1 files changed, 104 insertions, 0 deletions
diff --git a/include/cru/common/logger.hpp b/include/cru/common/logger.hpp
new file mode 100644
index 00000000..4da81eb1
--- /dev/null
+++ b/include/cru/common/logger.hpp
@@ -0,0 +1,104 @@
+#pragma once
+
+#include "cru/common/base.hpp"
+#include "cru/common/format.hpp"
+
+#include <iostream>
+#include <list>
+#include <string_view>
+
+namespace cru::log {
+
+enum class LogLevel { Debug, Info, Warn, Error };
+
+struct ILoggerSource : Interface {
+  // Write the s. LogLevel is just a helper. It has no effect on the content to
+  // write.
+  virtual void Write(LogLevel level, const std::wstring_view& s) = 0;
+};
+
+class StdioLoggerSource : public ILoggerSource {
+ public:
+  StdioLoggerSource() = default;
+
+  CRU_DELETE_COPY(StdioLoggerSource)
+  CRU_DELETE_MOVE(StdioLoggerSource)
+
+  ~StdioLoggerSource() = default;
+
+  void Write(LogLevel level, const std::wstring_view& s) override {
+    if (level == LogLevel::Error) {
+      std::wcerr << s;
+    } else {
+      std::wcout << s;
+    }
+  }
+};
+
+class Logger : public Object {
+ public:
+  static Logger* GetInstance();
+
+ public:
+  Logger() = default;
+
+  CRU_DELETE_COPY(Logger)
+  CRU_DELETE_MOVE(Logger)
+
+  ~Logger() override;
+
+ public:
+  void AddSource(ILoggerSource* source);
+  void RemoveSource(ILoggerSource* source);
+
+ public:
+  void Log(LogLevel level, const std::wstring_view& s);
+
+  template <typename... TArgs>
+  void Debug(const std::wstring_view& format, TArgs&&... args) {
+    Log(LogLevel::Debug, util::Format(format, std::forward<TArgs>(args)...));
+  }
+
+  template <typename... TArgs>
+  void Info(const std::wstring_view& format, TArgs&&... args) {
+    Log(LogLevel::Info, util::Format(format, std::forward<TArgs>(args)...));
+  }
+
+  template <typename... TArgs>
+  void Warn(const std::wstring_view& format, TArgs&&... args) {
+    Log(LogLevel::Warn, util::Format(format, std::forward<TArgs>(args)...));
+  }
+
+  template <typename... TArgs>
+  void Error(const std::wstring_view& format, TArgs&&... args) {
+    Log(LogLevel::Error, util::Format(format, std::forward<TArgs>(args)...));
+  }
+
+ public:
+  std::list<ILoggerSource*> sources_;
+};
+
+template <typename... TArgs>
+void Debug(const std::wstring_view& format, TArgs&&... args) {
+  Logger::GetInstance()->Log(
+      LogLevel::Debug, util::Format(format, std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void Info(const std::wstring_view& format, TArgs&&... args) {
+  Logger::GetInstance()->Log(
+      LogLevel::Info, util::Format(format, std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void Warn(const std::wstring_view& format, TArgs&&... args) {
+  Logger::GetInstance()->Log(
+      LogLevel::Warn, util::Format(format, std::forward<TArgs>(args)...));
+}
+
+template <typename... TArgs>
+void Error(const std::wstring_view& format, TArgs&&... args) {
+  Logger::GetInstance()->Log(
+      LogLevel::Error, util::Format(format, std::forward<TArgs>(args)...));
+}
+}  // namespace cru::logger