From a020d51bcc18cdf789a2aff80255865fe37d1e80 Mon Sep 17 00:00:00 2001
From: Jan Hoon <janhoon97@gmail.com>
Date: Tue, 29 Oct 2024 22:31:05 +0000
Subject: [PATCH] feat: allow external loggers to be used with glog as default

Signed-off-by: Jan Hoon <janhoon97@gmail.com>
---
 ginoauth2.go    | 21 -------------
 logging.go      | 82 +++++++++++++++++++++++++++++++++++++++++++++++++
 logging_test.go | 45 +++++++++++++++++++++++++++
 3 files changed, 127 insertions(+), 21 deletions(-)
 create mode 100644 logging.go
 create mode 100644 logging_test.go

diff --git a/ginoauth2.go b/ginoauth2.go
index 38af0ee..65a7deb 100644
--- a/ginoauth2.go
+++ b/ginoauth2.go
@@ -64,7 +64,6 @@ import (
 	"time"
 
 	"github.com/gin-gonic/gin"
-	"github.com/golang/glog"
 	"golang.org/x/oauth2"
 )
 
@@ -102,26 +101,6 @@ func maskAccessToken(a interface{}) string {
 	return s
 }
 
-func logf(l func(string, ...interface{}), f string, args ...interface{}) {
-	for i := range args {
-		args[i] = maskAccessToken(args[i])
-	}
-
-	l(f, args...)
-}
-
-func errorf(f string, args ...interface{}) {
-	logf(glog.Errorf, f, args...)
-}
-
-func infof(f string, args ...interface{}) {
-	logf(glog.Infof, f, args...)
-}
-
-func infofv2(f string, args ...interface{}) {
-	logf(glog.V(2).Infof, f, args...)
-}
-
 func extractToken(r *http.Request) (*oauth2.Token, error) {
 	hdr := r.Header.Get("Authorization")
 	if hdr == "" {
diff --git a/logging.go b/logging.go
new file mode 100644
index 0000000..fa9c369
--- /dev/null
+++ b/logging.go
@@ -0,0 +1,82 @@
+package ginoauth2
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/golang/glog"
+)
+
+// Logger is the interface used by GinOAuth2 to log messages.
+type Logger interface {
+	Errorf(format string, args ...interface{})
+	Infof(format string, args ...interface{})
+	Debugf(format string, args ...interface{})
+}
+
+type glogLogger struct {
+	output io.Writer
+}
+
+// DefaultLogger is the default logger used by GinOAuth2 if no other logger is provided.
+// To use a different logger, set the DefaultLogger variable to a logger of your choice.
+// Replacement loggers must implement the Logger interface.
+//
+// Example:
+//
+//	import "github.com/zalando/gin-oauth2"
+//
+//	ginoauth2.DefaultLogger = &logrusLogger{} // use logrus
+var DefaultLogger Logger = &glogLogger{output: os.Stderr}
+
+func maskLogArgs(args ...interface{}) []interface{} {
+	for i := range args {
+		args[i] = maskAccessToken(args[i])
+	}
+
+	return args
+}
+
+// SetOutput sets the output destination for the logger
+func (gl *glogLogger) setOutput(w io.Writer) {
+	gl.output = w
+}
+
+// Errorf is a logging function using glog.Errorf
+func (gl *glogLogger) Errorf(f string, args ...interface{}) {
+	glog.ErrorDepth(1, fmt.Sprintf(f, args...))
+	if gl.output != nil {
+		fmt.Fprintf(gl.output, f+"\n", args...)
+	}
+}
+
+// Infof is a logging function using glog.Infof
+func (gl *glogLogger) Infof(f string, args ...interface{}) {
+	glog.InfoDepth(1, fmt.Sprintf(f, args...))
+	if gl.output != nil {
+		fmt.Fprintf(gl.output, f+"\n", args...)
+	}
+}
+
+// Debugf is a verbose logging function using glog.V(2)
+func (gl *glogLogger) Debugf(f string, args ...interface{}) {
+	if glog.V(2) {
+		glog.InfoDepth(1, fmt.Sprintf(f, args...))
+	}
+	if gl.output != nil {
+		fmt.Fprintf(gl.output, f+"\n", args...)
+	}
+}
+
+func errorf(f string, args ...interface{}) {
+	DefaultLogger.Errorf(f, maskLogArgs(args...)...)
+}
+
+func infof(f string, args ...interface{}) {
+	DefaultLogger.Infof(f, maskLogArgs(args...)...)
+}
+
+func infofv2(f string, args ...interface{}) {
+	DefaultLogger.Debugf(f, maskLogArgs(args...)...)
+}
diff --git a/logging_test.go b/logging_test.go
new file mode 100644
index 0000000..501c37f
--- /dev/null
+++ b/logging_test.go
@@ -0,0 +1,45 @@
+package ginoauth2
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+	"testing"
+)
+
+type mockLogger struct{ buffer bytes.Buffer }
+
+func (m *mockLogger) Errorf(format string, args ...interface{}) {
+	m.buffer.WriteString(fmt.Sprintf("ERROR: "+format, args...))
+}
+func (m *mockLogger) Infof(format string, args ...interface{}) {
+	m.buffer.WriteString(fmt.Sprintf("INFO: "+format, args...))
+}
+func (m *mockLogger) Debugf(format string, args ...interface{}) {
+	m.buffer.WriteString(fmt.Sprintf("DEBUG: "+format, args...))
+}
+
+func TestLogWithMaskedAccessToken(t *testing.T) {
+	mockLog := &mockLogger{}
+	DefaultLogger = mockLog
+	tests := []struct{ name, input, expected string }{
+		{"With access token", "&access_token=abcdefghijklmnop&", "INFO: <MASK>&"},
+		{"Without access token", "no_token_here", "INFO: no_token_here"},
+		{"Empty string", "", "INFO: "},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mockLog.buffer.Reset()
+
+			infof("%s", tt.input)
+
+			logOutput := mockLog.buffer.String()
+			if logOutput != tt.expected {
+				t.Errorf("Expected log to contain %q, got %q", tt.expected, logOutput)
+			}
+			if strings.Contains(logOutput, "abcdefghijklmnop") {
+				t.Errorf("Log should not contain the original token")
+			}
+		})
+	}
+}