Add Powershell completion (#316)

Signed-off-by: Lukas Kämmerling <[email protected]>

README.md

@@ -82,7 +82,7 @@ To load completions for each session execute the following commands:
     mkdir -p ~/.config/hcloud/completion/zsh
     hcloud completion zsh > ~/.config/hcloud/completion/zsh/_hcloud
 
-Finally add the following line to your `~/.zshrc` file, *before* you
+Finally, add the following line to your `~/.zshrc` file, *before* you
 call the `compinit` function:
 
     fpath+=(~/.config/hcloud/completion/zsh)
@@ -107,6 +107,17 @@ In order to make the completions permanent execute once:
 
      hcloud completion fish > ~/.config/fish/completions/hcloud.fish
 
+### PowerShell:
+
+To load completions into the current shell execute:
+
+    PS> hcloud completion powershell | Out-String | Invoke-Expression
+
+To load completions for every new session, run
+and source this file from your PowerShell profile.
+
+    PS> hcloud completion powershell > hcloud.ps1
+
 ## Output configuration
 
 You can control output via the `-o` option:

internal/cmd/completion/completion.go

@@ -81,9 +81,20 @@ To load completions into the current shell execute:
 In order to make the completions permanent execute once:
 
      hcloud completion fish > ~/.config/fish/completions/hcloud.fish
+
+### PowerShell:
+
+To load completions into the current shell execute:
+
+  PS> hcloud completion powershell | Out-String | Invoke-Expression
+
+To load completions for every new session, run 
+and source this file from your PowerShell profile.
+
+  PS> hcloud completion powershell > hcloud.ps1
 `,
 		Args:                  cobra.ExactArgs(1),
-		ValidArgs:             []string{"bash", "fish", "zsh"},
+		ValidArgs:             []string{"bash", "fish", "zsh", "powershell"},
 		DisableFlagsInUseLine: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			var err error
@@ -95,6 +106,8 @@ In order to make the completions permanent execute once:
 				err = cmd.Root().GenFishCompletion(os.Stdout, true)
 			case "zsh":
 				err = cmd.Root().GenZshCompletion(os.Stdout)
+			case "powershell":
+				err = cmd.Root().GenPowerShellCompletion(os.Stdout)
 			default:
 				err = fmt.Errorf("Unsupported shell: %s", args[0])
 			}