feat: implement sync engine and scheduler

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/sync/scheduler.go

@@ -0,0 +1,74 @@
+package sync
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/robfig/cron/v3"
+	"gitm/internal/database"
+	"gitm/internal/models"
+)
+
+type Scheduler struct {
+	cron       *cron.Cron
+	engine     *Engine
+	serverJobs map[int64]cron.EntryID
+}
+
+func NewScheduler(engine *Engine) *Scheduler {
+	return &Scheduler{
+		cron:       cron.New(),
+		engine:     engine,
+		serverJobs: make(map[int64]cron.EntryID),
+	}
+}
+
+func (s *Scheduler) Start() {
+	s.cron.Start()
+	log.Println("Scheduler started")
+}
+
+func (s *Scheduler) Stop() {
+	s.cron.Stop()
+	log.Println("Scheduler stopped")
+}
+
+func (s *Scheduler) UpdateServer(server *models.GiteaServer) {
+	if entryID, exists := s.serverJobs[server.ID]; exists {
+		s.cron.Remove(entryID)
+		delete(s.serverJobs, server.ID)
+	}
+	if server.SyncInterval <= 0 || server.Status != "active" {
+		return
+	}
+	schedule := fmt.Sprintf("*/%d * * * *", server.SyncInterval)
+	entryID, err := s.cron.AddFunc(schedule, func() {
+		log.Printf("Scheduled sync for server %d (%s)", server.ID, server.Name)
+		if err := s.engine.SyncServer(server.ID); err != nil {
+			log.Printf("Scheduled sync failed for server %d: %v", server.ID, err)
+		}
+	})
+	if err != nil {
+		log.Printf("Failed to schedule for server %d: %v", server.ID, err)
+		return
+	}
+	s.serverJobs[server.ID] = entryID
+}
+
+func (s *Scheduler) RemoveServer(serverID int64) {
+	if entryID, exists := s.serverJobs[serverID]; exists {
+		s.cron.Remove(entryID)
+		delete(s.serverJobs, serverID)
+	}
+}
+
+func (s *Scheduler) ReloadAll() error {
+	servers, err := database.GetServers()
+	if err != nil {
+		return err
+	}
+	for _, server := range servers {
+		s.UpdateServer(&server)
+	}
+	return nil
+}