Add handling of accept headers like application/hal+json (#26)

* Add handling of accept headers like application/hal+json

Let request predicates produce sth like application/*+json

* Add tests for deserialization handler

Author: mduesterhoeft

router-protobuf/src/main/kotlin/io/moia/router/proto/ProtoDeserializationHandler.kt

@@ -1,20 +1,26 @@
 package io.moia.router.proto
 
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
-import io.moia.router.DeserializationHandler
-import io.moia.router.contentType
 import com.google.common.net.MediaType
 import com.google.protobuf.Parser
+import io.moia.router.DeserializationHandler
+import io.moia.router.contentType
+import isCompatibleWith
 import java.util.Base64
 import kotlin.reflect.KClass
 import kotlin.reflect.KType
 import kotlin.reflect.full.staticFunctions
 
 class ProtoDeserializationHandler : DeserializationHandler {
     private val proto = MediaType.parse("application/x-protobuf")
+    private val protoStructuredSuffixWildcard = MediaType.parse("application/*+x-protobuf")
 
     override fun supports(input: APIGatewayProxyRequestEvent): Boolean =
-        input.contentType() != null && MediaType.parse(input.contentType()).`is`(proto)
+        if (input.contentType() == null)
+            false
+        else {
+            MediaType.parse(input.contentType()).let { proto.isCompatibleWith(it) || protoStructuredSuffixWildcard.isCompatibleWith(it) }
+        }
 
     override fun deserialize(input: APIGatewayProxyRequestEvent, target: KType?): Any {
         val bytes = Base64.getDecoder().decode(input.body)

router-protobuf/src/main/kotlin/io/moia/router/proto/ProtoSerializationHandler.kt

@@ -3,18 +3,20 @@ package io.moia.router.proto
 import com.google.common.net.MediaType
 import com.google.protobuf.GeneratedMessageV3
 import io.moia.router.SerializationHandler
+import isCompatibleWith
 import java.util.Base64
 
 class ProtoSerializationHandler : SerializationHandler {
 
     private val json = MediaType.parse("application/json")
+    private val jsonStructuredSuffixWildcard = MediaType.parse("application/*+json")
 
     override fun supports(acceptHeader: MediaType, body: Any): Boolean =
         body is GeneratedMessageV3
 
     override fun serialize(acceptHeader: MediaType, body: Any): String {
         val message = body as GeneratedMessageV3
-        return if (acceptHeader.`is`(json)) {
+        return if (json.isCompatibleWith(acceptHeader) || jsonStructuredSuffixWildcard.isCompatibleWith(acceptHeader)) {
             ProtoBufUtils.toJsonWithoutWrappers(message)
         } else {
             Base64.getEncoder().encodeToString(message.toByteArray())

router-protobuf/src/test/kotlin/io/moia/router/proto/ProtoDeserializationHandlerTest.kt

@@ -21,5 +21,6 @@ internal class ProtoDeserializationHandlerTest {
     @Test
     fun `Deserializer should support if the content type of the input is protobuf`() {
         assertTrue(ProtoDeserializationHandler().supports(APIGatewayProxyRequestEvent().withHeader("content-type", "application/x-protobuf")))
+        assertTrue(ProtoDeserializationHandler().supports(APIGatewayProxyRequestEvent().withHeader("content-type", "application/vnd.moia.v1+x-protobuf")))
     }
 }

router-protobuf/src/test/kotlin/io/moia/router/proto/RequestHandlerTest.kt

@@ -35,6 +35,20 @@ class RequestHandlerTest {
         assert(response.body).isEqualTo("""{"hello":"Hello","request":""}""")
     }
 
+    @Test
+    fun `should match request to proto handler with version accept header and return json`() {
+
+        val response = testRequestHandler.handleRequest(
+            APIGatewayProxyRequestEvent()
+                .withPath("/some-proto")
+                .withHttpMethod("GET")
+                .withHeaders(mapOf("Accept" to "application/vnd.moia.v1+json")), mockk()
+        )
+
+        assert(response.statusCode).isEqualTo(200)
+        assert(response.body).isEqualTo("""{"hello":"v1","request":""}""")
+    }
+
     @Test
     fun `should match request to proto handler and return proto`() {
 
@@ -109,6 +123,9 @@ class RequestHandlerTest {
 
             defaultContentType = "application/x-protobuf"
 
+            GET("/some-proto") { _: Request<Unit> -> ResponseEntity.ok(Sample.newBuilder().setHello("v1").build()) }
+                .producing("application/vnd.moia.v1+x-protobuf", "application/vnd.moia.v1+json")
+
             GET("/some-proto") { _: Request<Unit> -> ResponseEntity.ok(Sample.newBuilder().setHello("Hello").build()) }
                 .producing("application/x-protobuf", "application/json")
             POST("/some-proto") { r: Request<Sample> -> ResponseEntity.ok(r.body) }

router/src/main/kotlin/io/moia/router/DeserializationHandler.kt

@@ -4,6 +4,7 @@ import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.type.TypeFactory
 import com.google.common.net.MediaType
+import isCompatibleWith
 import kotlin.reflect.KClass
 import kotlin.reflect.KType
 import kotlin.reflect.full.isSubclassOf
@@ -28,9 +29,14 @@ class DeserializationHandlerChain(private val handlers: List<DeserializationHand
 class JsonDeserializationHandler(private val objectMapper: ObjectMapper) : DeserializationHandler {
 
     private val json = MediaType.parse("application/json")
+    private val jsonStructuredSuffixWildcard = MediaType.parse("application/*+json")
 
     override fun supports(input: APIGatewayProxyRequestEvent) =
-        input.contentType() != null && MediaType.parse(input.contentType()!!).`is`(json)
+        if (input.contentType() == null)
+            false
+        else {
+            MediaType.parse(input.contentType()).let { json.isCompatibleWith(it) || jsonStructuredSuffixWildcard.isCompatibleWith(it) }
+        }
 
     override fun deserialize(input: APIGatewayProxyRequestEvent, target: KType?): Any? {
         val targetClass = target?.classifier as KClass<*>

router/src/main/kotlin/io/moia/router/MediaTypeExtensions.kt

@@ -0,0 +1,11 @@
+import com.google.common.net.MediaType
+
+fun MediaType.isCompatibleWith(other: MediaType): Boolean =
+    if (this.`is`(other))
+        true
+    else {
+        type() == other.type() &&
+        (subtype().contains("+") && other.subtype().contains("+")) &&
+            this.subtype().substringBeforeLast("+") == "*" &&
+                this.subtype().substringAfterLast("+") == other.subtype().substringAfterLast("+")
+    }

router/src/main/kotlin/io/moia/router/RequestPredicate.kt

@@ -2,6 +2,7 @@ package io.moia.router
 
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
 import com.google.common.net.MediaType
+import isCompatibleWith
 
 data class RequestPredicate(
     val method: String,
@@ -49,7 +50,7 @@ data class RequestPredicate(
     fun matchedAcceptType(acceptedMediaTypes: List<MediaType>) =
         produces
             .map { MediaType.parse(it) }
-            .firstOrNull { acceptedMediaTypes.any { acceptedType -> it.`is`(acceptedType) } }
+            .firstOrNull { acceptedMediaTypes.any { acceptedType -> it.isCompatibleWith(acceptedType) } }
 
     private fun acceptMatches(acceptedMediaTypes: List<MediaType>) =
         matchedAcceptType(acceptedMediaTypes) != null
@@ -58,7 +59,7 @@ data class RequestPredicate(
         when {
             consumes.isEmpty() -> true
             contentType == null -> false
-            else -> consumes.any { MediaType.parse(contentType).`is`(MediaType.parse(it)) }
+            else -> consumes.any { MediaType.parse(contentType).isCompatibleWith(MediaType.parse(it)) }
         }
 }
 

router/src/main/kotlin/io/moia/router/SerializationHandler.kt

@@ -2,6 +2,7 @@ package io.moia.router
 
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.google.common.net.MediaType
+import isCompatibleWith
 
 interface SerializationHandler {
 
@@ -23,8 +24,10 @@ class SerializationHandlerChain(private val handlers: List<SerializationHandler>
 class JsonSerializationHandler(private val objectMapper: ObjectMapper) : SerializationHandler {
 
     private val json = MediaType.parse("application/json")
+    private val jsonStructuredSuffixWildcard = MediaType.parse("application/*+json")
 
-    override fun supports(acceptHeader: MediaType, body: Any): Boolean = acceptHeader.`is`(json)
+    override fun supports(acceptHeader: MediaType, body: Any): Boolean =
+        json.isCompatibleWith(acceptHeader) || jsonStructuredSuffixWildcard.isCompatibleWith(acceptHeader)
 
     override fun serialize(acceptHeader: MediaType, body: Any): String =
         objectMapper.writeValueAsString(body)

router/src/test/kotlin/io/moia/router/JsonDeserializationHandlerTest.kt

@@ -0,0 +1,28 @@
+package io.moia.router
+
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+
+class JsonDeserializationHandlerTest {
+
+    val deserializationHandler = JsonDeserializationHandler(jacksonObjectMapper())
+
+    @Test
+    fun `should support json`() {
+        assertTrue(deserializationHandler.supports(APIGatewayProxyRequestEvent()
+            .withHeader("content-type", "application/json")))
+        assertTrue(deserializationHandler.supports(APIGatewayProxyRequestEvent()
+            .withHeader("content-type", "application/vnd.moia.v1+json")))
+    }
+
+    @Test
+    fun `should not support anything else than json`() {
+        assertFalse(deserializationHandler.supports(APIGatewayProxyRequestEvent()
+            .withHeader("content-type", "image/png")))
+        assertFalse(deserializationHandler.supports(APIGatewayProxyRequestEvent()
+            .withHeader("content-type", "text/plain")))
+    }
+}

router/src/test/kotlin/io/moia/router/MediaTypeTest.kt

@@ -0,0 +1,45 @@
+package io.moia.router
+
+import com.google.common.net.MediaType
+import isCompatibleWith
+import org.assertj.core.api.BDDAssertions.then
+import org.junit.jupiter.api.Test
+
+class MediaTypeTest {
+
+    @Test
+    fun `should match`() {
+        then(MediaType.parse("application/json").isCompatibleWith(MediaType.parse("application/json"))).isTrue()
+    }
+
+    @Test
+    fun `should match subtype wildcard`() {
+        then(MediaType.parse("application/json").isCompatibleWith(MediaType.parse("application/*"))).isTrue()
+    }
+
+    @Test
+    fun `should not match subtype wildcard in different tpye`() {
+        then(MediaType.parse("application/json").isCompatibleWith(MediaType.parse("image/*"))).isFalse()
+    }
+
+    @Test
+    fun `should match wildcard`() {
+        then(MediaType.parse("application/json").isCompatibleWith(MediaType.parse("*/*"))).isTrue()
+    }
+
+    @Test
+    fun `should match wildcard structured syntax suffix`() {
+        then(MediaType.parse("application/*+json").isCompatibleWith(MediaType.parse("application/vnd.moia+json"))).isTrue()
+        then(MediaType.parse("application/*+json").isCompatibleWith(MediaType.parse("application/vnd.moia.v1+json"))).isTrue()
+    }
+
+    @Test
+    fun `should not match wildcard structured syntax suffix on non suffix type`() {
+        then(MediaType.parse("application/*+json").isCompatibleWith(MediaType.parse("application/json"))).isFalse()
+    }
+
+    @Test
+    fun `should not match wildcard structured syntax suffix on differnt suffix`() {
+        then(MediaType.parse("application/*+json").isCompatibleWith(MediaType.parse("application/*+x-protobuf"))).isFalse()
+    }
+}