1 files changed, 152 insertions, 0 deletions
diff --git a/lib/log/logger.go b/lib/log/logger.go
new file mode 100644
index 00000000..2ece5f32
--- /dev/null
+++ b/lib/log/logger.go
@@ -0,0 +1,152 @@
+package log
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+)
+
+type LogLevel int
+
+const (
+	TRACE LogLevel = 5
+	DEBUG LogLevel = 10
+	INFO  LogLevel = 20
+	WARN  LogLevel = 30
+	ERROR LogLevel = 40
+)
+
+var (
+	trace    *log.Logger
+	dbg      *log.Logger
+	info     *log.Logger
+	warn     *log.Logger
+	err      *log.Logger
+	minLevel LogLevel = TRACE
+)
+
+func Init(file *os.File, level LogLevel) {
+	minLevel = level
+	flags := log.Ldate | log.Ltime | log.Lmicroseconds | log.Lshortfile
+	if file != nil {
+		trace = log.New(file, "TRACE ", flags)
+		dbg = log.New(file, "DEBUG ", flags)
+		info = log.New(file, "INFO  ", flags)
+		warn = log.New(file, "WARN  ", flags)
+		err = log.New(file, "ERROR ", flags)
+	}
+}
+
+func ParseLevel(value string) (LogLevel, error) {
+	switch strings.ToLower(value) {
+	case "trace":
+		return TRACE, nil
+	case "debug":
+		return DEBUG, nil
+	case "info":
+		return INFO, nil
+	case "warn", "warning":
+		return WARN, nil
+	case "err", "error":
+		return ERROR, nil
+	}
+	return 0, fmt.Errorf("%s: invalid log level", value)
+}
+
+func ErrorLogger() *log.Logger {
+	if err == nil {
+		return log.New(io.Discard, "", log.LstdFlags)
+	}
+	return err
+}
+
+type Logger interface {
+	Tracef(string, ...interface{})
+	Debugf(string, ...interface{})
+	Infof(string, ...interface{})
+	Warnf(string, ...interface{})
+	Errorf(string, ...interface{})
+}
+
+type logger struct {
+	name      string
+	calldepth int
+}
+
+func NewLogger(name string, calldepth int) Logger {
+	return &logger{name: name, calldepth: calldepth}
+}
+
+func (l *logger) format(message string, args ...interface{}) string {
+	if len(args) > 0 {
+		message = fmt.Sprintf(message, args...)
+	}
+	if l.name != "" {
+		message = fmt.Sprintf("[%s] %s", l.name, message)
+	}
+	return message
+}
+
+func (l *logger) Tracef(message string, args ...interface{}) {
+	if trace == nil || minLevel > TRACE {
+		return
+	}
+	message = l.format(message, args...)
+	trace.Output(l.calldepth, message) //nolint:errcheck // we can't do anything with what we log
+}
+
+func (l *logger) Debugf(message string, args ...interface{}) {
+	if dbg == nil || minLevel > DEBUG {
+		return
+	}
+	message = l.format(message, args...)
+	dbg.Output(l.calldepth, message) //nolint:errcheck // we can't do anything with what we log
+}
+
+func (l *logger) Infof(message string, args ...interface{}) {
+	if info == nil || minLevel > INFO {
+		return
+	}
+	message = l.format(message, args...)
+	info.Output(l.calldepth, message) //nolint:errcheck // we can't do anything with what we log
+}
+
+func (l *logger) Warnf(message string, args ...interface{}) {
+	if warn == nil || minLevel > WARN {
+		return
+	}
+	message = l.format(message, args...)
+	warn.Output(l.calldepth, message) //nolint:errcheck // we can't do anything with what we log
+}
+
+func (l *logger) Errorf(message string, args ...interface{}) {
+	if err == nil || minLevel > ERROR {
+		return
+	}
+	message = l.format(message, args...)
+	err.Output(l.calldepth, message) //nolint:errcheck // we can't do anything with what we log
+}
+
+var root = logger{calldepth: 3}
+
+func Tracef(message string, args ...interface{}) {
+	root.Tracef(message, args...)
+}
+
+func Debugf(message string, args ...interface{}) {
+	root.Debugf(message, args...)
+}
+
+func Infof(message string, args ...interface{}) {
+	root.Infof(message, args...)
+}
+
+func Warnf(message string, args ...interface{}) {
+	root.Warnf(message, args...)
+}
+
+func Errorf(message string, args ...interface{}) {
+	root.Errorf(message, args...)
+}