1 files changed, 137 insertions, 0 deletions
diff --git a/src/core/log.h b/src/core/log.h
new file mode 100644
index 0000000..db7440b
--- /dev/null
+++ b/src/core/log.h
@@ -0,0 +1,137 @@
+#pragma once
+
+#include <cstdint>
+#include <format>
+#include <iostream>
+#include <ostream>
+#include <print>
+#include <string_view>
+#include <utility>
+
+// there is no standard way to ask whether a stream is a terminal
+#ifdef HSDBG_WINDOWS
+    #include <io.h>
+#else
+    #include <unistd.h>
+#endif
+
+namespace Hsdbg::Log
+{
+    enum class Level : uint8_t
+    {
+        Trace,
+        Debug,
+        Info,
+        Warn,
+        Error,
+    };
+
+    namespace Detail
+    {
+        inline Level g_min_level =
+#ifdef HSDBG_DIST
+            Level::Info;
+#else
+            Level::Trace;
+#endif
+
+        inline auto label(Level level) -> std::string_view
+        {
+            switch (level)
+            {
+                case Level::Trace: return "trace";
+                case Level::Debug: return "debug";
+                case Level::Info:  return "info ";
+                case Level::Warn:  return "warn ";
+                case Level::Error: return "error";
+            }
+
+            return "?????";
+        }
+
+        inline auto color(Level level) -> std::string_view
+        {
+            switch (level)
+            {
+                case Level::Trace: return "\x1b[90m";
+                case Level::Debug: return "\x1b[36m";
+                case Level::Info:  return "\x1b[32m";
+                case Level::Warn:  return "\x1b[33m";
+                case Level::Error: return "\x1b[31m";
+            }
+
+            return "";
+        }
+
+        inline auto is_terminal(bool to_stderr) -> bool
+        {
+            constexpr int STDOUT_DESCRIPTOR = 1;
+            constexpr int STDERR_DESCRIPTOR = 2;
+
+            const int descriptor = to_stderr ? STDERR_DESCRIPTOR : STDOUT_DESCRIPTOR;
+
+#ifdef HSDBG_WINDOWS
+            return _isatty(descriptor) != 0;
+#else
+            return isatty(descriptor) != 0;
+#endif
+        }
+
+        inline auto write(Level level, std::string_view message) -> void
+        {
+            if (level < g_min_level)
+                return;
+
+            const bool to_stderr = level >= Level::Warn;
+            std::ostream& stream = to_stderr ? std::cerr : std::cout;
+
+            if (is_terminal(to_stderr))
+                std::println(stream, "{}{}\x1b[0m {}", color(level), label(level), message);
+            else
+                std::println(stream, "{} {}", label(level), message);
+
+            // never let a crash swallow the last lines that explain it
+            stream.flush();
+        }
+    }
+
+    inline auto set_min_level(Level level) -> void
+    {
+        Detail::g_min_level = level;
+    }
+
+    inline auto min_level() -> Level
+    {
+        return Detail::g_min_level;
+    }
+
+    template <typename... Args>
+    auto trace(std::format_string<Args...> fmt, Args&&... args) -> void
+    {
+        Detail::write(Level::Trace, std::format(fmt, std::forward<Args>(args)...));
+    }
+
+    template <typename... Args>
+    auto debug(std::format_string<Args...> fmt, Args&&... args) -> void
+    {
+        Detail::write(Level::Debug, std::format(fmt, std::forward<Args>(args)...));
+    }
+
+    template <typename... Args>
+    auto info(std::format_string<Args...> fmt, Args&&... args) -> void
+    {
+        Detail::write(Level::Info, std::format(fmt, std::forward<Args>(args)...));
+    }
+
+    template <typename... Args>
+    auto warn(std::format_string<Args...> fmt, Args&&... args) -> void
+    {
+        Detail::write(Level::Warn, std::format(fmt, std::forward<Args>(args)...));
+    }
+
+    template <typename... Args>
+    auto error(std::format_string<Args...> fmt, Args&&... args) -> void
+    {
+        Detail::write(Level::Error, std::format(fmt, std::forward<Args>(args)...));
+    }
+}