themis/notify.go

package themis

import (
	"context"
	"fmt"
	"time"
)

var loc *time.Location

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

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.")
	}

	first := time.NewTimer(time.Until(t))
	<-first.C
	select {
	case <-ctx.Done():
		return
	default:
		n.c <- struct{}{}
	}

	ticker := time.NewTicker(time.Hour * 24 * 7)
	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			n.c <- struct{}{}
		}
		time.Sleep(time.Hour)
	}
}

func (n *Notifier) NotifyFunc(ctx context.Context, f func()) {
	for {
		select {
		case <-ctx.Done():
			return
		case <-n.c:
			f()
		}
		time.Sleep(5 * time.Minute)
	}
}