Don't allow to install third-party themes that override the default one (fix #4226)

This fix 1) hides user themes whose name is the same as the default,
and are present in the user folders (i.e.  'extensions' and
'data/themes' folders), and 2) does't allow to install themes with the
same content/ID of the default aseprite-theme (fix #4226)

data/strings/en.ini

@@ -62,6 +62,7 @@ deleting_tilemaps_will_delete_tilesets = Warning\n<<Deleting the following tilem
 cannot_file_overwrite_on_export = Overwrite Warning\n<<You cannot Export with the same name (overwrite the original file).\n<<Use "File > Save As" menu option in that case.\n||&OK
 cannot_open_file = Problem<<Cannot open file:<<{0}||&OK
 cannot_open_folder = Problem<<Cannot open folder:<<{0}||&OK
+cannot_open_theme = Error<<The selected theme ID is "default". Please change<<the theme ID inside "package.json" to make it work.||&OK
 cannot_save_in_read_only_file = Problem<<The selected file is read-only. Try with other file.||&Go back
 clipboard_access_locked = Error<<Cannot access to the clipboard.<<Maybe other application is using it.||&OK
 clipboard_image_format_not_supported = Error<<The current clipboard image format is not supported.||&OK
@@ -90,6 +91,7 @@ job_working = {0}<<Working...||&Cancel
 nothing_to_report = Crash Report<<Nothing to report||&OK
 install_extension = Warning\n<<Do you really want to install the given extension?\n<<"{0}"\n||&Install||&Cancel
 uninstall_extension_warning = Warning\n<<Do you really want to uninstall "{0}" extension?\n||&Yes||&No
+cannot_install_default_extension = Error\n<<This theme cannot be installed because its name matches the default aseprite theme\n||&OK
 unknown_output_file_format_error = Aseprite\n<<Unknown file format "{0}" in output filename\n||&OK
 update_screen_ui_scaling_with_theme_values = Update Screen/UI Scaling\n<<The new theme "{0}" wants to adjust some values for you:\n<<  Screen Scaling: {1}% -> {2}%\n<<  UI Scaling: {3}% -> {4}%\n<<Allow these changes?\n||&Adjust Scaling||&Don't Adjust Scaling
 update_extension = Update Extension\n<<The extension "{0}" already exists.\n<<Do you want to {1} from v{2} to v{3}?\n||&Yes||&No

src/app/commands/cmd_options.cpp

@@ -926,6 +926,18 @@ public:
       }
     }
 
+    // Get the extension information from the compressed
+    // package.json file.
+    const ExtensionInfo info =
+      App::instance()->extensions().getCompressedExtensionInfo(filename);
+    // Check if the filename corresponds to aseprite-default theme
+    if (base::string_to_lower(info.name) ==
+        Extensions::kAsepriteDefaultThemeName) {
+      ui::Alert::show(
+        fmt::format(Strings::alerts_cannot_install_default_extension()));
+      return false;
+    }
+
     // Install?
     if (ui::Alert::show(Strings::alerts_install_extension(filename)) != 1)
       return false;
@@ -1378,7 +1390,8 @@ private:
       if (!ext->isEnabled())
         continue;
 
-      if (ext->themes().empty())
+      if (ext->themes().empty() ||
+          isExtensionADuplicatedDefaultTheme(ext))
         continue;
 
       if (first) {
@@ -1410,6 +1423,9 @@ private:
     extensionsList()->addChild(sep);
     for (auto e : App::instance()->extensions()) {
       if (e->category() == category) {
+        if (category == Extension::Category::Themes &&
+            isExtensionADuplicatedDefaultTheme(e))
+          continue;
         ExtensionItem* item = new ExtensionItem(e);
         extensionsList()->addChild(item);
         hasItems = true;
@@ -1571,6 +1587,11 @@ private:
       // package.json file.
       ExtensionInfo info = exts.getCompressedExtensionInfo(filename);
 
+      if (info.themeId == "default") {
+        ui::Alert::show(
+          fmt::format(Strings::alerts_cannot_open_theme()));
+        return;
+      }
       // Check if the extension already exist
       for (auto ext : exts) {
         if (base::string_to_lower(ext->name()) !=
@@ -1749,6 +1770,17 @@ private:
     return paths;
   }
 
+  static base::paths getUserDirPaths(const base::paths& dirNames) {
+    ResourceFinder rf;
+    for (auto& fn : dirNames)
+      rf.includeUserDir(fn.c_str());
+
+    base::paths paths;
+    while (rf.next())
+      paths.push_back(base::normalize_path(rf.filename()));
+    return paths;
+  }
+
   void updateCategoryVisibility() {
     bool visibleCategories[int(Extension::Category::Max)];
     for (auto& v : visibleCategories)
@@ -1764,6 +1796,20 @@ private:
     }
   }
 
+  // Function to determine if the input extension is the default theme
+  static bool isExtensionADuplicatedDefaultTheme(const Extension* e) {
+    if (!e->isDefaultTheme())
+      return false;
+    auto userThemePaths =
+      getUserDirPaths({"extensions", skin::SkinTheme::kThemesFolderName});
+    for (auto& p : userThemePaths) {
+      // Has the user path (p) the same path of the extension (e->path())?
+      if (std::strncmp(e->path().c_str(), p.c_str(), p.size()) == 0)
+        return true;
+    }
+    return false;
+  }
+
 #ifdef LAF_WINDOWS
   void onTabletAPIChange() {
     const bool pointerApi = tabletApiWindowsPointer()->isSelected();

src/app/extensions.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2020-2023  Igara Studio S.A.
+// Copyright (C) 2020-2024  Igara Studio S.A.
 // Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -51,12 +51,13 @@
 
 namespace app {
 
+const char* Extensions::kAsepriteDefaultThemeName = "aseprite-theme";
+
 namespace {
 
 const char* kPackageJson = "package.json";
 const char* kInfoJson = "__info.json";
 const char* kPrefLua = "__pref.lua";
-const char* kAsepriteDefaultThemeExtensionName = "aseprite-theme";
 
 class ReadArchive {
 public:
@@ -283,6 +284,8 @@ void Extension::addTheme(const std::string& id,
                          const std::string& path,
                          const std::string& variant)
 {
+  if (id == "default" && !isDefaultTheme())
+    return;
   m_themes[id] = ThemeInfo(path, variant);
   updateCategory(Category::Themes);
 }
@@ -519,7 +522,7 @@ bool Extension::isCurrentTheme() const
 
 bool Extension::isDefaultTheme() const
 {
-  return (name() == kAsepriteDefaultThemeExtensionName);
+  return name() == Extensions::kAsepriteDefaultThemeName;
 }
 
 void Extension::updateCategory(const Category newCategory)
@@ -1003,6 +1006,11 @@ ExtensionInfo Extensions::getCompressedExtensionInfo(const std::string& zipFn)
     std::string err;
     auto json = json11::Json::parse(out.str(), err);
     if (err.empty()) {
+      if (json["contributes"].is_object()) {
+        auto themes = json["contributes"]["themes"];
+        if (themes.is_array() && themes[0].is_object())
+          info.themeId = themes[0]["id"].string_value();
+      }
       info.name = json["name"].string_value();
       info.version = json["version"].string_value();
       info.dstPath = base::join_path(m_userExtensionsPath, info.name);

src/app/extensions.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2020-2023  Igara Studio S.A.
+// Copyright (C) 2020-2024  Igara Studio S.A.
 // Copyright (C) 2017-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -30,6 +30,7 @@ namespace app {
   class Extensions;
 
   struct ExtensionInfo {
+    std::string themeId;
     std::string name;
     std::string version;
     std::string dstPath;
@@ -54,6 +55,8 @@ namespace app {
       Max
     };
 
+    bool isDefaultTheme() const;
+
     class DitheringMatrixInfo {
     public:
       DitheringMatrixInfo();
@@ -150,7 +153,6 @@ namespace app {
     void uninstall(const DeletePluginPref delPref);
     void uninstallFiles(const std::string& path,
                         const DeletePluginPref delPref);
-    bool isDefaultTheme() const;
     void updateCategory(const Category newCategory);
 #ifdef ENABLE_SCRIPTING
     void initScripts();
@@ -196,6 +198,7 @@ namespace app {
   public:
     typedef std::vector<Extension*> List;
     typedef List::iterator iterator;
+    static const char* kAsepriteDefaultThemeName;
 
     Extensions();
     ~Extensions();