implement editor rename

cmd/mmv/main.go

@@ -1,10 +1,16 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"os"
+	"os/exec"
 	"runtime"
+	"strings"
+
+	"github.com/mattn/go-tty"
 
 	"github.com/itchyny/mmv"
 )
@@ -57,9 +63,58 @@ Options:
 		fmt.Printf("usage: %s files ...\n", name)
 		return exitCodeErr
 	}
-	if err := mmv.Rename(nil); err != nil {
+	if err := rename(args); err != nil {
 		fmt.Fprintf(os.Stderr, "%s: %s\n", name, err)
 		return exitCodeErr
 	}
 	return exitCodeOK
 }
+
+func rename(args []string) error {
+	f, err := ioutil.TempFile("", name+"-")
+	if err != nil {
+		return err
+	}
+	defer func() {
+		f.Close()
+		os.Remove(f.Name())
+	}()
+	for _, arg := range args {
+		f.WriteString(arg)
+		f.WriteString("\n")
+	}
+	editor := os.Getenv("EDITOR")
+	if editor != "" {
+		editor = "vi"
+	}
+	tty, err := tty.Open()
+	if err != nil {
+		return err
+	}
+	defer tty.Close()
+	cmd := exec.Command(editor, f.Name())
+	cmd.Stdin = tty.Input()
+	cmd.Stdout = tty.Output()
+	cmd.Stderr = tty.Output()
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+	cnt, err := ioutil.ReadFile(f.Name())
+	if err != nil {
+		return err
+	}
+	got := strings.Split(strings.TrimSpace(string(cnt)), "\n")
+	if len(args) != len(got) {
+		return errors.New("do not delete or add lines")
+	}
+	files := make(map[string]string, len(args))
+	for i, src := range args {
+		if dst := got[i]; src != dst {
+			files[src] = dst
+		}
+	}
+	return mmv.Rename(files)
+}