Split src/common/* into headers and definitions

src/common/logging.h

@@ -16,27 +16,7 @@
 
 #pragma once
 
-#ifdef __WINE__
-#include "../wine-host/boost-fix.h"
-#endif
-#include <boost/process/environment.hpp>
-#include <fstream>
-#include <iostream>
-
-/**
- * The environment variable indicating whether to log to a file. Will log to
- * STDERR if not specified.
- */
-constexpr char logging_file_environment_variable[] = "YABRIDGE_DEBUG_FILE";
-/**
- * The verbosity of the logging, defaults to `Logger::Verbosity::events` if
- * `logging_file_environment_variable` has been set and
- * `Logger::Verbosity::basic` otherwise.
- *
- * @see Logger::Verbosity
- */
-constexpr char logging_verbosity_environment_variable[] =
-    "YABRIDGE_DEBUG_VERBOSITY";
+#include <ostream>
 
 /**
  * Super basic logging facility meant for debugging malfunctioning VST
@@ -85,38 +65,16 @@ class Logger {
      */
     Logger(std::ostream&& stream,
            Verbosity verbosity_level,
-           std::string prefix = "")
-        : stream(stream), verbosity(verbosity_level), prefix(prefix){};
+           std::string prefix = "");
 
     /**
-     * Create a logger instance based on the set environment variables.
+     * Create a logger instance based on the set environment variables. See the
+     * constants in `logging.cpp` for more information.
      *
      * @param prefix A message to prepend for every log message, useful to
      *   differentiate between the Wine process and the Linus VST plugin.
      */
-    static Logger create_from_environment(std::string prefix = "") {
-        auto env = boost::this_process::environment();
-        std::string file_path = env.get(logging_file_environment_variable);
-        std::string verbosity = env.get(logging_verbosity_environment_variable);
-
-        // Default to `Verbosity::basic` if the environment variable has not
-        // been set or if it is not an integer.
-        Verbosity verbosity_level;
-        try {
-            verbosity_level = static_cast<Verbosity>(std::stoi(verbosity));
-        } catch (const std::invalid_argument&) {
-            verbosity_level = Verbosity::basic;
-        }
-
-        // If `file` points to a valid location then use create/truncate the
-        // file and write all of the logs there, otherwise use STDERR
-        std::ofstream log_file(file_path, std::fstream::out);
-        if (log_file.is_open()) {
-            return Logger(std::move(log_file), verbosity_level, prefix);
-        } else {
-            return Logger(std::move(std::cerr), verbosity_level, prefix);
-        }
-    }
+    static Logger create_from_environment(std::string prefix = "");
 
     // TODO: Add dedicated logging functions for events and the Wine process's
     //       STDOUT and STDERR