From 641b9edd89328b780c027c8dc60cafaa0d5b21c3 Mon Sep 17 00:00:00 2001
From: Kenneth Myhra <kennethmyhra@gmail.com>
Date: Fri, 7 Jul 2023 22:16:40 +0200
Subject: [PATCH] LibWeb: Add AO
 transform_stream_default_sink_close_algorithm()

---
 .../LibWeb/Streams/AbstractOperations.cpp     | 44 +++++++++++++++++++
 .../LibWeb/Streams/AbstractOperations.h       |  1 +
 2 files changed, 45 insertions(+)

diff --git a/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp b/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp
index 951c187218..b4e379d3ed 100644
--- a/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp
+++ b/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp
@@ -2857,6 +2857,50 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_
     return WebIDL::create_resolved_promise(realm, JS::js_undefined());
 }
 
+// https://streams.spec.whatwg.org/#transform-stream-default-sink-close-algorithm
+WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_sink_close_algorithm(TransformStream& stream)
+{
+    auto& realm = stream.realm();
+
+    // 1. Let readable be stream.[[readable]].
+    auto readable = stream.readable();
+
+    // 2. Let controller be stream.[[controller]].
+    auto controller = stream.controller();
+
+    // 3. Let flushPromise be the result of performing controller.[[flushAlgorithm]].
+    auto flush_promise = TRY((*controller->flush_algorithm())());
+
+    // 4. Perform ! TransformStreamDefaultControllerClearAlgorithms(controller).
+    transform_stream_default_controller_clear_algorithms(*controller);
+
+    // 5. Return the result of reacting to flushPromise:
+    auto react_result = WebIDL::react_to_promise(
+        *flush_promise,
+        // 1. If flushPromise was fulfilled, then:
+        [readable](auto const&) -> WebIDL::ExceptionOr<JS::Value> {
+            // 1. If readable.[[state]] is "errored", throw readable.[[storedError]].
+            if (readable->state() == ReadableStream::State::Errored)
+                return JS::throw_completion(readable->stored_error());
+
+            VERIFY(readable->controller().has_value() && readable->controller()->has<JS::NonnullGCPtr<ReadableStreamDefaultController>>());
+            // 2. Perform ! ReadableStreamDefaultControllerClose(readable.[[controller]]).
+            readable_stream_default_controller_close(readable->controller().value().get<JS::NonnullGCPtr<ReadableStreamDefaultController>>());
+
+            return JS::js_undefined();
+        },
+        // 2. If flushPromise was rejected with reason r, then:
+        [&stream, readable](auto const& reason) -> WebIDL::ExceptionOr<JS::Value> {
+            // 1. Perform ! TransformStreamError(stream, r).
+            TRY(transform_stream_error(stream, reason));
+
+            // 2. Throw readable.[[storedError]].
+            return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, TRY(readable->stored_error().as_string().utf8_string_view()) };
+        });
+
+    return WebIDL::create_resolved_promise(realm, react_result);
+}
+
 // https://streams.spec.whatwg.org/#transform-stream-default-sink-write-algorithm
 WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_sink_write_algorithm(TransformStream& stream, JS::Value chunk)
 {
diff --git a/Userland/Libraries/LibWeb/Streams/AbstractOperations.h b/Userland/Libraries/LibWeb/Streams/AbstractOperations.h
index 6590ea0f33..3484f4db86 100644
--- a/Userland/Libraries/LibWeb/Streams/AbstractOperations.h
+++ b/Userland/Libraries/LibWeb/Streams/AbstractOperations.h
@@ -139,6 +139,7 @@ WebIDL::ExceptionOr<void> transform_stream_default_controller_error(TransformStr
 WebIDL::ExceptionOr<void> transform_stream_default_controller_terminate(TransformStreamDefaultController&);
 WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_controller_perform_transform(TransformStreamDefaultController&, JS::Value chunk);
 WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_sink_abort_algorithm(TransformStream&, JS::Value reason);
+WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_sink_close_algorithm(TransformStream&);
 WebIDL::ExceptionOr<JS::NonnullGCPtr<WebIDL::Promise>> transform_stream_default_sink_write_algorithm(TransformStream&, JS::Value chunk);
 WebIDL::ExceptionOr<void> transform_stream_error(TransformStream&, JS::Value error);
 WebIDL::ExceptionOr<void> transform_stream_error_writable_and_unblock_write(TransformStream&, JS::Value error);