1package log
 2
 3import (
 4	"log"
 5	"strings"
 6)
 7
 8type stdLogWriter struct {
 9	l   *Logger
10	opt *StandardLogOptions
11}
12
13func (l *stdLogWriter) Write(p []byte) (n int, err error) {
14	str := strings.TrimSuffix(string(p), "\n")
15
16	if l.opt != nil {
17		switch l.opt.ForceLevel {
18		case DebugLevel:
19			l.l.Debug(str)
20		case InfoLevel:
21			l.l.Info(str)
22		case WarnLevel:
23			l.l.Warn(str)
24		case ErrorLevel:
25			l.l.Error(str)
26		}
27	} else {
28		switch {
29		case strings.HasPrefix(str, "DEBUG"):
30			l.l.Debug(strings.TrimSpace(str[5:]))
31		case strings.HasPrefix(str, "INFO"):
32			l.l.Info(strings.TrimSpace(str[4:]))
33		case strings.HasPrefix(str, "WARN"):
34			l.l.Warn(strings.TrimSpace(str[4:]))
35		case strings.HasPrefix(str, "ERROR"):
36			l.l.Error(strings.TrimSpace(str[5:]))
37		case strings.HasPrefix(str, "ERR"):
38			l.l.Error(strings.TrimSpace(str[3:]))
39		default:
40			l.l.Info(str)
41		}
42	}
43
44	return len(p), nil
45}
46
47// StandardLogOptions can be used to configure the standard log adapter.
48type StandardLogOptions struct {
49	ForceLevel Level
50}
51
52// StandardLog returns a standard logger from Logger. The returned logger
53// can infer log levels from message prefix. Expected prefixes are DEBUG, INFO,
54// WARN, ERROR, and ERR.
55func (l *Logger) StandardLog(opts ...StandardLogOptions) *log.Logger {
56	nl := l.With()
57	// The caller stack is
58	// log.Printf() -> l.Output() -> l.out.Write(stdLogger.Write)
59	nl.callerOffset += 3
60	sl := &stdLogWriter{
61		l: nl,
62	}
63	if len(opts) > 0 {
64		sl.opt = &opts[0]
65	}
66	return log.New(sl, "", 0)
67}