Add mod loading support

	Supports command line
	Supports loading from `user://mods.cfg`

Author: Spartan322

extension/doc_classes/GameSingleton.xml

@@ -89,6 +89,15 @@
 				Returns the localization key [String] of the mapmode with the specified [param index].
 			</description>
 		</method>
+		<method name="get_mod_info" qualifiers="const">
+			<return type="Dictionary[]" />
+			<description>
+				Returns an [Array] of [Dictionary] containing information about available mods, with each [Dictionary] containing values for the following [StringName] keys:
+				- [code]"identifier"[/code] - The mod's [String] name
+				- [code]"dependencies"[/code] - A [PackedStringArray] of dependency mod names
+				- [code]"is_loaded"[/code] - Is [code]true[/code] if the mod is a currently loaded mod, else [code]false[/code]
+			</description>
+		</method>
 		<method name="get_province_colour_texture" qualifiers="const">
 			<return type="ImageTexture" />
 			<description>
@@ -153,8 +162,10 @@
 		</method>
 		<method name="load_defines_compatibility_mode">
 			<return type="int" enum="Error" />
+			<param index="0" name="mods" type="PackedStringArray" default="PackedStringArray()" />
 			<description>
-				Load compatibility mode text defines, localization string and map and flag images. Returns [code]FAILED[/code] if there are any problems when loading all this data, otherwise returns [code]OK[/code].
+				Load compatibility mode text defines, localization string and map and flag images, loading data from [param mods] if not empty. Returns [code]FAILED[/code] if there are any problems when loading all this data, otherwise returns [code]OK[/code].
+				See [method get_mod_info] for a valid list of values.
 			</description>
 		</method>
 		<method name="lookup_file_path" qualifiers="const">
@@ -173,10 +184,9 @@
 		</method>
 		<method name="set_compatibility_mode_roots">
 			<return type="int" enum="Error" />
-			<param index="0" name="file_paths" type="PackedStringArray" />
-			<param index="1" name="replace_paths" type="PackedStringArray" default="PackedStringArray()" />
+			<param index="0" name="path" type="String" />
 			<description>
-				Set the dataloading roots to those provided in [param file_paths], ignoring the filepaths in [param replace_paths] in favor of mods, which should contain full filepaths to the base game's installation and to any mods that are to be loaded on top of it. Returns [code]FAILED[/code] if there are any problems when setting the dataloading roots, otherwise returns [code]OK[/code].
+				Set the dataloading roots to those provided in [param path] which should contain full filepaths to the base game's installation and where the search for mods will begin from. Returns [code]FAILED[/code] if there are any problems when setting the dataloading roots, otherwise returns [code]OK[/code].
 			</description>
 		</method>
 		<method name="set_mapmode">

extension/src/openvic-extension/singletons/GameSingleton.cpp

@@ -4,8 +4,10 @@
 
 #include <godot_cpp/classes/time.hpp>
 #include <godot_cpp/core/error_macros.hpp>
+#include <godot_cpp/variant/packed_string_array.hpp>
 #include <godot_cpp/variant/utility_functions.hpp>
 
+#include <openvic-simulation/dataloader/ModManager.hpp>
 #include <openvic-simulation/utility/Containers.hpp>
 #include <openvic-simulation/utility/Logger.hpp>
 
@@ -16,6 +18,8 @@
 #include "openvic-extension/utility/ClassBindings.hpp"
 #include "openvic-extension/utility/Utilities.hpp"
 
+#include <range/v3/algorithm/contains.hpp>
+
 #include <spdlog/spdlog.h>
 #include <spdlog/sinks/callback_sink.h>
 
@@ -39,12 +43,14 @@ StringName const& GameSingleton::_signal_mapmode_changed() {
 void GameSingleton::_bind_methods() {
 	OV_BIND_SMETHOD(setup_logger);
 
-	OV_BIND_METHOD(GameSingleton::load_defines_compatibility_mode);
-	OV_BIND_METHOD(GameSingleton::set_compatibility_mode_roots, { "file_paths", "replace_paths" }, DEFVAL(PackedStringArray{}));
+	OV_BIND_METHOD(GameSingleton::load_defines_compatibility_mode, { "mods" }, DEFVAL(PackedStringArray()));
+	OV_BIND_METHOD(GameSingleton::set_compatibility_mode_roots, { "path" });
 
 	OV_BIND_SMETHOD(search_for_game_path, { "hint_path" }, DEFVAL(String {}));
 	OV_BIND_METHOD(GameSingleton::lookup_file_path, { "path" });
 
+	OV_BIND_METHOD(GameSingleton::get_mod_info);
+
 	OV_BIND_METHOD(GameSingleton::get_bookmark_info);
 	OV_BIND_METHOD(GameSingleton::setup_game, { "bookmark_index" });
 	OV_BIND_METHOD(GameSingleton::is_game_instance_setup);
@@ -143,6 +149,37 @@ void GameSingleton::setup_logger() {
 	spdlog::default_logger_raw()->sinks().push_back(std::move(godot_sink));
 }
 
+TypedArray<Dictionary> GameSingleton::get_mod_info() const {
+	static const StringName identifier_key = "identifier";
+	static const StringName dependencies_key = "dependencies";
+	static const StringName is_loaded_key = "is_loaded";
+
+	TypedArray<Dictionary> results;
+
+	ModManager const& mod_manager = game_manager.get_mod_manager();
+	memory::vector<Mod const*> const& loaded_mods = mod_manager.get_loaded_mods();
+
+	for (Mod const& mod : mod_manager.get_mods()) {
+		Dictionary mod_info_dictionary;
+
+		mod_info_dictionary[identifier_key] = Utilities::std_to_godot_string(mod.get_identifier());
+
+		mod_info_dictionary[dependencies_key] = [&]() -> PackedStringArray {
+			PackedStringArray result;
+			for (std::string_view dep_id : mod.get_dependencies()) {
+				result.push_back(Utilities::std_to_godot_string(dep_id));
+			}
+			return result;
+		}();
+
+		mod_info_dictionary[is_loaded_key] = ranges::contains(loaded_mods, &mod);
+
+		results.push_back(std::move(mod_info_dictionary));
+	}
+
+	return results;
+}
+
 TypedArray<Dictionary> GameSingleton::get_bookmark_info() const {
 	static const StringName bookmark_info_name_key = "bookmark_name";
 	static const StringName bookmark_info_date_key = "bookmark_date";
@@ -662,30 +699,29 @@ Error GameSingleton::_load_flag_sheet() {
 	return ret;
 }
 
-Error GameSingleton::set_compatibility_mode_roots(
-	PackedStringArray const& file_paths, godot::PackedStringArray const& replace_paths
-) {
-	Dataloader::path_vector_t roots;
-	roots.reserve(file_paths.size());
-	for (String const& path : file_paths) {
-		roots.emplace_back(Utilities::godot_to_std_string(path));
-	}
-
-	// TODO @BrickPI https://github.com/OpenVicProject/OpenVic/pull/512
-	// Dataloader::path_vector_t replace;
-	// replace.reserve(replace_paths.size());
-	// for (String const& path : replace_paths) {
-	// 	replace.emplace_back(Utilities::godot_to_std_string(path));
-	// }
-
+Error GameSingleton::set_compatibility_mode_roots(String const& path) {
+	Dataloader::path_vector_t roots { Utilities::godot_to_std_string(path) };
 	ERR_FAIL_COND_V_MSG(!game_manager.set_base_path(roots), FAILED, "Failed to set dataloader roots!");
 	return OK;
 }
 
-Error GameSingleton::load_defines_compatibility_mode() {
+Error GameSingleton::load_defines_compatibility_mode(PackedStringArray const& mods) {
 	Error err = OK;
 	auto add_message = std::bind_front(&LoadLocalisation::add_message, LoadLocalisation::get_singleton());
 
+	ERR_FAIL_COND_V_MSG(!game_manager.load_mod_descriptors(), FAILED, "Failed to load mod descriptors!");
+
+	memory::vector<memory::string> std_mods;
+	std_mods.reserve(mods.size());
+	for (String const& mod : mods) {
+		std_mods.emplace_back(Utilities::godot_to_std_string(mod));
+	}
+
+	memory::vector<fs::path> roots = game_manager.get_dataloader().get_roots();
+	memory::vector<fs::path> replaces = game_manager.get_dataloader().get_replace_paths();
+
+	ERR_FAIL_COND_V_MSG(!game_manager.load_mods(roots, replaces, std_mods), FAILED, "Loading mods failed.");
+
 	if (!game_manager.load_definitions(add_message)) {
 		UtilityFunctions::push_error("Failed to load defines!");
 		err = FAILED;

extension/src/openvic-extension/singletons/GameSingleton.hpp

@@ -2,6 +2,7 @@
 
 #include <godot_cpp/classes/image_texture.hpp>
 #include <godot_cpp/classes/texture2d_array.hpp>
+#include <godot_cpp/variant/packed_string_array.hpp>
 
 #include <openvic-simulation/GameManager.hpp>
 #include <openvic-simulation/dataloader/Dataloader.hpp>
@@ -66,14 +67,14 @@ namespace OpenVic {
 
 		/* Load the game's defines in compatibility mode from the filepath
 		 * pointing to the defines folder. */
-		godot::Error set_compatibility_mode_roots(
-			godot::PackedStringArray const& file_paths, godot::PackedStringArray const& replace_paths = {}
-		);
-		godot::Error load_defines_compatibility_mode();
+		godot::Error set_compatibility_mode_roots(godot::String const& path);
+		godot::Error load_defines_compatibility_mode(godot::PackedStringArray const& mods = {});
 
 		static godot::String search_for_game_path(godot::String const& hint_path = {});
 		godot::String lookup_file_path(godot::String const& path) const;
 
+		godot::TypedArray<godot::Dictionary> get_mod_info() const;
+
 		godot::TypedArray<godot::Dictionary> get_bookmark_info() const;
 
 		/* After initial load or resigning a previous session game setup, all mutable components of the simulation

game/src/Systems/Startup/GameStart.gd

@@ -13,7 +13,7 @@ const GameMenuScene := preload("res://src/UI/GameMenu/GameMenu/GameMenu.tscn")
 @export var setting_name : String = "base_defines_path"
 
 var _settings_base_path : String = ""
-var _compatibility_path_list : PackedStringArray = []
+var _mod_list : PackedStringArray = []
 
 func _enter_tree() -> void:
 	Keychain.keep_binding_check = func(action_name : StringName) -> bool:
@@ -127,21 +127,22 @@ func _setup_compatibility_mode_paths() -> void:
 		# Save the path found in the search
 		Events.Options.save_settings_to_file()
 
-	_compatibility_path_list = [actual_base_path]
-
 	# Add mod paths
-	var settings_mod_names : PackedStringArray = ArgumentParser.get_option_value(&"mod")
-	for mod_name : String in settings_mod_names:
-		_compatibility_path_list.push_back(actual_base_path + "/mod/" + mod_name)
+	var mod_status_file := ConfigFile.new()
+	mod_status_file.load("user://mods.cfg")
+	_mod_list = mod_status_file.get_value("mods", "load_list", [])
+	for mod in ArgumentParser.get_option_value(&"mod"):
+		if mod not in _mod_list and mod != "":
+			_mod_list.push_back(mod)
 
 func _load_compatibility_mode() -> void:
-	if GameSingleton.set_compatibility_mode_roots(_compatibility_path_list) != OK:
+	if GameSingleton.set_compatibility_mode_roots(_settings_base_path) != OK:
 		push_error("Errors setting game roots!")
 
 	CursorManager.initial_cursor_setup()
 	setup_title_theme()
 
-	if GameSingleton.load_defines_compatibility_mode() != OK:
+	if GameSingleton.load_defines_compatibility_mode(_mod_list) != OK:
 		push_error("Errors loading game defines!")
 
 	SoundSingleton.load_sounds()