feat: enum and int enums as event headers

Author: 0marperez

.changes/08deb04f-bc93-4d3c-aa2f-d46b2dcce775.json

@@ -0,0 +1,5 @@
+{
+    "id": "08deb04f-bc93-4d3c-aa2f-d46b2dcce775",
+    "type": "feature",
+    "description": "Support enums and int enums as event headers"
+}

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/aws/protocols/eventstream/EventStreamParserGenerator.kt

@@ -147,7 +147,7 @@ class EventStreamParserGenerator(
                 val target = ctx.model.expectShape(hdrBinding.target)
                 val targetSymbol = ctx.symbolProvider.toSymbol(target)
 
-                // :test(boolean, byte, short, integer, long, blob, string, timestamp))
+                // :test(boolean, byte, short, integer, long, blob, string, timestamp, enum, int enum))
                 val conversionFn = when (target.type) {
                     ShapeType.BOOLEAN -> RuntimeTypes.AwsEventStream.expectBool
                     ShapeType.BYTE -> RuntimeTypes.AwsEventStream.expectByte
@@ -157,6 +157,8 @@ class EventStreamParserGenerator(
                     ShapeType.BLOB -> RuntimeTypes.AwsEventStream.expectByteArray
                     ShapeType.STRING -> RuntimeTypes.AwsEventStream.expectString
                     ShapeType.TIMESTAMP -> RuntimeTypes.AwsEventStream.expectTimestamp
+                    ShapeType.ENUM -> RuntimeTypes.AwsEventStream.expectString
+                    ShapeType.INT_ENUM -> RuntimeTypes.AwsEventStream.expectInt32
                     else -> throw CodegenException("unsupported eventHeader shape: member=$hdrBinding; targetShape=$target")
                 }
 
@@ -165,7 +167,16 @@ class EventStreamParserGenerator(
                 } else {
                     ""
                 }
-                writer.write("eb.#L = message.headers.find { it.name == #S }?.value?.#T()$defaultValuePostfix", hdrBinding.defaultName(), hdrBinding.memberName, conversionFn)
+                writer.writeInline("eb.#L = message.headers.find { it.name == #S }?.value?.#T()$defaultValuePostfix", hdrBinding.defaultName(), hdrBinding.memberName, conversionFn)
+                when (target.type) {
+                    ShapeType.ENUM, ShapeType.INT_ENUM -> {
+                        writer.write(
+                            "?.let { #T.fromValue(it) }",
+                            targetSymbol,
+                        )
+                    }
+                    else -> writer.write("")
+                }
             }
 
             if (eventPayloadBinding != null) {

codegen/smithy-aws-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/aws/protocols/eventstream/EventStreamSerializerGenerator.kt

@@ -183,9 +183,15 @@ class EventStreamSerializerGenerator(
             ShapeType.BLOB -> "ByteArray"
             ShapeType.STRING -> "String"
             ShapeType.TIMESTAMP -> "Timestamp"
+            ShapeType.ENUM -> "String"
+            ShapeType.INT_ENUM -> "Int32"
             else -> throw CodegenException("unsupported shape type `${target.type}` for eventHeader member `$member`; target: $target")
         }
-        val conversion = if (target.type == ShapeType.BYTE) ".toUByte()" else ""
+        val conversion = when (target.type) {
+            ShapeType.BYTE -> ".toUByte()"
+            ShapeType.ENUM, ShapeType.INT_ENUM -> ".value"
+            else -> ""
+        }
 
         writer.write(
             "input.value.#L?.let { addHeader(#S, #T.#L(it$conversion)) }",