Added logging

logging/logging.go

@@ -0,0 +1,162 @@
+package logging
+
+import (
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type Config struct {
+	Level     slog.Level
+	LevelName string
+	Format    string
+	Audit     bool
+	AddSource bool
+	DebugMode bool
+}
+
+func ConfigFromEnv() Config {
+	levelName := strings.ToLower(strings.TrimSpace(os.Getenv("LOG_LEVEL")))
+	if levelName == "" {
+		levelName = "info"
+	}
+	level := parseLevel(levelName)
+	levelName = level.String()
+
+	format := strings.ToLower(strings.TrimSpace(os.Getenv("LOG_FORMAT")))
+	if format == "" {
+		format = "text"
+	}
+	if format != "json" && format != "text" {
+		format = "text"
+	}
+
+	debugMode := level <= slog.LevelDebug
+	return Config{
+		Level:     level,
+		LevelName: levelName,
+		Format:    format,
+		Audit:     envBool("AUDIT_LOG", true),
+		AddSource: debugMode,
+		DebugMode: debugMode,
+	}
+}
+
+func NewLogger(cfg Config) *slog.Logger {
+	opts := &slog.HandlerOptions{
+		Level:     cfg.Level,
+		AddSource: cfg.AddSource,
+	}
+	opts.ReplaceAttr = func(_ []string, attr slog.Attr) slog.Attr {
+		if attr.Key == slog.SourceKey {
+			if src, ok := attr.Value.Any().(*slog.Source); ok && src != nil {
+				attr.Key = "src"
+				attr.Value = slog.StringValue(filepath.Base(src.File) + ":" + strconv.Itoa(src.Line))
+			}
+		}
+		return attr
+	}
+
+	var handler slog.Handler
+	if cfg.Format == "json" {
+		handler = slog.NewJSONHandler(os.Stdout, opts)
+	} else {
+		handler = slog.NewTextHandler(os.Stdout, opts)
+	}
+
+	logger := slog.New(handler)
+	slog.SetDefault(logger)
+	return logger
+}
+
+func HTTPMiddleware(logger *slog.Logger, cfg Config) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			start := time.Now()
+			ww := &responseWriter{ResponseWriter: w, status: http.StatusOK}
+
+			next.ServeHTTP(ww, r)
+
+			if !cfg.Audit && !cfg.DebugMode {
+				return
+			}
+
+			elapsed := time.Since(start)
+			attrs := []any{
+				"method", r.Method,
+				"path", r.URL.Path,
+				"status", ww.status,
+				"bytes", ww.bytes,
+				"remote_addr", r.RemoteAddr,
+			}
+			switch {
+			case elapsed < time.Microsecond:
+				attrs = append(attrs, "duration_ns", elapsed.Nanoseconds())
+			case elapsed < time.Millisecond:
+				attrs = append(attrs, "duration_us", elapsed.Microseconds())
+			default:
+				attrs = append(attrs, "duration_ms", elapsed.Milliseconds())
+			}
+
+			if cfg.DebugMode {
+				attrs = append(attrs,
+					"query", r.URL.RawQuery,
+					"user_agent", r.UserAgent(),
+					"content_length", r.ContentLength,
+					"content_type", r.Header.Get("Content-Type"),
+					"x_amz_sha256", r.Header.Get("x-amz-content-sha256"),
+				)
+				logger.Debug("http_request", attrs...)
+				return
+			}
+
+			logger.Info("http_request", attrs...)
+		})
+	}
+}
+
+type responseWriter struct {
+	http.ResponseWriter
+	status int
+	bytes  int
+}
+
+func (w *responseWriter) WriteHeader(statusCode int) {
+	w.status = statusCode
+	w.ResponseWriter.WriteHeader(statusCode)
+}
+
+func (w *responseWriter) Write(p []byte) (int, error) {
+	n, err := w.ResponseWriter.Write(p)
+	w.bytes += n
+	return n, err
+}
+
+func envBool(key string, defaultValue bool) bool {
+	raw := os.Getenv(key)
+	if raw == "" {
+		return defaultValue
+	}
+	value, err := strconv.ParseBool(raw)
+	if err != nil {
+		return defaultValue
+	}
+	return value
+}
+
+func parseLevel(levelName string) slog.Level {
+	switch levelName {
+	case "debug":
+		return slog.LevelDebug
+	case "warn", "warning":
+		return slog.LevelWarn
+	case "error":
+		return slog.LevelError
+	default:
+		return slog.LevelInfo
+	}
+}