primeiro commit

internal/daemon/daemon.go

@@ -0,0 +1,94 @@
+// Package daemon coordinates periodic sync cycles and change hooks.
+package daemon
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"s3watch/internal/syncer"
+)
+
+// Config controls daemon scheduling behavior.
+type Config struct {
+	Interval time.Duration
+	Once     bool
+}
+
+// Syncer synchronizes remote state into local state.
+type Syncer interface {
+	Sync(context.Context) (syncer.Result, error)
+}
+
+// HookRunner runs after a sync cycle applies changes.
+type HookRunner interface {
+	Run(context.Context, syncer.Result) error
+}
+
+// Run executes sync cycles until the context is canceled.
+func Run(ctx context.Context, cfg Config, syncService Syncer, runner HookRunner, logger *slog.Logger) error {
+	if cfg.Interval <= 0 {
+		return fmt.Errorf("interval must be greater than zero")
+	}
+	if syncService == nil {
+		return fmt.Errorf("syncer is required")
+	}
+	if logger == nil {
+		logger = slog.Default()
+	}
+
+	for {
+		if err := runCycle(ctx, syncService, runner, logger, cfg.Once); err != nil {
+			if cfg.Once {
+				return err
+			}
+			logger.Error("sync cycle failed", "error", err)
+		}
+
+		if cfg.Once {
+			return nil
+		}
+
+		timer := time.NewTimer(cfg.Interval)
+		select {
+		case <-ctx.Done():
+			if !timer.Stop() {
+				select {
+				case <-timer.C:
+				default:
+				}
+			}
+			return nil
+		case <-timer.C:
+		}
+	}
+}
+
+func runCycle(ctx context.Context, syncService Syncer, runner HookRunner, logger *slog.Logger, strict bool) error {
+	result, err := syncService.Sync(ctx)
+	if err != nil {
+		return fmt.Errorf("syncing: %w", err)
+	}
+
+	logger.Info("sync cycle completed",
+		"downloaded", result.Downloaded,
+		"uploaded", result.Uploaded,
+		"updated", result.Updated,
+		"deleted", result.Deleted,
+		"unchanged", result.Unchanged,
+	)
+
+	if !result.Changed() || runner == nil {
+		return nil
+	}
+
+	if err := runner.Run(ctx, result); err != nil {
+		if strict {
+			return fmt.Errorf("running hook: %w", err)
+		}
+		logger.Error("hook failed", "error", err)
+	}
+
+	return nil
+}