Add logging

1 files changed, 56 insertions, 0 deletions

diff --git a/logging/log.go b/logging/log.go
new file mode 100644
index 0000000..9bef591
--- /dev/null
+++ b/logging/log.go
@@ -0,0 +1,56 @@
+package logging
+
+import (
+	"io"
+	"log"
+)
+
+type Logger interface {
+	Print(v ...interface{})
+	Printf(format string, v ...interface{})
+	Println(v ...interface{})
+}
+
+type NopLogger struct{}
+
+func (NopLogger) Print(v ...interface{})                 {}
+func (NopLogger) Printf(format string, v ...interface{}) {}
+func (NopLogger) Println(v ...interface{})               {}
+
+type Level int
+
+const (
+	LQuiet Level = iota
+	LError
+	LWarn
+	LInfo
+	LDebug
+)
+
+type Log struct {
+	err, warn, info, debug Logger
+}
+
+func (l Log) Error() Logger { return l.err }
+func (l Log) Warn() Logger  { return l.warn }
+func (l Log) Info() Logger  { return l.info }
+func (l Log) Debug() Logger { return l.debug }
+
+func buildLogger(out io.Writer, prefix string, lWant, lHave Level) Logger {
+	if lWant <= lHave {
+		return log.New(out, prefix, log.LstdFlags)
+	} else {
+		return NopLogger{}
+	}
+}
+
+func NewLog(out io.Writer, level Level) *Log {
+	l := new(Log)
+
+	l.err = buildLogger(out, "[Err]", LError, level)
+	l.warn = buildLogger(out, "[Warn]", LWarn, level)
+	l.info = buildLogger(out, "[Info]", LInfo, level)
+	l.debug = buildLogger(out, "[Debug]", LDebug, level)
+
+	return l
+}