logger

type Config struct {
	// Skip defines a function to conditionally bypass this middleware.
	// When it returns true for a given request, no log entry is emitted
	// and c.Next() is called directly.
	Skip func(c *celeris.Context) bool

	// Output is the slog.Logger used to emit log records.
	// When nil, slog.Default() is used.
	Output *slog.Logger

	// Level maps an HTTP response status code to a slog.Level, controlling
	// the severity of each log entry. The default maps 5xx to Error,
	// 4xx to Warn, and everything else to Info.
	Level func(status int) slog.Level

	// Fields is an optional callback that returns additional slog.Attr
	// values to include in each log entry. It is called after the
	// downstream handler completes, so latency and response data are
	// available.
	Fields func(c *celeris.Context, latency time.Duration) []slog.Attr

	// Done is an optional callback invoked after the log entry is written.
	// It is always called, even when the log level is disabled, making it
	// suitable for alerting on 5xx responses or collecting metrics outside
	// the log pipeline.
	Done func(c *celeris.Context, latency time.Duration, status int)

	// SkipPaths is a list of request paths to exclude from logging.
	// Matching is exact (no glob or prefix support).
	SkipPaths []string

	// CaptureRequestBody enables logging of the request body, truncated
	// to MaxCaptureBytes. The body is emitted as the "request_body" attr.
	CaptureRequestBody bool

	// CaptureResponseBody enables logging of the response body, truncated
	// to MaxCaptureBytes. The body is emitted as the "response_body" attr
	// and requires the response to be captured via c.CaptureResponse().
	CaptureResponseBody bool

	// MaxCaptureBytes is the maximum number of body bytes to include in
	// the log entry when CaptureRequestBody or CaptureResponseBody is
	// enabled. Default: 4096. This cap prevents OOM on large payloads.
	MaxCaptureBytes int

	// SensitiveHeaders lists header names whose values should be redacted
	// in log output. Matched values are replaced with "[REDACTED]" and
	// header names are compared case-insensitively.
	//
	// When nil, DefaultSensitiveHeaders is used automatically. Set to an
	// empty slice ([]string{}) to disable all header redaction.
	SensitiveHeaders []string

	// TimeZone sets the timezone applied to log timestamps before they
	// are passed to the slog handler. When nil, the local timezone is
	// used.
	TimeZone *time.Location

	// TimeFormat sets a custom Go time layout string (e.g. time.RFC3339)
	// for FastHandler output. When empty, FastHandler uses its built-in
	// zero-alloc RFC3339-millis formatter.
	TimeFormat string

	// LogHost includes the request Host header as the "host" slog attr.
	// Disabled by default to keep log entries compact.
	LogHost bool

	// LogUserAgent includes the User-Agent request header as the
	// "user_agent" slog attr. Disabled by default.
	LogUserAgent bool

	// LogReferer includes the Referer request header as the "referer"
	// slog attr. Disabled by default.
	LogReferer bool

	// LogRoute includes the matched route pattern from c.FullPath() as
	// the "route" slog attr. Omitted when the route is empty (e.g., 404).
	LogRoute bool

	// LogPID includes the process ID (cached at init) as the "pid" slog
	// attr. Useful for distinguishing workers in multi-process deployments.
	LogPID bool

	// LogQueryParams includes the raw query string from the request URL
	// as the "query" slog attr. Omitted when there is no query string.
	LogQueryParams bool

	// LogFormValues includes URL-encoded form field names and values as
	// the "form" slog attr. Only active when the request content-type is
	// application/x-www-form-urlencoded. Use SensitiveFormFields to
	// redact secrets.
	LogFormValues bool

	// LogCookies includes cookie names (not values, for security) as the
	// "cookies" slog attr. Values are intentionally omitted to avoid
	// leaking session tokens into logs.
	LogCookies bool

	// LogBytesIn includes the request Content-Length as the "bytes_in"
	// slog attr (int64). Omitted when the content length is negative or
	// absent.
	LogBytesIn bool

	// LogScheme includes the request scheme from c.Scheme() (e.g.,
	// "https") as the "scheme" slog attr.
	LogScheme bool

	// DisableColors overrides the Color flag on FastHandlerOptions. When
	// true, the FastHandler emits plain text without ANSI escape codes.
	// Useful for log files, CI pipelines, or any non-terminal output.
	DisableColors bool

	// LogResponseHeaders lists specific response header names whose values
	// should be included in the log entry. Names are compared
	// case-insensitively and each matched header is logged as
	// "resp_header.<lowercased-name>".
	LogResponseHeaders []string

	// SensitiveFormFields lists form field names whose values should be
	// redacted when LogFormValues is true. Matched values are replaced
	// with "[REDACTED]" and field names are compared case-insensitively.
	//
	// IMPORTANT: Unlike SensitiveHeaders (where nil uses defaults), nil
	// here means NO redaction at all — every form value is logged verbatim,
	// including passwords and secrets. This asymmetry is intentional
	// because form field names are application-specific.
	//
	// Use [DefaultSensitiveFormFields] for a reasonable starting list:
	//
	//   SensitiveFormFields: logger.DefaultSensitiveFormFields()
	//
	// Semantics:
	//   - nil  → no form field redaction (all values logged as-is).
	//   - []string{} (empty) → no form field redaction (same as nil).
	//   - non-empty → matching fields are replaced with "[REDACTED]".
	SensitiveFormFields []string

	// LogContextKeys lists context store keys whose values should be
	// included in the log entry. For each key, the middleware calls
	// c.Get(key) and, if found, emits the value as a "ctx.<key>" slog
	// attr using fmt.Sprint for non-string types.
	LogContextKeys []string
}

type FastHandler struct {
	// contains filtered or unexported fields
}

type FastHandlerOptions struct {
	// Level is the minimum log level. Default: slog.LevelInfo.
	Level slog.Level
	// Color enables ANSI color codes in output.
	// Level names are colored: red=ERROR, yellow=WARN, green=INFO, cyan=DEBUG.
	Color bool
	// TimeFormat sets a custom Go time layout (e.g. time.RFC3339).
	// When empty, the built-in RFC3339-millis formatter is used.
	TimeFormat string
}