Use virtual paths to specify exact mod to enable (#11784)

6 files changed, 122 insertions, 50 deletions

diff --git a/src/content/mods.cpp b/src/content/mods.cpp
index 455506967..f75119bbb 100644
--- a/src/content/mods.cpp
+++ b/src/content/mods.cpp
@@ -89,7 +89,7 @@ void parseModContents(ModSpec &spec)
 			modpack2_is.close();
 
 		spec.is_modpack = true;
-		spec.modpack_content = getModsInPath(spec.path, true);
+		spec.modpack_content = getModsInPath(spec.path, spec.virtual_path, true);
 
 	} else {
 		Settings info;
@@ -167,13 +167,14 @@ void parseModContents(ModSpec &spec)
 }
 
 std::map<std::string, ModSpec> getModsInPath(
-		const std::string &path, bool part_of_modpack)
+		const std::string &path, const std::string &virtual_path, bool part_of_modpack)
 {
 	// NOTE: this function works in mutual recursion with parseModContents
 
 	std::map<std::string, ModSpec> result;
 	std::vector<fs::DirListNode> dirlist = fs::GetDirListing(path);
-	std::string modpath;
+	std::string mod_path;
+	std::string mod_virtual_path;
 
 	for (const fs::DirListNode &dln : dirlist) {
 		if (!dln.dir)
@@ -185,10 +186,14 @@ std::map<std::string, ModSpec> getModsInPath(
 		if (modname[0] == '.')
 			continue;
 
-		modpath.clear();
-		modpath.append(path).append(DIR_DELIM).append(modname);
+		mod_path.clear();
+		mod_path.append(path).append(DIR_DELIM).append(modname);
 
-		ModSpec spec(modname, modpath, part_of_modpack);
+		mod_virtual_path.clear();
+		// Intentionally uses / to keep paths same on different platforms
+		mod_virtual_path.append(virtual_path).append("/").append(modname);
+
+		ModSpec spec(modname, mod_path, part_of_modpack, mod_virtual_path);
 		parseModContents(spec);
 		result.insert(std::make_pair(modname, spec));
 	}
@@ -228,9 +233,9 @@ void ModConfiguration::printUnsatisfiedModsError() const
 	}
 }
 
-void ModConfiguration::addModsInPath(const std::string &path)
+void ModConfiguration::addModsInPath(const std::string &path, const std::string &virtual_path)
 {
-	addMods(flattenMods(getModsInPath(path)));
+	addMods(flattenMods(getModsInPath(path, virtual_path)));
 }
 
 void ModConfiguration::addMods(const std::vector<ModSpec> &new_mods)
@@ -294,29 +299,39 @@ void ModConfiguration::addMods(const std::vector<ModSpec> &new_mods)
 }
 
 void ModConfiguration::addModsFromConfig(
-		const std::string &settings_path, const std::set<std::string> &mods)
+		const std::string &settings_path,
+		const std::unordered_map<std::string, std::string> &modPaths)
 {
 	Settings conf;
-	std::set<std::string> load_mod_names;
+	std::unordered_map<std::string, std::string> load_mod_names;
 
 	conf.readConfigFile(settings_path.c_str());
 	std::vector<std::string> names = conf.getNames();
 	for (const std::string &name : names) {
-		if (name.compare(0, 9, "load_mod_") == 0 && conf.get(name) != "false" &&
-				conf.get(name) != "nil")
-			load_mod_names.insert(name.substr(9));
+		const auto &value = conf.get(name);
+		if (name.compare(0, 9, "load_mod_") == 0 && value != "false" &&
+				value != "nil")
+			load_mod_names[name.substr(9)] = value;
 	}
 
 	std::vector<ModSpec> addon_mods;
-	for (const std::string &i : mods) {
-		std::vector<ModSpec> addon_mods_in_path = flattenMods(getModsInPath(i));
+	std::unordered_map<std::string, std::vector<std::string>> candidates;
+
+	for (const auto &modPath : modPaths) {
+		std::vector<ModSpec> addon_mods_in_path = flattenMods(getModsInPath(modPath.second, modPath.first));
 		for (std::vector<ModSpec>::const_iterator it = addon_mods_in_path.begin();
 				it != addon_mods_in_path.end(); ++it) {
 			const ModSpec &mod = *it;
-			if (load_mod_names.count(mod.name) != 0)
-				addon_mods.push_back(mod);
-			else
+			const auto &pair = load_mod_names.find(mod.name);
+			if (pair != load_mod_names.end()) {
+				if (is_yes(pair->second) || pair->second == mod.virtual_path) {
+					addon_mods.push_back(mod);
+				} else {
+					candidates[pair->first].emplace_back(mod.virtual_path);
+				}
+			} else {
 				conf.setBool("load_mod_" + mod.name, false);
+			}
 		}
 	}
 	conf.updateConfigFile(settings_path.c_str());
@@ -335,9 +350,22 @@ void ModConfiguration::addModsFromConfig(
 
 	if (!load_mod_names.empty()) {
 		errorstream << "The following mods could not be found:";
-		for (const std::string &mod : load_mod_names)
-			errorstream << " \"" << mod << "\"";
+		for (const auto &pair : load_mod_names)
+			errorstream << " \"" << pair.first << "\"";
 		errorstream << std::endl;
+
+		for (const auto &pair : load_mod_names) {
+			const auto &candidate = candidates.find(pair.first);
+			if (candidate != candidates.end()) {
+				errorstream << "Unable to load " << pair.first << " as the specified path "
+					<< pair.second << " could not be found. "
+					<< "However, it is available in the following locations:"
+					<< std::endl;
+				for (const auto &path : candidate->second) {
+					errorstream << " - " << path << std::endl;
+				}
+			}
+		}
 	}
 }
 
@@ -413,10 +441,12 @@ void ModConfiguration::resolveDependencies()
 ClientModConfiguration::ClientModConfiguration(const std::string &path) :
 		ModConfiguration(path)
 {
-	std::set<std::string> paths;
+	std::unordered_map<std::string, std::string> paths;
 	std::string path_user = porting::path_user + DIR_DELIM + "clientmods";
-	paths.insert(path);
-	paths.insert(path_user);
+	if (path != path_user) {
+		paths["share"] = path;
+	}
+	paths["mods"] = path_user;
 
 	std::string settings_path = path_user + DIR_DELIM + "mods.conf";
 	addModsFromConfig(settings_path, paths);
diff --git a/src/content/mods.h b/src/content/mods.h
index dd3b6e0e6..ab0a9300e 100644
--- a/src/content/mods.h
+++ b/src/content/mods.h
@@ -51,17 +51,36 @@ struct ModSpec
 	bool part_of_modpack = false;
 	bool is_modpack = false;
 
+	/**
+	 * A constructed canonical path to represent this mod's location.
+	 * This intended to be used as an identifier for a modpath that tolerates file movement,
+	 * and cannot be used to read the mod files.
+	 *
+	 * Note that `mymod` is the directory name, not the mod name specified in mod.conf.
+	 *
+	 * Ex:
+	 *
+	 * - mods/mymod
+	 * - mods/mymod (1)
+	 *     (^ this would have name=mymod in mod.conf)
+	 * - mods/modpack1/mymod
+	 * - games/mygame/mods/mymod
+	 * - worldmods/mymod
+	 */
+	std::string virtual_path;
+
 	// For logging purposes
 	std::vector<const char *> deprecation_msgs;
 
 	// if modpack:
 	std::map<std::string, ModSpec> modpack_content;
-	ModSpec(const std::string &name = "", const std::string &path = "") :
-			name(name), path(path)
+
+	ModSpec()
 	{
 	}
-	ModSpec(const std::string &name, const std::string &path, bool part_of_modpack) :
-			name(name), path(path), part_of_modpack(part_of_modpack)
+
+	ModSpec(const std::string &name, const std::string &path, bool part_of_modpack, const std::string &virtual_path) :
+			name(name), path(path), part_of_modpack(part_of_modpack), virtual_path(virtual_path)
 	{
 	}
 
@@ -71,8 +90,16 @@ struct ModSpec
 // Retrieves depends, optdepends, is_modpack and modpack_content
 void parseModContents(ModSpec &mod);
 
-std::map<std::string, ModSpec> getModsInPath(
-		const std::string &path, bool part_of_modpack = false);
+/**
+ * Gets a list of all mods and modpacks in path
+ *
+ * @param Path to search, should be absolute
+ * @param part_of_modpack Is this searching within a modpack?
+ * @param virtual_path Virtual path for this directory, see comment in ModSpec
+ * @returns map of mods
+ */
+std::map<std::string, ModSpec> getModsInPath(const std::string &path,
+		const std::string &virtual_path, bool part_of_modpack = false);
 
 // replaces modpack Modspecs with their content
 std::vector<ModSpec> flattenMods(const std::map<std::string, ModSpec> &mods);
@@ -97,15 +124,25 @@ public:
 
 protected:
 	ModConfiguration(const std::string &worldpath);
-	// adds all mods in the given path. used for games, modpacks
-	// and world-specific mods (worldmods-folders)
-	void addModsInPath(const std::string &path);
+
+	/**
+	 * adds all mods in the given path. used for games, modpacks
+	 * and world-specific mods (worldmods-folders)
+	 *
+	 * @param path To search, should be absolute
+	 * @param virtual_path Virtual path for this directory, see comment in ModSpec
+	 */
+	void addModsInPath(const std::string &path, const std::string &virtual_path);
 
 	// adds all mods in the set.
 	void addMods(const std::vector<ModSpec> &new_mods);
 
+	/**
+	 * @param settings_path Path to world.mt
+	 * @param modPaths Map from virtual name to mod path
+	 */
 	void addModsFromConfig(const std::string &settings_path,
-			const std::set<std::string> &mods);
+			const std::unordered_map<std::string, std::string> &modPaths);
 
 	void checkConflictsAndDeps();
 
diff --git a/src/content/subgames.cpp b/src/content/subgames.cpp
index 62e82e0e4..23355990e 100644
--- a/src/content/subgames.cpp
+++ b/src/content/subgames.cpp
@@ -107,14 +107,13 @@ SubgameSpec findSubgame(const std::string &id)
 	std::string gamemod_path = game_path + DIR_DELIM + "mods";
 
 	// Find mod directories
-	std::set<std::string> mods_paths;
-	if (!user_game)
-		mods_paths.insert(share + DIR_DELIM + "mods");
-	if (user != share || user_game)
-		mods_paths.insert(user + DIR_DELIM + "mods");
+	std::unordered_map<std::string, std::string> mods_paths;
+	mods_paths["mods"] = user + DIR_DELIM + "mods";
+	if (!user_game && user != share)
+		mods_paths["share"] = share + DIR_DELIM + "mods";
 
 	for (const std::string &mod_path : getEnvModPaths()) {
-		mods_paths.insert(mod_path);
+		mods_paths[fs::AbsolutePath(mod_path)] = mod_path;
 	}
 
 	// Get meta
diff --git a/src/content/subgames.h b/src/content/subgames.h
index 4a50803e8..d36b4952f 100644
--- a/src/content/subgames.h
+++ b/src/content/subgames.h
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include <string>
 #include <set>
+#include <unordered_map>
 #include <vector>
 
 class Settings;
@@ -33,13 +34,16 @@ struct SubgameSpec
 	int release;
 	std::string path;
 	std::string gamemods_path;
-	std::set<std::string> addon_mods_paths;
+
+	/**
+	 * Map from virtual path to mods path
+	 */
+	std::unordered_map<std::string, std::string> addon_mods_paths;
 	std::string menuicon_path;
 
 	SubgameSpec(const std::string &id = "", const std::string &path = "",
 			const std::string &gamemods_path = "",
-			const std::set<std::string> &addon_mods_paths =
-					std::set<std::string>(),
+			const std::unordered_map<std::string, std::string> &addon_mods_paths = {},
 			const std::string &name = "",
 			const std::string &menuicon_path = "",
 			const std::string &author = "", int release = 0) :
diff --git a/src/script/lua_api/l_mainmenu.cpp b/src/script/lua_api/l_mainmenu.cpp
index 736ad022f..db031dde5 100644
--- a/src/script/lua_api/l_mainmenu.cpp
+++ b/src/script/lua_api/l_mainmenu.cpp
@@ -323,9 +323,9 @@ int ModApiMainMenu::l_get_games(lua_State *L)
 		lua_newtable(L);
 		int table2 = lua_gettop(L);
 		int internal_index = 1;
-		for (const std::string &addon_mods_path : game.addon_mods_paths) {
+		for (const auto &addon_mods_path : game.addon_mods_paths) {
 			lua_pushnumber(L, internal_index);
-			lua_pushstring(L, addon_mods_path.c_str());
+			lua_pushstring(L, addon_mods_path.second.c_str());
 			lua_settable(L,   table2);
 			internal_index++;
 		}
@@ -533,14 +533,14 @@ int ModApiMainMenu::l_get_modpath(lua_State *L)
 /******************************************************************************/
 int ModApiMainMenu::l_get_modpaths(lua_State *L)
 {
-	int index = 1;
 	lua_newtable(L);
+
 	ModApiMainMenu::l_get_modpath(L);
-	lua_rawseti(L, -2, index);
+	lua_setfield(L, -2, "mods");
+
 	for (const std::string &component : getEnvModPaths()) {
-		index++;
 		lua_pushstring(L, component.c_str());
-		lua_rawseti(L, -2, index);
+		lua_setfield(L, -2, fs::AbsolutePath(component).c_str());
 	}
 	return 1;
 }
diff --git a/src/server/mods.cpp b/src/server/mods.cpp
index 609d8c346..ba76d4746 100644
--- a/src/server/mods.cpp
+++ b/src/server/mods.cpp
@@ -41,8 +41,10 @@ ServerModManager::ServerModManager(const std::string &worldpath) :
 	SubgameSpec gamespec = findWorldSubgame(worldpath);
 
 	// Add all game mods and all world mods
-	addModsInPath(gamespec.gamemods_path);
-	addModsInPath(worldpath + DIR_DELIM + "worldmods");
+	std::string game_virtual_path;
+	game_virtual_path.append("games/").append(gamespec.id).append("/mods");
+	addModsInPath(gamespec.gamemods_path, game_virtual_path);
+	addModsInPath(worldpath + DIR_DELIM + "worldmods", "worldmods");
 
 	// Load normal mods
 	std::string worldmt = worldpath + DIR_DELIM + "world.mt";