implement mmv cli base

cmd/mmv/main.go

@@ -1,7 +1,65 @@
 package main
 
-import "fmt"
+import (
+	"flag"
+	"fmt"
+	"os"
+	"runtime"
+
+	"github.com/itchyny/mmv"
+)
+
+const name = "mmv"
+
+const version = "0.0.0"
+
+var revision = "HEAD"
 
 func main() {
-	fmt.Print("mmv")
+	os.Exit(run(os.Args[1:]))
+}
+
+const (
+	exitCodeOK = iota
+	exitCodeErr
+)
+
+func run(args []string) int {
+	fs := flag.NewFlagSet(name, flag.ContinueOnError)
+	fs.SetOutput(os.Stderr)
+	fs.Usage = func() {
+		fs.SetOutput(os.Stdout)
+		fmt.Printf(`%[1]s - rename multiple files with editor
+
+Version: %s (rev: %s/%s)
+
+Synopsis:
+  %% %[1]s files ...
+
+Options:
+`, name, version, revision, runtime.Version())
+		fs.PrintDefaults()
+	}
+	var showVersion bool
+	fs.BoolVar(&showVersion, "v", false, "print version")
+	if err := fs.Parse(args); err != nil {
+		if err == flag.ErrHelp {
+			return exitCodeOK
+		}
+		return exitCodeErr
+	}
+	if showVersion {
+		fmt.Printf("%s %s (rev: %s/%s)\n", name, version, revision, runtime.Version())
+		return exitCodeOK
+	}
+	args = fs.Args()
+	if len(args) == 0 {
+		fmt.Printf("usage: %s files ...\n", name)
+		return exitCodeErr
+	}
+	if err := mmv.Rename(nil); err != nil {
+		fmt.Fprintf(os.Stderr, "%s: %s\n", name, err)
+		return exitCodeErr
+	}
+	return exitCodeOK
 }