custom response writer and logger

net/http/httputil/chain.go

@@ -0,0 +1,19 @@
+package httputil
+
+import "net/http"
+
+// Chain applies middlewares to a http.Handler
+func Chain(h http.Handler, ff ...func(http.Handler) http.Handler) http.Handler {
+	for _, f := range ff {
+		h = f(h)
+	}
+	return h
+}
+
+// ChainFunc applies middlewares to a http.HandlerFunc
+func ChainFunc(hf http.HandlerFunc, ff ...func(http.HandlerFunc) http.HandlerFunc) http.HandlerFunc {
+	for _, f := range ff {
+		hf = f(hf)
+	}
+	return hf
+}

net/http/httputil/hlog/log.go

@@ -0,0 +1,50 @@
+package hlog
+
+import (
+	"log/slog"
+	"net/http"
+	"time"
+
+	"go.adoublef.dev/sdk/net/http/httputil"
+)
+
+// Log wraps a http.Handler with a request logger.
+func Log(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rw := httputil.Wrap(w, r)
+
+		start := time.Now()
+		defer func() {
+			duration := time.Since(start)
+
+			slog.LogAttrs(
+				r.Context(),
+				statusLevel(rw.Status()),
+				"http request",
+				slog.String("method", r.Method),
+				slog.Int64("time_ms", int64(duration/time.Millisecond)),
+				slog.String("path", r.URL.Path),
+				slog.Int("status", rw.Status()),
+				slog.String("duration", duration.String()),
+			)
+		}()
+
+		h.ServeHTTP(rw, r)
+	})
+}
+
+func statusLevel(status int) slog.Level {
+	switch {
+	case status <= 0:
+		return slog.LevelWarn
+	case status < 400: // for codes in 100s, 200s, 300s
+		return slog.LevelInfo
+	case status >= 400 && status < 500:
+		// switching to info level to be less noisy
+		return slog.LevelInfo
+	case status >= 500:
+		return slog.LevelError
+	default:
+		return slog.LevelInfo
+	}
+}

net/http/httputil/response_writer.go

@@ -0,0 +1,107 @@
+package httputil
+
+import (
+	"bufio"
+	"errors"
+	"net"
+	"net/http"
+)
+
+type ResponseWriter interface {
+	http.ResponseWriter
+	http.Flusher
+	// Status returns the status code of the response or 0 if the response has not been written.
+	Status() int
+	// Written returns whether or not the ResponseWriter has been written.
+	Written() bool
+	// Size returns the size of the response body.
+	Size() int
+	Unwrap() http.ResponseWriter
+}
+
+type response struct {
+	http.ResponseWriter
+	method string
+	status int
+	size   int
+}
+
+// Size implements ResponseWriter.
+func (rw *response) Size() int {
+	return rw.size
+}
+
+// Unwrap implements ResponseWriter.
+func (rw *response) Unwrap() http.ResponseWriter {
+	return rw.ResponseWriter
+}
+
+// Written implements ResponseWriter.
+func (rw *response) Written() bool {
+	return rw.status != 0
+}
+
+// Status implements ResponseWriter.
+func (rw *response) Status() int {
+	return rw.status
+}
+
+// Write implements ResponseWriter.
+// Subtle: this method shadows the method (ResponseWriter).Write of response.ResponseWriter.
+func (rw *response) Write(b []byte) (size int, err error) {
+	if !rw.Written() {
+		// The status will be StatusOK if WriteHeader has not been called yet
+		rw.WriteHeader(http.StatusOK)
+	}
+	if rw.method != http.MethodHead {
+		size, err = rw.ResponseWriter.Write(b)
+		rw.size += size
+	}
+	return size, err
+}
+
+// WriteHeader implements ResponseWriter.
+// Subtle: this method shadows the method (ResponseWriter).WriteHeader of response.ResponseWriter.
+func (rw *response) WriteHeader(s int) {
+	// Avoid panic if status code is not a valid HTTP status code
+	if s < 100 || s > 999 {
+		rw.ResponseWriter.WriteHeader(500)
+		rw.status = 500
+		return
+	}
+
+	rw.ResponseWriter.WriteHeader(s)
+	rw.status = s
+}
+
+func (rw *response) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hijacker, ok := rw.ResponseWriter.(http.Hijacker)
+	if !ok {
+		return nil, nil, ErrHijackUnsupported
+	}
+
+	conn, brw, err := hijacker.Hijack()
+	if err == nil {
+		rw.status = -1
+	}
+
+	return conn, brw, err
+}
+
+func (rw *response) Flush() {
+	if flusher, ok := rw.ResponseWriter.(http.Flusher); ok {
+		flusher.Flush()
+	}
+}
+
+// Wrap
+func Wrap(w http.ResponseWriter, r *http.Request) ResponseWriter {
+	if rw, ok := w.(ResponseWriter); ok {
+		return rw
+	}
+	return &response{w, r.Method, 0, 0}
+}
+
+var (
+	ErrHijackUnsupported = errors.New("the ResponseWriter doesn't support the Hijacker interface")
+)