package activitypub

import (
	"context"
	"sync"
	"time"
)

type hostLimiter struct {
	mu      sync.Mutex
	buckets map[string]*bucket
}

type bucket struct {
	mu   sync.Mutex
	last time.Time
}

func newHostLimiter() *hostLimiter {
	return &hostLimiter{buckets: make(map[string]*bucket)}
}

func (h *hostLimiter) Wait(ctx context.Context, host string) error {
	h.mu.Lock()
	b, ok := h.buckets[host]
	if !ok {
		b = &bucket{}
		h.buckets[host] = b
		if len(h.buckets) > 1024 {
			for k, v := range h.buckets {
				if time.Since(v.last) > 10*time.Minute {
					delete(h.buckets, k)
				}
			}
		}
	}
	h.mu.Unlock()

	b.mu.Lock()
	defer b.mu.Unlock()

	if b.last.IsZero() {
		b.last = time.Now()
		return nil
	}
	wait := time.Until(b.last.Add(time.Second))
	if wait <= 0 {
		b.last = time.Now()
		return nil
	}
	select {
	case <-time.After(wait):
		b.last = time.Now()
		return nil
	case <-ctx.Done():
		return ctx.Err()
	}
}