From a3a148b0ff29a0196649336ec5603cd3f2bce8cc Mon Sep 17 00:00:00 2001
From: Knut Ahlers <knut@ahlers.me>
Date: Mon, 6 Jul 2015 22:48:54 +0200
Subject: [PATCH] Write access-log

---
 logResponseWriter.go | 40 ++++++++++++++++++++++++++++++++++++++++
 main.go              | 15 ++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 logResponseWriter.go

diff --git a/logResponseWriter.go b/logResponseWriter.go
new file mode 100644
index 0000000..ebbaca9
--- /dev/null
+++ b/logResponseWriter.go
@@ -0,0 +1,40 @@
+package main
+
+import "net/http"
+
+// LogResponseWriter wraps the standard http.ResponseWritter allowing for more
+// verbose logging
+type LogResponseWriter struct {
+	Status int
+	Size   int
+	http.ResponseWriter
+}
+
+// NewLogResponseWriter instanciates a new LogResponseWriter
+func NewLogResponseWriter(res http.ResponseWriter) *LogResponseWriter {
+	// Default the status code to 200
+	return &LogResponseWriter{200, 0, res}
+}
+
+// Header returns & satisfies the http.ResponseWriter interface
+func (w *LogResponseWriter) Header() http.Header {
+	return w.ResponseWriter.Header()
+}
+
+// Write satisfies the http.ResponseWriter interface and
+// captures data written, in bytes
+func (w *LogResponseWriter) Write(data []byte) (int, error) {
+
+	written, err := w.ResponseWriter.Write(data)
+	w.Size += written
+
+	return written, err
+}
+
+// WriteHeader satisfies the http.ResponseWriter interface and
+// allows us to cach the status code
+func (w *LogResponseWriter) WriteHeader(statusCode int) {
+
+	w.Status = statusCode
+	w.ResponseWriter.WriteHeader(statusCode)
+}
diff --git a/main.go b/main.go
index 820fc80..f0da838 100644
--- a/main.go
+++ b/main.go
@@ -4,6 +4,7 @@ import (
 	"crypto/md5"
 	"fmt"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"time"
 
@@ -49,10 +50,22 @@ func main() {
 
 	go runWelcomePage(cfg)
 
-	http.Handle("/", r)
+	http.Handle("/", logHTTPRequest(r))
 	http.ListenAndServe(cfg.Listen, nil)
 }
 
+func logHTTPRequest(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(res http.ResponseWriter, r *http.Request) {
+		start := time.Now().UnixNano()
+		w := NewLogResponseWriter(res)
+
+		h.ServeHTTP(w, r)
+
+		d := (time.Now().UnixNano() - start) / 1000
+		log.Printf("%s %s %d %dµs %dB\n", r.Method, r.URL.Path, w.Status, d, w.Size)
+	})
+}
+
 func generateAPIKey() string {
 	t := time.Now().String()
 	sum := md5.Sum([]byte(t))