support openfigi api key

internal/open_figi.go

@@ -13,9 +13,12 @@ import (
 	"golang.org/x/time/rate"
 )
 
-// OpenFIGI is a small adapter for the openfigi.com api
+var OpenFIGIAPIKeyHeader = http.CanonicalHeaderKey("X-OPENFIGI-APIKEY")
+
+// OpenFIGI is a small adapter for the openfigi.com api.
 type OpenFIGI struct {
 	client         *http.Client
+	apiKey         string
 	mappingLimiter *rate.Limiter
 
 	mu sync.RWMutex
@@ -25,11 +28,18 @@ type OpenFIGI struct {
 	securityTypeCache map[string]string
 }
 
-func NewOpenFIGI(c *http.Client) *OpenFIGI {
-	return &OpenFIGI{
-		client:         c,
-		mappingLimiter: rate.NewLimiter(rate.Every(time.Minute), 25), // https://www.openfigi.com/api/documentation#rate-limits
+// NewOpenFIGI creates an OpenFIGI client that uses the API key if provided
+func NewOpenFIGI(c *http.Client, apiKey string) *OpenFIGI {
+	// Rate limits as per https://www.openfigi.com/api/documentation#rate-limits
+	limiter := rate.NewLimiter(rate.Every(time.Minute), 25)
+	if len(apiKey) > 0 {
+		limiter = rate.NewLimiter(rate.Every(time.Second*6), 25)
+	}
 
+	return &OpenFIGI{
+		client:            c,
+		apiKey:            apiKey,
+		mappingLimiter:    limiter,
 		securityTypeCache: make(map[string]string),
 	}
 }
@@ -71,6 +81,10 @@ func (of *OpenFIGI) SecurityTypeByISIN(ctx context.Context, isin string) (string
 
 	req.Header.Add("Content-Type", "application/json")
 
+	if len(of.apiKey) > 0 {
+		req.Header.Add(OpenFIGIAPIKeyHeader, of.apiKey)
+	}
+
 	err = of.mappingLimiter.Wait(ctx)
 	if err != nil {
 		return "", fmt.Errorf("wait for mapping request capacity: %w", err)