18 files changed, 569 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index 27d5402..180afb8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 build
 doxygen
 .cache
+*.db
 
 CMakeLists.txt.user
 CMakeCache.txt
@@ -14,3 +15,4 @@ compile_commands.json
 CTestTestfile.cmake
 _deps
 CMakeUserPresets.json
+
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index b60a0cd..de9e990 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -11,6 +11,7 @@ find_package(SDL2 REQUIRED)
 find_package(SDL2_image REQUIRED)
 find_package(SoLoud REQUIRED)
 find_package(GTest REQUIRED)
+find_library(BERKELEY_DB db)
 
 add_library(crepe SHARED)
 add_executable(test_main EXCLUDE_FROM_ALL)
@@ -23,6 +24,7 @@ target_link_libraries(crepe
 	PRIVATE soloud
 	PUBLIC SDL2
 	PUBLIC SDL2_image
+	PUBLIC ${BERKELEY_DB}
 )
 
 add_subdirectory(crepe)
diff --git a/src/crepe/CMakeLists.txt b/src/crepe/CMakeLists.txt
index d938eb8..750a47d 100644
--- a/src/crepe/CMakeLists.txt
+++ b/src/crepe/CMakeLists.txt
@@ -12,8 +12,8 @@ target_sources(crepe PUBLIC
 	CollisionSystem.cpp
 	Collider.cpp
 	SDLContext.cpp
-
 	RenderSystem.cpp
+	DB.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -31,6 +31,9 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Collider.h
 	SDLContext.h
 	RenderSystem.h
+	ValueBroker.h
+	ValueBroker.hpp
+	DB.h
 )
 
 add_subdirectory(api)
diff --git a/src/crepe/DB.cpp b/src/crepe/DB.cpp
new file mode 100644
index 0000000..bd2f089
--- /dev/null
+++ b/src/crepe/DB.cpp
@@ -0,0 +1,67 @@
+#include <cstring>
+
+#include "util/log.h"
+
+#include "DB.h"
+
+using namespace std;
+using namespace crepe;
+
+DB::DB(const string & path) {
+	dbg_trace();
+	int ret;
+
+	// init database struct
+	libdb::DB * db;
+	if ((ret = libdb::db_create(&db, NULL, 0)) != 0)
+		throw nullptr; // TODO: exception
+	this->db = { db, [] (libdb::DB * db) { db->close(db, 0); } };
+
+	// load or create database file
+	if ((ret = this->db->open(this->db.get(), NULL, path.c_str(), NULL, libdb::DB_BTREE, DB_CREATE, 0)) != 0) {
+		throw nullptr;
+	}
+
+	// create cursor
+	libdb::DBC * cursor;
+	if ((ret = this->db->cursor(this->db.get(), NULL, &cursor, 0)) != 0) {
+		throw nullptr;
+	}
+	this->cursor = { cursor, [] (libdb::DBC * cursor) { cursor->close(cursor); } };
+}
+
+
+libdb::DBT DB::to_thing(const string & thing) const {
+	libdb::DBT thang;
+	memset(&thang, 0, sizeof(libdb::DBT));
+	thang.data = (void *) thing.data();
+	thang.size = thing.size();
+	return thang;
+}
+
+string DB::get(const string & key) {
+	libdb::DBT db_key = this->to_thing(key);
+	libdb::DBT db_val;
+	memset(&db_val, 0, sizeof(libdb::DBT));
+
+	int ret = this->cursor->get(this->cursor.get(), &db_key, &db_val, DB_FIRST);
+	if (ret != 0) throw nullptr; // TODO: proper exception
+	return { static_cast<char *>(db_val.data), db_val.size };
+}
+
+void DB::set(const string & key, const string & value) {
+	libdb::DBT db_key = this->to_thing(key);
+	libdb::DBT db_val = this->to_thing(value);
+	int ret = this->db->put(this->db.get(), NULL, &db_key, &db_val, 0);
+	if (ret != 0) throw nullptr; // TODO: proper exception
+}
+
+bool DB::has(const std::string & key) noexcept {
+	try {
+		this->get(key);
+	} catch (...) {
+		return false;
+	}
+	return true;
+}
+
diff --git a/src/crepe/DB.h b/src/crepe/DB.h
new file mode 100644
index 0000000..06442ad
--- /dev/null
+++ b/src/crepe/DB.h
@@ -0,0 +1,34 @@
+#pragma once
+
+#include <string>
+#include <functional>
+#include <memory>
+
+namespace libdb {
+extern "C" {
+#include <db.h>
+}
+}
+
+namespace crepe {
+
+class DB {
+public:
+	DB(const std::string & path);
+	virtual ~DB() = default;
+
+public:
+	std::string get(const std::string & key);
+	void set(const std::string & key, const std::string & value);
+	bool has(const std::string & key) noexcept;
+
+private:
+	std::unique_ptr<libdb::DB, std::function<void(libdb::DB *)>> db;
+	std::unique_ptr<libdb::DBC, std::function<void(libdb::DBC *)>> cursor;
+
+private:
+	libdb::DBT to_thing(const std::string & thing) const;
+};
+
+}
+
diff --git a/src/crepe/ValueBroker.h b/src/crepe/ValueBroker.h
new file mode 100644
index 0000000..c3359a1
--- /dev/null
+++ b/src/crepe/ValueBroker.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <functional>
+
+namespace crepe {
+
+template <typename T>
+class ValueBroker {
+public:
+	virtual void set(const T &);
+	virtual const T & get();
+
+	typedef std::function<void(const T & target)> setter_t;
+	typedef std::function<const T & ()> getter_t;
+private:
+	setter_t setter;
+	getter_t getter;
+public:
+	ValueBroker(const setter_t &, const getter_t &);
+	ValueBroker(T &);
+};
+
+}
+
+#include "ValueBroker.hpp"
+
diff --git a/src/crepe/ValueBroker.hpp b/src/crepe/ValueBroker.hpp
new file mode 100644
index 0000000..61f7f6c
--- /dev/null
+++ b/src/crepe/ValueBroker.hpp
@@ -0,0 +1,38 @@
+#pragma once
+
+#include <memory>
+
+#include "ValueBroker.h"
+
+namespace crepe {
+
+template <typename T>
+ValueBroker<T>::ValueBroker(T & value) :
+	setter([&value] (const T & target) {
+		value = std::move(target);
+	}),
+	getter([&value] () -> const int & {
+		return value;
+	})
+	{
+}
+
+template <typename T>
+ValueBroker<T>::ValueBroker(const setter_t & setter, const getter_t & getter) :
+	setter(setter),
+	getter(getter)
+	{
+}
+
+template <typename T>
+const T & ValueBroker<T>::get() {
+	return this->getter();
+}
+
+template <typename T>
+void ValueBroker<T>::set(const T & value) {
+	this->setter(value);
+}
+
+}
+
diff --git a/src/crepe/api/CMakeLists.txt b/src/crepe/api/CMakeLists.txt
index 0bb1263..abc96ab 100644
--- a/src/crepe/api/CMakeLists.txt
+++ b/src/crepe/api/CMakeLists.txt
@@ -11,6 +11,7 @@ target_sources(crepe PUBLIC
 	Texture.cpp
 	AssetManager.cpp
 	Sprite.cpp
+	SaveManager.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -28,4 +29,5 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Texture.h 
 	AssetManager.h 
 	AssetManager.hpp
+	SaveManager.h
 )
diff --git a/src/crepe/api/Config.h b/src/crepe/api/Config.h
index 8a7f268..aef4d54 100644
--- a/src/crepe/api/Config.h
+++ b/src/crepe/api/Config.h
@@ -35,6 +35,11 @@ public:
 		 */
 		bool color = true;
 	} log;
+
+	//! Save manager
+	struct {
+		std::string location = "save.crepe.db";
+	} savemgr;
 };
 
 } // namespace crepe::api
diff --git a/src/crepe/api/SaveManager.cpp b/src/crepe/api/SaveManager.cpp
new file mode 100644
index 0000000..87e634b
--- /dev/null
+++ b/src/crepe/api/SaveManager.cpp
@@ -0,0 +1,160 @@
+#include "../DB.h"
+#include "../util/log.h"
+
+#include "Config.h"
+#include "ValueBroker.h"
+#include "SaveManager.h"
+
+using namespace std;
+using namespace crepe;
+using namespace crepe::api;
+
+template <>
+string SaveManager::serialize(const string & value) {
+	return value;
+}
+template <typename T>
+string SaveManager::serialize(const T & value) {
+	return to_string(value);
+}
+template string SaveManager::serialize(const uint8_t &);
+template string SaveManager::serialize(const int8_t &);
+template string SaveManager::serialize(const uint16_t &);
+template string SaveManager::serialize(const int16_t &);
+template string SaveManager::serialize(const uint32_t &);
+template string SaveManager::serialize(const int32_t &);
+template string SaveManager::serialize(const uint64_t &);
+template string SaveManager::serialize(const int64_t &);
+template string SaveManager::serialize(const float &);
+template string SaveManager::serialize(const double &);
+
+template <>
+uint64_t SaveManager::deserialize(const string & value) {
+	try {
+		return stoul(value);
+	} catch (std::invalid_argument &) {
+		return 0;
+	}
+}
+template <>
+int64_t SaveManager::deserialize(const string & value) {
+	try {
+		return stol(value);
+	} catch (std::invalid_argument &) {
+		return 0;
+	}
+}
+template <>
+float SaveManager::deserialize(const string & value) {
+	try {
+		return stof(value);
+	} catch (std::invalid_argument &) {
+		return 0;
+	}
+	return stof(value);
+}
+template <>
+double SaveManager::deserialize(const string & value) {
+	try {
+		return stod(value);
+	} catch (std::invalid_argument &) {
+		return 0;
+	}
+}
+template <>
+string SaveManager::deserialize(const string & value) {
+	return value;
+}
+
+template <> uint8_t SaveManager::deserialize(const string & value) { return deserialize<uint64_t>(value); }
+template <> int8_t SaveManager::deserialize(const string & value) { return deserialize<int64_t>(value); }
+template <> uint16_t SaveManager::deserialize(const string & value) { return deserialize<uint64_t>(value); }
+template <> int16_t SaveManager::deserialize(const string & value) { return deserialize<int64_t>(value); }
+template <> uint32_t SaveManager::deserialize(const string & value) { return deserialize<uint64_t>(value); }
+template <> int32_t SaveManager::deserialize(const string & value) { return deserialize<int64_t>(value); }
+
+SaveManager::SaveManager() {
+	dbg_trace();
+}
+
+SaveManager & SaveManager::get_instance() {
+	dbg_trace();
+	static SaveManager instance;
+	return instance;
+}
+
+DB & SaveManager::get_db() {
+	Config & cfg = Config::get_instance();
+	// TODO: make this path relative to XDG_DATA_HOME on Linux and whatever the
+	// default equivalent is on Windows using some third party library
+	static DB db(cfg.savemgr.location);
+	return db;
+}
+
+bool SaveManager::has(const string & key) {
+	DB & db = this->get_db();
+	return db.has(key);
+}
+
+template <>
+void SaveManager::set(const string & key, const string & value) {
+	DB & db = this->get_db();
+	db.set(key, value);
+}
+template <typename T>
+void SaveManager::set(const string & key, const T & value) {
+	DB & db = this->get_db();
+	db.set(key, std::to_string(value));
+}
+template void SaveManager::set(const string &, const uint8_t &);
+template void SaveManager::set(const string &, const int8_t &);
+template void SaveManager::set(const string &, const uint16_t &);
+template void SaveManager::set(const string &, const int16_t &);
+template void SaveManager::set(const string &, const uint32_t &);
+template void SaveManager::set(const string &, const int32_t &);
+template void SaveManager::set(const string &, const uint64_t &);
+template void SaveManager::set(const string &, const int64_t &);
+template void SaveManager::set(const string &, const float &);
+template void SaveManager::set(const string &, const double &);
+
+template <typename T>
+ValueBroker<T> SaveManager::get(const string & key, const T & default_value) {
+	if (!this->has(key))
+		this->set<T>(key, default_value);
+	return this->get<T>(key);
+}
+template ValueBroker<uint8_t> SaveManager::get(const string &, const uint8_t &);
+template ValueBroker<int8_t> SaveManager::get(const string &, const int8_t &);
+template ValueBroker<uint16_t> SaveManager::get(const string &, const uint16_t &);
+template ValueBroker<int16_t> SaveManager::get(const string &, const int16_t &);
+template ValueBroker<uint32_t> SaveManager::get(const string &, const uint32_t &);
+template ValueBroker<int32_t> SaveManager::get(const string &, const int32_t &);
+template ValueBroker<uint64_t> SaveManager::get(const string &, const uint64_t &);
+template ValueBroker<int64_t> SaveManager::get(const string &, const int64_t &);
+template ValueBroker<float> SaveManager::get(const string &, const float &);
+template ValueBroker<double> SaveManager::get(const string &, const double &);
+template ValueBroker<string> SaveManager::get(const string &, const string &);
+
+template <typename T>
+ValueBroker<T> SaveManager::get(const string & key) {
+	T value;
+	return {
+		[this, key] (const T & target) { this->set<T>(key, target); },
+		[this, key, value] () mutable -> const T & {
+			value = this->deserialize<T>(this->get_db().get(key));
+			return value;
+		},
+	};
+}
+template ValueBroker<uint8_t> SaveManager::get(const string &);
+template ValueBroker<int8_t> SaveManager::get(const string &);
+template ValueBroker<uint16_t> SaveManager::get(const string &);
+template ValueBroker<int16_t> SaveManager::get(const string &);
+template ValueBroker<uint32_t> SaveManager::get(const string &);
+template ValueBroker<int32_t> SaveManager::get(const string &);
+template ValueBroker<uint64_t> SaveManager::get(const string &);
+template ValueBroker<int64_t> SaveManager::get(const string &);
+template ValueBroker<float> SaveManager::get(const string &);
+template ValueBroker<double> SaveManager::get(const string &);
+template ValueBroker<string> SaveManager::get(const string &);
+
diff --git a/src/crepe/api/SaveManager.h b/src/crepe/api/SaveManager.h
new file mode 100644
index 0000000..a1f239d
--- /dev/null
+++ b/src/crepe/api/SaveManager.h
@@ -0,0 +1,54 @@
+#pragma once
+
+#include <memory>
+
+#include "../ValueBroker.h"
+
+namespace crepe {
+class DB;
+}
+
+namespace crepe::api {
+
+class SaveManager {
+public:
+	//! Get a reference to a value and initialize it with a value if it does not yet exist
+	template <typename T>
+	ValueBroker<T> get(const std::string & key, const T & default_value);
+
+	//! Get a reference to a value
+	template <typename T>
+	ValueBroker<T> get(const std::string & key);
+
+	//! Set a value directly
+	template <typename T>
+	void set(const std::string & key, const T & value);
+
+	//! Check if the save file has a value for this \c key
+	bool has(const std::string & key);
+
+private:
+	SaveManager();
+	virtual ~SaveManager() = default;
+
+private:
+	template <typename T>
+	std::string serialize(const T &);
+
+	template <typename T>
+	T deserialize(const std::string &);
+
+public:
+	// singleton
+	static SaveManager & get_instance();
+	SaveManager(const SaveManager &) = delete;
+	SaveManager(SaveManager &&) = delete;
+	SaveManager & operator = (const SaveManager &) = delete;
+	SaveManager & operator = (SaveManager &&) = delete;
+
+private:
+	static DB & get_db();
+};
+
+}
+
diff --git a/src/crepe/util/CMakeLists.txt b/src/crepe/util/CMakeLists.txt
index bbeaad9..01d8f22 100644
--- a/src/crepe/util/CMakeLists.txt
+++ b/src/crepe/util/CMakeLists.txt
@@ -8,5 +8,7 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	color.h
 	log.h
 	fmt.h
+	Proxy.h
+	Proxy.hpp
 )
 
diff --git a/src/crepe/util/Proxy.h b/src/crepe/util/Proxy.h
new file mode 100644
index 0000000..89cb3c3
--- /dev/null
+++ b/src/crepe/util/Proxy.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "ValueBroker.h"
+
+namespace crepe::util {
+
+template <typename T>
+class Proxy {
+public:
+	Proxy & operator = (const T &);
+	operator const T & () const;
+
+public:
+	Proxy(ValueBroker<T>);
+
+private:
+	ValueBroker<T> broker;
+};
+
+}
+
+#include "Proxy.hpp"
+
diff --git a/src/crepe/util/Proxy.hpp b/src/crepe/util/Proxy.hpp
new file mode 100644
index 0000000..c2cae93
--- /dev/null
+++ b/src/crepe/util/Proxy.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "Proxy.h"
+
+namespace crepe::util {
+
+template <typename T>
+Proxy<T>::Proxy(ValueBroker<T> broker) : broker(broker) { }
+
+template <typename T>
+Proxy<T> & Proxy<T>::operator = (const T & val) {
+	this->broker.set(val);
+	return *this;
+}
+
+template <typename T>
+Proxy<T>::operator const T & () const {
+	return this->broker.get();
+}
+
+}
+
diff --git a/src/example/CMakeLists.txt b/src/example/CMakeLists.txt
index fea6f60..9698c41 100644
--- a/src/example/CMakeLists.txt
+++ b/src/example/CMakeLists.txt
@@ -24,3 +24,7 @@ add_example(rendering)
 add_example(asset_manager)
 add_example(particle)
 add_example(physics)
+add_example(savemgr)
+add_example(proxy)
+add_example(db)
+
diff --git a/src/example/db.cpp b/src/example/db.cpp
new file mode 100644
index 0000000..b1ab196
--- /dev/null
+++ b/src/example/db.cpp
@@ -0,0 +1,30 @@
+#include <crepe/DB.h>
+#include <crepe/api/Config.h>
+#include <crepe/util/log.h>
+
+using namespace crepe;
+using namespace std;
+
+// run before main
+static auto _ = [] () {
+	auto & cfg = api::Config::get_instance();
+	cfg.log.level = util::LogLevel::TRACE;
+	return 0;
+}();
+
+int main() {
+	dbg_trace();
+
+	DB db("file.db");
+
+	const char * test_key = "test-key";
+	string test_data = "Hello world!";
+
+	dbg_logf("DB has key = %d", db.has(test_key));
+
+	db.set(test_key, test_data);
+
+	dbg_logf("key = \"%s\"", db.get(test_key).c_str());
+
+	return 0;
+}
diff --git a/src/example/proxy.cpp b/src/example/proxy.cpp
new file mode 100644
index 0000000..0be4fac
--- /dev/null
+++ b/src/example/proxy.cpp
@@ -0,0 +1,47 @@
+/** \file
+ * 
+ * Standalone example for usage of the proxy type
+ */
+
+#include "ValueBroker.h"
+#include <crepe/api/Config.h>
+#include <crepe/util/log.h>
+#include <crepe/util/Proxy.h>
+
+using namespace std;
+using namespace crepe;
+using namespace crepe::util;
+
+void test_ro_ref(const int & val) { }
+void test_rw_ref(int & val) { }
+void test_ro_val(int val) { }
+
+int main() {
+	auto & cfg = api::Config::get_instance();
+	cfg.log.level = util::LogLevel::DEBUG;
+
+	int real_value = 0;
+
+	ValueBroker<int> broker {
+		[&real_value] (const int & target) {
+			dbg_logf("set %s to %s", to_string(real_value).c_str(), to_string(target).c_str());
+			real_value = target;
+		},
+		[&real_value] () -> const int & {
+			dbg_logf("get %s", to_string(real_value).c_str());
+			return real_value;
+		},
+	};
+
+	Proxy<int> proxy { broker };
+
+	broker.set(54);
+	proxy = 84;
+
+	test_ro_ref(proxy); // this is allowed
+	// test_rw_ref(proxy); // this should throw a compile error
+	test_ro_val(proxy);
+
+	return 0;
+}
+
diff --git a/src/example/savemgr.cpp b/src/example/savemgr.cpp
new file mode 100644
index 0000000..6d011e5
--- /dev/null
+++ b/src/example/savemgr.cpp
@@ -0,0 +1,47 @@
+/** \file
+ * 
+ * Standalone example for usage of the save manager
+ */
+
+#include <cassert>
+#include <crepe/util/log.h>
+#include <crepe/util/Proxy.h>
+#include <crepe/api/SaveManager.h>
+#include <crepe/api/Config.h>
+
+using namespace crepe;
+using namespace crepe::api;
+using namespace crepe::util;
+
+// unrelated setup code
+int _ = [] () {
+	// make sure all log messages get printed
+	auto & cfg = Config::get_instance();
+	cfg.log.level = util::LogLevel::TRACE;
+
+	return 0; // satisfy compiler
+} ();
+
+int main() {
+	const char * key = "mygame.test";
+
+	SaveManager & mgr = SaveManager::get_instance();
+
+	dbg_logf("has key = %s", mgr.has(key) ? "true" : "false");
+	ValueBroker<int> prop = mgr.get<int>(key, 0);
+	Proxy<int> val        = mgr.get<int>(key, 0);
+
+	dbg_logf("val = %d", mgr.get<int>(key).get());
+	prop.set(1);
+	dbg_logf("val = %d", mgr.get<int>(key).get());
+	val = 2;
+	dbg_logf("val = %d", mgr.get<int>(key).get());
+	mgr.set<int>(key, 3);
+	dbg_logf("val = %d", mgr.get<int>(key).get());
+
+	dbg_logf("has key = %s", mgr.has(key) ? "true" : "false");
+	assert(true == mgr.has(key));
+
+	return 0;
+}
+