Create basic Go project

go.mod

@@ -0,0 +1,3 @@
+module rpjosh.de/ncDocConverter
+
+go 1.18

logger/logger.go

@@ -0,0 +1,165 @@
+package logger
+
+import (
+	"fmt"
+	"log"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+	"os"
+)
+
+// define available log levels
+type Level uint8
+const (
+	LevelDebug	Level = iota
+	LevelInfo
+	LevelWarning
+	LevelError
+	LevelFatal
+)
+
+type Logger struct {
+	PrintLevel 		Level
+	LogLevel		Level
+	LogFilePath		string
+	PrintSource		bool
+
+	consoleLogger		*log.Logger
+	consoleLoggerErr 	*log.Logger
+	fileLogger			*log.Logger
+	logFile				*os.File
+}
+
+var dLogger Logger
+
+func init() {
+
+	dLogger = Logger {
+		PrintLevel: LevelDebug,
+		LogLevel: LevelInfo,
+		LogFilePath: "",
+		PrintSource: false,
+	}
+
+	dLogger.setup()
+}
+
+func (l Logger) Log(level Level, message string, parameters ...any) {
+	// this function is needed that runtime.Caller(2) is always correct (even on direct call)
+	l.log(level, message, parameters...)
+}
+
+func (l Logger) log(level Level, message string, parameters ...any) {
+	pc, file, line, ok := runtime.Caller(2)
+	if (!ok) {
+		file = "#unknown"
+		line = 0
+	}
+
+	// get the name of the level
+	var levelName string
+	switch (level) {
+		case LevelDebug:	 	levelName = "DEBUG"
+		case LevelInfo: 		levelName = "INFO "
+		case LevelWarning:		levelName = "WARN "
+		case LevelError: 		levelName = "ERROR"
+		case LevelFatal:		levelName = "FATAL"
+	}
+
+	if (levelName == "") {
+		message = fmt.Sprintf("Invalid level value given: %d. Original message: ", level) + message
+		levelName = "WARN "
+		level = LevelWarning
+	}
+
+	printMessage := "[" + levelName + "] " + time.Now().UTC().Format("2006-01-02 03:04:05") + 
+		getSourceMessage(file, line, pc, l) + 
+		fmt.Sprintf(message, parameters...)
+
+	if (l.LogLevel <= level && l.fileLogger != nil) {
+		l.fileLogger.Println(printMessage)
+		l.logFile.Sync()
+
+		if (level == LevelFatal) {
+			l.CloseFile()
+		}
+	}
+
+	if (l.PrintLevel <= level) {
+		if (level == LevelError) {
+			l.consoleLoggerErr.Println(printMessage)
+		} else if (level == LevelFatal) {
+			l.consoleLoggerErr.Fatal(printMessage)
+		} else {
+			l.consoleLogger.Println(printMessage)
+		}
+	}
+
+}
+
+func getSourceMessage(file string, line int, pc uintptr, l Logger) (string) {
+	if (!l.PrintSource) {
+		return " - "
+	}
+
+	fileName := file[strings.LastIndex(file, "/")+1:] + ":" + strconv.Itoa(line)
+
+	return " (" + fileName + ") - "
+}
+
+func (l *Logger) setup() {
+	l.consoleLogger = log.New(os.Stdout, "", 0)
+	l.consoleLoggerErr = log.New(os.Stderr, "", 0)
+
+	if (l.LogFilePath != "") {
+		file, err := os.OpenFile(l.LogFilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+		if err == nil {
+			l.fileLogger = log.New(file, "", 0)
+			l.logFile = file
+		} else {
+			l.Log(LevelError, fmt.Sprintf("Cannot access the log file '%s'\n%s", l.LogFilePath, err.Error()))
+		}
+	} else {
+		l.fileLogger = nil
+		if (l.logFile != nil) {
+			l.logFile.Close()
+			l.logFile = nil
+		}
+	}
+}
+
+func (l *Logger) CloseFile() {
+	if (dLogger.logFile != nil) {
+		dLogger.logFile.Close()
+		dLogger.logFile = nil
+		dLogger.fileLogger = nil
+	}
+}
+
+
+func SetGlobalLogger(l *Logger) {
+	dLogger = *l
+	dLogger.setup()
+}
+
+func Debug(message string, parameters ...any) {
+	dLogger.Log(LevelDebug, message, parameters...)
+}
+func Info(message string, parameters ...any) {
+	dLogger.Log(LevelInfo, message, parameters...)
+}
+func Warning(message string, parameters ...any) {
+	dLogger.Log(LevelWarning, message, parameters...)
+}
+func Error(message string, parameters ...any) {
+	dLogger.Log(LevelError, message, parameters...)
+}
+func Fatal(message string, parameters ...any) {
+	dLogger.Log(LevelFatal, message, parameters...)
+}
+
+func CloseFile() {
+	dLogger.CloseFile()
+}

main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"rpjosh.de/ncDocConverter/logger"
+)
+
+func init() {
+	defaultLogger := logger.Logger {
+		PrintLevel: 0,
+		LogLevel: 1,
+		LogFilePath: "log.log",
+		PrintSource: true,
+	}
+
+	logger.SetGlobalLogger(&defaultLogger)
+}
+
+func main() {
+	defer logger.CloseFile()
+
+
+}