[CSM] implement client side mod loading (#5123)

* client side mods are located in clientmods/
* move builtin/preview.lua to clientmods/preview/init.lua as a preview mod
* refactor ModConfiguration class to work properly with client and server using child objects
* move some Server constructor mod load code to ModConfiguration to reduce code duplication between client and server
* remove mods.{cpp,h} unused functions
* use UNORDERED_SET instead of std::set in some modspec storages

9 files changed, 194 insertions, 148 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d2568a9ae..7fe950c81 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -152,6 +152,7 @@ endif()
 
 install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/builtin" DESTINATION "${SHAREDIR}")
 install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/client" DESTINATION "${SHAREDIR}")
+install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/clientmods" DESTINATION "${SHAREDIR}")
 install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/games" DESTINATION "${SHAREDIR}" PATTERN ".git*" EXCLUDE)
 
 if(BUILD_CLIENT)
diff --git a/builtin/client/chatcommands.lua b/builtin/client/chatcommands.lua
index b49c222ef..43b4d9a72 100644
--- a/builtin/client/chatcommands.lua
+++ b/builtin/client/chatcommands.lua
@@ -5,24 +5,24 @@ core.register_on_sending_chat_messages(function(message)
 	if not (message:sub(1,1) == "/") then
 		return false
 	end
-	
+
 	core.display_chat_message("issued command: " .. message)
-	
+
 	local cmd, param = string.match(message, "^/([^ ]+) *(.*)")
 	if not param then
 		param = ""
 	end
-	
+
 	local cmd_def = core.registered_chatcommands[cmd]
-	
+
 	if cmd_def then
 		core.set_last_run_mod(cmd_def.mod_origin)
-		local success, message = cmd_def.func(param)
+		local _, message = cmd_def.func(param)
 		if message then
 			core.display_chat_message(message)
 		end
 		return true
 	end
-	
+
 	return false
-end)
\ No newline at end of file
+end)
diff --git a/builtin/client/init.lua b/builtin/client/init.lua
index b204ee5e6..592274540 100644
--- a/builtin/client/init.lua
+++ b/builtin/client/init.lua
@@ -7,7 +7,6 @@ dofile(clientpath .. "register.lua")
 dofile(commonpath .. "after.lua")
 dofile(commonpath .. "chatcommands.lua")
 dofile(clientpath .. "chatcommands.lua")
-dofile(clientpath .. "preview.lua")
 
 core.register_on_death(function()
 	core.display_chat_message("You died.")
diff --git a/builtin/client/preview.lua b/clientmods/preview/init.lua
index 4c01d665f..4c01d665f 100644
--- a/builtin/client/preview.lua
+++ b/clientmods/preview/init.lua
diff --git a/src/client.cpp b/src/client.cpp
index 3b8074252..4bb63fef1 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -268,14 +268,50 @@ Client::Client(
 
 void Client::initMods()
 {
-	std::string script_path = getBuiltinLuaPath() + DIR_DELIM "init.lua";
+	m_script->loadMod(getBuiltinLuaPath() + DIR_DELIM "init.lua", BUILTIN_MOD_NAME);
+
+	ClientModConfiguration modconf(getClientModsLuaPath());
+	std::vector<ModSpec> mods = modconf.getMods();
+	std::vector<ModSpec> unsatisfied_mods = modconf.getUnsatisfiedMods();
+	// complain about mods with unsatisfied dependencies
+	if (!modconf.isConsistent()) {
+		modconf.printUnsatisfiedModsError();
+	}
+
+	// Print mods
+	infostream << "Client Loading mods: ";
+	for (std::vector<ModSpec>::const_iterator i = mods.begin();
+		i != mods.end(); ++i) {
+		infostream << (*i).name << " ";
+	}
+
+	infostream << std::endl;
+	// Load and run "mod" scripts
+	for (std::vector<ModSpec>::const_iterator it = mods.begin();
+		it != mods.end(); ++it) {
+		const ModSpec &mod = *it;
+		if (!string_allowed(mod.name, MODNAME_ALLOWED_CHARS)) {
+			throw ModError("Error loading mod \"" + mod.name +
+				"\": Mod name does not follow naming conventions: "
+					"Only chararacters [a-z0-9_] are allowed.");
+		}
+		std::string script_path = mod.path + DIR_DELIM + "init.lua";
+		infostream << "  [" << padStringRight(mod.name, 12) << "] [\""
+			<< script_path << "\"]" << std::endl;
+		m_script->loadMod(script_path, mod.name);
+	}
+}
 
-	m_script->loadMod(script_path, BUILTIN_MOD_NAME);
+const std::string &Client::getBuiltinLuaPath()
+{
+	static const std::string builtin_dir = porting::path_share + DIR_DELIM + "builtin";
+	return builtin_dir;
 }
 
-const std::string Client::getBuiltinLuaPath()
+const std::string &Client::getClientModsLuaPath()
 {
-	return porting::path_share + DIR_DELIM + "builtin";
+	static const std::string clientmods_dir = porting::path_share + DIR_DELIM + "clientmods";
+	return clientmods_dir;
 }
 
 const std::vector<ModSpec>& Client::getMods() const
diff --git a/src/client.h b/src/client.h
index d170f9a07..9b7130268 100644
--- a/src/client.h
+++ b/src/client.h
@@ -433,7 +433,8 @@ public:
 	ClientEnvironment& getEnv() { return m_env; }
 	ITextureSource *tsrc() { return getTextureSource(); }
 	ISoundManager *sound() { return getSoundManager(); }
-	static const std::string getBuiltinLuaPath();
+	static const std::string &getBuiltinLuaPath();
+	static const std::string &getClientModsLuaPath();
 
 	virtual const std::vector<ModSpec> &getMods() const;
 	virtual const ModSpec* getModSpec(const std::string &modname) const;
diff --git a/src/mods.cpp b/src/mods.cpp
index bae9a42d3..5a7dc6dca 100644
--- a/src/mods.cpp
+++ b/src/mods.cpp
@@ -25,6 +25,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "subgame.h"
 #include "settings.h"
 #include "convert_json.h"
+#include "exceptions.h"
+#include "porting.h"
 
 static bool parseDependsLine(std::istream &is,
 		std::string &dep, std::set<char> &symbols)
@@ -107,28 +109,6 @@ std::map<std::string, ModSpec> getModsInPath(std::string path, bool part_of_modp
 	return result;
 }
 
-std::map<std::string, ModSpec> flattenModTree(std::map<std::string, ModSpec> mods)
-{
-	std::map<std::string, ModSpec> result;
-	for(std::map<std::string,ModSpec>::iterator it = mods.begin();
-		it != mods.end(); ++it)
-	{
-		ModSpec mod = (*it).second;
-		if(mod.is_modpack)
-		{
-			std::map<std::string, ModSpec> content =
-				flattenModTree(mod.modpack_content);
-			result.insert(content.begin(),content.end());
-			result.insert(std::make_pair(mod.name,mod));
-		}
-		else //not a modpack
-		{
-			result.insert(std::make_pair(mod.name,mod));
-		}
-	}
-	return result;
-}
-
 std::vector<ModSpec> flattenMods(std::map<std::string, ModSpec> mods)
 {
 	std::vector<ModSpec> result;
@@ -151,78 +131,32 @@ std::vector<ModSpec> flattenMods(std::map<std::string, ModSpec> mods)
 	return result;
 }
 
-ModConfiguration::ModConfiguration(std::string worldpath)
+ModConfiguration::ModConfiguration(const std::string &worldpath):
+	m_unsatisfied_mods(),
+	m_sorted_mods(),
+	m_name_conflicts()
 {
-	SubgameSpec gamespec = findWorldSubgame(worldpath);
-
-	// Add all game mods and all world mods
-	addModsInPath(gamespec.gamemods_path);
-	addModsInPath(worldpath + DIR_DELIM + "worldmods");
-
-	// check world.mt file for mods explicitely declared to be
-	// loaded or not by a load_mod_<modname> = ... line.
-	std::string worldmt = worldpath+DIR_DELIM+"world.mt";
-	Settings worldmt_settings;
-	worldmt_settings.readConfigFile(worldmt.c_str());
-	std::vector<std::string> names = worldmt_settings.getNames();
-	std::set<std::string> include_mod_names;
-	for(std::vector<std::string>::iterator it = names.begin();
-		it != names.end(); ++it)
-	{
-		std::string name = *it;
-		// for backwards compatibility: exclude only mods which are
-		// explicitely excluded. if mod is not mentioned at all, it is
-		// enabled. So by default, all installed mods are enabled.
-		if (name.compare(0,9,"load_mod_") == 0 &&
-			worldmt_settings.getBool(name))
-		{
-			include_mod_names.insert(name.substr(9));
-		}
-	}
-
-	// Collect all mods that are also in include_mod_names
-	std::vector<ModSpec> addon_mods;
-	for(std::set<std::string>::const_iterator it_path = gamespec.addon_mods_paths.begin();
-			it_path != gamespec.addon_mods_paths.end(); ++it_path)
-	{
-		std::vector<ModSpec> addon_mods_in_path = flattenMods(getModsInPath(*it_path));
-		for(std::vector<ModSpec>::iterator it = addon_mods_in_path.begin();
-			it != addon_mods_in_path.end(); ++it)
-		{
-			ModSpec& mod = *it;
-			if(include_mod_names.count(mod.name) != 0)
-				addon_mods.push_back(mod);
-			else
-				worldmt_settings.setBool("load_mod_" + mod.name, false);
-		}
-	}
-	worldmt_settings.updateConfigFile(worldmt.c_str());
-
-	addMods(addon_mods);
+}
 
-	// report on name conflicts
-	if(!m_name_conflicts.empty()){
-		std::string s = "Unresolved name conflicts for mods ";
-		for(std::set<std::string>::const_iterator it = m_name_conflicts.begin();
-				it != m_name_conflicts.end(); ++it)
-		{
-			if(it != m_name_conflicts.begin()) s += ", ";
-			s += std::string("\"") + (*it) + "\"";
-		}
-		s += ".";
-		throw ModError(s);
+void ModConfiguration::printUnsatisfiedModsError() const
+{
+	for (std::vector<ModSpec>::const_iterator it = m_unsatisfied_mods.begin();
+		it != m_unsatisfied_mods.end(); ++it) {
+		ModSpec mod = *it;
+		errorstream << "mod \"" << mod.name << "\" has unsatisfied dependencies: ";
+		for (UNORDERED_SET<std::string>::iterator dep_it = mod.unsatisfied_depends.begin();
+			dep_it != mod.unsatisfied_depends.end(); ++dep_it)
+			errorstream << " \"" << *dep_it << "\"";
+		errorstream << std::endl;
 	}
-
-	// get the mods in order
-	resolveDependencies();
 }
 
-void ModConfiguration::addModsInPath(std::string path)
+void ModConfiguration::addModsInPath(const std::string &path)
 {
 	addMods(flattenMods(getModsInPath(path)));
 }
 
-void ModConfiguration::addMods(std::vector<ModSpec> new_mods)
+void ModConfiguration::addMods(const std::vector<ModSpec> &new_mods)
 {
 	// Maintain a map of all existing m_unsatisfied_mods.
 	// Keys are mod names and values are indices into m_unsatisfied_mods.
@@ -240,8 +174,8 @@ void ModConfiguration::addMods(std::vector<ModSpec> new_mods)
 
 		std::set<std::string> seen_this_iteration;
 
-		for(std::vector<ModSpec>::const_iterator it = new_mods.begin();
-				it != new_mods.end(); ++it){
+		for (std::vector<ModSpec>::const_iterator it = new_mods.begin();
+				it != new_mods.end(); ++it) {
 			const ModSpec &mod = *it;
 			if(mod.part_of_modpack != (bool)want_from_modpack)
 				continue;
@@ -280,6 +214,24 @@ void ModConfiguration::addMods(std::vector<ModSpec> new_mods)
 	}
 }
 
+void ModConfiguration::checkConflictsAndDeps()
+{
+	// report on name conflicts
+	if (!m_name_conflicts.empty()) {
+		std::string s = "Unresolved name conflicts for mods ";
+		for (UNORDERED_SET<std::string>::const_iterator it = m_name_conflicts.begin();
+			it != m_name_conflicts.end(); ++it) {
+			if (it != m_name_conflicts.begin()) s += ", ";
+			s += std::string("\"") + (*it) + "\"";
+		}
+		s += ".";
+		throw ModError(s);
+	}
+
+	// get the mods in order
+	resolveDependencies();
+}
+
 void ModConfiguration::resolveDependencies()
 {
 	// Step 1: Compile a list of the mod names we're working with
@@ -293,19 +245,19 @@ void ModConfiguration::resolveDependencies()
 	// of each mod, split mods into satisfied and unsatisfied
 	std::list<ModSpec> satisfied;
 	std::list<ModSpec> unsatisfied;
-	for(std::vector<ModSpec>::iterator it = m_unsatisfied_mods.begin();
-			it != m_unsatisfied_mods.end(); ++it){
+	for (std::vector<ModSpec>::iterator it = m_unsatisfied_mods.begin();
+			it != m_unsatisfied_mods.end(); ++it) {
 		ModSpec mod = *it;
 		mod.unsatisfied_depends = mod.depends;
 		// check which optional dependencies actually exist
-		for(std::set<std::string>::iterator it_optdep = mod.optdepends.begin();
-				it_optdep != mod.optdepends.end(); ++it_optdep){
+		for (UNORDERED_SET<std::string>::iterator it_optdep = mod.optdepends.begin();
+				it_optdep != mod.optdepends.end(); ++it_optdep) {
 			std::string optdep = *it_optdep;
-			if(modnames.count(optdep) != 0)
+			if (modnames.count(optdep) != 0)
 				mod.unsatisfied_depends.insert(optdep);
 		}
 		// if a mod has no depends it is initially satisfied
-		if(mod.unsatisfied_depends.empty())
+		if (mod.unsatisfied_depends.empty())
 			satisfied.push_back(mod);
 		else
 			unsatisfied.push_back(mod);
@@ -335,6 +287,65 @@ void ModConfiguration::resolveDependencies()
 	m_unsatisfied_mods.assign(unsatisfied.begin(), unsatisfied.end());
 }
 
+ServerModConfiguration::ServerModConfiguration(const std::string &worldpath):
+	ModConfiguration(worldpath)
+{
+	SubgameSpec gamespec = findWorldSubgame(worldpath);
+
+	// Add all game mods and all world mods
+	addModsInPath(gamespec.gamemods_path);
+	addModsInPath(worldpath + DIR_DELIM + "worldmods");
+
+	// check world.mt file for mods explicitely declared to be
+	// loaded or not by a load_mod_<modname> = ... line.
+	std::string worldmt = worldpath+DIR_DELIM+"world.mt";
+	Settings worldmt_settings;
+	worldmt_settings.readConfigFile(worldmt.c_str());
+	std::vector<std::string> names = worldmt_settings.getNames();
+	std::set<std::string> include_mod_names;
+	for (std::vector<std::string>::const_iterator it = names.begin();
+		it != names.end(); ++it) {
+		std::string name = *it;
+		// for backwards compatibility: exclude only mods which are
+		// explicitely excluded. if mod is not mentioned at all, it is
+		// enabled. So by default, all installed mods are enabled.
+		if (name.compare(0,9,"load_mod_") == 0 &&
+			worldmt_settings.getBool(name)) {
+			include_mod_names.insert(name.substr(9));
+		}
+	}
+
+	// Collect all mods that are also in include_mod_names
+	std::vector<ModSpec> addon_mods;
+	for (std::set<std::string>::const_iterator it_path = gamespec.addon_mods_paths.begin();
+		it_path != gamespec.addon_mods_paths.end(); ++it_path) {
+		std::vector<ModSpec> addon_mods_in_path = flattenMods(getModsInPath(*it_path));
+		for (std::vector<ModSpec>::const_iterator it = addon_mods_in_path.begin();
+			it != addon_mods_in_path.end(); ++it) {
+			const ModSpec& mod = *it;
+			if (include_mod_names.count(mod.name) != 0)
+				addon_mods.push_back(mod);
+			else
+				worldmt_settings.setBool("load_mod_" + mod.name, false);
+		}
+	}
+	worldmt_settings.updateConfigFile(worldmt.c_str());
+
+	addMods(addon_mods);
+
+	checkConflictsAndDeps();
+}
+
+#ifndef SERVER
+ClientModConfiguration::ClientModConfiguration(const std::string &path):
+	ModConfiguration(path)
+{
+	addModsInPath(path);
+	addModsInPath(porting::path_user + DIR_DELIM + "clientmods");
+	checkConflictsAndDeps();
+}
+#endif
+
 #if USE_CURL
 Json::Value getModstoreUrl(std::string url)
 {
diff --git a/src/mods.h b/src/mods.h
index 61af5e5d1..c9bd51d99 100644
--- a/src/mods.h
+++ b/src/mods.h
@@ -27,6 +27,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <string>
 #include <map>
 #include <json/json.h>
+#include "util/cpp11_container.h"
 #include "config.h"
 #include "metadata.h"
 
@@ -37,9 +38,9 @@ struct ModSpec
 	std::string name;
 	std::string path;
 	//if normal mod:
-	std::set<std::string> depends;
-	std::set<std::string> optdepends;
-	std::set<std::string> unsatisfied_depends;
+	UNORDERED_SET<std::string> depends;
+	UNORDERED_SET<std::string> optdepends;
+	UNORDERED_SET<std::string> unsatisfied_depends;
 
 	bool part_of_modpack;
 	bool is_modpack;
@@ -62,12 +63,6 @@ void parseModContents(ModSpec &mod);
 
 std::map<std::string,ModSpec> getModsInPath(std::string path, bool part_of_modpack = false);
 
-// If failed, returned modspec has name==""
-ModSpec findCommonMod(const std::string &modname);
-
-// expands modpack contents, but does not replace them.
-std::map<std::string, ModSpec> flattenModTree(std::map<std::string, ModSpec> mods);
-
 // replaces modpack Modspecs with their content
 std::vector<ModSpec> flattenMods(std::map<std::string,ModSpec> mods);
 
@@ -77,17 +72,8 @@ std::vector<ModSpec> flattenMods(std::map<std::string,ModSpec> mods);
 class ModConfiguration
 {
 public:
-	ModConfiguration():
-		m_unsatisfied_mods(),
-		m_sorted_mods(),
-		m_name_conflicts()
-	{}
-
-
-	ModConfiguration(std::string worldpath);
-
 	// checks if all dependencies are fullfilled.
-	bool isConsistent()
+	bool isConsistent() const
 	{
 		return m_unsatisfied_mods.empty();
 	}
@@ -97,19 +83,24 @@ public:
 		return m_sorted_mods;
 	}
 
-	std::vector<ModSpec> getUnsatisfiedMods()
+	const std::vector<ModSpec> &getUnsatisfiedMods() const
 	{
 		return m_unsatisfied_mods;
 	}
 
-private:
+	void printUnsatisfiedModsError() const;
+
+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(std::string path);
+	void addModsInPath(const std::string &path);
 
 	// adds all mods in the set.
-	void addMods(std::vector<ModSpec> new_mods);
+	void addMods(const std::vector<ModSpec> &new_mods);
 
+	void checkConflictsAndDeps();
+private:
 	// move mods from m_unsatisfied_mods to m_sorted_mods
 	// in an order that satisfies dependencies
 	void resolveDependencies();
@@ -132,10 +123,28 @@ private:
 	// 1. game mod in modpack; 2. game mod;
 	// 3. world mod in modpack; 4. world mod;
 	// 5. addon mod in modpack; 6. addon mod.
-	std::set<std::string> m_name_conflicts;
+	UNORDERED_SET<std::string> m_name_conflicts;
+
+	// Deleted default constructor
+	ModConfiguration() {}
 
 };
 
+class ServerModConfiguration: public ModConfiguration
+{
+public:
+	ServerModConfiguration(const std::string &worldpath);
+
+};
+
+#ifndef SERVER
+class ClientModConfiguration: public ModConfiguration
+{
+public:
+	ClientModConfiguration(const std::string &path);
+};
+#endif
+
 #if USE_CURL
 Json::Value getModstoreUrl(std::string url);
 #else
diff --git a/src/server.cpp b/src/server.cpp
index 3adbf40cc..dd6c9a418 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -218,20 +218,12 @@ Server::Server(
 	std::string ban_path = m_path_world + DIR_DELIM "ipban.txt";
 	m_banmanager = new BanManager(ban_path);
 
-	ModConfiguration modconf(m_path_world);
+	ServerModConfiguration modconf(m_path_world);
 	m_mods = modconf.getMods();
 	std::vector<ModSpec> unsatisfied_mods = modconf.getUnsatisfiedMods();
 	// complain about mods with unsatisfied dependencies
-	if(!modconf.isConsistent()) {
-		for(std::vector<ModSpec>::iterator it = unsatisfied_mods.begin();
-			it != unsatisfied_mods.end(); ++it) {
-			ModSpec mod = *it;
-			errorstream << "mod \"" << mod.name << "\" has unsatisfied dependencies: ";
-			for(std::set<std::string>::iterator dep_it = mod.unsatisfied_depends.begin();
-				dep_it != mod.unsatisfied_depends.end(); ++dep_it)
-				errorstream << " \"" << *dep_it << "\"";
-			errorstream << std::endl;
-		}
+	if (!modconf.isConsistent()) {
+		modconf.printUnsatisfiedModsError();
 	}
 
 	Settings worldmt_settings;
@@ -271,20 +263,17 @@ Server::Server(
 
 	m_script = new ServerScripting(this);
 
-	std::string script_path = getBuiltinLuaPath() + DIR_DELIM "init.lua";
-
-	m_script->loadMod(script_path, BUILTIN_MOD_NAME);
+	m_script->loadMod(getBuiltinLuaPath() + DIR_DELIM "init.lua", BUILTIN_MOD_NAME);
 
 	// Print mods
 	infostream << "Server: Loading mods: ";
-	for(std::vector<ModSpec>::iterator i = m_mods.begin();
+	for (std::vector<ModSpec>::const_iterator i = m_mods.begin();
 			i != m_mods.end(); ++i) {
-		const ModSpec &mod = *i;
-		infostream << mod.name << " ";
+		infostream << (*i).name << " ";
 	}
 	infostream << std::endl;
 	// Load and run "mod" scripts
-	for (std::vector<ModSpec>::iterator it = m_mods.begin();
+	for (std::vector<ModSpec>::const_iterator it = m_mods.begin();
 			it != m_mods.end(); ++it) {
 		const ModSpec &mod = *it;
 		if (!string_allowed(mod.name, MODNAME_ALLOWED_CHARS)) {