Add dryrun flag -n

internal/indexgen/indexgen.go

@@ -166,6 +166,7 @@ type Options struct {
 	IncludeHidden bool
 	ExcludeRegex  *regexp.Regexp
 	Verbose       bool
+	DryRun        bool
 }
 
 type FileEntry struct {
@@ -194,12 +195,6 @@ func ProcessDir(topDir string, opts *Options) error {
 
 	indexPath := filepath.Join(absPath, opts.OutputFile)
 
-	file, err := os.Create(indexPath)
-	if err != nil {
-		return fmt.Errorf("cannot create file %s: %w", indexPath, err)
-	}
-	defer file.Close()
-
 	dirName := filepath.Base(absPath)
 
 	entries, err := ReadDirEntries(absPath, opts)
@@ -226,9 +221,30 @@ func ProcessDir(topDir string, opts *Options) error {
 		OutputFile: opts.OutputFile,
 	}
 
-	err = GetHTMLTemplate().Execute(file, templateData)
-	if err != nil {
-		return fmt.Errorf("failed to execute template: %w", err)
+	if opts.DryRun {
+		// Dry run mode: show what would be written
+		fmt.Printf("Would write index file: %s\n", indexPath)
+		fmt.Printf("Directory: %s\n", dirName)
+		fmt.Printf("Entries found: %d\n", len(entries))
+		for _, entry := range entries {
+			entryType := "file"
+			if entry.IsDir {
+				entryType = "directory"
+			}
+			fmt.Printf("  %s: %s\n", entryType, entry.Name)
+		}
+	} else {
+		// Normal mode: actually write the file
+		file, err := os.Create(indexPath)
+		if err != nil {
+			return fmt.Errorf("cannot create file %s: %w", indexPath, err)
+		}
+		defer file.Close()
+
+		err = GetHTMLTemplate().Execute(file, templateData)
+		if err != nil {
+			return fmt.Errorf("failed to execute template: %w", err)
+		}
 	}
 
 	if opts.Recursive {