Allow parsing request and writing responses using java streams

This fixes actions-on-google#39

src/main/kotlin/com/google/actions/api/ActionResponse.kt

@@ -20,6 +20,8 @@ import com.google.api.services.actions_fulfillment.v2.model.AppResponse
 import com.google.api.services.actions_fulfillment.v2.model.ExpectedIntent
 import com.google.api.services.actions_fulfillment.v2.model.RichResponse
 import com.google.api.services.dialogflow_fulfillment.v2.model.WebhookResponse
+import java.io.IOException
+import java.io.OutputStream
 
 /**
  * Defines requirements of an object that represents a response from the Actions
@@ -58,6 +60,16 @@ interface ActionResponse {
      */
     val helperIntent: ExpectedIntent?
 
+    /**
+     * Writes the JSON representation of the response to the given output stream.
+     *
+     * This is more efficient than calling [toJson] first and then writing the string.
+     *
+     * @param outputStream The output stream to write to. Must be closed by the caller.
+     */
+    @Throws(IOException::class)
+    fun writeTo(outputStream: OutputStream)
+
     /**
      * Returns the JSON representation of the response.
      */

src/main/kotlin/com/google/actions/api/ActionsSdkApp.kt

@@ -19,6 +19,7 @@ package com.google.actions.api
 import com.google.actions.api.impl.AogRequest
 import com.google.actions.api.response.ResponseBuilder
 import org.slf4j.LoggerFactory
+import java.io.InputStream
 
 /**
  * Implementation of App for ActionsSDK based webhook. Developers must extend
@@ -50,6 +51,11 @@ open class ActionsSdkApp : DefaultApp() {
         return AogRequest.create(inputJson, headers)
     }
 
+    override fun createRequest(inputStream: InputStream, headers: Map<*, *>?): ActionRequest {
+        LOG.info("ActionsSdkApp.createRequest..")
+        return AogRequest.create(inputStream, headers)
+    }
+
     override fun getResponseBuilder(request: ActionRequest): ResponseBuilder {
         val responseBuilder = ResponseBuilder(
                 usesDialogflow = false,

src/main/kotlin/com/google/actions/api/DefaultApp.kt

@@ -18,6 +18,7 @@ package com.google.actions.api
 
 import com.google.actions.api.response.ResponseBuilder
 import org.slf4j.LoggerFactory
+import java.io.InputStream
 import java.util.concurrent.CompletableFuture
 
 /**
@@ -42,6 +43,20 @@ abstract class DefaultApp : App {
     abstract fun createRequest(inputJson: String, headers: Map<*, *>?):
             ActionRequest
 
+    /**
+     * Creates an ActionRequest from the specified input stream and metadata.
+     *
+     * This is semantically equivalent to reading the stream as a String using
+     * UTF-8 encoding and then calling `createRequest` with the resulting
+     * string.
+     *
+     * @param inputStream The input stream. Must be closed by the caller
+     * @param headers Map containing metadata, usually from the HTTP request
+     *   headers.
+     */
+    abstract fun createRequest(inputStream: InputStream, headers: Map<*, *>?):
+            ActionRequest
+
     /**
      * @return A ResponseBuilder for this App.
      */

src/main/kotlin/com/google/actions/api/DialogflowApp.kt

@@ -18,6 +18,7 @@ package com.google.actions.api
 
 import com.google.actions.api.impl.DialogflowRequest
 import com.google.actions.api.response.ResponseBuilder
+import java.io.InputStream
 
 /**
  * Implementation of App for Dialogflow based webhook. Developers must extend
@@ -48,6 +49,10 @@ open class DialogflowApp : DefaultApp() {
         return DialogflowRequest.create(inputJson, headers)
     }
 
+    override fun createRequest(inputStream: InputStream, headers: Map<*, *>?): ActionRequest {
+        return DialogflowRequest.create(inputStream, headers)
+    }
+
     override fun getResponseBuilder(request: ActionRequest): ResponseBuilder {
         val responseBuilder = ResponseBuilder(
                 usesDialogflow = true,

src/main/kotlin/com/google/actions/api/impl/AogResponse.kt

@@ -22,6 +22,7 @@ import com.google.actions.api.response.ResponseBuilder
 import com.google.api.services.actions_fulfillment.v2.model.*
 import com.google.api.services.dialogflow_fulfillment.v2.model.WebhookResponse
 import com.google.gson.Gson
+import java.io.OutputStream
 import java.util.*
 
 internal class AogResponse internal constructor(
@@ -85,12 +86,12 @@ internal class AogResponse internal constructor(
             if (conversationData != null) {
                 val dataMap = HashMap<String, Any?>()
                 dataMap["data"] = conversationData
-                appResponse?.conversationToken = Gson().toJson(dataMap)
+                appResponse?.conversationToken = gson.toJson(dataMap)
             }
             if (userStorage != null) {
                 val dataMap = HashMap<String, Any?>()
                 dataMap["data"] = userStorage
-                appResponse?.userStorage = Gson().toJson(dataMap)
+                appResponse?.userStorage = gson.toJson(dataMap)
             }
         }
     }
@@ -132,7 +133,15 @@ internal class AogResponse internal constructor(
         appResponse?.expectedInputs = expectedInputs
     }
 
+    override fun writeTo(outputStream: OutputStream) {
+        ResponseSerializer(sessionId).writeJsonV2To(this, outputStream)
+    }
+
     override fun toJson(): String {
         return ResponseSerializer(sessionId).toJsonV2(this)
     }
+
+    companion object {
+        private val gson = Gson()
+    }
 }

src/main/kotlin/com/google/actions/api/impl/DialogflowRequest.kt

@@ -23,6 +23,8 @@ import com.google.api.services.actions_fulfillment.v2.model.*
 import com.google.api.services.dialogflow_fulfillment.v2.model.*
 import com.google.gson.*
 import com.google.gson.reflect.TypeToken
+import java.io.InputStream
+import java.io.InputStreamReader
 import java.lang.reflect.Type
 import java.util.*
 
@@ -168,38 +170,43 @@ internal class DialogflowRequest internal constructor(
     }
 
     companion object {
-
-        fun create(body: String, headers: Map<*, *>?): DialogflowRequest {
-            val gson = Gson()
-            return create(gson.fromJson(body, JsonObject::class.java), headers)
-        }
-
-        fun create(json: JsonObject, headers: Map<*, *>?): DialogflowRequest {
-            val gsonBuilder = GsonBuilder()
-            gsonBuilder
-                    .registerTypeAdapter(WebhookRequest::class.java,
-                            WebhookRequestDeserializer())
-                    .registerTypeAdapter(QueryResult::class.java,
-                            QueryResultDeserializer())
-                    .registerTypeAdapter(Context::class.java,
-                            ContextDeserializer())
-                    .registerTypeAdapter(OriginalDetectIntentRequest::class.java,
-                            OriginalDetectIntentRequestDeserializer())
-
-            val gson = gsonBuilder.create()
-            val webhookRequest = gson.fromJson<WebhookRequest>(json,
-                    WebhookRequest::class.java)
-            val aogRequest: AogRequest
+        private val gson = GsonBuilder()
+            .registerTypeAdapter(WebhookRequest::class.java,
+                WebhookRequestDeserializer())
+            .registerTypeAdapter(QueryResult::class.java,
+                QueryResultDeserializer())
+            .registerTypeAdapter(Context::class.java,
+                ContextDeserializer())
+            .registerTypeAdapter(OriginalDetectIntentRequest::class.java,
+                OriginalDetectIntentRequestDeserializer())
+            .create()
+
+        fun create(body: String, headers: Map<*, *>?): DialogflowRequest =
+            create(gson.fromJson(body, WebhookRequest::class.java), headers)
+
+        fun create(json: JsonObject, headers: Map<*, *>?): DialogflowRequest =
+            create(gson.fromJson(json, WebhookRequest::class.java), headers)
+
+        fun create(inputStream: InputStream, headers: Map<*, *>?): DialogflowRequest =
+            create(
+                gson.fromJson(InputStreamReader(inputStream), WebhookRequest::class.java),
+                headers
+            )
+
+        private fun create(
+            webhookRequest: WebhookRequest,
+            headers: Map<*, *>?
+        ): DialogflowRequest {
 
             val originalDetectIntentRequest =
-                    webhookRequest.originalDetectIntentRequest
+                webhookRequest.originalDetectIntentRequest
             val payload = originalDetectIntentRequest?.payload
-            if (payload != null) {
-                aogRequest = AogRequest.create(gson.toJson(payload), headers,
-                        partOfDialogflowRequest = true)
+            val aogRequest = if (payload != null) {
+                AogRequest.create(gson.toJson(payload), headers,
+                    partOfDialogflowRequest = true)
             } else {
-                aogRequest = AogRequest.create(JsonObject(), headers,
-                        partOfDialogflowRequest = true)
+                AogRequest.create(JsonObject(), headers,
+                    partOfDialogflowRequest = true)
             }
 
             return DialogflowRequest(webhookRequest, aogRequest)

src/main/kotlin/com/google/actions/api/impl/DialogflowResponse.kt

@@ -25,6 +25,7 @@ import com.google.api.services.actions_fulfillment.v2.model.AppResponse
 import com.google.api.services.actions_fulfillment.v2.model.ExpectedIntent
 import com.google.api.services.actions_fulfillment.v2.model.RichResponse
 import com.google.api.services.dialogflow_fulfillment.v2.model.WebhookResponse
+import java.io.OutputStream
 
 internal class DialogflowResponse internal constructor(
         responseBuilder: ResponseBuilder) : ActionResponse {
@@ -59,6 +60,10 @@ internal class DialogflowResponse internal constructor(
     override val helperIntent: ExpectedIntent?
         get() = googlePayload?.helperIntent
 
+    override fun writeTo(outputStream: OutputStream) {
+        ResponseSerializer(sessionId).writeJsonV2To(this, outputStream)
+    }
+
     override fun toJson(): String {
         return ResponseSerializer(sessionId).toJsonV2(this)
     }

src/main/kotlin/com/google/actions/api/impl/io/ResponseSerializer.kt

@@ -26,6 +26,10 @@ import com.google.api.services.dialogflow_fulfillment.v2.model.WebhookResponse
 import com.google.gson.Gson
 import com.google.gson.GsonBuilder
 import org.slf4j.LoggerFactory
+import java.io.OutputStream
+import java.io.OutputStreamWriter
+import java.io.StringWriter
+import java.io.Writer
 import java.util.*
 import kotlin.collections.ArrayList
 import kotlin.collections.set
@@ -36,6 +40,7 @@ internal class ResponseSerializer(
     private companion object {
         val includeVersionMetadata = false
         val LOG = LoggerFactory.getLogger(ResponseSerializer::class.java.name)
+        val gson = GsonBuilder().create()
 
         fun getLibraryMetadata(): Map<String, String> {
             val metadataProperties = ResourceBundle.getBundle("metadata")
@@ -53,19 +58,27 @@ internal class ResponseSerializer(
         )
     }
 
-    fun toJsonV2(response: ActionResponse): String {
+    fun toJsonV2(response: ActionResponse): String =
+        StringWriter().use { writeJsonV2To(response, it) }.toString()
+
+    fun writeJsonV2To(response: ActionResponse, outputStream: OutputStream) {
+        val writer = OutputStreamWriter(outputStream, Charsets.UTF_8)
+        writeJsonV2To(response, writer)
+        writer.flush()
+    }
+
+    private fun writeJsonV2To(response: ActionResponse, writer: Writer) {
         when (response) {
-            is DialogflowResponse -> return serializeDialogflowResponseV2(
-                    response)
-            is AogResponse -> return serializeAogResponse(response)
+            is DialogflowResponse -> serializeDialogflowResponseV2(response, writer)
+            is AogResponse -> serializeAogResponse(response, writer)
         }
         LOG.warn("Unable to serialize the response.")
         throw Exception("Unable to serialize the response")
     }
 
     private fun serializeDialogflowResponseV2(
-            dialogflowResponse: DialogflowResponse): String {
-        val gson = GsonBuilder().create()
+            dialogflowResponse: DialogflowResponse,
+            writer: Writer) {
         val googlePayload = dialogflowResponse.googlePayload
         val webhookResponse = dialogflowResponse.webhookResponse
         val conversationData = dialogflowResponse.conversationData
@@ -97,7 +110,7 @@ internal class ResponseSerializer(
             metadata["google_library"] = getLibraryMetadata()
             webhookResponseMap["metadata"] = metadata
         }
-        return gson.toJson(webhookResponseMap)
+        gson.toJson(webhookResponseMap, writer)
     }
 
     private fun setContext(
@@ -194,7 +207,7 @@ internal class ResponseSerializer(
             if (userStorage != null) {
                 val dataMap = HashMap<String, Any?>()
                 dataMap["data"] = userStorage
-                this.userStorage = Gson().toJson(dataMap)
+                this.userStorage = gson.toJson(dataMap)
             }
             this.isSsml = false
         }
@@ -228,7 +241,7 @@ internal class ResponseSerializer(
     }
 
     @Throws(Exception::class)
-    private fun serializeAogResponse(aogResponse: AogResponse): String {
+    private fun serializeAogResponse(aogResponse: AogResponse, writer: Writer) {
         aogResponse.prepareAppResponse()
         checkSimpleResponseIsPresent(aogResponse)
         val appResponseMap = aogResponse.appResponse!!.toMutableMap()
@@ -239,7 +252,7 @@ internal class ResponseSerializer(
             appResponseMap["ResponseMetadata"] = map
         }
 
-        return Gson().toJson(appResponseMap)
+        gson.toJson(appResponseMap, writer)
     }
 
     @Throws(Exception::class)

src/main/kotlin/com/google/actions/api/smarthome/SmartHomeApp.kt

@@ -23,6 +23,7 @@ import com.google.home.graph.v1.HomeGraphApiServiceProto
 import io.grpc.ManagedChannelBuilder
 import io.grpc.auth.MoreCallCredentials
 import java.io.FileInputStream
+import java.io.InputStream
 import java.util.concurrent.CompletableFuture
 
 abstract class SmartHomeApp : App {
@@ -49,6 +50,18 @@ abstract class SmartHomeApp : App {
         return SmartHomeRequest.create(inputJson)
     }
 
+    /**
+     * Builds a [SmartHomeRequest] object from an [InputStream].
+     *
+     * This is semantically equivalent as reading the input stream as an UTF-8 string and then calling createRequest
+     * with the resulting string.
+     *
+     * @param inputStream The input stream to read from. The stream must be closed by the caller.
+     * @return A parsed request object
+     */
+    fun createRequest(inputStream: InputStream): SmartHomeRequest =
+        SmartHomeRequest.create(inputStream)
+
     /**
      * The intent handler for action.devices.SYNC that is implemented in your smart home Action
      *
@@ -140,17 +153,24 @@ abstract class SmartHomeApp : App {
 
         return try {
             val request = createRequest(inputJson)
-            val response = routeRequest(request, headers)
-
-            val future: CompletableFuture<SmartHomeResponse> = CompletableFuture()
-            future.complete(response)
-            future.thenApply { this.getAsJson(it) }
-                  .exceptionally { throwable -> throwable.message }
+            handleRequest(request, headers)
+                .thenApply { getAsJson(it) }
+                .exceptionally { throwable -> throwable.message }
         } catch (e: Exception) {
             handleError(e)
         }
     }
 
+    fun handleRequest(request: SmartHomeRequest, headers: Map<*, *>?): CompletableFuture<SmartHomeResponse> =
+        try {
+            val response = routeRequest(request, headers)
+            CompletableFuture.completedFuture(response)
+        } catch (e: Exception) {
+            CompletableFuture<SmartHomeResponse>()
+                .apply { completeExceptionally(e) }
+        }
+
+
     @Throws(Exception::class)
     private fun routeRequest(request: SmartHomeRequest, headers: Map<*, *>?): SmartHomeResponse {
         when (request.javaClass) {