feat: adding shell completions

Author: ehfeng

cmd/completion.go

@@ -0,0 +1,59 @@
+package cmd
+
+import (
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var completionCmd = &cobra.Command{
+	Use:   "completion [bash|zsh|fish]",
+	Short: "Generate shell completion scripts",
+	Long: `Generate shell completion scripts for Kernel CLI.
+
+To load completions:
+
+Bash:
+  $ source <(kernel completion bash)
+
+  # To load completions for each session, execute once:
+  # Linux:
+  $ kernel completion bash > /etc/bash_completion.d/kernel
+  # macOS:
+  $ kernel completion bash > $(brew --prefix)/etc/bash_completion.d/kernel
+
+Zsh:
+  # If shell completion is not already enabled in your environment,
+  # you will need to enable it. You can execute the following once:
+  $ echo "autoload -U compinit; compinit" >> ~/.zshrc
+
+  # To load completions for each session, execute once:
+  $ kernel completion zsh > "${fpath[1]}/_kernel"
+
+  # You will need to start a new shell for this setup to take effect.
+
+Fish:
+  $ kernel completion fish | source
+
+  # To load completions for each session, execute once:
+  $ kernel completion fish > ~/.config/fish/completions/kernel.fish
+`,
+	DisableFlagsInUseLine: true,
+	ValidArgs:             []string{"bash", "zsh", "fish"},
+	Args:                  cobra.MatchAll(cobra.ExactArgs(1), cobra.OnlyValidArgs),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		switch args[0] {
+		case "bash":
+			return cmd.Root().GenBashCompletion(os.Stdout)
+		case "zsh":
+			return cmd.Root().GenZshCompletion(os.Stdout)
+		case "fish":
+			return cmd.Root().GenFishCompletion(os.Stdout, true)
+		}
+		return nil
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(completionCmd)
+}