5 files changed, 636 insertions, 0 deletions

diff --git a/logging/http/http.go b/logging/http/http.go
new file mode 100644
index 0000000..b88ae3a
--- /dev/null
+++ b/logging/http/http.go
@@ -0,0 +1,134 @@
+// Package http provides HTTP middleware and utilities, including request logging using slog.
+//
+// The LoggingHandler middleware logs HTTP request details, response status, bytes written,
+// and handles panics gracefully with stack trace logging.
+
+package http
+
+import (
+	"bufio"
+	"log/slog"
+	"net"
+	"net/http"
+	"time"
+
+	"go.sudomsg.com/kit/logging"
+)
+
+type tracingWriter struct {
+	http.ResponseWriter
+	StatusCode   int
+	BytesWritten int
+	Hijacked     bool
+}
+
+var (
+	_ http.ResponseWriter                       = &tracingWriter{}
+	_ http.Flusher                              = &tracingWriter{}
+	_ http.Hijacker                             = &tracingWriter{}
+	_ interface{ Unwrap() http.ResponseWriter } = &tracingWriter{}
+)
+
+func (tw *tracingWriter) WriteHeader(code int) {
+	tw.ResponseWriter.WriteHeader(code)
+	tw.StatusCode = code
+}
+
+func (tw *tracingWriter) Write(b []byte) (int, error) {
+	if tw.StatusCode == 0 {
+		tw.WriteHeader(http.StatusOK)
+	}
+	n, err := tw.ResponseWriter.Write(b)
+	tw.BytesWritten += n
+	return n, err
+}
+
+func (tw *tracingWriter) Flush() {
+	rc := http.NewResponseController(tw.ResponseWriter)
+	_ = rc.Flush()
+}
+
+func (tw *tracingWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	rc := http.NewResponseController(tw.ResponseWriter)
+	conn, rw, err := rc.Hijack()
+	if err == nil {
+		tw.Hijacked = true
+	}
+	return conn, rw, err
+}
+
+func (tw *tracingWriter) Unwrap() http.ResponseWriter {
+	return tw.ResponseWriter
+}
+
+// LoggingHandler is an HTTP middleware that logs requests and responses using slog.
+//
+// It recovers panics during request processing, logs them with stack traces,
+// and returns a 500 Internal Server Error if the connection is not hijacked.
+type LoggingHandler struct {
+	next   http.Handler
+	logger *slog.Logger
+}
+
+var _ http.Handler = &LoggingHandler{}
+
+// New creates a new LoggingHandler wrapping the next http.Handler, using the provided slog.Logger.
+//
+// If logger is nil, it attempts to obtain one from the request context.
+func New(next http.Handler, logger *slog.Logger) *LoggingHandler {
+	return &LoggingHandler{
+		next:   next,
+		logger: logger,
+	}
+}
+
+// ServeHTTP implements the http.Handler interface.
+//
+// It logs the HTTP method, path, client IP, protocol, host, user-agent, referer,
+// request latency, response status, and bytes written.
+// It also recovers panics, logs them, and returns HTTP 500 if appropriate.
+func (h *LoggingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	logger := h.logger
+	if logger == nil {
+		logger = logging.FromContext(ctx)
+	}
+
+	logger = logger.With(
+		slog.String("method", r.Method),
+		slog.String("path", r.URL.RequestURI()),
+		slog.String("ip", r.RemoteAddr),
+	)
+	ctx = logging.WithLogger(ctx, logger)
+	r = r.WithContext(ctx)
+
+	tw := &tracingWriter{ResponseWriter: w}
+
+	defer func() {
+		if err := recover(); err != nil {
+			logging.RecoverAndLog(ctx, "http panic", err)
+			if !tw.Hijacked && tw.StatusCode == 0 {
+				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+			}
+		}
+	}()
+
+	start := time.Now()
+
+	h.next.ServeHTTP(tw, r)
+
+	if !tw.Hijacked {
+		latency := time.Since(start)
+
+		logger.LogAttrs(r.Context(), slog.LevelInfo, "HTTP request Handled",
+			slog.String("proto", r.Proto),
+			slog.String("host", r.Host),
+			slog.String("user-agent", r.UserAgent()),
+			slog.String("referer", r.Referer()),
+			slog.Duration("latency", latency),
+			slog.Int("status", tw.StatusCode),
+			slog.Int("bytes", tw.BytesWritten),
+		)
+	}
+}
diff --git a/logging/http/http_test.go b/logging/http/http_test.go
new file mode 100644
index 0000000..26e5974
--- /dev/null
+++ b/logging/http/http_test.go
@@ -0,0 +1,113 @@
+package http_test
+
+import (
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	httpHandler "go.sudomsg.com/kit/logging/http"
+	"go.sudomsg.com/kit/logging/test"
+)
+
+func TestNew(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		method  string
+		url     string
+		status  int
+		handler http.HandlerFunc
+	}{
+		{
+			name:   "No Status",
+			method: http.MethodGet,
+			url:    "http://example.com/",
+			status: http.StatusOK,
+			handler: func(w http.ResponseWriter, r *http.Request) {
+				w.Write([]byte{})
+			},
+		},
+		{
+			name:    "NotFound",
+			method:  http.MethodGet,
+			url:     "http://example.com/",
+			status:  http.StatusNotFound,
+			handler: http.NotFound,
+		},
+		{
+			name:    "Query",
+			method:  http.MethodGet,
+			url:     "http://example.com/a?b",
+			status:  http.StatusNotFound,
+			handler: http.NotFound,
+		},
+		{
+			name:   "Flush",
+			method: http.MethodGet,
+			url:    "http://example.com/",
+			status: http.StatusOK,
+			handler: func(w http.ResponseWriter, r *http.Request) {
+				rc := http.NewResponseController(w)
+				w.Write([]byte{})
+				rc.Flush()
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			log := test.NewMockLogHandler(t)
+
+			logger := slog.New(log)
+
+			handler := httpHandler.New(tt.handler, logger)
+
+			r := httptest.NewRequest(tt.method, tt.url, nil)
+			w := httptest.NewRecorder()
+
+			handler.ServeHTTP(w, r)
+
+			records := log.Records()
+
+			if len(records) != 1 {
+				t.Fatalf("expected 1 log record, got %d", len(records))
+			}
+
+			record := records[0]
+
+			attrs := map[string]slog.Value{}
+			record.Attrs(func(a slog.Attr) bool {
+				attrs[a.Key] = a.Value
+				return true
+			})
+
+			method := attrs["method"]
+			if got := method.String(); got != tt.method {
+				t.Fatalf("expected %v log record, got %v", tt.method, got)
+			}
+			status := attrs["status"]
+			if got := int(status.Int64()); got != tt.status {
+				t.Fatalf("expected %v log record, got %v", tt.status, got)
+			}
+
+			url, err := url.Parse(tt.url)
+			if err != nil {
+				t.Fatalf("Unexpected error: %v", err)
+			}
+
+			host := attrs["host"]
+			if got := host.String(); got != url.Host {
+				t.Fatalf("expected %v log record, got %v", url.Host, got)
+			}
+			path := attrs["path"]
+			if got := path.String(); got != url.RequestURI() {
+				t.Fatalf("expected %v log record, got %v", url.RequestURI(), got)
+			}
+		})
+	}
+}
diff --git a/logging/log.go b/logging/log.go
new file mode 100644
index 0000000..8dc8017
--- /dev/null
+++ b/logging/log.go
@@ -0,0 +1,136 @@
+// Package logging provides helpers for context-aware logging using Go's slog package.
+//
+// It allows attaching loggers to context.Context for structured logging,
+// recovering and logging panics with stack traces,
+// and provides a simple package-level logger setup function.
+package logging
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log/slog"
+	"os"
+	"runtime"
+	"strings"
+)
+
+type ctxLoggerKeyType struct{}
+
+var ctxLoggerKey = ctxLoggerKeyType{}
+
+// WithLogger returns a new context derived from ctx that carries the provided slog.Logger.
+//
+// Typical usage:
+//
+//	ctx = logging.WithLogger(ctx, logger)
+func WithLogger(ctx context.Context, logger *slog.Logger) context.Context {
+	return context.WithValue(ctx, ctxLoggerKey, logger)
+}
+
+// FromContext retrieves the slog.Logger stored in ctx if any.
+// If no logger is attached to the context, returns slog.Default().
+func FromContext(ctx context.Context) *slog.Logger {
+	if logger, ok := ctx.Value(ctxLoggerKey).(*slog.Logger); ok {
+		return logger
+	}
+	return slog.Default()
+}
+
+// With returns a new slog.Logger augmented with the passed key-value pairs,
+// and a new context holding this logger.
+//
+// Typical usage:
+//
+//	logger, ctx := logging.With(ctx, "user_id", userID)
+func With(ctx context.Context, args ...any) (*slog.Logger, context.Context) {
+	logger := FromContext(ctx)
+	logger = logger.With(args...)
+	ctx = WithLogger(ctx, logger)
+	return logger, ctx
+}
+
+// WithGroup returns a new slog.Logger grouped under name,
+// and a new context holding this logger.
+//
+// Typical usage:
+//
+//	logger, ctx := logging.WithGroup(ctx, "http")
+func WithGroup(ctx context.Context, name string) (*slog.Logger, context.Context) {
+	logger := FromContext(ctx)
+	logger = logger.WithGroup(name)
+	ctx = WithLogger(ctx, logger)
+	return logger, ctx
+}
+
+// RecoverAndLog logs a recovered panic or error with a stack trace using the logger from ctx.
+//
+// Typically used in a deferred recover block:
+//
+//	defer func() {
+//	  if err := recover(); err != nil {
+//	    logging.RecoverAndLog(ctx, "Panic recovered", err)
+//	    os.Exit(1)
+//	  }
+//	}()
+func RecoverAndLog(ctx context.Context, msg string, err any) {
+	const size = 64 << 10 // 64 KB stack trace buffer
+	buf := make([]byte, size)
+	buf = buf[:runtime.Stack(buf, false)]
+	logger := FromContext(ctx)
+	logger.ErrorContext(ctx, msg, "Error", err, "stack", string(buf))
+}
+
+type LogSink string
+
+const (
+	SinkStdout LogSink = "stdout"
+	SinkStderr LogSink = "stderr"
+	SinkFile   LogSink = "file"
+)
+
+type LogConfig struct {
+	Level  slog.Level `toml:"level"`
+	Sink   LogSink    `toml:"sink"`
+	Format string     `toml:"format"`
+	File   string     `toml:"file"`
+}
+
+func Setup(cfg LogConfig) error {
+	var w io.Writer
+
+	switch cfg.Sink {
+	case SinkStdout, "":
+		w = os.Stdout
+	case SinkStderr:
+		w = os.Stderr
+	case SinkFile:
+		if cfg.File == "" {
+			return fmt.Errorf("log sink set to 'file' but no file path provided")
+		}
+		f, err := os.OpenFile(cfg.File, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+		if err != nil {
+			return fmt.Errorf("failed to open log file: %w", err)
+		}
+		w = f
+	default:
+		return fmt.Errorf("unsupported log sink: %s", cfg.Sink)
+	}
+
+	var handler slog.Handler
+	opts := &slog.HandlerOptions{
+		Level: cfg.Level,
+	}
+
+	switch strings.ToLower(cfg.Format) {
+	case "text":
+		handler = slog.NewTextHandler(w, opts)
+	case "json", "":
+		handler = slog.NewJSONHandler(w, opts)
+	default:
+		return fmt.Errorf("unsupported log format: %s", cfg.Format)
+	}
+
+	slog.SetDefault(slog.New(handler))
+	return nil
+}
diff --git a/logging/log_test.go b/logging/log_test.go
new file mode 100644
index 0000000..93ceaf6
--- /dev/null
+++ b/logging/log_test.go
@@ -0,0 +1,141 @@
+package logging_test
+
+import (
+	"errors"
+	"log/slog"
+	"testing"
+
+	"go.sudomsg.com/kit/logging"
+	"go.sudomsg.com/kit/logging/test"
+)
+
+func TestWithLogger_And_FromContext(t *testing.T) {
+	ctx := t.Context()
+	mock := test.NewMockLogHandler(t)
+	logger := slog.New(mock)
+
+	ctx = logging.WithLogger(ctx, logger)
+
+	got := logging.FromContext(ctx)
+	if got != logger {
+		t.Errorf("expected logger from context to match original logger")
+	}
+}
+
+func TestFromContext_DefaultFallback(t *testing.T) {
+	ctx := t.Context()
+	got := logging.FromContext(ctx)
+
+	if got != slog.Default() {
+		t.Errorf("expected default logger when no logger is in context")
+	}
+}
+
+func TestRecoverAndLog(t *testing.T) {
+	ctx := t.Context()
+	mock := test.NewMockLogHandler(t)
+
+	logger := slog.New(mock)
+	ctx = logging.WithLogger(ctx, logger)
+
+	err := errors.New("something broke")
+	logging.RecoverAndLog(ctx, "panic recovered", err)
+
+	records := mock.Records()
+	if len(records) != 1 {
+		t.Fatalf("expected 1 log record, got %d", len(records))
+	}
+
+	record := records[0]
+	if record.Message != "panic recovered" {
+		t.Errorf("expected message 'panic recAvered', got %q", record.Message)
+	}
+
+	foundStack := false
+	record.Attrs(func(a slog.Attr) bool {
+		if a.Key == "stack" {
+			foundStack = true
+		}
+		return true
+	})
+
+	if !foundStack {
+		t.Errorf("expected 'stack' attribute in log")
+	}
+}
+
+func TestWith(t *testing.T) {
+	ctx := t.Context()
+
+	mock := test.NewMockLogHandler(t)
+
+	logger := slog.New(mock)
+	ctx = logging.WithLogger(ctx, logger)
+
+	user := "user"
+	id := "1234"
+
+	logger2, newCtx := logging.With(ctx, "user", user, "id", id)
+	logger2.InfoContext(ctx, "test message")
+
+	records := mock.Records()
+	if len(records) != 1 {
+		t.Fatalf("expected 1 record, got %d", len(records))
+	}
+
+	record := records[0]
+	foundUser := false
+	foundID := false
+
+	record.Attrs(func(attr slog.Attr) bool {
+		switch attr.Key {
+		case "user":
+			foundUser = attr.Value.String() == user
+		case "id":
+			foundID = attr.Value.String() == id
+		}
+		return true
+	})
+
+	if !foundUser || !foundID {
+		t.Errorf("expected 'user' and 'id' attributes in log record, %v", records)
+	}
+
+	// Test context carries logger with same attributes
+	logFromCtx := logging.FromContext(newCtx)
+	logFromCtx.InfoContext(ctx, "second message")
+
+	if len(mock.Records()) != 2 {
+		t.Errorf("expected 2 log records, got %d", len(mock.Records()))
+	}
+}
+
+func TestWithGroup(t *testing.T) {
+	ctx := t.Context()
+
+	mock := test.NewMockLogHandler(t)
+
+	logger := slog.New(mock)
+	ctx = logging.WithLogger(ctx, logger)
+
+	logger2, _ := logging.WithGroup(ctx, "foo")
+	logger2.InfoContext(ctx, "test message", "key", "value")
+
+	records := mock.Records()
+	if len(records) != 1 {
+		t.Fatalf("expected 1 record, got %d", len(records))
+	}
+
+	record := records[0]
+	var foundGroup bool
+
+	record.Attrs(func(attr slog.Attr) bool {
+		foundGroup = attr.Value.Kind() == slog.KindGroup
+
+		return false
+	})
+
+	if !foundGroup {
+		t.Errorf("expected 'user' and 'id' attributes in log record, %v", records)
+	}
+}
diff --git a/logging/test/handler.go b/logging/test/handler.go
new file mode 100644
index 0000000..d1f5d40
--- /dev/null
+++ b/logging/test/handler.go
@@ -0,0 +1,112 @@
+package test
+
+// Package test provides mocks and helpers for testing code that uses slog logging.
+//
+// It includes MockHandler, a thread-safe slog.Handler implementation for capturing log records in tests.
+
+import (
+	"context"
+	"log/slog"
+	"slices"
+	"sync"
+	"testing"
+)
+
+type logRecorder struct {
+	mu      sync.Mutex
+	records []slog.Record
+}
+
+func (h *logRecorder) Append(r slog.Record) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	h.records = append(h.records, r.Clone())
+}
+
+func (h *logRecorder) Records() []slog.Record {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return slices.Clone(h.records)
+}
+
+// MockHandler is a slog.Handler that records log records for testing.
+//
+// It supports attribute and group chaining like slog's built-in handlers.
+// Use NewMockLogHandler to construct one, then pass it to slog.New in your tests.
+//
+// All recorded logs can be retrieved with the Records method.
+type MockHandler struct {
+	recorder *logRecorder
+	parent   *MockHandler
+	group    string
+	attrs    []slog.Attr
+}
+
+var _ slog.Handler = &MockHandler{}
+
+// NewMockLogHandler creates a new MockHandler for use in tests.
+func NewMockLogHandler(tb testing.TB) *MockHandler {
+	tb.Helper()
+
+	return &MockHandler{
+		recorder: &logRecorder{},
+	}
+}
+
+func (h *MockHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	return true // Capture all logs
+}
+
+func (h *MockHandler) Handle(ctx context.Context, r slog.Record) error {
+	if h.parent == nil {
+		r.Clone()
+		h.recorder.Append(r)
+		return nil
+	}
+
+	newRecord := slog.NewRecord(r.Time, r.Level, r.Message, r.PC)
+
+	attrs := slices.Clone(h.attrs)
+	r.Attrs(func(attr slog.Attr) bool {
+		attrs = append(attrs, attr)
+		return true
+	})
+
+	if h.group != "" {
+		newRecord.AddAttrs(slog.Attr{
+			Key:   h.group,
+			Value: slog.GroupValue(attrs...),
+		})
+	} else {
+		newRecord.AddAttrs(attrs...)
+	}
+
+	return h.parent.Handle(ctx, newRecord)
+}
+
+func (h *MockHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return &MockHandler{
+		recorder: h.recorder,
+		parent:   h,
+		attrs:    attrs,
+	}
+}
+
+func (h *MockHandler) WithGroup(name string) slog.Handler {
+	if name == "" {
+		return h
+	}
+	return &MockHandler{
+		recorder: h.recorder,
+		parent:   h,
+		group:    name,
+	}
+}
+
+// Records returns a copy of all slog.Records captured by this handler so far.
+//
+// It is safe to call from multiple goroutines.
+func (h *MockHandler) Records() []slog.Record {
+	return h.recorder.Records()
+}