add string type enums and retry config

pkg/client/client.go

@@ -25,8 +25,18 @@ import (
 	"time"
 )
 
-// TODO: Implement client retry configuration
-// Also support exponential backoff
+// RetryConfig controls how transient request failures (transport errors and 5xx
+// responses) are retried. The zero value disables retries.
+type RetryConfig struct {
+	// MaxRetries is the number of additional attempts made after the initial
+	// request. Zero means no retries.
+	MaxRetries int
+	// BaseDelay is the wait before the first retry. It doubles on each
+	// subsequent retry (exponential backoff). Zero means retry immediately.
+	BaseDelay time.Duration
+	// MaxDelay caps the per-retry backoff delay. Zero means no cap.
+	MaxDelay time.Duration
+}
 
 // Default ports exposed by an MGW310 station.
 const (
@@ -92,6 +102,7 @@ type Client struct {
 	tar1090   *Endpoint
 	http      *http.Client
 	userAgent string
+	retry     RetryConfig
 }
 
 // Option customizes a Client.
@@ -125,6 +136,11 @@ func WithUserAgent(ua string) Option {
 	return func(c *Client) { c.userAgent = ua }
 }
 
+// WithRetry enables retries with exponential backoff for transient failures.
+func WithRetry(cfg RetryConfig) Option {
+	return func(c *Client) { c.retry = cfg }
+}
+
 // New constructs a Client from options. A Wingbits endpoint with a non-empty
 // Host must be supplied via WithWingbitsEndpoint.
 func New(opts ...Option) (*Client, error) {