DolphinQt: Show a warning when launching an NKit disc image

It is my opinion that nobody should use NKit disc images without
being aware of the drawbacks of them. Since it seems like almost
nobody who is using NKit disc images knows what NKit is (hmm, now
how could that have happened...?), I am adding a warning to Dolphin
so that you can't run NKit disc images without finding out about the
drawbacks. In case someone really does want to use NKit disc images,
the warning has a "Don't show this again" option. Unfortunately, I
can't retroactively add the warning where it's most needed:
in Dolphin 5.0, which does not support Wii NKit disc images.

Source/Core/Core/Config/MainSettings.cpp

@@ -142,6 +142,7 @@ const Info<std::string> MAIN_FS_PATH{{System::Main, "General", "NANDRootPath"},
 const Info<std::string> MAIN_SD_PATH{{System::Main, "General", "WiiSDCardPath"}, ""};
 
 // Main.Network
+
 const Info<bool> MAIN_NETWORK_SSL_DUMP_READ{{System::Main, "Network", "SSLDumpRead"}, false};
 const Info<bool> MAIN_NETWORK_SSL_DUMP_WRITE{{System::Main, "Network", "SSLDumpWrite"}, false};
 const Info<bool> MAIN_NETWORK_SSL_VERIFY_CERTIFICATES{
@@ -149,4 +150,8 @@ const Info<bool> MAIN_NETWORK_SSL_VERIFY_CERTIFICATES{
 const Info<bool> MAIN_NETWORK_SSL_DUMP_ROOT_CA{{System::Main, "Network", "SSLDumpRootCA"}, false};
 const Info<bool> MAIN_NETWORK_SSL_DUMP_PEER_CERT{{System::Main, "Network", "SSLDumpPeerCert"},
                                                  false};
+
+// Main.Interface
+
+const Info<bool> MAIN_SKIP_NKIT_WARNING{{System::Main, "Interface", "SkipNKitWarning"}, false};
 }  // namespace Config

Source/Core/Core/Config/MainSettings.h

@@ -126,4 +126,8 @@ extern const Info<bool> MAIN_NETWORK_SSL_DUMP_WRITE;
 extern const Info<bool> MAIN_NETWORK_SSL_VERIFY_CERTIFICATES;
 extern const Info<bool> MAIN_NETWORK_SSL_DUMP_ROOT_CA;
 extern const Info<bool> MAIN_NETWORK_SSL_DUMP_PEER_CERT;
+
+// Main.Interface
+
+extern const Info<bool> MAIN_SKIP_NKIT_WARNING;
 }  // namespace Config

Source/Core/Core/ConfigLoaders/IsSettingSaveable.cpp

@@ -32,7 +32,7 @@ bool IsSettingSaveable(const Config::Location& config_location)
     }
   }
 
-  static constexpr std::array<const Config::Location*, 12> s_setting_saveable = {
+  static constexpr std::array<const Config::Location*, 13> s_setting_saveable = {
       // Main.Core
 
       &Config::MAIN_DEFAULT_ISO.location,
@@ -47,6 +47,10 @@ bool IsSettingSaveable(const Config::Location& config_location)
       &Config::MAIN_MEM2_SIZE.location,
       &Config::MAIN_GFX_BACKEND.location,
 
+      // Main.Interface
+
+      &Config::MAIN_SKIP_NKIT_WARNING.location,
+
       // UI.General
 
       &Config::MAIN_USE_DISCORD_PRESENCE.location,

Source/Core/DiscIO/Volume.h

@@ -116,6 +116,7 @@ public:
   }
   virtual Platform GetVolumeType() const = 0;
   virtual bool IsDatelDisc() const = 0;
+  virtual bool IsNKit() const = 0;
   virtual bool SupportsIntegrityCheck() const { return false; }
   virtual bool CheckH3TableIntegrity(const Partition& partition) const { return false; }
   virtual bool CheckBlockIntegrity(u64 block_index, const std::vector<u8>& encrypted_data,

Source/Core/DiscIO/VolumeDisc.cpp

@@ -84,4 +84,10 @@ std::optional<u8> VolumeDisc::GetDiscNumber(const Partition& partition) const
   return ReadSwapped<u8>(6, partition);
 }
 
+bool VolumeDisc::IsNKit() const
+{
+  constexpr u32 NKIT_MAGIC = 0x4E4B4954;  // "NKIT"
+  return ReadSwapped<u32>(0x200, PARTITION_NONE) == NKIT_MAGIC;
+}
+
 }  // namespace DiscIO

Source/Core/DiscIO/VolumeDisc.h

@@ -22,6 +22,7 @@ public:
   std::string GetInternalName(const Partition& partition = PARTITION_NONE) const override;
   std::string GetApploaderDate(const Partition& partition) const override;
   std::optional<u8> GetDiscNumber(const Partition& partition = PARTITION_NONE) const override;
+  bool IsNKit() const override;
 
 protected:
   Region RegionCodeToRegion(std::optional<u32> region_code) const;

Source/Core/DiscIO/VolumeVerifier.cpp

@@ -988,22 +988,18 @@ void VolumeVerifier::CheckMisc()
     }
   }
 
-  if (IsDisc(m_volume.GetVolumeType()))
+  if (m_volume.IsNKit())
   {
-    constexpr u32 NKIT_MAGIC = 0x4E4B4954;  // "NKIT"
-    if (m_volume.ReadSwapped<u32>(0x200, PARTITION_NONE) == NKIT_MAGIC)
-    {
-      AddProblem(
-          Severity::Low,
-          Common::GetStringT("This disc image is in the NKit format. It is not a good dump in its "
-                             "current form, but it might become a good dump if converted back. "
-                             "The CRC32 of this file might match the CRC32 of a good dump even "
-                             "though the files are not identical."));
-    }
-
-    if (StringBeginsWith(game_id_unencrypted, "R8P"))
-      CheckSuperPaperMario();
+    AddProblem(
+        Severity::Low,
+        Common::GetStringT("This disc image is in the NKit format. It is not a good dump in its "
+                           "current form, but it might become a good dump if converted back. "
+                           "The CRC32 of this file might match the CRC32 of a good dump even "
+                           "though the files are not identical."));
   }
+
+  if (IsDisc(m_volume.GetVolumeType()) && StringBeginsWith(game_id_unencrypted, "R8P"))
+    CheckSuperPaperMario();
 }
 
 void VolumeVerifier::CheckSuperPaperMario()

Source/Core/DiscIO/VolumeWad.cpp

@@ -289,6 +289,11 @@ bool VolumeWAD::IsDatelDisc() const
   return false;
 }
 
+bool VolumeWAD::IsNKit() const
+{
+  return false;
+}
+
 std::map<Language, std::string> VolumeWAD::GetLongNames() const
 {
   if (!m_tmd.IsValid() || !IOS::ES::IsChannel(m_tmd.GetTitleId()))

Source/Core/DiscIO/VolumeWad.h

@@ -60,6 +60,7 @@ public:
   }
   Platform GetVolumeType() const override;
   bool IsDatelDisc() const override;
+  bool IsNKit() const override;
   Region GetRegion() const override;
   Country GetCountry(const Partition& partition = PARTITION_NONE) const override;
 

Source/Core/DolphinQt/CMakeLists.txt

@@ -37,6 +37,8 @@ add_executable(dolphin-emu
   MainWindow.h
   MenuBar.cpp
   MenuBar.h
+  NKitWarningDialog.cpp
+  NKitWarningDialog.h
   RenderWidget.cpp
   RenderWidget.h
   Resources.cpp

Source/Core/DolphinQt/DolphinQt.vcxproj

@@ -178,6 +178,7 @@
     <QtMoc Include="NetPlay\NetPlayDialog.h" />
     <QtMoc Include="NetPlay\NetPlaySetupDialog.h" />
     <QtMoc Include="NetPlay\PadMappingDialog.h" />
+    <QtMoc Include="NKitWarningDialog.h" />
     <QtMoc Include="QtUtils\AspectRatioWidget.h" />
     <QtMoc Include="QtUtils\BlockUserInputFilter.h" />
     <QtMoc Include="QtUtils\DoubleClickEventFilter.h" />
@@ -290,6 +291,7 @@
     <ClCompile Include="$(QtMocOutPrefix)NetPlaySetupDialog.cpp" />
     <ClCompile Include="$(QtMocOutPrefix)NewBreakpointDialog.cpp" />
     <ClCompile Include="$(QtMocOutPrefix)NewPatchDialog.cpp" />
+    <ClCompile Include="$(QtMocOutPrefix)NKitWarningDialog.cpp" />
     <ClCompile Include="$(QtMocOutPrefix)PadMappingDialog.cpp" />
     <ClCompile Include="$(QtMocOutPrefix)ParallelProgressDialog.cpp" />
     <ClCompile Include="$(QtMocOutPrefix)UTF8CodePointCountValidator.cpp" />
@@ -394,6 +396,7 @@
     <ClCompile Include="DiscordJoinRequestDialog.cpp" />
     <ClCompile Include="FIFO\FIFOAnalyzer.cpp" />
     <ClCompile Include="FIFO\FIFOPlayerWindow.cpp" />
+    <ClCompile Include="NKitWarningDialog.cpp" />
     <ClCompile Include="QtUtils\WinIconHelper.cpp" />
     <ClCompile Include="ResourcePackManager.cpp" />
     <ClCompile Include="TAS\GCTASInputWindow.cpp" />

Source/Core/DolphinQt/MainWindow.cpp

@@ -18,6 +18,7 @@
 
 #include <future>
 #include <optional>
+#include <variant>
 
 #if defined(__unix__) || defined(__unix) || defined(__APPLE__)
 #include <signal.h>
@@ -83,6 +84,7 @@
 #include "DolphinQt/HotkeyScheduler.h"
 #include "DolphinQt/MainWindow.h"
 #include "DolphinQt/MenuBar.h"
+#include "DolphinQt/NKitWarningDialog.h"
 #include "DolphinQt/NetPlay/NetPlayBrowser.h"
 #include "DolphinQt/NetPlay/NetPlayDialog.h"
 #include "DolphinQt/NetPlay/NetPlaySetupDialog.h"
@@ -952,6 +954,15 @@ void MainWindow::StartGame(const std::vector<std::string>& paths,
 
 void MainWindow::StartGame(std::unique_ptr<BootParameters>&& parameters)
 {
+  if (std::holds_alternative<BootParameters::Disc>(parameters->parameters))
+  {
+    if (std::get<BootParameters::Disc>(parameters->parameters).volume->IsNKit())
+    {
+      if (!NKitWarningDialog::ShowUnlessDisabled())
+        return;
+    }
+  }
+
   // If we're running, only start a new game once we've stopped the last.
   if (Core::GetState() != Core::State::Uninitialized)
   {

Source/Core/DolphinQt/NKitWarningDialog.cpp

@@ -0,0 +1,87 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "DolphinQt/NKitWarningDialog.h"
+
+#include <QApplication>
+#include <QCheckBox>
+#include <QHBoxLayout>
+#include <QIcon>
+#include <QLabel>
+#include <QPushButton>
+#include <QStyle>
+#include <QVBoxLayout>
+
+#include "Common/Config/Config.h"
+#include "Core/Config/MainSettings.h"
+#include "DolphinQt/Resources.h"
+
+bool NKitWarningDialog::ShowUnlessDisabled(QWidget* parent)
+{
+  if (Config::Get(Config::MAIN_SKIP_NKIT_WARNING))
+    return true;
+  else
+    return NKitWarningDialog(parent).exec() == QDialog::Accepted;
+}
+
+NKitWarningDialog::NKitWarningDialog(QWidget* parent) : QDialog(parent)
+{
+  setWindowTitle(tr("NKit Warning"));
+  setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
+  setWindowIcon(Resources::GetAppIcon());
+
+  QVBoxLayout* main_layout = new QVBoxLayout;
+
+  QLabel* warning = new QLabel(
+      tr("You are about to run an NKit disc image. NKit disc images cause problems that don't "
+         "happen with normal disc images. These problems include:\n"
+         "\n"
+         "• The emulated loading times are longer\n"
+         "• You can't use NetPlay with people who have normal disc images\n"
+         "• Input recordings are not compatible between NKit disc images and normal disc images\n"
+         "• Savestates are not compatible between NKit disc images and normal disc images\n"
+         "• Some games crash, such as Super Paper Mario\n"
+         "• Wii games don't work at all in older versions of Dolphin and in many other programs\n"
+         "\n"
+         "Are you sure you want to continue anyway?\n"));
+  warning->setWordWrap(true);
+  main_layout->addWidget(warning);
+
+  QCheckBox* checkbox_accept = new QCheckBox(tr("I am aware of the risks and want to continue"));
+  main_layout->addWidget(checkbox_accept);
+
+  QCheckBox* checkbox_skip = new QCheckBox(tr("Don't show this again"));
+  main_layout->addWidget(checkbox_skip);
+
+  QHBoxLayout* button_layout = new QHBoxLayout;
+  QPushButton* ok = new QPushButton(tr("OK"));
+  button_layout->addWidget(ok);
+  QPushButton* cancel = new QPushButton(tr("Cancel"));
+  button_layout->addWidget(cancel);
+  main_layout->addLayout(button_layout);
+
+  QHBoxLayout* top_layout = new QHBoxLayout;
+
+  QIcon icon = QApplication::style()->standardIcon(QStyle::SP_MessageBoxWarning);
+  QLabel* icon_label = new QLabel;
+  icon_label->setPixmap(icon.pixmap(100));
+  icon_label->setAlignment(Qt::AlignTop);
+  top_layout->addWidget(icon_label);
+  top_layout->addSpacing(10);
+
+  top_layout->addLayout(main_layout);
+
+  setLayout(top_layout);
+
+  connect(ok, &QPushButton::clicked, this, &QDialog::accept);
+  connect(cancel, &QPushButton::clicked, this, &QDialog::reject);
+
+  ok->setEnabled(false);
+  connect(checkbox_accept, &QCheckBox::stateChanged,
+          [&ok](int state) { ok->setEnabled(state == Qt::Checked); });
+
+  connect(this, &QDialog::accepted, [checkbox_skip] {
+    Config::SetBase(Config::MAIN_SKIP_NKIT_WARNING, checkbox_skip->isChecked());
+  });
+}

Source/Core/DolphinQt/NKitWarningDialog.h

@@ -0,0 +1,19 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <QDialog>
+#include <QWidget>
+
+class NKitWarningDialog final : public QDialog
+{
+  Q_OBJECT
+
+public:
+  static bool ShowUnlessDisabled(QWidget* parent = nullptr);
+
+private:
+  explicit NKitWarningDialog(QWidget* parent = nullptr);
+};