maps of maps") {
+      data class Foo(val map: Map<String, Map<String, Int>>)
+
+      val maps = mapOf("a" to mapOf("a" to 1, "b" to 2), "b" to mapOf("a" to 3, "b" to 4))
+
+      val schema = SchemaBuilder.record("Foo").namespace(Foo::class.java.packageName)
+         .fields()
+         .name("map").type().map().values(SchemaBuilder.builder().map().values().intType()).noDefault()
+         .endRecord()
+
+      val record = GenericData.Record(schema)
+      record.put("map", maps)
+
+      ReflectionRecordEncoder().encode(schema, Foo(maps)) shouldBe record
+   }
 })
 
 enum class Wine { Shiraz, Malbec }
diff --git a/changelog.md b/changelog.md
new file mode 100644
index 0000000..3cb8587
--- /dev/null
+++ b/changelog.md
@@ -0,0 +1,9 @@
+## Changelog
+
+### 1.1.0
+
+* Added Map encoding support
+
+### 1.1.0
+
+* Added Avro4s port of Encoders, Decoder, Writers and Readers