Lua: Dynamic mod loading

Source/options.cpp

@@ -14,7 +14,10 @@
 #include <iterator>
 #include <optional>
 #include <span>
+#include <string>
+#include <unordered_set>
 
+#include <SDL.h>
 #include <SDL_version.h>
 #include <expected.hpp>
 #include <fmt/format.h>
@@ -58,6 +61,44 @@ namespace devilution {
 
 namespace {
 
+void LoadUserMods()
+{
+	const std::string modsPath = paths::BasePath() + "assets/lua/mods/";
+
+	// Check if the mods directory exists.
+	if (!DirectoryExists(modsPath.c_str()))
+		return;
+
+	// Use our helper function to get a list of directory names.
+	std::vector<std::string> modFolders = ListDirectories(modsPath.c_str());
+	std::unordered_set<std::string> modsInFolder;
+
+	// Iterate through each found mod folder.
+	for (const std::string &modFolder : modFolders) {
+		// Build the full path to the expected init.lua file.
+		std::string modScriptPath = modsPath + modFolder + DIRECTORY_SEPARATOR_STR + "init.lua";
+		// Only consider this folder if the init.lua file exists.
+		if (!FileExists(modScriptPath.c_str()))
+			continue;
+
+		// Record that this mod folder is present.
+		modsInFolder.insert(modFolder);
+
+		// Get the list of mods currently stored in the INI.
+		auto existingMods = GetOptions().Mods.GetModList();
+		// If the mod isn’t already registered, add it.
+		if (std::find(existingMods.begin(), existingMods.end(), modFolder) == existingMods.end())
+			GetOptions().Mods.AddModEntry(modFolder);
+	}
+
+	// Remove mods that are in the INI but no longer in the mods folder.
+	auto existingMods = GetOptions().Mods.GetModList();
+	for (const std::string_view &mod : existingMods) {
+		if (modsInFolder.find(std::string(mod)) == modsInFolder.end())
+			GetOptions().Mods.RemoveModEntry(std::string(mod));
+	}
+}
+
 std::optional<Ini> ini;
 
 #if defined(__ANDROID__) || (defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE == 1)
@@ -158,6 +199,7 @@ bool HardwareCursorSupported()
 void LoadOptions()
 {
 	LoadIni();
+	LoadUserMods();
 	Options &options = GetOptions();
 	for (OptionCategoryBase *pCategory : options.GetCategories()) {
 		for (OptionEntryBase *pEntry : pCategory->GetEntries()) {
@@ -1478,20 +1520,31 @@ std::vector<OptionEntryBase *> ModOptions::GetEntries()
 	return optionEntries;
 }
 
+void ModOptions::AddModEntry(const std::string &modName)
+{
+	auto &entries = GetModEntries();
+	entries.emplace_front(modName);
+}
+
+void ModOptions::RemoveModEntry(const std::string &modName)
+{
+	if (!modEntries) {
+		return;
+	}
+
+	auto &entries = *modEntries;
+	entries.remove_if([&](const ModEntry &entry) {
+		return entry.name == modName;
+	});
+}
+
 std::forward_list<ModOptions::ModEntry> &ModOptions::GetModEntries()
 {
 	if (modEntries)
 		return *modEntries;
 
 	std::vector<std::string> modNames = ini->getKeys(key);
 
-	// Add mods available by default:
-	for (const std::string_view modName : { "clock" }) {
-		if (c_find(modNames, modName) != modNames.end()) continue;
-		ini->set(key, modName, false);
-		modNames.emplace_back(modName);
-	}
-
 	std::forward_list<ModOptions::ModEntry> &newModEntries = modEntries.emplace();
 	for (auto &modName : modNames) {
 		newModEntries.emplace_front(modName);

Source/options.h

@@ -830,6 +830,8 @@ struct ModOptions : OptionCategoryBase {
 	std::vector<std::string_view> GetActiveModList();
 	std::vector<std::string_view> GetModList();
 	std::vector<OptionEntryBase *> GetEntries() override;
+	void AddModEntry(const std::string &modName);
+	void RemoveModEntry(const std::string &modName);
 
 private:
 	struct ModEntry {

Source/utils/file_util.cpp

@@ -5,9 +5,6 @@
 #include <cstdint>
 #include <cstring>
 #include <limits>
-#include <string>
-#include <string_view>
-#include <vector>
 
 #include <SDL.h>
 
@@ -47,6 +44,12 @@
 #endif
 #endif
 
+#ifdef NXDK
+#include <windows.h> // For WIN32_FIND_DATAA, FindFirstFileA, etc.
+#else
+#include <filesystem>
+#endif
+
 namespace devilution {
 
 #if defined(_WIN32) && !defined(DEVILUTIONX_WINDOWS_NO_WCHAR)
@@ -472,4 +475,34 @@ FILE *OpenFile(const char *path, const char *mode)
 #endif
 }
 
+std::vector<std::string> ListDirectories(const char *path)
+{
+	std::vector<std::string> dirs;
+#ifdef NXDK
+	// Use the NXDK Windows API.
+	WIN32_FIND_DATAA findData;
+	// Construct the search path by appending the directory separator and wildcard.
+	std::string searchPath = std::string(path) + DIRECTORY_SEPARATOR_STR + "*";
+	HANDLE hFind = FindFirstFileA(searchPath.c_str(), &findData);
+	if (hFind == INVALID_HANDLE_VALUE)
+		return dirs;
+	do {
+		std::string folder = findData.cFileName;
+		// Skip the special entries "." and ".."
+		if (folder == "." || folder == "..")
+			continue;
+		if (findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+			dirs.push_back(folder);
+	} while (FindNextFileA(hFind, &findData));
+	FindClose(hFind);
+#else
+	// For platforms that support std::filesystem.
+	for (const auto &entry : std::filesystem::directory_iterator(path)) {
+		if (entry.is_directory())
+			dirs.push_back(entry.path().filename().string());
+	}
+#endif
+	return dirs;
+}
+
 } // namespace devilution

Source/utils/file_util.h

@@ -5,6 +5,7 @@
 #include <memory>
 #include <string>
 #include <string_view>
+#include <vector>
 
 namespace devilution {
 
@@ -46,4 +47,6 @@ FILE *OpenFile(const char *path, const char *mode);
 std::unique_ptr<wchar_t[]> ToWideChar(std::string_view path);
 #endif
 
+std::vector<std::string> ListDirectories(const char *path);
+
 } // namespace devilution