Align with go library layout

logger.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+)
+
+const (
+	LogLevelError = iota
+	LogLevelInfo
+	LogLevelDebug
+)
+
+type Logger struct {
+	Debug *log.Logger
+	Info  *log.Logger
+	Error *log.Logger
+}
+
+func NewLogger(level int, prepend string) *Logger {
+	output := os.Stdout
+	logger := new(Logger)
+
+	logErr, logInfo, logDebug := func() (io.Writer, io.Writer, io.Writer) {
+		if level >= LogLevelDebug {
+			return output, output, output
+		}
+		if level >= LogLevelInfo {
+			return output, output, ioutil.Discard
+		}
+		return output, ioutil.Discard, ioutil.Discard
+	}()
+
+	logger.Debug = log.New(logDebug,
+		"DEBUG: "+prepend,
+		log.Ldate|log.Ltime|log.Lshortfile,
+	)
+
+	logger.Info = log.New(logInfo,
+		"INFO: "+prepend,
+		log.Ldate|log.Ltime,
+	)
+	logger.Error = log.New(logErr,
+		"ERROR: "+prepend,
+		log.Ldate|log.Ltime,
+	)
+	return logger
+}