Refactored common rate limit code into separate module

internal/ratelimit/httpheader.go

@@ -0,0 +1,52 @@
+/*
+Copyright © 2023 Philipp Wolfer <phw@uploadedlobster.com>
+
+Scotty is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later version.
+
+Scotty is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+Scotty. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+package ratelimit
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/go-resty/resty/v2"
+)
+
+const (
+	RetryCount                  = 5
+	DefaultRateLimitWaitSeconds = 5
+	MaxWaitTimeSeconds          = 60
+)
+
+func EnableHTTPHeaderRateLimit(client *resty.Client, resetInHeader string) {
+	client.SetRetryCount(RetryCount)
+	client.AddRetryCondition(
+		func(r *resty.Response, err error) bool {
+			code := r.StatusCode()
+			return code == http.StatusTooManyRequests || code >= http.StatusInternalServerError
+		},
+	)
+	client.SetRetryMaxWaitTime(time.Duration(MaxWaitTimeSeconds * time.Second))
+	client.SetRetryAfter(func(client *resty.Client, resp *resty.Response) (time.Duration, error) {
+		var err error
+		var retryAfter int = DefaultRateLimitWaitSeconds
+		if resp.StatusCode() == http.StatusTooManyRequests {
+			retryAfter, err = strconv.Atoi(resp.Header().Get(resetInHeader))
+			if err != nil {
+				retryAfter = DefaultRateLimitWaitSeconds
+			}
+		}
+		return time.Duration(retryAfter * int(time.Second)), err
+	})
+}