OAuth Support (#53)

Rips out the old auth method, adds OAuth support. Fixes #51.

Tested Platforms:
- [x] Linux
    - [x] Flatpak
    - [x] Native (Nix)
- [x] Android
- [ ] Windows
- [ ] MacOS

Reviewed-on: Nexus/nexus#53

windows/flutter/generated_plugin_registrant.cc

@@ -6,6 +6,7 @@
 
 #include "generated_plugin_registrant.h"
 
+#include <app_links/app_links_plugin_c_api.h>
 #include <dynamic_color/dynamic_color_plugin_c_api.h>
 #include <file_selector_windows/file_selector_windows.h>
 #include <media_kit_libs_windows_video/media_kit_libs_windows_video_plugin_c_api.h>
@@ -15,6 +16,8 @@
 #include <window_manager/window_manager_plugin.h>
 
 void RegisterPlugins(flutter::PluginRegistry* registry) {
+  AppLinksPluginCApiRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("AppLinksPluginCApi"));
   DynamicColorPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("DynamicColorPluginCApi"));
   FileSelectorWindowsRegisterWithRegistrar(

windows/flutter/generated_plugins.cmake

@@ -3,6 +3,7 @@
 #
 
 list(APPEND FLUTTER_PLUGIN_LIST
+  app_links
   dynamic_color
   file_selector_windows
   media_kit_libs_windows_video

windows/installer.iss

@@ -14,4 +14,8 @@ Source: "..\build\windows\x64\runner\Release\*"; DestDir: "{app}"; Flags: recurs
 
 [Icons]
 Name: "{group}\Nexus"; Filename: "{app}\nexus.exe"
-Name: "{commondesktop}\Nexus"; Filename: "{app}\nexus.exe"
+Name: "{commondesktop}\Nexus"; Filename: "{app}\nexus.exe"
+
+[Registry]
+Root: HKCU; Subkey: "Software\Classes\nexus.federated.nexus"; ValueType: string; ValueName: "URL Protocol"; ValueData: ""
+Root: HKCU; Subkey: "Software\Classes\nexus.federated.nexus\shell\open\command"; ValueType: string; ValueName: ""; ValueData: """{app}\nexus.exe"" ""%1"""

windows/runner/Runner.rc

@@ -89,11 +89,11 @@ BEGIN
     BEGIN
         BLOCK "040904e4"
         BEGIN
-            VALUE "CompanyName", "nexus.federated.Nexus" "\0"
+            VALUE "CompanyName", "nexus.federated.nexus" "\0"
             VALUE "FileDescription", "nexus" "\0"
             VALUE "FileVersion", VERSION_AS_STRING "\0"
             VALUE "InternalName", "nexus" "\0"
-            VALUE "LegalCopyright", "Copyright (C) 2025 nexus.federated.Nexus. All rights reserved." "\0"
+            VALUE "LegalCopyright", "Copyright (C) 2025 nexus.federated.nexus. All rights reserved." "\0"
             VALUE "OriginalFilename", "nexus.exe" "\0"
             VALUE "ProductName", "nexus" "\0"
             VALUE "ProductVersion", VERSION_AS_STRING "\0"

windows/runner/main.cpp

@@ -1,12 +1,17 @@
 #include <flutter/dart_project.h>
 #include <flutter/flutter_view_controller.h>
 #include <windows.h>
-
+#include "app_links/app_links_plugin_c_api.h"
 #include "flutter_window.h"
 #include "utils.h"
 
 int APIENTRY wWinMain(_In_ HINSTANCE instance, _In_opt_ HINSTANCE prev,
                       _In_ wchar_t *command_line, _In_ int show_command) {
+  // Forward the link to an existing instance, if any, then exit.
+  // You may ignore the result if you need to create another window.
+  if (SendAppLinkToInstance()) {
+    return EXIT_SUCCESS;
+  }
   // Attach to console when present (e.g., 'flutter run') or create a
   // new console when running with a debugger.
   if (!::AttachConsole(ATTACH_PARENT_PROCESS) && ::IsDebuggerPresent()) {