/*
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
)

// 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(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
	})
}