// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "third_party/blink/renderer/modules/webtransport/incoming_stream.h"

#include <string.h>

#include <utility>

#include "base/compiler_specific.h"
#include "third_party/blink/renderer/bindings/core/v8/script_function.h"
#include "third_party/blink/renderer/bindings/core/v8/v8_throw_dom_exception.h"
#include "third_party/blink/renderer/bindings/modules/v8/v8_web_transport_error.h"
#include "third_party/blink/renderer/core/execution_context/execution_context.h"
#include "third_party/blink/renderer/core/streams/readable_stream.h"
#include "third_party/blink/renderer/core/streams/readable_stream_byob_request.h"
#include "third_party/blink/renderer/core/streams/readable_stream_default_controller_with_script_scope.h"
#include "third_party/blink/renderer/core/streams/readable_stream_generic_reader.h"
#include "third_party/blink/renderer/core/streams/readable_stream_transferring_optimizer.h"
#include "third_party/blink/renderer/core/streams/underlying_byte_source_base.h"
#include "third_party/blink/renderer/core/typed_arrays/array_buffer/array_buffer_contents.h"
#include "third_party/blink/renderer/core/typed_arrays/dom_array_buffer.h"
#include "third_party/blink/renderer/core/typed_arrays/dom_array_piece.h"
#include "third_party/blink/renderer/core/typed_arrays/dom_typed_array.h"
#include "third_party/blink/renderer/modules/webtransport/web_transport_error.h"
#include "third_party/blink/renderer/platform/bindings/exception_code.h"
#include "third_party/blink/renderer/platform/bindings/exception_state.h"
#include "third_party/blink/renderer/platform/bindings/script_state.h"
#include "third_party/blink/renderer/platform/bindings/trace_wrapper_v8_reference.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/heap/persistent.h"
#include "third_party/blink/renderer/platform/wtf/functional.h"
#include "v8/include/v8.h"

namespace blink {

// An implementation of UnderlyingByteSourceBase that forwards all operations to
// the IncomingStream object that created it.
class IncomingStream::UnderlyingByteSource final
    : public UnderlyingByteSourceBase {
 public:
  explicit UnderlyingByteSource(ScriptState* script_state,
                                IncomingStream* stream)
      : script_state_(script_state), incoming_stream_(stream) {}

  ScriptPromise<IDLUndefined> Pull(ReadableByteStreamController* controller,
                                   ExceptionState& exception_state) override {
    DCHECK_EQ(controller, incoming_stream_->controller_);
    incoming_stream_->ReadFromPipeAndEnqueue(exception_state);
    return ToResolvedUndefinedPromise(script_state_.Get());
  }

  ScriptPromise<IDLUndefined> Cancel() override {
    return Cancel(v8::Undefined(script_state_->GetIsolate()));
  }

  ScriptPromise<IDLUndefined> Cancel(v8::Local<v8::Value> reason) override {
    uint8_t code = 0;
    WebTransportError* exception =
        V8WebTransportError::ToWrappable(script_state_->GetIsolate(), reason);
    if (exception) {
      code = exception->streamErrorCode().value_or(0);
    }
    incoming_stream_->AbortAndReset(code);
    return ToResolvedUndefinedPromise(script_state_.Get());
  }

  ScriptState* GetScriptState() override { return script_state_.Get(); }

  void Trace(Visitor* visitor) const override {
    visitor->Trace(script_state_);
    visitor->Trace(incoming_stream_);
    UnderlyingByteSourceBase::Trace(visitor);
  }

 private:
  const Member<ScriptState> script_state_;
  const Member<IncomingStream> incoming_stream_;
};

IncomingStream::IncomingStream(
    ScriptState* script_state,
    base::OnceCallback<void(std::optional<uint8_t>, bool)> on_abort,
    mojo::ScopedDataPipeConsumerHandle handle)
    : script_state_(script_state),
      on_abort_(std::move(on_abort)),
      data_pipe_(std::move(handle)),
      read_watcher_(FROM_HERE, mojo::SimpleWatcher::ArmingPolicy::MANUAL) {}

IncomingStream::~IncomingStream() = default;

void IncomingStream::Init(ExceptionState& exception_state) {
  DVLOG(1) << "IncomingStream::Init() this=" << this;
  auto* stream = MakeGarbageCollected<ReadableStream>(script_state_);
  InitWithExistingReadableStream(stream, exception_state);
}

void IncomingStream::InitWithExistingReadableStream(
    ReadableStream* stream,
    ExceptionState& exception_state) {
  read_watcher_.Watch(
      data_pipe_.get(),
      MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_PEER_CLOSED,
      MOJO_TRIGGER_CONDITION_SIGNALS_SATISFIED,
      BindRepeating(&IncomingStream::OnHandleReady, WrapWeakPersistent(this)));
  ReadableStream::InitByteStream(
      script_state_, stream,
      MakeGarbageCollected<UnderlyingByteSource>(script_state_, this),
      exception_state);
  if (exception_state.HadException()) {
    return;
  }

  readable_ = stream;
  controller_ = To<ReadableByteStreamController>(stream->GetController());
}

void IncomingStream::OnIncomingStreamClosed(bool fin_received) {
  DVLOG(1) << "IncomingStream::OnIncomingStreamClosed(" << fin_received
           << ") this=" << this;

  DCHECK_NE(state_, State::kClosed);
  state_ = State::kClosed;

  DCHECK(!fin_received_.has_value());

  fin_received_ = fin_received;

  // Wait until HandlePipeClosed() has also been called before processing the
  // close.
  if (is_pipe_closed_) {
    ProcessClose();
  } else {
    // Wait for MOJO_HANDLE_SIGNAL_PEER_CLOSED.
    read_watcher_.ArmOrNotify();
  }
}

void IncomingStream::Error(ScriptValue reason) {
  DVLOG(1) << "IncomingStream::Error() this=" << this;

  // We no longer need to call |on_abort_|.
  on_abort_.Reset();

  ErrorStreamAbortAndReset(reason);
}

void IncomingStream::ContextDestroyed() {
  DVLOG(1) << "IncomingStream::ContextDestroyed() this=" << this;

  ResetPipe();
}

void IncomingStream::Trace(Visitor* visitor) const {
  visitor->Trace(script_state_);
  visitor->Trace(readable_);
  visitor->Trace(controller_);
}

void IncomingStream::OnHandleReady(MojoResult result,
                                   const mojo::HandleSignalsState&) {
  DVLOG(1) << "IncomingStream::OnHandleReady() this=" << this
           << " result=" << result;
  // |ReadFromPipeAndEnqueue| throws if close has been requested, stream state
  // is not readable, or buffer is invalid. Because both
  // |ErrorStreamAbortAndReset| and |ProcessClose| reset pipe, stream should be
  // readable here. Buffer returned by |BeginReadData| is expected to be valid
  // with size > 0.
  NonThrowableExceptionState exception_state;
  ReadFromPipeAndEnqueue(exception_state);
}

void IncomingStream::HandlePipeClosed() {
  DVLOG(1) << "IncomingStream::HandlePipeClosed() this=" << this;

  DCHECK(!is_pipe_closed_);

  is_pipe_closed_ = true;

  // Reset the pipe immediately to prevent being called in a loop.
  ResetPipe();

  // Wait until OnIncomingStreamClosed() has also been called before processing
  // the close.
  if (fin_received_.has_value()) {
    ProcessClose();
  }
}

void IncomingStream::ProcessClose() {
  DVLOG(1) << "IncomingStream::ProcessClose() this=" << this;

  DCHECK(fin_received_.has_value());

  if (fin_received_.value()) {
    ScriptState::Scope scope(script_state_);
    // Ignore exception because stream will be errored soon.
    CloseAbortAndReset(IGNORE_EXCEPTION);
  }

  ScriptValue error;
  {
    ScriptState::Scope scope(script_state_);
    DOMExceptionCode code = DOMExceptionCode::kNetworkError;
    String message = "The stream was aborted by the remote server";

    error = ScriptValue(script_state_->GetIsolate(),
                        V8ThrowDOMException::CreateOrEmpty(
                            script_state_->GetIsolate(), code, message));
  }
  ErrorStreamAbortAndReset(error);
}

void IncomingStream::ReadFromPipeAndEnqueue(ExceptionState& exception_state) {
  DVLOG(1) << "IncomingStream::ReadFromPipeAndEnqueue() this=" << this
           << " in_two_phase_read_=" << in_two_phase_read_
           << " read_pending_=" << read_pending_;
  if (is_pipe_closed_) {
    return;
  }

  // Protect against re-entrancy.
  if (in_two_phase_read_) {
    read_pending_ = true;
    return;
  }
  DCHECK(!read_pending_);

  base::span<const uint8_t> buffer;
  auto result =
      data_pipe_->BeginReadData(MOJO_BEGIN_READ_DATA_FLAG_NONE, buffer);
  switch (result) {
    case MOJO_RESULT_OK: {
      in_two_phase_read_ = true;

      // RespondBYOBRequestOrEnqueueBytes() may re-enter this method via pull().
      size_t read_bytes =
          RespondBYOBRequestOrEnqueueBytes(buffer, exception_state);
      if (exception_state.HadException()) {
        return;
      }
      // Casting back to `uint32_t` is safe because `read_bytes` cannot be
      // greater than `buffer_num_bytes`.
      data_pipe_->EndReadData(read_bytes);
      in_two_phase_read_ = false;
      if (read_pending_) {
        read_pending_ = false;
        // pull() will not be called when another pull() is in progress, so the
        // maximum recursion depth is 1.
        ReadFromPipeAndEnqueue(exception_state);
        if (exception_state.HadException()) {
          return;
        }
      }
      break;
    }

    case MOJO_RESULT_SHOULD_WAIT:
      read_watcher_.ArmOrNotify();
      return;

    case MOJO_RESULT_FAILED_PRECONDITION:
      HandlePipeClosed();
      return;

    default:
      NOTREACHED() << "Unexpected result: " << result;
  }
}

size_t IncomingStream::RespondBYOBRequestOrEnqueueBytes(
    base::span<const uint8_t> source,
    ExceptionState& exception_state) {
  DVLOG(1) << "IncomingStream::RespondBYOBRequestOrEnqueueBytes() this="
           << this;

  ScriptState::Scope scope(script_state_);

  if (ReadableStreamBYOBRequest* request = controller_->byobRequest()) {
    DOMArrayPiece view(request->view().Get());
    size_t byob_response_length = std::min(view.ByteLength(), source.size());
    view.ByteSpan().copy_prefix_from(source.first(byob_response_length));
    request->respond(script_state_, byob_response_length, exception_state);
    return byob_response_length;
  }

  auto* buffer = DOMUint8Array::Create(source);
  controller_->enqueue(script_state_, NotShared(buffer), exception_state);
  return source.size();
}

void IncomingStream::CloseAbortAndReset(ExceptionState& exception_state) {
  DVLOG(1) << "IncomingStream::CloseAbortAndReset() this=" << this;

  if (controller_) {
    ScriptState::Scope scope(script_state_);
    readable_->CloseStream(script_state_, exception_state);
    if (!exception_state.HadException()) {
      controller_ = nullptr;
    }
  }

  AbortAndReset(std::nullopt);
}

void IncomingStream::ErrorStreamAbortAndReset(ScriptValue exception) {
  DVLOG(1) << "IncomingStream::ErrorStreamAbortAndReset() this=" << this;

  if (controller_) {
    controller_->error(script_state_, exception);
    controller_ = nullptr;
  }

  AbortAndReset(std::nullopt);
}

void IncomingStream::AbortAndReset(std::optional<uint8_t> code) {
  DVLOG(1) << "IncomingStream::AbortAndReset() this=" << this;

  state_ = State::kAborted;

  if (on_abort_) {
    // Cause WebTransport to drop its reference to us.
    // Pass whether OnIncomingStreamClosed() was called (fin_received_ is set).
    std::move(on_abort_).Run(code, fin_received_.has_value());
  }

  ResetPipe();
}

void IncomingStream::ResetPipe() {
  DVLOG(1) << "IncomingStream::ResetPipe() this=" << this;

  read_watcher_.Cancel();
  data_pipe_.reset();
}

void IncomingStream::Dispose() {
  DVLOG(1) << "IncomingStream::Dispose() this=" << this;

  ResetPipe();
}

}  // namespace blink