Support version output

Author: CrSjimo

internal/cli/root.go

@@ -3,11 +3,22 @@ package cli
 import (
 	"diffscope-package-manager/internal/cli/commands"
 	"diffscope-package-manager/internal/config"
+	"encoding/json"
+	"fmt"
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
 
+var (
+	version = "0.0.0+dev"
+)
+
+type versionJsonOutput struct {
+	Name    string `json:"name"`
+	Version string `json:"version"`
+}
+
 var (
 	rootCmd = &cobra.Command{
 		Use:           "dspm",
@@ -17,6 +28,32 @@ var (
 		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 			return initConfig(cmd)
 		},
+		RunE: func(cmd *cobra.Command, arg []string) error {
+			showVersion, err := cmd.Flags().GetBool("version")
+			if err != nil {
+				return err
+			}
+			if showVersion {
+				if loadedConfig.JSON {
+					output := versionJsonOutput{
+						Name:    cmd.Use,
+						Version: version,
+					}
+					jsonBytes, err := json.Marshal(output)
+					if err != nil {
+						return err
+					}
+					fmt.Fprintln(cmd.OutOrStdout(), string(jsonBytes))
+				} else {
+					fmt.Fprintf(cmd.OutOrStdout(), "%s version %s\n", cmd.Use, version)
+				}
+				return nil
+			}
+			return cmd.Help()
+		},
+		CompletionOptions: cobra.CompletionOptions{
+			DisableDefaultCmd: true,
+		},
 	}
 
 	loadedConfig config.Config
@@ -35,6 +72,7 @@ func Config() config.Config {
 func init() {
 	rootCmd.PersistentFlags().Bool("json", false, "output JSON")
 	rootCmd.PersistentFlags().String("packages-dir", "", "packages installation directory")
+	rootCmd.Flags().BoolP("version", "v", false, "version for "+rootCmd.Use)
 
 	rootCmd.AddCommand(
 		commands.NewInstallCmd(),