global: begin modularization

1 files changed, 59 insertions, 0 deletions

diff --git a/device/logger.go b/device/logger.go
new file mode 100644
index 0000000..7c8b704
--- /dev/null
+++ b/device/logger.go
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package device
+
+import (
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+)
+
+const (
+	LogLevelSilent = iota
+	LogLevelError
+	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
+		}
+		if level >= LogLevelError {
+			return output, ioutil.Discard, ioutil.Discard
+		}
+		return ioutil.Discard, ioutil.Discard, ioutil.Discard
+	}()
+
+	logger.Debug = log.New(logDebug,
+		"DEBUG: "+prepend,
+		log.Ldate|log.Ltime,
+	)
+
+	logger.Info = log.New(logInfo,
+		"INFO: "+prepend,
+		log.Ldate|log.Ltime,
+	)
+	logger.Error = log.New(logErr,
+		"ERROR: "+prepend,
+		log.Ldate|log.Ltime,
+	)
+	return logger
+}