feat: add mode selecting (#15)

Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

pkg/realDynDns/realDynDns.go

@@ -0,0 +1,94 @@
+package realDynDns
+
+import (
+	"fmt"
+	"time"
+
+	"realdnydns/pkg/config"
+	"realdnydns/pkg/dnsProvider"
+	"realdnydns/pkg/externalIpProvider"
+	"realdnydns/pkg/notificationProvider"
+
+	"github.com/go-co-op/gocron"
+)
+
+type ChangeDetector struct {
+	externalIpProvider   externalIpProvider.ExternalIpProvider
+	dnsProvider          dnsProvider.DNSProvider
+	notificationProvider notificationProvider.NotificationProvider
+	domains              []config.DomainConfig
+}
+
+func New(
+	externalIpProvider externalIpProvider.ExternalIpProvider,
+	dnsProvider dnsProvider.DNSProvider,
+	notificationProvider notificationProvider.NotificationProvider,
+	domains []config.DomainConfig,
+) ChangeDetector {
+	return ChangeDetector{
+		externalIpProvider:   externalIpProvider,
+		dnsProvider:          dnsProvider,
+		notificationProvider: notificationProvider,
+		domains:              domains,
+	}
+}
+
+func (c *ChangeDetector) RunWithSchedule(checkInterval string) (*gocron.Scheduler, *gocron.Job, error) {
+	s := gocron.NewScheduler(time.UTC)
+	s.SingletonMode()
+	s.CronWithSeconds(checkInterval)
+
+	job, err := s.DoWithJobDetails(func(job gocron.Job) {
+		numberChanged, err := c.detectAndApplyChanges()
+		if err != nil {
+			panic(err)
+		}
+		fmt.Printf("Number of changes: %d\n", numberChanged)
+		fmt.Println("Next run:", job.NextRun())
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return s, job, nil
+}
+
+func (c *ChangeDetector) RunOnce() (int, error) {
+	return c.detectAndApplyChanges()
+}
+
+func (c *ChangeDetector) detectAndApplyChanges() (int, error) {
+	externalIp, err := c.externalIpProvider.GetExternalIp()
+	if err != nil {
+		return 0, err
+	}
+
+	var numberUpdated int
+
+	for _, domain := range c.domains {
+		for _, subdomain := range domain.Subdomains {
+			currentRecord, err := c.dnsProvider.GetRecord(domain.TLD, subdomain)
+			if err != nil {
+				return numberUpdated, err
+			}
+
+			if currentRecord.IP != externalIp.String() {
+				err = c.notificationProvider.SendNotification(
+					fmt.Sprintf("Update %s.%s", subdomain, domain.TLD),
+					fmt.Sprintf("The IP of %s has changed from %s to %s", domain.TLD, currentRecord.IP, externalIp.String()),
+				)
+				if err != nil {
+					return numberUpdated, err
+				}
+
+				_, err = c.dnsProvider.UpdateRecord(domain.TLD, subdomain, externalIp, currentRecord.TTL, currentRecord.Prio, currentRecord.Disabled)
+				numberUpdated++
+				if err != nil {
+					return numberUpdated, err
+				}
+			}
+		}
+	}
+
+	return numberUpdated, nil
+}