main: use standard flag parsing

I had to read the code to find out the correct form of the version flag.
Moving to the standard library's flag implementation provides a better
usage message out of the box and allows for better extensibility for
future flags.

1 files changed, 15 insertions, 10 deletions

diff --git a/main.go b/main.go
index 4d11a98..e3bf794 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"flag"
 	"fmt"
 	"github.com/caarlos0/spin"
 	"gopkg.in/cheggaaa/pb.v1"
@@ -18,21 +19,24 @@ type state struct {
 }
 
 func main() {
-	var args = os.Args[1:]
-	s := state{step: 0, total: 0, sent: 0}
-
-	if len(args) != 1 {
-		fmt.Println("Usage: wally-cli <firmware file>")
-		os.Exit(2)
+	flag.Usage = func() {
+		fmt.Fprintf(flag.CommandLine.Output(), "Usage of %s: [flags] <firmware file>\n", os.Args[0])
+		flag.PrintDefaults()
 	}
+	version := flag.Bool("version", false, "print the version and exit")
+	flag.Parse()
 
-	if args[0] == "--version" {
-		appVersion := fmt.Sprintf("wally-cli v%s", appVersion)
-		fmt.Println(appVersion)
+	if *version {
+		fmt.Println(fmt.Sprintf("wally-cli v%s", appVersion))
 		os.Exit(0)
 	}
 
-	path := args[0]
+	if flag.NArg() != 1 {
+		flag.Usage()
+		os.Exit(2)
+	}
+
+	path := flag.Arg(0)
 	extension := filepath.Ext(path)
 	if extension != ".bin" && extension != ".hex" {
 		fmt.Println("Please provide a valid firmware file: a .hex file (ErgoDox EZ) or a .bin file (Moonlander / Planck EZ)")
@@ -51,6 +55,7 @@ func main() {
 	var progress *pb.ProgressBar
 	progressStarted := false
 
+	s := state{step: 0, total: 0, sent: 0}
 	if extension == ".bin" {
 		go dfuFlash(path, &s)
 	}