dry run by default

main.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"log"
 	"os"
 	"os/signal"
 	"path"
@@ -29,6 +30,7 @@ func main() {
 	overridesS := flags.String("c", `{"title":"","season":"","episode":""}`, "overrides")
 	ind := flags.String("i", "/dev/null", "in dir")
 	outd := flags.String("o", "/dev/null", "out dir")
+	dry := flags.Bool("d", true, "dry run")
 	if err := flags.Parse(os.Args[1:]); err != nil {
 		panic(err)
 	}
@@ -36,12 +38,30 @@ func main() {
 	var overrides Fields
 	json.Unmarshal([]byte(*overridesS), &overrides)
 
+	mvNLn := RealMvNLn
+	if *dry {
+		outd := map[string]struct{}{}
+		mvNLn = func(outf, inf string) error {
+			if _, err := os.Stat(outf); err == nil {
+				return nil
+			}
+
+			if _, ok := outd[outf]; ok {
+				return nil
+			}
+			outd[outf] = struct{}{}
+
+			log.Printf("mv %q %q", inf, outf)
+			return nil
+		}
+	}
+
 	if err := Run(ctx,
 		*outd,
 		*ind,
 		flags.Args(),
 		overrides,
-		RealMvNLn,
+		mvNLn,
 	); err != nil {
 		panic(err)
 	}