From 2bedc2bb00377971ff53cb8d6bf491a8261fbc1f Mon Sep 17 00:00:00 2001
From: Tobe O <thosakwe@gmail.com>
Date: Fri, 29 Mar 2019 15:39:52 -0400
Subject: [PATCH] Add Angel functionality for handling subscription streams

---
 angel_graphql/lib/src/graphql_http.dart | 48 ++++++++++++++++---------
 angel_graphql/pubspec.yaml              |  6 +++-
 2 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/angel_graphql/lib/src/graphql_http.dart b/angel_graphql/lib/src/graphql_http.dart
index a0161351..61e11305 100644
--- a/angel_graphql/lib/src/graphql_http.dart
+++ b/angel_graphql/lib/src/graphql_http.dart
@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'package:angel_framework/angel_framework.dart';
@@ -19,13 +20,30 @@ final Validator graphQlPostBody = new Validator({
 ///
 /// Follows the guidelines listed here:
 /// https://graphql.org/learn/serving-over-http/
-RequestHandler graphQLHttp(GraphQL graphQL) {
+RequestHandler graphQLHttp(GraphQL graphQL,
+    {Function(RequestContext, ResponseContext, Stream<Map<String, dynamic>>)
+        onSubscription}) {
   return (req, res) async {
     var globalVariables = <String, dynamic>{
       '__requestctx': req,
       '__responsectx': res,
     };
 
+    sendGraphQLResponse(result) async {
+      if (result is Stream<Map<String, dynamic>>) {
+        if (onSubscription == null) {
+          throw StateError(
+              'The GraphQL backend returned a Stream, but no `onSubscription` callback was provided.');
+        } else {
+          return await onSubscription(req, res, result);
+        }
+      }
+
+      return {
+        'data': result,
+      };
+    }
+
     executeMap(Map map) async {
       var body = await req.parseBody().then((_) => req.bodyAsMap);
       var text = body['query'] as String;
@@ -36,15 +54,13 @@ RequestHandler graphQLHttp(GraphQL graphQL) {
         variables = json.decode(variables as String);
       }
 
-      return {
-        'data': await graphQL.parseAndExecute(
-          text,
-          sourceUrl: 'input',
-          operationName: operationName,
-          variableValues: foldToStringDynamic(variables as Map),
-          globalVariables: globalVariables,
-        ),
-      };
+      return await sendGraphQLResponse(await graphQL.parseAndExecute(
+        text,
+        sourceUrl: 'input',
+        operationName: operationName,
+        variableValues: foldToStringDynamic(variables as Map),
+        globalVariables: globalVariables,
+      ));
     }
 
     try {
@@ -55,13 +71,11 @@ RequestHandler graphQLHttp(GraphQL graphQL) {
       } else if (req.method == 'POST') {
         if (req.headers.contentType?.mimeType == graphQlContentType.mimeType) {
           var text = await req.body.transform(utf8.decoder).join();
-          return {
-            'data': await graphQL.parseAndExecute(
-              text,
-              sourceUrl: 'input',
-              globalVariables: globalVariables,
-            ),
-          };
+          return sendGraphQLResponse(await graphQL.parseAndExecute(
+            text,
+            sourceUrl: 'input',
+            globalVariables: globalVariables,
+          ));
         } else if (req.headers.contentType?.mimeType == 'application/json') {
           if (await validate(graphQlPostBody)(req, res) as bool) {
             return await executeMap(req.bodyAsMap);
diff --git a/angel_graphql/pubspec.yaml b/angel_graphql/pubspec.yaml
index ae5219c6..8cdb6f34 100644
--- a/angel_graphql/pubspec.yaml
+++ b/angel_graphql/pubspec.yaml
@@ -7,6 +7,7 @@ environment:
   sdk: ">=2.0.0-dev <3.0.0"
 dependencies:
   angel_framework: ^2.0.0-alpha
+  angel_websocket: ^2.0.0
   angel_validate: ^2.0.0-alpha
   graphql_parser: ^1.0.0
   graphql_schema: ^1.0.0
@@ -14,4 +15,7 @@ dependencies:
   http_parser: ^3.0.0
 dev_dependencies:
   angel_serialize: ^2.0.0
-  logging: ^0.11.0
\ No newline at end of file
+  logging: ^0.11.0
+dependency_overrides:
+  graphql_server:
+    path: ../graphql_server
\ No newline at end of file