Add getting the next reminder in a cron

pkg/cron/cron.go

@@ -16,13 +16,16 @@
 
 package cron
 
-import "github.com/robfig/cron/v3"
+import (
+	"github.com/robfig/cron/v3"
+)
 
 var c *cron.Cron
 
 // Init starts the cron
 func Init() {
 	c = cron.New()
+	c.Start()
 }
 
 // Schedule schedules a job as a cron job

pkg/initialize/init.go

@@ -84,4 +84,5 @@ func FullInit() {
 
 	// Start the cron
 	cron.Init()
+	models.RegisterReminderCron()
 }

pkg/models/task_reminder.go

@@ -16,7 +16,12 @@
 
 package models
 
-import "time"
+import (
+	"code.vikunja.io/api/pkg/config"
+	"code.vikunja.io/api/pkg/cron"
+	"code.vikunja.io/api/pkg/log"
+	"time"
+)
 
 // TaskReminder holds a reminder on a task
 type TaskReminder struct {
@@ -30,3 +35,41 @@ type TaskReminder struct {
 func (TaskReminder) TableName() string {
 	return "task_reminders"
 }
+
+// RegisterReminderCron registers a cron function which runs every minute to check if any reminders are due the
+// next minute to send emails.
+func RegisterReminderCron() {
+	if !config.MailerEnabled.GetBool() {
+		log.Info("Mailer is disabled, not sending reminders per mail")
+		return
+	}
+
+	tz := config.GetTimeZone()
+	const dbFormat = `2006-01-02 15:04:05`
+
+	log.Debugf("[Task Reminder Cron] Timezone is %s", tz)
+
+	err := cron.Schedule("* * * * *", func() {
+		// By default, time.Now() includes nanoseconds which we don't save. That results in getting the wrong dates,
+		// so we make sure the time we use to get the reminders don't contain nanoseconds.
+		now := time.Now()
+		now = time.Date(now.Year(), now.Month(), now.Day(), now.Hour(), now.Minute(), 0, 0, now.Location()).In(tz)
+		nextMinute := now.Add(1 * time.Minute)
+
+		log.Debugf("[Task Reminder Cron] Looking for reminders between %s and %s to send...", now, nextMinute)
+
+		reminders := []*TaskReminder{}
+		err := x.
+			Where("reminder >= ? and reminder < ?", now.Format(dbFormat), nextMinute.Format(dbFormat)).
+			Find(&reminders)
+		if err != nil {
+			log.Errorf("[Task Reminder Cron] Could not get reminders for the next minute: %s", err)
+			return
+		}
+
+		log.Debugf("[Task Reminder Cron] Found %d reminders", len(reminders))
+	})
+	if err != nil {
+		log.Fatalf("Could not register reminder cron: %s", err)
+	}
+}