// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "extensions/browser/api/sockets_udp/udp_socket_event_dispatcher.h"

#include <memory>
#include <utility>

#include "base/containers/to_vector.h"
#include "base/functional/bind.h"
#include "base/lazy_instance.h"
#include "base/task/single_thread_task_runner.h"
#include "content/public/browser/browser_thread.h"
#include "extensions/browser/api/socket/udp_socket.h"
#include "extensions/browser/event_router.h"
#include "extensions/browser/extensions_browser_client.h"
#include "extensions/common/extension_id.h"
#include "net/base/net_errors.h"

namespace extensions {
namespace api {

using content::BrowserThread;

static base::LazyInstance<
    BrowserContextKeyedAPIFactory<UDPSocketEventDispatcher>>::DestructorAtExit
    g_factory = LAZY_INSTANCE_INITIALIZER;

// static
BrowserContextKeyedAPIFactory<UDPSocketEventDispatcher>*
UDPSocketEventDispatcher::GetFactoryInstance() {
  return g_factory.Pointer();
}

// static
UDPSocketEventDispatcher* UDPSocketEventDispatcher::Get(
    content::BrowserContext* context) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  return BrowserContextKeyedAPIFactory<UDPSocketEventDispatcher>::Get(context);
}

UDPSocketEventDispatcher::UDPSocketEventDispatcher(
    content::BrowserContext* context)
    : thread_id_(Socket::kThreadId), browser_context_(context) {
  ApiResourceManager<ResumableUDPSocket>* manager =
      ApiResourceManager<ResumableUDPSocket>::Get(browser_context_);
  DCHECK(manager)
      << "There is no socket manager. "
         "If this assertion is failing during a test, then it is likely that "
         "TestExtensionSystem is failing to provide an instance of "
         "ApiResourceManager<ResumableUDPSocket>.";
  sockets_ = manager->data_;
}

UDPSocketEventDispatcher::~UDPSocketEventDispatcher() = default;

UDPSocketEventDispatcher::ReceiveParams::ReceiveParams() = default;

UDPSocketEventDispatcher::ReceiveParams::ReceiveParams(
    const ReceiveParams& other) = default;

UDPSocketEventDispatcher::ReceiveParams::~ReceiveParams() = default;

void UDPSocketEventDispatcher::OnSocketBind(const ExtensionId& extension_id,
                                            int socket_id) {
  OnSocketResume(extension_id, socket_id);
}

void UDPSocketEventDispatcher::OnSocketResume(const ExtensionId& extension_id,
                                              int socket_id) {
  DCHECK_CURRENTLY_ON(thread_id_);

  ReceiveParams params;
  params.thread_id = thread_id_;
  params.browser_context_id = browser_context_;
  params.extension_id = extension_id;
  params.sockets = sockets_;
  params.socket_id = socket_id;

  StartReceive(params);
}

/* static */
void UDPSocketEventDispatcher::StartReceive(const ReceiveParams& params) {
  DCHECK_CURRENTLY_ON(params.thread_id);

  ResumableUDPSocket* socket =
      params.sockets->Get(params.extension_id, params.socket_id);
  if (socket == nullptr) {
    // This can happen if the socket is closed while our callback is active.
    return;
  }
  DCHECK(params.extension_id == socket->owner_extension_id())
      << "Socket has wrong owner.";

  // Don't start another read if the socket has been paused.
  if (socket->paused()) {
    return;
  }

  int buffer_size = socket->buffer_size() <= 0 ? 4096 : socket->buffer_size();
  socket->RecvFrom(
      buffer_size,
      base::BindOnce(&UDPSocketEventDispatcher::ReceiveCallback, params));
}

/* static */
void UDPSocketEventDispatcher::ReceiveCallback(
    const ReceiveParams& params,
    int bytes_read,
    scoped_refptr<net::IOBuffer> io_buffer,
    bool socket_destroying,
    const std::string& address,
    uint16_t port) {
  DCHECK_CURRENTLY_ON(params.thread_id);

  // If |bytes_read| == 0, the message contained no data.
  // If |bytes_read| < 0, there was a network error, and |bytes_read| is a value
  // from "net::ERR_".

  if (bytes_read >= 0) {
    // Dispatch "onReceive" event.
    sockets_udp::ReceiveInfo receive_info;
    receive_info.socket_id = params.socket_id;
    receive_info.data =
        base::ToVector(io_buffer->first(static_cast<size_t>(bytes_read)));
    receive_info.remote_address = address;
    receive_info.remote_port = port;
    auto args = sockets_udp::OnReceive::Create(receive_info);
    auto event = std::make_unique<Event>(events::SOCKETS_UDP_ON_RECEIVE,
                                         sockets_udp::OnReceive::kEventName,
                                         std::move(args));
    PostEvent(params, std::move(event));

    // Post a task to delay the read until the socket is available, as
    // calling StartReceive at this point would error with ERR_IO_PENDING.
    base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
        FROM_HERE,
        base::BindOnce(&UDPSocketEventDispatcher::StartReceive, params));
  } else if (bytes_read == net::ERR_IO_PENDING) {
    // This happens when resuming a socket which already had an
    // active "recv" callback.
  } else if (bytes_read == net::ERR_CONNECTION_CLOSED) {
    // This happens when the socket closes, which is expected since we
    // continually add a receive listener in the success block above.
  } else {
    // Dispatch "onReceiveError" event but don't start another read to avoid
    // potential infinite reads if we have a persistent network error.
    sockets_udp::ReceiveErrorInfo receive_error_info;
    receive_error_info.socket_id = params.socket_id;
    receive_error_info.result_code = bytes_read;
    auto args = sockets_udp::OnReceiveError::Create(receive_error_info);
    std::unique_ptr<Event> event(
        new Event(events::SOCKETS_UDP_ON_RECEIVE_ERROR,
                  sockets_udp::OnReceiveError::kEventName, std::move(args)));
    PostEvent(params, std::move(event));

    // Do not try to access |socket| when we are destroying it.
    if (!socket_destroying) {
      // Since we got an error, the socket is now "paused" until the application
      // "resumes" it.
      ResumableUDPSocket* socket =
          params.sockets->Get(params.extension_id, params.socket_id);
      if (socket) {
        socket->set_paused(true);
      }
    }
  }
}

/* static */
void UDPSocketEventDispatcher::PostEvent(const ReceiveParams& params,
                                         std::unique_ptr<Event> event) {
  DCHECK_CURRENTLY_ON(params.thread_id);

  content::GetUIThreadTaskRunner({})->PostTask(
      FROM_HERE, base::BindOnce(&DispatchEvent, params.browser_context_id,
                                params.extension_id, std::move(event)));
}

/*static*/
void UDPSocketEventDispatcher::DispatchEvent(void* browser_context_id,
                                             const ExtensionId& extension_id,
                                             std::unique_ptr<Event> event) {
  DCHECK_CURRENTLY_ON(BrowserThread::UI);

  if (!ExtensionsBrowserClient::Get()->IsValidContext(browser_context_id)) {
    return;
  }

  content::BrowserContext* context =
      reinterpret_cast<content::BrowserContext*>(browser_context_id);
  EventRouter* router = EventRouter::Get(context);
  if (router) {
#if BUILDFLAG(IS_CHROMEOS)
    // Terminal app is the only non-extension to use sockets
    // (crbug.com/1350479).
    if (extension_id == kCrOSTerminal) {
      router->DispatchEventToURL(GURL(extension_id), std::move(event));
      return;
    }
#endif
    router->DispatchEventToExtension(extension_id, std::move(event));
  }
}

}  // namespace api
}  // namespace extensions