/*
Copyright © 2023-2025 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/>.
*/

// Helper functions to set up rate limiting with resty.
package ratelimit

import (
	"net/http"
	"strconv"
	"time"

	"github.com/go-resty/resty/v2"
)

const (
	RetryCount           = 5
	DefaultRateLimitWait = 5 * time.Second
	MaxWaitTime          = 60 * time.Second
)

// Implements rate HTTP header based limiting for resty.
//
// This works with servers that return the status code 429 (Too Many Requests)
// and an HTTP header indicating the time in seconds until rate limit resets.
// Common headers used are "X-RateLimit-Reset-In" or "Retry-After".
//
// Usage:
//
//	ratelimit.EnableHTTPHeaderRateLimit(client, "Retry-After")
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(MaxWaitTime)
	client.SetRetryAfter(func(client *resty.Client, resp *resty.Response) (time.Duration, error) {
		retryAfter := DefaultRateLimitWait
		if resp.StatusCode() == http.StatusTooManyRequests {
			retryAfterHeader, err := strconv.Atoi(resp.Header().Get(resetInHeader))
			if err == nil {
				retryAfter = time.Duration(retryAfterHeader) * time.Second
			}
		}
		return retryAfter, nil
	})
}