4 files changed, 201 insertions, 0 deletions
diff --git a/src/Logger/Logger.c b/src/Logger/Logger.c
new file mode 100644
index 0000000..c43b24b
--- /dev/null
+++ b/src/Logger/Logger.c
@@ -0,0 +1,102 @@
+#include "Logger/Logger.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+static LogLevel current_level = LOG_LEVEL_INFO;
+
+static const char *level_name(LogLevel level) {
+  switch (level) {
+  case LOG_LEVEL_ERROR:
+    return "error";
+  case LOG_LEVEL_WARNING:
+    return "warning";
+  case LOG_LEVEL_INFO:
+    return "info";
+  case LOG_LEVEL_DEBUG:
+    return "debug";
+  case LOG_LEVEL_SILENT:
+    return "silent";
+  }
+  return "unknown";
+}
+
+int logger_is_enabled(LogLevel level) {
+  return current_level != LOG_LEVEL_SILENT && level <= current_level;
+}
+
+static void log_message(LogLevel level, const char *format, va_list arguments)
+    YAPSSG_FORMAT_PRINTF(2, 0);
+
+static void log_message(LogLevel level, const char *format, va_list arguments) {
+  if (!logger_is_enabled(level)) {
+    return;
+  }
+
+  fprintf(stderr, "yapssg: %s: ", level_name(level));
+  vfprintf(stderr, format, arguments);
+  fputc('\n', stderr);
+  fflush(stderr);
+}
+
+void logger_set_level(LogLevel level) { current_level = level; }
+
+LogLevel logger_get_level(void) { return current_level; }
+
+int logger_parse_level(const char *name, LogLevel *level) {
+  if (strcmp(name, "error") == 0) {
+    *level = LOG_LEVEL_ERROR;
+  } else if (strcmp(name, "warning") == 0 || strcmp(name, "warn") == 0) {
+    *level = LOG_LEVEL_WARNING;
+  } else if (strcmp(name, "info") == 0) {
+    *level = LOG_LEVEL_INFO;
+  } else if (strcmp(name, "debug") == 0) {
+    *level = LOG_LEVEL_DEBUG;
+  } else if (strcmp(name, "silent") == 0 || strcmp(name, "quiet") == 0) {
+    *level = LOG_LEVEL_SILENT;
+  } else {
+    return -1;
+  }
+  return 0;
+}
+
+void logger_log(LogLevel level, const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(level, format, arguments);
+  va_end(arguments);
+}
+
+void logger_error(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_ERROR, format, arguments);
+  va_end(arguments);
+}
+
+void logger_warning(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_WARNING, format, arguments);
+  va_end(arguments);
+}
+
+void logger_info(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_INFO, format, arguments);
+  va_end(arguments);
+}
+
+void logger_debug(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_DEBUG, format, arguments);
+  va_end(arguments);
+}
diff --git a/src/Logger/Logger.h b/src/Logger/Logger.h
new file mode 100644
index 0000000..f0bef12
--- /dev/null
+++ b/src/Logger/Logger.h
@@ -0,0 +1,31 @@
+#ifndef YAPSSG_LOGGER_H
+#define YAPSSG_LOGGER_H
+
+#if defined(__GNUC__) || defined(__clang__)
+#define YAPSSG_FORMAT_PRINTF(format_index, arguments_index)                    \
+  __attribute__((format(printf, format_index, arguments_index)))
+#else
+#define YAPSSG_FORMAT_PRINTF(format_index, arguments_index)
+#endif
+
+typedef enum {
+  LOG_LEVEL_SILENT = -1,
+  LOG_LEVEL_ERROR,
+  LOG_LEVEL_WARNING,
+  LOG_LEVEL_INFO,
+  LOG_LEVEL_DEBUG
+} LogLevel;
+
+void logger_set_level(LogLevel level);
+LogLevel logger_get_level(void);
+int logger_is_enabled(LogLevel level);
+int logger_parse_level(const char *name, LogLevel *level);
+
+void logger_log(LogLevel level, const char *format, ...)
+    YAPSSG_FORMAT_PRINTF(2, 3);
+void logger_error(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+void logger_warning(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+void logger_info(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+void logger_debug(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+
+#endif
diff --git a/src/Logger/LuaLogger.c b/src/Logger/LuaLogger.c
new file mode 100644
index 0000000..5739791
--- /dev/null
+++ b/src/Logger/LuaLogger.c
@@ -0,0 +1,60 @@
+#include "Logger/LuaLogger.h"
+
+#include "Logger/Logger.h"
+
+#include <lauxlib.h>
+#include <lua.h>
+
+static void add_value(lua_State *lua, luaL_Buffer *buffer, int index) {
+  int type = lua_type(lua, index);
+
+  if (type == LUA_TSTRING || type == LUA_TNUMBER) {
+    luaL_addstring(buffer, lua_tostring(lua, index));
+  } else if (type == LUA_TBOOLEAN) {
+    luaL_addstring(buffer, lua_toboolean(lua, index) ? "true" : "false");
+  } else if (type == LUA_TNIL) {
+    luaL_addstring(buffer, "nil");
+  } else {
+    luaL_addchar(buffer, '<');
+    luaL_addstring(buffer, lua_typename(lua, type));
+    luaL_addchar(buffer, '>');
+  }
+}
+
+static int log_from_lua(lua_State *lua) {
+  LogLevel level = (LogLevel)lua_tointeger(lua, lua_upvalueindex(1));
+  int argument_count = lua_gettop(lua);
+  int index;
+  luaL_Buffer buffer;
+
+  if (!logger_is_enabled(level)) {
+    return 0;
+  }
+
+  luaL_buffinit(lua, &buffer);
+  for (index = 1; index <= argument_count; ++index) {
+    if (index > 1) {
+      luaL_addchar(&buffer, '\t');
+    }
+    add_value(lua, &buffer, index);
+  }
+  luaL_pushresult(&buffer);
+  logger_log(level, "%s", lua_tostring(lua, -1));
+  lua_pop(lua, 1);
+  return 0;
+}
+
+static void set_log_function(lua_State *lua, const char *name, LogLevel level) {
+  lua_pushinteger(lua, (lua_Integer)level);
+  lua_pushcclosure(lua, log_from_lua, 1);
+  lua_setfield(lua, -2, name);
+}
+
+void lua_logger_register(lua_State *lua) {
+  lua_newtable(lua);
+  set_log_function(lua, "error", LOG_LEVEL_ERROR);
+  set_log_function(lua, "warn", LOG_LEVEL_WARNING);
+  set_log_function(lua, "info", LOG_LEVEL_INFO);
+  set_log_function(lua, "debug", LOG_LEVEL_DEBUG);
+  lua_setglobal(lua, "log");
+}
diff --git a/src/Logger/LuaLogger.h b/src/Logger/LuaLogger.h
new file mode 100644
index 0000000..98c9a8f
--- /dev/null
+++ b/src/Logger/LuaLogger.h
@@ -0,0 +1,8 @@
+#ifndef YAPSSG_LUA_LOGGER_H
+#define YAPSSG_LUA_LOGGER_H
+
+#include <lua.h>
+
+void lua_logger_register(lua_State *lua);
+
+#endif