2 files changed, 150 insertions, 0 deletions
diff --git a/logging/logger.go b/logging/logger.go
new file mode 100644
index 0000000..f80a1ae
--- /dev/null
+++ b/logging/logger.go
@@ -0,0 +1,43 @@
+package logging
+
+import (
+	"os"
+
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"github.com/go-kit/log/term"
+)
+
+// Logger records log lines to an output.
+type Logger interface {
+	Log(keyvals ...any) error
+}
+
+// DefaultLoggers produces helpful base loggers for each level.
+//
+// They write logfmt to standard out, annotated with ANSI colors depending on the level.
+func DefaultLoggers() (debug, info, warn, error Logger) {
+	base := term.NewLogger(os.Stdout, log.NewLogfmtLogger, func(keyvals ...any) term.FgBgColor {
+		for i := 0; i < len(keyvals)-1; i += 2 {
+			if keyvals[i] != "level" {
+				continue
+			}
+
+			switch keyvals[i+1] {
+			case level.DebugValue():
+				return term.FgBgColor{Fg: term.DarkGray}
+			case level.InfoValue():
+				return term.FgBgColor{Fg: term.Green}
+			case level.WarnValue():
+				return term.FgBgColor{Fg: term.Yellow}
+			case level.ErrorValue():
+				return term.FgBgColor{Fg: term.Red}
+			}
+		}
+
+		return term.FgBgColor{}
+	})
+	base = log.NewSyncLogger(base)
+
+	return level.Debug(base), level.Info(base), level.Warn(base), level.Error(base)
+}
diff --git a/logging/middleware.go b/logging/middleware.go
new file mode 100644
index 0000000..cbb345a
--- /dev/null
+++ b/logging/middleware.go
@@ -0,0 +1,107 @@
+package logging
+
+import (
+	"context"
+	"errors"
+	"io"
+	"time"
+
+	"tildegit.org/tjp/gus"
+)
+
+func LogRequests(logger Logger) gus.Middleware {
+	return func(inner gus.Handler) gus.Handler {
+		return func(ctx context.Context, request *gus.Request) *gus.Response {
+			start := time.Now()
+
+			response := inner(ctx, request)
+			if response != nil {
+				body := loggedResponseBody{
+					request:  request,
+					response: response,
+					body:     response.Body,
+					start:    start,
+					logger:   logger,
+				}
+				response.Body = &body
+			}
+
+			return response
+		}
+	}
+}
+
+type loggedResponseBody struct {
+	request  *gus.Request
+	response *gus.Response
+	body     io.Reader
+
+	start time.Time
+
+	written int
+	logger  Logger
+}
+
+func loggingBody(logger Logger, request *gus.Request, response *gus.Response) io.Reader {
+	body := &loggedResponseBody{
+		request: request,
+		response: response,
+		body: response.Body,
+		start: time.Now(),
+		written: 0,
+		logger: logger,
+	}
+
+	if _, ok := response.Body.(io.WriterTo); ok {
+		return loggedWriteToResponseBody{body}
+	}
+
+	return body
+}
+
+func (lr *loggedResponseBody) log() {
+	end := time.Now()
+	_ = lr.logger.Log(
+		"msg", "request",
+		"ts", end,
+		"dur", end.Sub(lr.start),
+		"url", lr.request.URL,
+		"status", lr.response.Status,
+		"bodylen", lr.written,
+	)
+}
+
+func (lr *loggedResponseBody) Read(b []byte) (int, error) {
+	if lr.body == nil {
+		return 0, io.EOF
+	}
+
+	wr, err := lr.body.Read(b)
+	lr.written += wr
+
+	if errors.Is(err, io.EOF) {
+		lr.log()
+	}
+
+	return wr, err
+}
+
+func (lr *loggedResponseBody) Close() error {
+	if cl, ok := lr.body.(io.Closer); ok {
+		return cl.Close()
+	}
+	return nil
+}
+
+type loggedWriteToResponseBody struct {
+	*loggedResponseBody
+}
+
+func (lwtr loggedWriteToResponseBody) WriteTo(dst io.Writer) (int64, error) {
+	n, err := lwtr.body.(io.WriterTo).WriteTo(dst)
+	if err == nil {
+		lwtr.written += int(n)
+		lwtr.log()
+	}
+	return n, err
+}