From 2662ed89e2cd41477582140e482f1ddbbfdb235e Mon Sep 17 00:00:00 2001
From: Florent Le Coz <louiz@louiz.org>
Date: Tue, 3 Dec 2013 18:27:20 +0100
Subject: Add a logger class

---
 CMakeLists.txt         | 15 ++++++++++-
 src/irc/irc_client.cpp |  1 +
 src/logger/logger.cpp  | 41 +++++++++++++++++++++++++++++
 src/logger/logger.hpp  | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/test.cpp           |  9 +++++++
 5 files changed, 135 insertions(+), 1 deletion(-)
 create mode 100644 src/logger/logger.cpp
 create mode 100644 src/logger/logger.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index daa6cf6..51253cc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,10 @@ set(${PROJECT_NAME}_VERSION_MINOR 1)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -pedantic -Wall -Wextra")
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -Og")
 
+# Define a __FILENAME__ macro to get the filename of each file, instead of
+# the full path as in __FILE__
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D__FILENAME__='\"$(subst ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'")
+
 #
 ## Look for external libraries
 #
@@ -46,6 +50,14 @@ file(GLOB source_config
 add_library(config STATIC ${source_config})
 target_link_libraries(config utils)
 
+#
+## logger
+#
+file(GLOB source_logger
+  src/logger/*.[hc]pp)
+add_library(logger STATIC ${source_logger})
+target_link_libraries(logger config)
+
 #
 ## network
 #
@@ -99,6 +111,7 @@ target_link_libraries(test
   irc
   bridge
   utils
-  config)
+  config
+  logger)
 
 configure_file(config.h.cmake src/config.h)
diff --git a/src/irc/irc_client.cpp b/src/irc/irc_client.cpp
index 0061561..4e5efe1 100644
--- a/src/irc/irc_client.cpp
+++ b/src/irc/irc_client.cpp
@@ -4,6 +4,7 @@
 #include <irc/irc_user.hpp>
 
 #include <utils/make_unique.hpp>
+// #include <logger/logger.hpp>
 #include <utils/tolower.hpp>
 #include <utils/split.hpp>
 
diff --git a/src/logger/logger.cpp b/src/logger/logger.cpp
new file mode 100644
index 0000000..eac833f
--- /dev/null
+++ b/src/logger/logger.cpp
@@ -0,0 +1,41 @@
+#include <utils/make_unique.hpp>
+#include <logger/logger.hpp>
+#include <config/config.hpp>
+
+Logger::Logger(const int log_level):
+  log_level(log_level),
+  stream(std::cout.rdbuf())
+{
+  std::cout << "Logger(1)" << std::endl;
+}
+
+Logger::Logger(const int log_level, const std::string& log_file):
+  log_level(log_level),
+  ofstream(log_file.data(), std::ios_base::app),
+  stream(ofstream.rdbuf())
+{
+  std::cout << "Logger(" << this->log_level << ")" << std::endl;
+}
+
+std::unique_ptr<Logger>& Logger::instance()
+{
+  static std::unique_ptr<Logger> instance;
+
+  if (!instance)
+    {
+      const std::string log_file = Config::get("log_file", "");
+      const int log_level = Config::get_int("log_level", 0);
+      if (log_file.empty())
+        instance = std::make_unique<Logger>(log_level);
+      else
+        instance = std::make_unique<Logger>(log_level, log_file);
+    }
+  return instance;
+}
+
+std::ostream& Logger::get_stream(const int lvl)
+{
+  if (lvl >= this->log_level)
+    return this->stream;
+  return this->null_stream;
+}
diff --git a/src/logger/logger.hpp b/src/logger/logger.hpp
new file mode 100644
index 0000000..182c517
--- /dev/null
+++ b/src/logger/logger.hpp
@@ -0,0 +1,70 @@
+#ifndef LOGGER_INCLUDED
+# define LOGGER_INCLUDED
+
+/**
+ * Singleton used in logger macros to write into files or stdout, with
+ * various levels of severity.
+ * Only the macros should be used.
+ * @class Logger
+ */
+
+#include <memory>
+#include <iostream>
+#include <fstream>
+
+#define debug_lvl 0
+#define info_lvl 1
+#define warning_lvl 2
+#define error_lvl 3
+
+// Macro defined to get the filename instead of the full path. But if it is
+// not properly defined by the build system, we fallback to __FILE__
+#ifndef __FILENAME__
+# define __FILENAME__ __FILE__
+#endif
+
+#define WHERE\
+  __FILENAME__ << ":" << __LINE__
+
+#define log_debug(text)\
+  Logger::instance()->get_stream(debug_lvl) << "[DEBUG]:" << WHERE << ":\t" << text << std::endl;
+
+#define log_info(text)\
+  Logger::instance()->get_stream(info_lvl) << "[INFO]:" << WHERE << ":\t" << text << std::endl;
+
+#define log_warning(text)\
+  Logger::instance()->get_stream(warning_lvl) << "[WARNING]:" << WHERE << ":\t" << text << std::endl;
+
+#define log_error(text)\
+  Logger::instance()->get_stream(error_lvl) << "[ERROR]:" << WHERE << ":\t" << text << std::endl;
+
+/**
+ * Juste a structure representing a stream doing nothing with its input.
+ */
+class nullstream: public std::ostream
+{
+public:
+  nullstream():
+    std::ostream(0)
+  { }
+};
+
+class Logger
+{
+public:
+  static std::unique_ptr<Logger>& instance();
+  std::ostream& get_stream(const int);
+  Logger(const int log_level, const std::string& log_file);
+  Logger(const int log_level);
+
+private:
+  Logger(const Logger&);
+  Logger& operator=(const Logger&);
+
+  const int log_level;
+  std::ofstream ofstream;
+  nullstream null_stream;
+  std::ostream stream;
+};
+
+#endif // LOGGER_INCLUDED
diff --git a/src/test.cpp b/src/test.cpp
index 234ab2d..ac1a85d 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -4,6 +4,7 @@
 
 #include <xmpp/xmpp_parser.hpp>
 #include <utils/encoding.hpp>
+#include <logger/logger.hpp>
 #include <config/config.hpp>
 #include <bridge/colors.hpp>
 #include <utils/tolower.hpp>
@@ -170,5 +171,13 @@ int main()
     }
   assert(error == false);
 
+  Config::set("log_level", "3");
+  Config::set("log_file", "");
+
+  log_debug("coucou");
+  log_info("coucou");
+  log_warning("coucou");
+  log_error("coucou");
+
   return 0;
 }
-- 
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