Fluorine Manager: full Linux port of Mod Organizer 2

Complete native Linux port with FUSE-based virtual filesystem,
Proton/umu-run integration, and Flatpak packaging.

Key features:
- FUSE VFS replacing Windows USVFS (in-process + standalone helper for Flatpak)
- Proton/GE-Proton/umu-run launcher with env var forwarding
- Flatpak support (sandbox-aware VFS, NXM handler, umu-run)
- Wine prefix management UI
- Case-insensitive path resolution for Linux filesystems
- QSettings-safe INI handling (avoids Bethesda INI corruption)
- Portable instance support with auto-generated launcher scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

17 files changed, 936 insertions, 0 deletions

diff --git a/libs/installer_bain/.clang-format b/libs/installer_bain/.clang-format
new file mode 100644
index 0000000..6098e1f
--- /dev/null
+++ b/libs/installer_bain/.clang-format
@@ -0,0 +1,41 @@
+---
+# We'll use defaults from the LLVM style, but with 4 columns indentation.
+BasedOnStyle: LLVM
+IndentWidth: 2
+---
+Language: Cpp
+DeriveLineEnding: false
+UseCRLF: true
+DerivePointerAlignment: false
+PointerAlignment: Left
+AlignConsecutiveAssignments: true
+AllowShortFunctionsOnASingleLine: Inline
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLambdasOnASingleLine: Empty
+AlwaysBreakTemplateDeclarations: Yes
+AccessModifierOffset: -2
+AlignTrailingComments: true
+SpacesBeforeTrailingComments: 2
+NamespaceIndentation: Inner
+MaxEmptyLinesToKeep: 1
+BreakBeforeBraces: Custom
+BraceWrapping:
+  AfterCaseLabel: false
+  AfterClass: true
+  AfterControlStatement: false
+  AfterEnum: true
+  AfterFunction: true
+  AfterNamespace: true
+  AfterStruct: true
+  AfterUnion: true
+  AfterExternBlock: true
+  BeforeCatch: false
+  BeforeElse: false
+  BeforeLambdaBody: false
+  BeforeWhile: false
+  IndentBraces: false
+  SplitEmptyFunction: false
+  SplitEmptyRecord: false
+  SplitEmptyNamespace: true
+ColumnLimit: 88
+ForEachMacros: ['Q_FOREACH', 'foreach']
diff --git a/libs/installer_bain/.git-blame-ignore-revs b/libs/installer_bain/.git-blame-ignore-revs
new file mode 100644
index 0000000..d0c3535
--- /dev/null
+++ b/libs/installer_bain/.git-blame-ignore-revs
@@ -0,0 +1 @@
+60e7642364b534d9cb405acfa750b7bbe73869a9
diff --git a/libs/installer_bain/.gitattributes b/libs/installer_bain/.gitattributes
new file mode 100644
index 0000000..f869712
--- /dev/null
+++ b/libs/installer_bain/.gitattributes
@@ -0,0 +1,7 @@
+# Set the default behavior, in case people don't have core.autocrlf set.
+* text=auto
+
+# Explicitly declare text files you want to always be normalized and converted
+# to native line endings on checkout.
+*.cpp text eol=crlf
+*.h text eol=crlf
diff --git a/libs/installer_bain/.github/workflows/build.yml b/libs/installer_bain/.github/workflows/build.yml
new file mode 100644
index 0000000..e7f10a1
--- /dev/null
+++ b/libs/installer_bain/.github/workflows/build.yml
@@ -0,0 +1,20 @@
+name: Build Installer BAIN
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+env:
+  VCPKG_BINARY_SOURCES: clear;x-azblob,${{ vars.AZ_BLOB_VCPKG_URL }},${{ secrets.AZ_BLOB_SAS }},readwrite
+
+jobs:
+  build:
+    runs-on: windows-2022
+    steps:
+      - name: Build Installer BAIN
+        id: build-installer-bain
+        uses: ModOrganizer2/build-with-mob-action@master
+        with:
+          mo2-dependencies: uibase
diff --git a/libs/installer_bain/.github/workflows/linting.yml b/libs/installer_bain/.github/workflows/linting.yml
new file mode 100644
index 0000000..75c294e
--- /dev/null
+++ b/libs/installer_bain/.github/workflows/linting.yml
@@ -0,0 +1,16 @@
+name: Lint Installer BAIN Plugin
+
+on:
+  push:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Check format
+        uses: ModOrganizer2/check-formatting-action@master
+        with:
+          check-path: "."
diff --git a/libs/installer_bain/.gitignore b/libs/installer_bain/.gitignore
new file mode 100644
index 0000000..cf71be7
--- /dev/null
+++ b/libs/installer_bain/.gitignore
@@ -0,0 +1,5 @@
+edit
+CMakeLists.txt.user
+/msbuild.log
+/*std*.log
+/*build
diff --git a/libs/installer_bain/.pre-commit-config.yaml b/libs/installer_bain/.pre-commit-config.yaml
new file mode 100644
index 0000000..eb8969c
--- /dev/null
+++ b/libs/installer_bain/.pre-commit-config.yaml
@@ -0,0 +1,20 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v6.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-merge-conflict
+      - id: check-case-conflict
+  - repo: https://github.com/pre-commit/mirrors-clang-format
+    rev: v21.1.8
+    hooks:
+    - id: clang-format
+      'types_or': [c++, c]
+
+ci:
+  autofix_commit_msg: "[pre-commit.ci] Auto fixes from pre-commit.com hooks."
+  autofix_prs: true
+  autoupdate_commit_msg: "[pre-commit.ci] Pre-commit autoupdate."
+  autoupdate_schedule: quarterly
+  submodules: false
diff --git a/libs/installer_bain/CMakeLists.txt b/libs/installer_bain/CMakeLists.txt
new file mode 100644
index 0000000..4834057
--- /dev/null
+++ b/libs/installer_bain/CMakeLists.txt
@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 3.16)
+
+project(installer_bain)
+
+add_subdirectory(src)
diff --git a/libs/installer_bain/CMakePresets.json b/libs/installer_bain/CMakePresets.json
new file mode 100644
index 0000000..5a63c77
--- /dev/null
+++ b/libs/installer_bain/CMakePresets.json
@@ -0,0 +1,67 @@
+{
+  "configurePresets": [
+    {
+      "errors": {
+        "deprecated": true
+      },
+      "hidden": true,
+      "name": "cmake-dev",
+      "warnings": {
+        "deprecated": true,
+        "dev": true
+      }
+    },
+    {
+      "cacheVariables": {
+        "VCPKG_MANIFEST_NO_DEFAULT_FEATURES": {
+          "type": "BOOL",
+          "value": "ON"
+        }
+      },
+      "toolchainFile": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake",
+      "hidden": true,
+      "name": "vcpkg"
+    },
+    {
+      "hidden": true,
+      "inherits": ["vcpkg"],
+      "name": "vcpkg-dev"
+    },
+    {
+      "binaryDir": "${sourceDir}/vsbuild",
+      "architecture": {
+        "strategy": "set",
+        "value": "x64"
+      },
+      "cacheVariables": {
+        "CMAKE_CXX_FLAGS": "/EHsc /MP /W4",
+        "VCPKG_TARGET_TRIPLET": {
+          "type": "STRING",
+          "value": "x64-windows-static-md"
+        }
+      },
+      "generator": "Visual Studio 17 2022",
+      "inherits": ["cmake-dev", "vcpkg-dev"],
+      "name": "vs2022-windows",
+      "toolset": "v143"
+    },
+    {
+      "cacheVariables": {
+        "VCPKG_MANIFEST_FEATURES": {
+          "type": "STRING",
+          "value": "standalone"
+        }
+      },
+      "inherits": "vs2022-windows",
+      "name": "vs2022-windows-standalone"
+    }
+  ],
+  "buildPresets": [
+    {
+      "name": "vs2022-windows",
+      "resolvePackageReferences": "on",
+      "configurePreset": "vs2022-windows"
+    }
+  ],
+  "version": 4
+}
diff --git a/libs/installer_bain/src/CMakeLists.txt b/libs/installer_bain/src/CMakeLists.txt
new file mode 100644
index 0000000..de57063
--- /dev/null
+++ b/libs/installer_bain/src/CMakeLists.txt
@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.16)
+
+file(GLOB installer_bain_SOURCES CONFIGURE_DEPENDS
+  ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/*.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/*.ui
+  ${CMAKE_CURRENT_SOURCE_DIR}/*.qrc
+)
+
+add_library(installer_bain SHARED ${installer_bain_SOURCES})
+mo2_configure_plugin(installer_bain NO_SOURCES WARNINGS OFF)
+target_link_libraries(installer_bain PRIVATE mo2::uibase)
+mo2_install_plugin(installer_bain)
diff --git a/libs/installer_bain/src/baincomplexinstallerdialog.cpp b/libs/installer_bain/src/baincomplexinstallerdialog.cpp
new file mode 100644
index 0000000..2c25d76
--- /dev/null
+++ b/libs/installer_bain/src/baincomplexinstallerdialog.cpp
@@ -0,0 +1,121 @@
+/*
+Copyright (C) 2012 Sebastian Herbord. All rights reserved.
+
+This file is part of Mod Organizer.
+
+Mod Organizer is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Mod Organizer is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "ui_baincomplexinstallerdialog.h"
+
+#include <QCompleter>
+
+#include <uibase/textviewer.h>
+
+#include "baincomplexinstallerdialog.h"
+
+using namespace MOBase;
+
+BainComplexInstallerDialog::BainComplexInstallerDialog(
+    const std::vector<std::shared_ptr<const MOBase::FileTreeEntry>>& subpackages,
+    const GuessedValue<QString>& modName, const QStringList& defaultOptions,
+    const QString& packageTXT, QWidget* parent)
+    : TutorableDialog("BainInstaller", parent), ui(new Ui::BainComplexInstallerDialog),
+      m_Manual(false), m_PackageTXT(packageTXT)
+{
+  ui->setupUi(this);
+
+  for (auto iter = modName.variants().begin(); iter != modName.variants().end();
+       ++iter) {
+    ui->nameCombo->addItem(*iter);
+  }
+
+  ui->nameCombo->setCurrentIndex(ui->nameCombo->findText(modName));
+
+  for (const auto& subpackage : subpackages) {
+
+    auto name = subpackage->name();
+
+    QListWidgetItem* item = new QListWidgetItem(name, ui->optionsList);
+    item->setFlags(item->flags() | Qt::ItemIsUserCheckable);
+
+    if (name.mid(0, 2) == "00" || defaultOptions.contains(name, Qt::CaseInsensitive)) {
+      item->setCheckState(Qt::Checked);
+    } else {
+      item->setCheckState(Qt::Unchecked);
+    }
+
+    ui->optionsList->addItem(item);
+  }
+
+  ui->packageBtn->setEnabled(!packageTXT.isEmpty());
+  ui->nameCombo->completer()->setCaseSensitivity(Qt::CaseSensitive);
+}
+
+BainComplexInstallerDialog::~BainComplexInstallerDialog()
+{
+  delete ui;
+}
+
+QString BainComplexInstallerDialog::getName() const
+{
+  return ui->nameCombo->currentText();
+}
+
+QStringList BainComplexInstallerDialog::updateTree(std::shared_ptr<IFileTree>& tree)
+{
+  // Retrieve the list of selected names:
+  std::set<QString, FileNameComparator> selectedNames;
+  for (int i = 0; i < ui->optionsList->count(); ++i) {
+    QListWidgetItem* item = ui->optionsList->item(i);
+    if (item->checkState() == Qt::Checked) {
+      selectedNames.insert(item->text());
+    }
+  }
+
+  // Create a new empty tree and merge all the selected folder in it:
+  auto newTree = tree->createOrphanTree();
+  for (auto& entry : *tree) {
+    if (entry->isDir() && selectedNames.count(entry->name()) > 0) {
+      newTree->merge(entry->astree());
+    }
+  }
+
+  tree = newTree;
+
+  return QStringList(selectedNames.begin(), selectedNames.end());
+}
+
+void BainComplexInstallerDialog::on_okBtn_clicked()
+{
+  this->accept();
+}
+
+void BainComplexInstallerDialog::on_cancelBtn_clicked()
+{
+  this->reject();
+}
+
+void BainComplexInstallerDialog::on_manualBtn_clicked()
+{
+  m_Manual = true;
+  this->reject();
+}
+
+void BainComplexInstallerDialog::on_packageBtn_clicked()
+{
+  TextViewer viewer(m_PackageTXT, this);
+  viewer.setDescription("");
+  viewer.addFile(m_PackageTXT, false);
+  viewer.exec();
+}
diff --git a/libs/installer_bain/src/baincomplexinstallerdialog.h b/libs/installer_bain/src/baincomplexinstallerdialog.h
new file mode 100644
index 0000000..f657627
--- /dev/null
+++ b/libs/installer_bain/src/baincomplexinstallerdialog.h
@@ -0,0 +1,94 @@
+/*
+Copyright (C) 2012 Sebastian Herbord. All rights reserved.
+
+This file is part of Mod Organizer.
+
+Mod Organizer is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Mod Organizer is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef BAINCOMPLEXINSTALLERDIALOG_H
+#define BAINCOMPLEXINSTALLERDIALOG_H
+
+#include <uibase/guessedvalue.h>
+#include <uibase/ifiletree.h>
+#include <uibase/tutorabledialog.h>
+
+namespace Ui
+{
+class BainComplexInstallerDialog;
+}
+
+/**
+ * @brief Dialog to choose from options offered by a (complex) bain package
+ **/
+class BainComplexInstallerDialog : public MOBase::TutorableDialog
+{
+  Q_OBJECT
+
+public:
+  /**
+   * @brief Constructor
+   *
+   * @param tree the directory tree of the archive. The caller is resonsible to verify
+   *this actually qualifies as a bain installer
+   * @param modName proposed name for the mod. The dialog allows the user to change this
+   * @param defaultOptions The default options to select. Can contains options not
+   *actually present.
+   * @param packageTXT path to the extracted package.txt file or an empty string if
+   *there is none
+   * @param parent parent widget
+   **/
+  explicit BainComplexInstallerDialog(
+      const std::vector<std::shared_ptr<const MOBase::FileTreeEntry>>& subpackages,
+      const MOBase::GuessedValue<QString>& modName, const QStringList& defaultOptions,
+      const QString& packageTXT, QWidget* parent);
+  ~BainComplexInstallerDialog();
+
+  /**
+   * @return bool true if the user requested the manual dialog
+   **/
+  bool manualRequested() const { return m_Manual; }
+
+  /**
+   * @return QString the (user-modified) name to be used for the mod
+   **/
+  QString getName() const;
+
+  /**
+   * @brief Remove from the given tree the option not selected by the user.
+   *
+   * @param tree The input tree.
+   *
+   * @return the list of options selected by the user.
+   **/
+  QStringList updateTree(std::shared_ptr<MOBase::IFileTree>& tree);
+
+private slots:
+
+  void on_manualBtn_clicked();
+
+  void on_okBtn_clicked();
+
+  void on_cancelBtn_clicked();
+
+  void on_packageBtn_clicked();
+
+private:
+  Ui::BainComplexInstallerDialog* ui;
+
+  bool m_Manual;
+  QString m_PackageTXT;
+};
+
+#endif  // BAINCOMPLEXINSTALLERDIALOG_H
diff --git a/libs/installer_bain/src/baincomplexinstallerdialog.ui b/libs/installer_bain/src/baincomplexinstallerdialog.ui
new file mode 100644
index 0000000..0ab5214
--- /dev/null
+++ b/libs/installer_bain/src/baincomplexinstallerdialog.ui
@@ -0,0 +1,126 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>BainComplexInstallerDialog</class>
+ <widget class="QDialog" name="BainComplexInstallerDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>424</width>
+    <height>365</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>BAIN Package Installer</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_2" stretch="1,2">
+     <item>
+      <widget class="QLabel" name="label">
+       <property name="text">
+        <string>Name</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QComboBox" name="nameCombo">
+       <property name="editable">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QLabel" name="label_2">
+     <property name="text">
+      <string>This looks like a Package prepared for Installation through BAIN. You can select options from the list below. If there is a package.txt file, it should contain detailed information about the options.</string>
+     </property>
+     <property name="wordWrap">
+      <bool>true</bool>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QListWidget" name="optionsList">
+     <property name="toolTip">
+      <string>Components of this package.</string>
+     </property>
+     <property name="whatsThis">
+      <string>Components of this package.
+If there is a component called &quot;00 Core&quot; it is usually required. Options are ordered by priority as set up by the author.</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <widget class="QPushButton" name="manualBtn">
+       <property name="toolTip">
+        <string>Opens a Dialog that allows custom modifications.</string>
+       </property>
+       <property name="whatsThis">
+        <string>Opens a Dialog that allows custom modifications.</string>
+       </property>
+       <property name="text">
+        <string>Manual</string>
+       </property>
+       <property name="autoDefault">
+        <bool>false</bool>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QPushButton" name="packageBtn">
+       <property name="toolTip">
+        <string>The package.txt is often part of BAIN packages and contains details about the options available.</string>
+       </property>
+       <property name="whatsThis">
+        <string>The package.txt is often part of BAIN packages and contains details about the options available.</string>
+       </property>
+       <property name="text">
+        <string notr="true">Package.txt</string>
+       </property>
+       <property name="autoDefault">
+        <bool>false</bool>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="horizontalSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QPushButton" name="okBtn">
+       <property name="text">
+        <string>Ok</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QPushButton" name="cancelBtn">
+       <property name="text">
+        <string>Cancel</string>
+       </property>
+       <property name="autoDefault">
+        <bool>false</bool>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/libs/installer_bain/src/installer_bain_en.ts b/libs/installer_bain/src/installer_bain_en.ts
new file mode 100644
index 0000000..fe78e5d
--- /dev/null
+++ b/libs/installer_bain/src/installer_bain_en.ts
@@ -0,0 +1,83 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE TS>
+<TS version="2.1" language="en_US">
+<context>
+    <name>BainComplexInstallerDialog</name>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="14"/>
+        <source>BAIN Package Installer</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="22"/>
+        <source>Name</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="38"/>
+        <source>This looks like a Package prepared for Installation through BAIN. You can select options from the list below. If there is a package.txt file, it should contain detailed information about the options.</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="48"/>
+        <source>Components of this package.</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="51"/>
+        <source>Components of this package.
+If there is a component called &quot;00 Core&quot; it is usually required. Options are ordered by priority as set up by the author.</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="61"/>
+        <location filename="baincomplexinstallerdialog.ui" line="64"/>
+        <source>Opens a Dialog that allows custom modifications.</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="67"/>
+        <source>Manual</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="77"/>
+        <location filename="baincomplexinstallerdialog.ui" line="80"/>
+        <source>The package.txt is often part of BAIN packages and contains details about the options available.</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="106"/>
+        <source>Ok</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="baincomplexinstallerdialog.ui" line="113"/>
+        <source>Cancel</source>
+        <translation type="unfinished"></translation>
+    </message>
+</context>
+<context>
+    <name>InstallerBAIN</name>
+    <message>
+        <location filename="installerbain.cpp" line="51"/>
+        <source>BAIN Installer</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="installerbain.cpp" line="61"/>
+        <source>Installer for BAIN archives (originally targeting Wrye Bash)</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="installerbain.cpp" line="173"/>
+        <source>May be BAIN installer</source>
+        <translation type="unfinished"></translation>
+    </message>
+    <message>
+        <location filename="installerbain.cpp" line="174"/>
+        <source>This installer looks like it may contain a BAIN installer but I&apos;m not sure. Install as BAIN installer?</source>
+        <translation type="unfinished"></translation>
+    </message>
+</context>
+</TS>
diff --git a/libs/installer_bain/src/installerbain.cpp b/libs/installer_bain/src/installerbain.cpp
new file mode 100644
index 0000000..d39590e
--- /dev/null
+++ b/libs/installer_bain/src/installerbain.cpp
@@ -0,0 +1,222 @@
+/*
+Copyright (C) 2012 Sebastian Herbord. All rights reserved.
+
+This file is part of Mod Organizer.
+
+Mod Organizer is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Mod Organizer is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "installerbain.h"
+
+#include <uibase/game_features/igamefeatures.h>
+#include <uibase/game_features/moddatachecker.h>
+#include <uibase/iinstallationmanager.h>
+#include <uibase/iplugingame.h>
+#include <uibase/log.h>
+
+#include <QDir>
+#include <QMessageBox>
+#include <QtPlugin>
+
+#include "baincomplexinstallerdialog.h"
+
+using namespace MOBase;
+
+InstallerBAIN::InstallerBAIN() : m_MOInfo(nullptr) {}
+
+bool InstallerBAIN::init(IOrganizer* moInfo)
+{
+  m_MOInfo = moInfo;
+  return true;
+}
+
+QString InstallerBAIN::name() const
+{
+  return "BAIN Installer";
+}
+
+QString InstallerBAIN::localizedName() const
+{
+  return tr("BAIN Installer");
+}
+
+QString InstallerBAIN::author() const
+{
+  return "Tannin";
+}
+
+QString InstallerBAIN::description() const
+{
+  return tr("Installer for BAIN archives (originally targeting Wrye Bash)");
+}
+
+VersionInfo InstallerBAIN::version() const
+{
+  return VersionInfo(1, 1, 0, VersionInfo::RELEASE_FINAL);
+}
+
+QList<PluginSetting> InstallerBAIN::settings() const
+{
+  return QList<PluginSetting>();
+}
+
+unsigned int InstallerBAIN::priority() const
+{
+  return 40;
+}
+
+bool InstallerBAIN::isManualInstaller() const
+{
+  return false;
+}
+
+void InstallerBAIN::onInstallationStart(QString const&, bool, IModInterface* currentMod)
+{
+  // We reset some field and fetch the previously installed options:
+  m_InstallerUsed = false;
+  m_PreviousOptions.clear();
+  m_SelectedOptions.clear();
+
+  if (currentMod) {
+    auto settings = currentMod->pluginSettings(name());
+    for (auto& [name, value] : settings) {
+      if (name.startsWith("option")) {
+        m_PreviousOptions.append(value.toString());
+      }
+    }
+  }
+}
+
+void InstallerBAIN::onInstallationEnd(EInstallResult result, IModInterface* newMod)
+{
+  if (result == EInstallResult::RESULT_SUCCESS && m_InstallerUsed) {
+    newMod->clearPluginSettings(name());
+    for (auto i = 0; i < m_SelectedOptions.size(); ++i) {
+      newMod->setPluginSetting(name(), QString("option%1").arg(i),
+                               m_SelectedOptions[i]);
+    }
+  }
+}
+
+std::vector<std::shared_ptr<const MOBase::FileTreeEntry>>
+InstallerBAIN::findSubpackages(std::shared_ptr<const MOBase::IFileTree> tree,
+                               std::size_t* invalidFolders) const
+{
+  // Folders that can be present but do not impact the installation:
+  static const std::set<QString, FileNameComparator> IGNORED_FOLDERS{
+      "fomod", "omod conversion data", "images", "screenshots", "docs"};
+
+  auto checker = m_MOInfo->gameFeatures()->gameFeature<ModDataChecker>();
+
+  if (!checker) {
+    return {};
+  }
+
+  // each directory would have to serve as a top-level directory
+  std::vector<std::shared_ptr<const MOBase::FileTreeEntry>> subpackages;
+  std::size_t ninvalids = 0;
+  for (auto entry : *tree) {
+
+    if (!entry->isDir()) {
+      continue;
+    }
+
+    // ignore fomod in case of combined fomod/bain packages.
+    // dirs starting with -- are supposed to be ignored
+    if (IGNORED_FOLDERS.contains(entry->name()) || entry->name().startsWith("--")) {
+      continue;
+    }
+
+    if (checker->dataLooksValid(entry->astree()) ==
+        ModDataChecker::CheckReturn::VALID) {
+      subpackages.push_back(entry);
+    } else {
+      ninvalids++;
+    }
+  }
+
+  if (invalidFolders) {
+    *invalidFolders = ninvalids;
+  }
+
+  return subpackages;
+}
+
+bool InstallerBAIN::isArchiveSupported(std::shared_ptr<const IFileTree> tree) const
+{
+  auto checker = m_MOInfo->gameFeatures()->gameFeature<ModDataChecker>();
+
+  if (!checker) {
+    return false;
+  }
+
+  std::size_t numInvalidDirs = 0;
+  auto subpackages           = findSubpackages(tree, &numInvalidDirs);
+
+  if (subpackages.size() < 2) {
+    // a complex bain package contains at least 2 directories to choose from
+    return false;
+  } else if (numInvalidDirs == 0) {
+    return true;
+  } else {
+    return QMessageBox::question(parentWidget(), tr("May be BAIN installer"),
+                                 tr("This installer looks like it may contain a BAIN "
+                                    "installer but I'm not sure. "
+                                    "Install as BAIN installer?"),
+                                 QMessageBox::Yes | QMessageBox::No) ==
+           QMessageBox::Yes;
+  }
+
+  return true;
+}
+
+IPluginInstaller::EInstallResult
+InstallerBAIN::install(GuessedValue<QString>& modName, std::shared_ptr<IFileTree>& tree,
+                       QString&, int&)
+{
+  auto entry = tree->find("package.txt", FileTreeEntry::FILE);
+
+  QString packageTXT;
+  if (entry != nullptr) {
+    packageTXT = manager()->extractFile(entry);
+  }
+
+  auto subpackages = findSubpackages(tree);
+
+  BainComplexInstallerDialog dialog(subpackages, modName, m_PreviousOptions, packageTXT,
+                                    parentWidget());
+
+  int res = dialog.exec();
+
+  if (res == QDialog::Accepted) {
+    modName.update(dialog.getName(), GUESS_USER);
+
+    // Update the tree:
+    m_SelectedOptions = dialog.updateTree(tree);
+    m_InstallerUsed   = true;
+
+    return IPluginInstaller::RESULT_SUCCESS;
+  } else {
+    if (dialog.manualRequested()) {
+      modName.update(dialog.getName(), GUESS_USER);
+      return IPluginInstaller::RESULT_MANUALREQUESTED;
+    } else {
+      return IPluginInstaller::RESULT_CANCELED;
+    }
+  }
+}
+
+#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
+Q_EXPORT_PLUGIN2(installerBAIN, InstallerBAIN)
+#endif
diff --git a/libs/installer_bain/src/installerbain.h b/libs/installer_bain/src/installerbain.h
new file mode 100644
index 0000000..535a31a
--- /dev/null
+++ b/libs/installer_bain/src/installerbain.h
@@ -0,0 +1,80 @@
+/*
+Copyright (C) 2012 Sebastian Herbord. All rights reserved.
+
+This file is part of Mod Organizer.
+
+Mod Organizer is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Mod Organizer is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef INSTALLERBAIN_H
+#define INSTALLERBAIN_H
+
+#include <uibase/iplugininstallersimple.h>
+
+class InstallerBAIN : public MOBase::IPluginInstallerSimple
+{
+  Q_OBJECT
+  Q_INTERFACES(MOBase::IPlugin MOBase::IPluginInstaller MOBase::IPluginInstallerSimple)
+#if QT_VERSION >= QT_VERSION_CHECK(5, 0, 0)
+  Q_PLUGIN_METADATA(IID "org.tannin.InstallerBAIN")
+#endif
+
+public:
+  InstallerBAIN();
+
+  virtual bool init(MOBase::IOrganizer* moInfo) override;
+  virtual QString name() const override;
+  virtual QString localizedName() const override;
+  virtual QString author() const override;
+  virtual QString description() const override;
+  virtual MOBase::VersionInfo version() const override;
+  virtual QList<MOBase::PluginSetting> settings() const override;
+
+  virtual unsigned int priority() const;
+  virtual bool isManualInstaller() const;
+
+  virtual void onInstallationStart(QString const& archive, bool reinstallation,
+                                   MOBase::IModInterface* currentMod) override;
+  virtual void onInstallationEnd(EInstallResult result,
+                                 MOBase::IModInterface* newMod) override;
+
+  virtual bool isArchiveSupported(std::shared_ptr<const MOBase::IFileTree> tree) const;
+  virtual EInstallResult install(MOBase::GuessedValue<QString>& modName,
+                                 std::shared_ptr<MOBase::IFileTree>& tree,
+                                 QString& version, int& modID);
+
+protected:
+  /**
+   * @brief Retrieve the entries corresponding to subpackages in the given tree.
+   *
+   * @param tree The tree to check for subpackages.
+   * @param invalidFolders If not null, will contain the number of invalid folders.
+   *
+   * @return the list of entries corresponding to subpackages.
+   */
+  std::vector<std::shared_ptr<const MOBase::FileTreeEntry>>
+  findSubpackages(std::shared_ptr<const MOBase::IFileTree> tree,
+                  std::size_t* invalidFolders = nullptr) const;
+
+private:
+  const MOBase::IOrganizer* m_MOInfo;
+
+  // Indicates if the installer was used:
+  bool m_InstallerUsed;
+
+  // List of options currently installed and being installed:
+  QStringList m_PreviousOptions, m_SelectedOptions;
+};
+
+#endif  // INSTALLERBAIN_H
diff --git a/libs/installer_bain/vcpkg.json b/libs/installer_bain/vcpkg.json
new file mode 100644
index 0000000..28051ad
--- /dev/null
+++ b/libs/installer_bain/vcpkg.json
@@ -0,0 +1,15 @@
+{
+  "features": {
+    "standalone": {
+      "description": "Build Standalone.",
+      "dependencies": ["mo2-cmake", "mo2-uibase"]
+    }
+  },
+  "vcpkg-configuration": {
+    "default-registry": {
+      "kind": "git",
+      "repository": "https://github.com/ModOrganizer2/vcpkg-registry",
+      "baseline": "8beb2e0efa9c17dd6d17bb05288dd1e40727f673"
+    }
+  }
+}