Adding HttpCodeDecider to core GraphQLite

src/Http/HttpCodeDecider.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TheCodingMachine\GraphQLite\Http;
+
+use GraphQL\Executor\ExecutionResult;
+use function max;
+
+class HttpCodeDecider implements HttpCodeDeciderInterface
+{
+    /**
+     * Decides the HTTP status code based on the answer.
+     *
+     * @see https://github.com/APIs-guru/graphql-over-http#status-codes
+     */
+    public function decideHttpStatusCode(ExecutionResult $result): int
+    {
+        // If the data entry in the response has any value other than null (when the operation has successfully executed without error) then the response should use the 200 (OK) status code.
+        if ($result->data !== null && empty($result->errors)) {
+            return 200;
+        }
+
+        $status = 0;
+        // There might be many errors. Let's return the highest code we encounter.
+        foreach ($result->errors as $error) {
+            $wrappedException = $error->getPrevious();
+            if ($wrappedException !== null) {
+                $code = $wrappedException->getCode();
+                if ($code < 400 || $code >= 600) {
+                    // The exception code is not a valid HTTP code. Let's ignore it
+                    continue;
+                }
+            } else {
+                $code = 400;
+            }
+            $status = max($status, $code);
+        }
+
+        // If exceptions have been thrown and they have not a "HTTP like code", let's throw a 500.
+        if ($status < 200) {
+            $status = 500;
+        }
+
+        return $status;
+    }
+}

src/Http/HttpCodeDeciderInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TheCodingMachine\GraphQLite\Http;
+
+use GraphQL\Executor\ExecutionResult;
+
+interface HttpCodeDeciderInterface
+{
+    /**
+     * Decides the HTTP status code based on the answer.
+     *
+     * @see https://github.com/APIs-guru/graphql-over-http#status-codes
+     */
+    public function decideHttpStatusCode(ExecutionResult $result): int;
+}

tests/Http/HttpCodeDeciderTest.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace TheCodingMachine\GraphQLite\Http;
+
+use Exception;
+use GraphQL\Error\Error;
+use GraphQL\Executor\ExecutionResult;
+use PHPUnit\Framework\TestCase;
+
+class HttpCodeDeciderTest extends TestCase
+{
+
+    public function testDecideHttpStatusCode(): void
+    {
+        $codeDecider = new HttpCodeDecider();
+
+        $executionResult = new ExecutionResult(['someData'], []);
+
+        $this->assertSame(200, $codeDecider->decideHttpStatusCode($executionResult));
+
+        $graphqlError = new Error('Foo');
+
+        $exception = new Exception('foo', 0);
+        $errorCode0 = new Error('Foo', null, null, null, null, $exception);
+
+        $exception401 = new Exception('foo', 401);
+        $errorCode401 = new Error('Foo', null, null, null, null, $exception401);
+
+        $exception404 = new Exception('foo', 404);
+        $errorCode404 = new Error('Foo', null, null, null, null, $exception404);
+
+        $exception600 = new Exception('foo', 600);
+        $errorCode600 = new Error('Foo', null, null, null, null, $exception600);
+
+        $executionResult = new ExecutionResult(null, [ $errorCode0 ]);
+        $this->assertSame(500, $codeDecider->decideHttpStatusCode($executionResult));
+
+        $executionResult = new ExecutionResult(['foo'], [ $errorCode401, $errorCode404, $errorCode600 ]);
+        $this->assertSame(404, $codeDecider->decideHttpStatusCode($executionResult));
+
+        $executionResult = new ExecutionResult(null, [ $graphqlError ]);
+        $this->assertSame(400, $codeDecider->decideHttpStatusCode($executionResult));
+    }
+}