feat: add structured logging middleware

option/middleware.go

@@ -3,9 +3,12 @@
 package option
 
 import (
+	"context"
 	"log"
+	"log/slog"
 	"net/http"
 	"net/http/httputil"
+	"time"
 )
 
 // WithDebugLog logs the HTTP request and response content.
@@ -36,3 +39,46 @@ func WithDebugLog(logger *log.Logger) RequestOption {
 		return resp, err
 	})
 }
+
+// WithLogger logs the HTTP request and response information using a structured
+// logger.
+func WithLogger(logger StructuredLogger) RequestOption {
+	return WithMiddleware(func(req *http.Request, nxt MiddlewareNext) (*http.Response, error) {
+		if logger == nil {
+			logger = slog.Default()
+		}
+
+		start := time.Now()
+		resp, err := nxt(req)
+		duration := time.Since(start)
+
+		if err != nil {
+			logger.Error("HTTP request failed",
+				slog.String("method", req.Method),
+				slog.String("url", req.URL.String()),
+				slog.Duration("duration", duration),
+				slog.Any("error", err),
+			)
+			return resp, err
+		}
+
+		logger.Info("HTTP request completed",
+			slog.String("method", req.Method),
+			slog.String("url", req.URL.String()),
+			slog.Int("status", resp.StatusCode),
+			slog.Duration("duration", duration),
+		)
+
+		return resp, err
+	})
+}
+
+// StructuredLogger is an interface for structured logging, compatible with
+// [log/slog.Logger].
+type StructuredLogger interface {
+	Info(msg string, args ...any)
+	Error(msg string, args ...any)
+	Warn(msg string, args ...any)
+	Debug(msg string, args ...any)
+	Log(ctx context.Context, level slog.Level, msg string, args ...any)
+}

option/middleware_test.go

@@ -0,0 +1,68 @@
+package option_test
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"log/slog"
+	"net/http"
+	"testing"
+
+	"github.com/logchimp/logchimp-go"
+	"github.com/logchimp/logchimp-go/option"
+)
+
+type mockLogger struct {
+	infoCalled  bool
+	errorCalled bool
+	lastMsg     string
+}
+
+func (m *mockLogger) Info(msg string, args ...any) {
+	m.infoCalled = true
+	m.lastMsg = msg
+}
+
+func (m *mockLogger) Error(msg string, args ...any) {
+	m.errorCalled = true
+	m.lastMsg = msg
+}
+
+func (m *mockLogger) Warn(msg string, args ...any)                                       {}
+func (m *mockLogger) Debug(msg string, args ...any)                                      {}
+func (m *mockLogger) Log(ctx context.Context, level slog.Level, msg string, args ...any) {}
+
+type closureTransport struct {
+	fn func(req *http.Request) (*http.Response, error)
+}
+
+func (t *closureTransport) Do(req *http.Request) (*http.Response, error) {
+	return t.fn(req)
+}
+
+func TestWithLogger(t *testing.T) {
+	logger := &mockLogger{}
+	client := logchimp.NewClient(
+		option.WithHTTPClient(&closureTransport{
+			fn: func(req *http.Request) (*http.Response, error) {
+				return &http.Response{
+					StatusCode: http.StatusOK,
+					Body:       io.NopCloser(bytes.NewBufferString("{}")),
+				}, nil
+			},
+		}),
+		option.WithLogger(logger),
+	)
+
+	client.Auth.Login(context.Background(), logchimp.AuthLoginParams{
+		Email:    "[email protected]",
+		Password: "password",
+	})
+
+	if !logger.infoCalled {
+		t.Error("Expected logger.Info to be called")
+	}
+	if logger.lastMsg != "HTTP request completed" {
+		t.Errorf("Expected message 'HTTP request completed', got %q", logger.lastMsg)
+	}
+}