package orders

import (
	"net"
	"net/http"
	"strings"
	"sync"
	"time"

	"golang.org/x/time/rate"
)

type visitor struct {
	lim  *rate.Limiter
	seen time.Time
}

func Limit(next http.Handler, every time.Duration, burst int) http.Handler {
	var mu sync.Mutex
	visitors := map[string]*visitor{}

	go func() {
		for range time.Tick(10 * time.Minute) {
			mu.Lock()
			for ip, v := range visitors {
				if time.Since(v.seen) > 10*time.Minute {
					delete(visitors, ip)
				}
			}
			mu.Unlock()
		}
	}()

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ip := clientIP(r)
		mu.Lock()
		v, ok := visitors[ip]
		if !ok {
			v = &visitor{lim: rate.NewLimiter(rate.Every(every), burst)}
			visitors[ip] = v
		}
		v.seen = time.Now()
		allowed := v.lim.Allow()
		mu.Unlock()

		if !allowed {
			http.Error(w, "Zbyt wiele prób. Spróbuj ponownie za chwilę.", http.StatusTooManyRequests)
			return
		}
		next.ServeHTTP(w, r)
	})
}

func clientIP(r *http.Request) string {
	host, _, _ := net.SplitHostPort(r.RemoteAddr)
	if ip := net.ParseIP(host); ip != nil && ip.IsLoopback() {
		if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
			return strings.TrimSpace(strings.Split(xff, ",")[0])
		}
	}
	return host
}