server: Make sync lazy

Use streams to save memory

Useful when there is not much space.

composer.json

@@ -4,14 +4,16 @@
     "type": "project",
     "require": {
         "php": ">= 5.6",
+        "ext-gd": "*",
         "bcosca/fatfree-core": "^3.7.0",
         "danielstjules/stringy": "^3.1",
-        "fossar/tcpdf-parser": "^6.2",
         "fossar/guzzle-transcoder": "^0.2.0",
+        "fossar/htmlawed": "^1.2.4.1",
+        "fossar/tcpdf-parser": "^6.2",
         "guzzlehttp/guzzle": "^6.3",
         "guzzlehttp/oauth-subscriber": "^0.4.0",
         "guzzlehttp/psr7": "^1.5",
-        "fossar/htmlawed": "^1.2.4.1",
+        "http-interop/response-sender": "^1.0",
         "j0k3r/graby": "2.0.0-alpha.0",
         "level-2/dice": "^2.0",
         "lordelph/icofileloader": "^2.0",
@@ -20,8 +22,8 @@
         "php-http/guzzle6-adapter": "^1.0",
         "simplepie/simplepie": "^1.3",
         "smottt/wideimage": "^1.1",
-        "willwashburn/phpamo": "^1.0",
-        "ext-gd": "*"
+        "violet/streaming-json-encoder": "^1.1",
+        "willwashburn/phpamo": "^1.0"
     },
     "require-dev": {
         "php-parallel-lint/php-parallel-lint": "^1.0",

src/controllers/Items/Sync.php

@@ -4,6 +4,7 @@
 
 use Base;
 use helpers\Authentication;
+use function helpers\json_response;
 use helpers\View;
 use helpers\ViewHelper;
 
@@ -115,7 +116,9 @@ public function sync(Base $f3) {
             }
         }
 
-        $this->view->jsonSuccess($sync);
+        $encoder = new \Violet\StreamingJsonEncoder\BufferJsonEncoder($sync);
+        $stream = new \Violet\StreamingJsonEncoder\JsonStream($encoder);
+        $this->view->sendResponse(json_response($stream));
     }
 
     /**

src/helpers/View.php

@@ -2,6 +2,10 @@
 
 namespace helpers;
 
+use function Http\Response\send;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
+
 /**
  * Helper class for rendering template
  *
@@ -120,4 +124,22 @@ public function jsonSuccess($data) {
         header('Content-type: application/json');
         die(json_encode($data));
     }
+
+    /**
+     * Send a PSR-7 response.
+     *
+     * @return void
+     */
+    public function sendResponse(ResponseInterface $response) {
+        send($response);
+        die;
+    }
+}
+
+function json_response(StreamInterface $stream) {
+    $response = new \GuzzleHttp\Psr7\Response();
+    $response = $response->withHeader('Content-type', 'application/json');
+    $response = $response->withBody($stream);
+
+    return $response;
 }