Add regex command implementation

cmd/regex.go

@@ -0,0 +1,102 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	"github.com/rogeecn/renamer/internal/listing"
+	"github.com/rogeecn/renamer/internal/regex"
+)
+
+func newRegexCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "regex <pattern> <template>",
+		Short: "Rename files using regex capture groups",
+		Long: `Preview and apply filename changes by extracting capture groups from a regular
+expression pattern. Placeholders like @1, @2 refer to captured groups; @0 expands to the full match,
+and @@ emits a literal @. Undefined placeholders and invalid replacement templates result in
+validation errors before any filesystem changes occur.`,
+		Args: cobra.ExactArgs(2),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			scope, err := listing.ScopeFromCmd(cmd)
+			if err != nil {
+				return err
+			}
+
+			dryRun, err := getBool(cmd, "dry-run")
+			if err != nil {
+				return err
+			}
+			autoApply, err := getBool(cmd, "yes")
+			if err != nil {
+				return err
+			}
+			if dryRun && autoApply {
+				return errors.New("--dry-run cannot be combined with --yes; remove one of them")
+			}
+
+			request := regex.NewRequest(scope.WorkingDir)
+			request.Pattern = args[0]
+			request.Template = args[1]
+			request.IncludeDirectories = scope.IncludeDirectories
+			request.Recursive = scope.Recursive
+			request.IncludeHidden = scope.IncludeHidden
+			request.Extensions = append([]string(nil), scope.Extensions...)
+			request.DryRun = dryRun
+			request.AutoConfirm = autoApply
+
+			out := cmd.OutOrStdout()
+			summary, planned, err := regex.Preview(cmd.Context(), request, out)
+			if err != nil {
+				return err
+			}
+
+			for _, warning := range summary.Warnings {
+				fmt.Fprintf(out, "Warning: %s\n", warning)
+			}
+
+			if len(summary.Conflicts) > 0 {
+				for _, conflict := range summary.Conflicts {
+					fmt.Fprintf(out, "CONFLICT: %s -> %s (%s)\n", conflict.OriginalPath, conflict.ProposedPath, conflict.Reason)
+				}
+				return errors.New("conflicts detected; aborting")
+			}
+
+			if summary.Changed == 0 {
+				fmt.Fprintln(out, "No regex renames required.")
+				return nil
+			}
+
+			if !autoApply {
+				fmt.Fprintf(out, "Preview complete: %d matched, %d changed, %d skipped.\n", summary.Matched, summary.Changed, summary.Skipped)
+				fmt.Fprintln(out, "Preview complete. Re-run with --yes to apply.")
+				return nil
+			}
+
+			entry, err := regex.Apply(cmd.Context(), request, planned, summary)
+			if err != nil {
+				return err
+			}
+
+			if len(entry.Operations) == 0 {
+				fmt.Fprintln(out, "Nothing to apply; files already matched requested pattern.")
+				return nil
+			}
+
+			fmt.Fprintf(out, "Applied %d regex renames. Ledger updated.\n", len(entry.Operations))
+			return nil
+		},
+	}
+
+	cmd.Example = `  renamer regex "^(\\w+)-(\\d+)" "@2_@1" --dry-run
+  renamer regex "^(build)_(\\d+)_v(.*)$" "release-@2-@1-v@3" --yes --path ./artifacts
+  renamer regex "^(.*)$" "release-@1" --dry-run   # fails when placeholders are undefined`
+
+	return cmd
+}
+
+func init() {
+	rootCmd.AddCommand(newRegexCommand())
+}