package markdown

import "time"

const (
	DefaultInterval = time.Second * 60
	DevInterval     = time.Second * 1
)

// Watch monitors the configured markdown directory for changes. It calls GenerateLinks
// when there are changes.
func Watch(md Markdown, c *Config, interval time.Duration) (stopChan chan struct{}) {
	return TickerFunc(interval, func() {
		GenerateLinks(md, c)
	})
}

// TickerFunc runs f at interval. If interval is <= 0, it loops f. A message to the
// returned channel will stop the executing goroutine.
func TickerFunc(interval time.Duration, f func()) chan struct{} {
	stopChan := make(chan struct{})

	ticker := time.NewTicker(interval)
	go func() {
	loop:
		for {
			select {
			case <-ticker.C:
				f()
			case <-stopChan:
				ticker.Stop()
				break loop
			}
		}
	}()

	return stopChan
}