add version subcommand (#36)

* add version subcommand

* prepare for --format=json output

* Apply suggestion from code review: reintroduce `cobra.NoArgs`

* refactor public/private vars and functions

Author: umbynos

cli/cli.go

@@ -27,6 +27,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/arduino/FirmwareUploader/cli/version"
 	"github.com/arduino/FirmwareUploader/modules/nina"
 	"github.com/arduino/FirmwareUploader/modules/sara"
 	"github.com/arduino/FirmwareUploader/modules/winc"
@@ -49,6 +50,8 @@ func NewCommand() *cobra.Command {
 		Run:     run,
 	}
 
+	firmwareUploaderCli.AddCommand(version.NewCommand())
+
 	firmwareUploaderCli.Flags().StringVar(&ctx.PortName, "port", "", "serial port to use for flashing")
 	firmwareUploaderCli.Flags().StringVar(&ctx.RootCertDir, "certs", "", "root certificate directory")
 	firmwareUploaderCli.Flags().StringSliceVar(&ctx.Addresses, "address", []string{}, "address (host:port) to fetch and flash root certificate for, multiple values allowed")

cli/version/version.go

@@ -0,0 +1,25 @@
+package version
+
+import (
+	"fmt"
+	"os"
+
+	v "github.com/arduino/FirmwareUploader/version"
+	"github.com/spf13/cobra"
+)
+
+// NewCommand created a new `version` command
+func NewCommand() *cobra.Command {
+	return &cobra.Command{
+		Use:     "version",
+		Short:   "Shows version number of FirmwareUploader.",
+		Long:    "Shows the version number of FirmwareUploader which is installed on your system.",
+		Example: "  " + os.Args[0] + " version",
+		Args:    cobra.NoArgs,
+		Run:     run,
+	}
+}
+
+func run(cmd *cobra.Command, args []string) {
+	fmt.Print(v.VersionInfo)
+}

version/version.go

@@ -0,0 +1,38 @@
+package version
+
+import "fmt"
+
+var (
+	defaultVersionString = "0.0.0-git"
+	versionString        = ""
+	commit               = ""
+	date                 = ""
+	VersionInfo          *info
+)
+
+type info struct {
+	Application   string `json:"Application"`
+	VersionString string `json:"VersionString"`
+	Commit        string `json:"Commit"`
+	Date          string `json:"Date"`
+}
+
+func newInfo(application string) *info {
+	return &info{
+		Application:   application,
+		VersionString: versionString,
+		Commit:        commit,
+		Date:          date,
+	}
+}
+
+func (i *info) String() string {
+	return fmt.Sprintf("%s Version: %s Commit: %s Date: %s", i.Application, i.VersionString, i.Commit, i.Date)
+}
+
+func init() {
+	if versionString == "" {
+		versionString = defaultVersionString
+	}
+	VersionInfo = newInfo("FirmwareUploader")
+}