[feat] add in-app Windows updates with automatic download and setup launch

apps/desktop/src/platform/windows/windows_updater.cpp

@@ -0,0 +1,123 @@
+#include "windows_updater.h"
+
+#include <httplib.h>
+#include <shellapi.h>
+#include <windows.h>
+
+#include <random>
+#include <stdexcept>
+
+#include "installer_download.h"
+#include "rd_log.h"
+
+namespace crossdesk {
+
+WindowsUpdater::~WindowsUpdater() {
+  Cancel();
+  if (worker_.joinable()) worker_.join();
+  RemoveDownload();
+}
+
+void WindowsUpdater::RemoveDownload() {
+  // A running NSIS installer still needs its source file. Leave that one in
+  // the user's temporary directory; clean up cancelled/failed attempts.
+  if (installer_.empty() || installer_launched_) return;
+  std::error_code error;
+  std::filesystem::remove(installer_, error);
+  std::filesystem::remove(installer_.parent_path(), error);
+}
+
+void WindowsUpdater::Start(const nlohmann::json& metadata) {
+  const State state = GetState();
+  if (state == State::Downloading || state == State::Launching) return;
+  if (state == State::Ready || state == State::LaunchFailed ||
+      state == State::Launched) {
+    cancelled_ = false;
+    Launch();
+    return;
+  }
+  if (worker_.joinable()) worker_.join();
+  RemoveDownload();
+  installer_.clear();
+  installer_launched_ = false;
+  cancelled_ = false;
+  downloaded_ = 0;
+  total_ = 0;
+  const auto download = GetWindowsInstallerDownload(metadata);
+  if (!download) {
+    LOG_WARN("No valid Windows installer for the advertised version");
+    state_ = State::Failed;
+    return;
+  }
+  try {
+    std::random_device random;
+    const auto temp = std::filesystem::temp_directory_path();
+    for (int attempt = 0; attempt < 10; ++attempt) {
+      const auto directory =
+          temp / ("CrossDesk-update-" + std::to_string(random()) + "-" +
+                  std::to_string(random()));
+      if (std::filesystem::create_directory(directory)) {
+        installer_ = directory / download->filename;
+        break;
+      }
+    }
+    if (installer_.empty())
+      throw std::runtime_error("Cannot create update directory");
+    client_ = std::make_shared<httplib::Client>(download->origin);
+    client_->set_connection_timeout(5);
+    client_->set_read_timeout(5);
+    client_->set_write_timeout(5);
+    state_ = State::Downloading;
+    worker_ = std::thread([this, path = download->path] {
+      const bool success =
+          DownloadInstaller(*client_, path, installer_,
+                            [this](uint64_t received, uint64_t total) {
+                              downloaded_ = received;
+                              total_ = total;
+                              return !cancelled_.load();
+                            });
+      state_ = success ? State::Ready : State::Failed;
+      if (cancelled_) state_ = State::Idle;
+    });
+  } catch (const std::exception& error) {
+    LOG_WARN("Cannot start Windows update: {}", error.what());
+    state_ = State::Failed;
+  }
+}
+
+void WindowsUpdater::Cancel() {
+  cancelled_ = true;
+  if (client_) client_->stop();
+  if (GetState() == State::Ready) state_ = State::Idle;
+}
+
+void WindowsUpdater::Launch() {
+  if (cancelled_) return;
+  const State state = GetState();
+  if (state != State::Ready && state != State::LaunchFailed &&
+      state != State::Launched)
+    return;
+  if (worker_.joinable()) worker_.join();
+  const std::wstring executable = installer_.wstring();
+  const std::wstring directory = installer_.parent_path().wstring();
+  state_ = State::Launching;
+  SHELLEXECUTEINFOW info{};
+  info.cbSize = sizeof(info);
+  info.fMask = SEE_MASK_NOCLOSEPROCESS | SEE_MASK_NOASYNC | SEE_MASK_FLAG_NO_UI;
+  info.lpVerb = L"runas";
+  info.lpFile = executable.c_str();
+  info.lpDirectory = directory.c_str();
+  info.nShow = SW_SHOWNORMAL;
+  if (!ShellExecuteExW(&info)) {
+    LOG_WARN("Cannot launch Windows installer, error={}", GetLastError());
+    state_ = State::LaunchFailed;
+    return;
+  }
+  if (info.hProcess) CloseHandle(info.hProcess);
+  installer_launched_ = true;
+  state_ = State::Launched;
+  // NSIS already prompts to close CrossDesk and stops the installed service.
+  // Keep this process alive if the user subsequently cancels installation.
+}
+
+}  // namespace crossdesk

apps/desktop/src/platform/windows/windows_updater.h

@@ -0,0 +1,57 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-09-09
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _WINDOWS_UPDATER_H_
+#define _WINDOWS_UPDATER_H_
+
+#include <atomic>
+#include <filesystem>
+#include <memory>
+#include <nlohmann/json.hpp>
+#include <thread>
+
+namespace httplib {
+class Client;
+}
+
+namespace crossdesk {
+
+class WindowsUpdater {
+ public:
+  enum class State {
+    Idle,
+    Downloading,
+    Ready,
+    Launching,
+    Failed,
+    LaunchFailed,
+    Launched
+  };
+
+  ~WindowsUpdater();
+  void Start(const nlohmann::json& metadata);
+  void Cancel();
+  void Launch();
+  State GetState() const { return state_.load(); }
+  uint64_t Downloaded() const { return downloaded_.load(); }
+  uint64_t Total() const { return total_.load(); }
+
+ private:
+  void RemoveDownload();
+
+  std::atomic<State> state_{State::Idle};
+  std::atomic<bool> cancelled_{false};
+  std::atomic<uint64_t> downloaded_{0};
+  std::atomic<uint64_t> total_{0};
+  std::shared_ptr<httplib::Client> client_;
+  std::thread worker_;
+  std::filesystem::path installer_;
+  bool installer_launched_ = false;
+};
+
+}  // namespace crossdesk
+
+#endif