package jobs

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

const slotWaitInterval = 500 * time.Millisecond

type slotLimiter struct {
	mutex  sync.Mutex
	active int
}

func (limiter *slotLimiter) acquire(ctx context.Context, limit func() int) bool {
	ticker := time.NewTicker(slotWaitInterval)
	defer ticker.Stop()
	for {
		if limiter.tryAcquire(limit()) {
			return true
		}
		select {
		case <-ctx.Done():
			return false
		case <-ticker.C:
		}
	}
}

func (limiter *slotLimiter) tryAcquire(limit int) bool {
	limiter.mutex.Lock()
	defer limiter.mutex.Unlock()
	if limiter.active >= limit {
		return false
	}
	limiter.active++
	return true
}

func (limiter *slotLimiter) release() {
	limiter.mutex.Lock()
	defer limiter.mutex.Unlock()
	limiter.active--
}