// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "remoting/host/ipc_desktop_environment.h"

#include <algorithm>
#include <cstdint>
#include <memory>
#include <string>
#include <string_view>
#include <utility>

#include "base/check.h"
#include "base/functional/bind.h"
#include "base/functional/callback.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/single_thread_task_runner.h"
#include "build/build_config.h"
#include "mojo/public/cpp/bindings/associated_remote.h"
#include "mojo/public/cpp/bindings/pending_associated_receiver.h"
#include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
#include "mojo/public/cpp/system/message_pipe.h"
#include "remoting/base/errors.h"
#include "remoting/base/fifo_buffer.h"
#include "remoting/base/ipc_fifo_buffer.h"
#include "remoting/base/logging.h"
#include "remoting/host/action_executor.h"
#include "remoting/host/active_display_monitor.h"
#include "remoting/host/audio_capturer.h"
#include "remoting/host/base/desktop_environment_options.h"
#include "remoting/host/base/screen_controls.h"
#include "remoting/host/client_session_control.h"
#include "remoting/host/desktop_display_info_monitor.h"
#include "remoting/host/desktop_environment.h"
#include "remoting/host/desktop_session.h"
#include "remoting/host/desktop_session_proxy.h"
#include "remoting/host/file_transfer/file_operations.h"
#include "remoting/host/input_injector.h"
#include "remoting/host/ipc_audio_injector.h"
#include "remoting/host/ipc_keyboard_layout_monitor.h"
#include "remoting/host/keyboard_layout_monitor.h"
#include "remoting/host/mojom/desktop_session.mojom.h"
#include "remoting/host/mojom/remoting_host.mojom.h"
#include "remoting/host/remote_open_url/url_forwarder_configurator.h"
#include "remoting/protocol/mouse_cursor_monitor.h"
#include "remoting/signaling/signaling_id_util.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capture_types.h"

namespace remoting {

IpcDesktopEnvironment::IpcDesktopEnvironment(
    scoped_refptr<base::SingleThreadTaskRunner> network_task_runner,
    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
    base::WeakPtr<ClientSessionControl> client_session_control,
    base::WeakPtr<ClientSessionEvents> client_session_events,
    base::WeakPtr<DesktopSessionConnector> desktop_session_connector,
    const DesktopEnvironmentOptions& options)
    : desktop_session_proxy_(
          base::MakeRefCounted<DesktopSessionProxy>(io_task_runner,
                                                    client_session_control,
                                                    client_session_events,
                                                    desktop_session_connector,
                                                    options)) {
  DCHECK(network_task_runner->BelongsToCurrentThread());
}

IpcDesktopEnvironment::~IpcDesktopEnvironment() = default;

std::unique_ptr<ActionExecutor> IpcDesktopEnvironment::CreateActionExecutor() {
  return desktop_session_proxy_->CreateActionExecutor();
}

std::unique_ptr<AudioCapturer> IpcDesktopEnvironment::CreateAudioCapturer() {
  return desktop_session_proxy_->CreateAudioCapturer();
}

std::unique_ptr<InputInjector> IpcDesktopEnvironment::CreateInputInjector() {
  return desktop_session_proxy_->CreateInputInjector();
}

std::unique_ptr<ScreenControls> IpcDesktopEnvironment::CreateScreenControls() {
  return desktop_session_proxy_->CreateScreenControls();
}

DesktopDisplayInfoMonitor* IpcDesktopEnvironment::GetDisplayInfoMonitor() {
  // Not used in the Network process.
  return nullptr;
}

std::unique_ptr<protocol::MouseCursorMonitor>
IpcDesktopEnvironment::CreateMouseCursorMonitor() {
  return desktop_session_proxy_->CreateMouseCursorMonitor();
}

std::unique_ptr<KeyboardLayoutMonitor>
IpcDesktopEnvironment::CreateKeyboardLayoutMonitor(
    base::RepeatingCallback<void(const protocol::KeyboardLayout&)> callback) {
  return desktop_session_proxy_->CreateKeyboardLayoutMonitor(
      std::move(callback));
}

std::unique_ptr<ActiveDisplayMonitor>
IpcDesktopEnvironment::CreateActiveDisplayMonitor(
    ActiveDisplayMonitor::Callback callback) {
  return nullptr;
}

std::unique_ptr<DesktopCapturer> IpcDesktopEnvironment::CreateVideoCapturer(
    webrtc::ScreenId id) {
  return desktop_session_proxy_->CreateVideoCapturer(id);
}

std::unique_ptr<FileOperations> IpcDesktopEnvironment::CreateFileOperations() {
  return desktop_session_proxy_->CreateFileOperations();
}

std::unique_ptr<UrlForwarderConfigurator>
IpcDesktopEnvironment::CreateUrlForwarderConfigurator() {
  return desktop_session_proxy_->CreateUrlForwarderConfigurator();
}

std::string IpcDesktopEnvironment::GetCapabilities() const {
  return desktop_session_proxy_->GetCapabilities();
}

void IpcDesktopEnvironment::SetCapabilities(const std::string& capabilities) {
  return desktop_session_proxy_->SetCapabilities(capabilities);
}

std::unique_ptr<RemoteWebAuthnStateChangeNotifier>
IpcDesktopEnvironment::CreateRemoteWebAuthnStateChangeNotifier() {
  return desktop_session_proxy_->CreateRemoteWebAuthnStateChangeNotifier();
}

std::unique_ptr<AudioInjector> IpcDesktopEnvironment::CreateAudioInjector(
    std::unique_ptr<IpcFifoBufferReader> reader) {
  return std::make_unique<IpcAudioInjector>(desktop_session_proxy_,
                                            std::move(reader));
}

IpcDesktopEnvironmentFactory::DesktopConnection::DesktopConnection(
    DesktopSessionProxy* desktop_session_proxy,
    std::string_view client_id)
    : desktop_session_proxy(desktop_session_proxy), client_id(client_id) {}

IpcDesktopEnvironmentFactory::DesktopConnection::~DesktopConnection() = default;

IpcDesktopEnvironmentFactory::DesktopConnection::DesktopConnection(
    DesktopConnection&&) = default;

IpcDesktopEnvironmentFactory::DesktopConnection&
IpcDesktopEnvironmentFactory::DesktopConnection::operator=(
    DesktopConnection&&) = default;

class IpcDesktopEnvironmentFactory::Core : public mojom::DesktopSessionEvents {
 public:
  explicit Core(GetDesktopSessionCallback get_desktop_session_callback);
  Core(const Core&) = delete;
  Core& operator=(const Core&) = delete;
  ~Core() override;

  void ConnectTerminal(DesktopSessionProxy* desktop_session_proxy,
                       const ScreenResolution& resolution,
                       bool is_curtained);
  void DisconnectTerminal(DesktopSessionProxy* desktop_session_proxy);
  void SetScreenResolution(DesktopSessionProxy* desktop_session_proxy,
                           const ScreenResolution& resolution);
  void SetRequiredUsername(std::string_view username);

  void OnDesktopSessionAgentAttached(
      int terminal_id,
      mojo::ScopedMessagePipeHandle desktop_pipe);
  void OnTerminalDisconnected(int terminal_id,
                              ErrorCode error_code,
                              const std::string& error_details,
                              const SourceLocation& error_location);
#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX)
  void OnSessionServicesClientConnected(
      int terminal_id,
      mojo::PendingReceiver<mojom::ChromotingSessionServices> receiver);
#endif

  // mojom::DesktopSessionEvents implementation.
  void OnDesktopSessionAgentAttached(
      mojo::ScopedMessagePipeHandle desktop_pipe) override;
  void OnTerminalDisconnected(ErrorCode error_code,
                              const std::string& error_details,
                              const SourceLocation& error_location) override;
#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX)
  void OnSessionServicesClientConnected(
      mojo::PendingReceiver<mojom::ChromotingSessionServices> receiver)
      override;
#endif

  void set_persist_desktop_sessions_for_testing(bool persistent) {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    persist_desktop_sessions_ = persistent;
  }
  size_t active_desktop_sessions_count_for_testing() const {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    return connections_.size();
  }
  const DesktopConnection* GetConnectionForTesting(int terminal_id) const {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    auto it = connections_.find(terminal_id);
    return it != connections_.end() ? it->second.get() : nullptr;
  }

 private:
  // List of DesktopEnvironment instances we've told the daemon process about.
  using ConnectionsList =
      absl::flat_hash_map<int, std::unique_ptr<DesktopConnection>>;
  ConnectionsList::iterator FindConnection(const DesktopSessionProxy* proxy);
  mojo::ReceiverSet<mojom::DesktopSessionEvents, int>& GetEventsReceivers();
  void OnDesktopSessionRemoteDisconnected(int terminal_id);

  // If `persist_desktop_sessions_` is true, instead of closing the desktop
  // session when the client disconnects, the session will remain active while
  // the pipe to the desktop process is disconnected. When the client with
  // the same email address reconnects, the desktop session will be reused and
  // the desktop process will be requested to send a new desktop pipe.
  // TODO: yuweih - see if it makes sense to enable it on Windows.
#if BUILDFLAG(IS_LINUX)
  bool persist_desktop_sessions_ = true;
#else
  bool persist_desktop_sessions_ = false;
#endif

  ConnectionsList connections_;

  // Next desktop session ID. IDs are allocated sequentially starting from 0.
  // This gives us more than 67 years of unique IDs assuming a new ID is
  // allocated every second.
  int next_id_ = 0;

  // See DesktopSessionConnector::SetRequiredUsername().
  std::string required_username_;
  GetDesktopSessionCallback get_desktop_session_callback_;
  std::unique_ptr<mojo::ReceiverSet<mojom::DesktopSessionEvents, int>>
      desktop_session_events_receivers_;

  SEQUENCE_CHECKER(sequence_checker_);
};

IpcDesktopEnvironmentFactory::Core::Core(
    GetDesktopSessionCallback get_desktop_session_callback)
    : get_desktop_session_callback_(std::move(get_desktop_session_callback)) {
  DETACH_FROM_SEQUENCE(sequence_checker_);
}

IpcDesktopEnvironmentFactory::Core::~Core() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}

mojo::ReceiverSet<mojom::DesktopSessionEvents, int>&
IpcDesktopEnvironmentFactory::Core::GetEventsReceivers() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  if (!desktop_session_events_receivers_) {
    desktop_session_events_receivers_ =
        std::make_unique<mojo::ReceiverSet<mojom::DesktopSessionEvents, int>>();
  }
  return *desktop_session_events_receivers_;
}

void IpcDesktopEnvironmentFactory::Core::ConnectTerminal(
    DesktopSessionProxy* desktop_session_proxy,
    const ScreenResolution& resolution,
    bool is_curtained) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(desktop_session_proxy);

  std::string_view client_jid = desktop_session_proxy->client_jid();
  if (client_jid.empty()) {
    LOG(ERROR) << "Cannot connect terminal. Client JID is empty.";
    return;
  }
  std::string client_id;
  SplitSignalingIdResource(client_jid, &client_id, /*resource=*/nullptr);

  mojom::DesktopSessionOptionsPtr options = mojom::DesktopSessionOptions::New();
  options->screen_resolution = resolution;
  options->is_curtained = is_curtained;
  options->required_username = required_username_;
  options->client_id = client_id;

  if (persist_desktop_sessions_) {
    auto it =
        std::ranges::find_if(connections_, [&client_id](const auto& pair) {
          return pair.second->client_id == client_id &&
                 // Find an unused session.
                 !pair.second->desktop_session_proxy;
        });
    if (it != connections_.end()) {
      int id = it->first;
      VLOG(1) << "Network: reconnecting desktop session " << id;
      it->second->desktop_session_proxy = desktop_session_proxy;
      if (it->second->pending_desktop_pipe.is_valid()) {
        VLOG(1) << "Network: using buffered desktop pipe for session " << id;
        desktop_session_proxy->AttachToDesktop(
            std::move(it->second->pending_desktop_pipe));
      } else {
        it->second->desktop_session.reset();
        mojo::PendingRemote<mojom::DesktopSessionEvents> events_remote;
        GetEventsReceivers().Add(
            this, events_remote.InitWithNewPipeAndPassReceiver(), id);
        if (get_desktop_session_callback_) {
          get_desktop_session_callback_.Run(
              it->second->desktop_session.BindNewPipeAndPassReceiver(),
              std::move(events_remote), std::move(options));
        }
        if (it->second->desktop_session.is_bound()) {
          it->second->desktop_session.set_disconnect_handler(
              base::BindOnce(&Core::OnDesktopSessionRemoteDisconnected,
                             base::Unretained(this), id));
        }
      }
      return;
    }
  }

  int id = next_id_++;
  auto connection =
      std::make_unique<DesktopConnection>(desktop_session_proxy, client_id);
  auto [it, inserted] = connections_.emplace(id, std::move(connection));
  CHECK(inserted);

  VLOG(1) << "Network: registered desktop session " << id;

  mojo::PendingRemote<mojom::DesktopSessionEvents> events_remote;
  GetEventsReceivers().Add(this, events_remote.InitWithNewPipeAndPassReceiver(),
                           id);
  if (get_desktop_session_callback_) {
    get_desktop_session_callback_.Run(
        it->second->desktop_session.BindNewPipeAndPassReceiver(),
        std::move(events_remote), std::move(options));
  }
  if (it->second->desktop_session.is_bound()) {
    it->second->desktop_session.set_disconnect_handler(base::BindOnce(
        &Core::OnDesktopSessionRemoteDisconnected, base::Unretained(this), id));
  }
}

void IpcDesktopEnvironmentFactory::Core::DisconnectTerminal(
    DesktopSessionProxy* desktop_session_proxy) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  auto it = FindConnection(desktop_session_proxy);
  if (it == connections_.end()) {
    return;
  }

  if (persist_desktop_sessions_) {
    it->second->desktop_session_proxy = nullptr;
    return;
  }

  int id = it->first;
  if (it->second->desktop_session.is_bound()) {
    it->second->desktop_session->CloseDesktopSession();
  }
  connections_.erase(it);

  VLOG(1) << "Network: unregistered desktop session " << id;
}

void IpcDesktopEnvironmentFactory::Core::SetScreenResolution(
    DesktopSessionProxy* desktop_session_proxy,
    const ScreenResolution& resolution) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  auto it = FindConnection(desktop_session_proxy);
  if (it != connections_.end() && it->second->desktop_session.is_bound()) {
    it->second->desktop_session->SetScreenResolution(resolution);
  }
}

void IpcDesktopEnvironmentFactory::Core::SetRequiredUsername(
    std::string_view username) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  if (required_username_ == username) {
    return;
  }

  // TODO: yuweih - see if we should just terminate sessions with a mismatched
  // username.
  CHECK(connections_.empty())
      << "Cannot change required username when there are active connections.";

  required_username_ = std::string(username);
}

void IpcDesktopEnvironmentFactory::Core::OnDesktopSessionAgentAttached(
    mojo::ScopedMessagePipeHandle desktop_pipe) {
  OnDesktopSessionAgentAttached(GetEventsReceivers().current_context(),
                                std::move(desktop_pipe));
}

void IpcDesktopEnvironmentFactory::Core::OnTerminalDisconnected(
    ErrorCode error_code,
    const std::string& error_details,
    const SourceLocation& error_location) {
  OnTerminalDisconnected(GetEventsReceivers().current_context(), error_code,
                         error_details, error_location);
}

#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX)
void IpcDesktopEnvironmentFactory::Core::OnSessionServicesClientConnected(
    mojo::PendingReceiver<mojom::ChromotingSessionServices> receiver) {
  OnSessionServicesClientConnected(GetEventsReceivers().current_context(),
                                   std::move(receiver));
}
#endif

void IpcDesktopEnvironmentFactory::Core::OnDesktopSessionAgentAttached(
    int terminal_id,
    mojo::ScopedMessagePipeHandle desktop_pipe) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  VLOG(1)
      << "IpcDesktopEnvironmentFactory::Core::OnDesktopSessionAgentAttached() "
      << "terminal_id=" << terminal_id;

  auto it = connections_.find(terminal_id);
  if (it != connections_.end()) {
    DesktopSessionProxy* proxy = it->second->desktop_session_proxy;
    if (!proxy) {
      VLOG(1) << "Network: buffering desktop pipe for session " << terminal_id;
      it->second->pending_desktop_pipe = std::move(desktop_pipe);
      return;
    }
    proxy->DetachFromDesktop();
    proxy->AttachToDesktop(std::move(desktop_pipe));
  }
}

void IpcDesktopEnvironmentFactory::Core::OnTerminalDisconnected(
    int terminal_id,
    ErrorCode error_code,
    const std::string& error_details,
    const SourceLocation& error_location) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  auto it = connections_.find(terminal_id);
  if (it != connections_.end()) {
    DesktopSessionProxy* desktop_session_proxy =
        it->second->desktop_session_proxy;
    connections_.erase(it);

    if (desktop_session_proxy) {
      // Disconnect the client session.
      std::string details =
          error_details.empty() ? "Terminal disconnected." : error_details;
      desktop_session_proxy->DisconnectSession(error_code, details,
                                               error_location);
    }
  }
}

#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX)
void IpcDesktopEnvironmentFactory::Core::OnSessionServicesClientConnected(
    int terminal_id,
    mojo::PendingReceiver<mojom::ChromotingSessionServices> receiver) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  auto it = connections_.find(terminal_id);
  if (it != connections_.end()) {
    DesktopSessionProxy* proxy = it->second->desktop_session_proxy;
    if (proxy) {
      proxy->OnSessionServicesClientConnected(std::move(receiver));
    } else {
      LOG(WARNING) << "ChromotingSessionServices bind request rejected: "
                   << "Terminal is not connected to any client.";
    }
  } else {
    LOG(WARNING) << "ChromotingSessionServices bind request rejected: "
                 << "Invalid terminal ID " << terminal_id;
  }
}
#endif

void IpcDesktopEnvironmentFactory::Core::OnDesktopSessionRemoteDisconnected(
    int terminal_id) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  auto it = connections_.find(terminal_id);
  if (it == connections_.end()) {
    return;
  }

  LOG(WARNING) << "DesktopSession control remote disconnected for terminal "
               << terminal_id;

  if (persist_desktop_sessions_) {
    it->second->desktop_session.reset();
  } else {
    DesktopSessionProxy* proxy = it->second->desktop_session_proxy;
    connections_.erase(it);
    if (proxy) {
      proxy->DisconnectSession(ErrorCode::CHANNEL_CONNECTION_ERROR,
                               "DesktopSession control remote disconnected.",
                               FROM_HERE);
    }
  }
}

IpcDesktopEnvironmentFactory::Core::ConnectionsList::iterator
IpcDesktopEnvironmentFactory::Core::FindConnection(
    const DesktopSessionProxy* proxy) {
  return std::ranges::find_if(connections_, [proxy](const auto& pair) {
    return pair.second->desktop_session_proxy == proxy;
  });
}

IpcDesktopEnvironmentFactory::IpcDesktopEnvironmentFactory(
    scoped_refptr<base::SingleThreadTaskRunner> network_task_runner,
    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
    GetDesktopSessionCallback get_desktop_session_callback)
    : network_task_runner_(network_task_runner),
      io_task_runner_(io_task_runner),
      core_(new Core(std::move(get_desktop_session_callback)),
            base::OnTaskRunnerDeleter(network_task_runner)) {}

IpcDesktopEnvironmentFactory::~IpcDesktopEnvironmentFactory() = default;

void IpcDesktopEnvironmentFactory::Create(
    base::WeakPtr<ClientSessionControl> client_session_control,
    base::WeakPtr<ClientSessionEvents> client_session_events,
    const DesktopEnvironmentOptions& options,
    CreateCallback callback) {
  DCHECK(network_task_runner_->BelongsToCurrentThread());

  base::SequencedTaskRunner::GetCurrentDefault()->PostTask(
      FROM_HERE,
      base::BindOnce(std::move(callback),
                     std::make_unique<IpcDesktopEnvironment>(
                         network_task_runner_, io_task_runner_,
                         client_session_control, client_session_events,
                         connector_factory_.GetWeakPtr(), options)));
}

bool IpcDesktopEnvironmentFactory::SupportsAudioCapture() const {
  DCHECK(network_task_runner_->BelongsToCurrentThread());

  return AudioCapturer::IsSupported();
}

void IpcDesktopEnvironmentFactory::ConnectTerminal(
    DesktopSessionProxy* desktop_session_proxy,
    const ScreenResolution& resolution,
    bool is_curtained) {
  core_->ConnectTerminal(desktop_session_proxy, resolution, is_curtained);
}

void IpcDesktopEnvironmentFactory::DisconnectTerminal(
    DesktopSessionProxy* desktop_session_proxy) {
  core_->DisconnectTerminal(desktop_session_proxy);
}

void IpcDesktopEnvironmentFactory::SetScreenResolution(
    DesktopSessionProxy* desktop_session_proxy,
    const ScreenResolution& resolution) {
  core_->SetScreenResolution(desktop_session_proxy, resolution);
}

void IpcDesktopEnvironmentFactory::SetRequiredUsername(
    std::string_view username) {
  core_->SetRequiredUsername(username);
}

void IpcDesktopEnvironmentFactory::OnDesktopSessionAgentAttachedForTesting(
    int terminal_id,
    mojo::ScopedMessagePipeHandle desktop_pipe) {
  core_->OnDesktopSessionAgentAttached(terminal_id, std::move(desktop_pipe));
}

void IpcDesktopEnvironmentFactory::OnTerminalDisconnectedForTesting(
    int terminal_id,
    ErrorCode error_code,
    const std::string& error_details,
    const SourceLocation& error_location) {
  core_->OnTerminalDisconnected(terminal_id, error_code, error_details,
                                error_location);
}

#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX)
void IpcDesktopEnvironmentFactory::OnSessionServicesClientConnectedForTesting(
    int terminal_id,
    mojo::PendingReceiver<mojom::ChromotingSessionServices> receiver) {
  core_->OnSessionServicesClientConnected(terminal_id, std::move(receiver));
}
#endif

void IpcDesktopEnvironmentFactory::set_persist_desktop_sessions_for_testing(
    bool persistent) {
  core_->set_persist_desktop_sessions_for_testing(persistent);  // IN-TEST
}

size_t IpcDesktopEnvironmentFactory::active_desktop_sessions_count_for_testing()
    const {
  return core_->active_desktop_sessions_count_for_testing();  // IN-TEST
}

const IpcDesktopEnvironmentFactory::DesktopConnection*
IpcDesktopEnvironmentFactory::GetConnectionForTesting(int terminal_id) const {
  return core_->GetConnectionForTesting(terminal_id);  // IN-TEST
}

}  // namespace remoting