themis/notify.go

package themis

import (
	"context"
	"fmt"
	"time"

	"github.com/rs/zerolog/log"
)

var loc *time.Location

func init() {
	loc, _ = time.LoadLocation("America/New_York")
}

type Notifier struct {
	c chan struct{}
}

func NewNotifier(c chan struct{}) *Notifier {
	return &Notifier{
		c: c,
	}
}

func (n *Notifier) Start(ctx context.Context) {
	m := NextMonday()
	sat := m.AddDate(0, 0, -2)
	if sat.Before(time.Now()) {
		sat = sat.AddDate(0, 0, 7)
	}

	t, err := time.ParseInLocation(time.DateTime, fmt.Sprintf("%s 17:00:00", sat.Format(time.DateOnly)), loc)
	if err != nil {
		panic("failed to parse next monday notif time. this is likely a bug.")
	}

	log.Debug().Time("next", t).Msg("starting notifier instance")

	first := time.NewTimer(time.Until(t))
	<-first.C
	select {
	case <-ctx.Done():
		log.Debug().Msg("context deadline exceeded, exiting notifier")
		return
	default:
		log.Debug().Msg("notifier tick")
		n.c <- struct{}{}
	}

	ticker := time.NewTicker(time.Hour * 24 * 7)
	for {
		select {
		case <-ctx.Done():
			log.Debug().Msg("context deadline exceeded, exiting notifier")
			return
		case <-ticker.C:
			log.Debug().Msg("notifier tick")
			n.c <- struct{}{}
		}
		time.Sleep(time.Second)
	}
}

// Trigger the notifier manually. Should be used for testing purposes only.
func (n *Notifier) Send() {
	n.c <- struct{}{}
}

func (n *Notifier) NotifyFunc(ctx context.Context, f func()) {
	for {
		select {
		case <-ctx.Done():
			log.Debug().Msg("context deadline exceeded, exiting notify func")
			return
		case <-n.c:
			log.Debug().Msg("tick received, notifying function")
			f()
		}
		time.Sleep(time.Second)
	}
}