From 263e77c8038664968e0d9ad3f3e88966e08b397e Mon Sep 17 00:00:00 2001
From: Frank Chiarulli Jr <frank@svix.com>
Date: Wed, 2 Jun 2021 19:19:20 -0400
Subject: [PATCH] add completion function for generating shell completions

---
 ChangeLog.md             |  6 ++++
 README.md                |  1 +
 cmd/completion.go        | 75 ++++++++++++++++++++++++++++++++++++++++
 cmd/root.go              |  1 +
 validators/validators.go | 29 +++++++++++-----
 5 files changed, 104 insertions(+), 8 deletions(-)
 create mode 100644 cmd/completion.go

diff --git a/ChangeLog.md b/ChangeLog.md
index 0204d15..1823b2a 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Version 0.8.0
+* add `completion` function to generate shell completion scripts
+
+## Version 0.7.0
+* enable colorized output by default if stdout is a TTY
+
 ## Version 0.6.1
 * fix bug in `endpoint create` which caused a panic
 
diff --git a/README.md b/README.md
index 3fb444c..e403826 100644
--- a/README.md
+++ b/README.md
@@ -71,6 +71,7 @@ The Svix CLI supports the following commands:
 | message         | List & create messages                                  |
 | message-attempt | List, lookup & resend message attempts                  |
 | verify          | Verify the signature of a webhook message               |
+| completion      | Generate completion script                              |
 | version         | Get the version of the Svix CLI                         |
 | help            | Help about any command                                  |
 
diff --git a/cmd/completion.go b/cmd/completion.go
new file mode 100644
index 0000000..1ffe2c7
--- /dev/null
+++ b/cmd/completion.go
@@ -0,0 +1,75 @@
+package cmd
+
+import (
+	"os"
+
+	"github.com/spf13/cobra"
+	"github.com/svixhq/svix-cli/validators"
+)
+
+type completionCmd struct {
+	cmd *cobra.Command
+}
+
+func newCompletionCmd() *completionCmd {
+	return &completionCmd{
+		cmd: &cobra.Command{
+			Use:   "completion [bash|zsh|fish|powershell]",
+			Short: "Generate completion script",
+			Long: `To load completions:
+
+Bash:
+
+  $ source <(svix completion bash)
+
+  # To load completions for each session, execute once:
+  # Linux:
+  $ svix completion bash > /etc/bash_completion.d/svix
+  # macOS:
+  $ svix completion bash > /usr/local/etc/bash_completion.d/svix
+
+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:
+  $ svix completion zsh > "${fpath[1]}/_svix"
+
+  # You will need to start a new shell for this setup to take effect.
+
+fish:
+
+  $ svix completion fish | source
+
+  # To load completions for each session, execute once:
+  $ svix completion fish > ~/.config/fish/completions/svix.fish
+
+PowerShell:
+
+  PS> svix completion powershell | Out-String | Invoke-Expression
+
+  # To load completions for every new session, run:
+  PS> svix completion powershell > svix.ps1
+  # and source this file from your PowerShell profile.
+`,
+			DisableFlagsInUseLine: true,
+			ValidArgs:             []string{"bash", "zsh", "fish", "powershell"},
+			Args:                  validators.ExactValidArgs(1),
+			Run: func(cmd *cobra.Command, args []string) {
+				switch args[0] {
+				case "bash":
+					cobra.CheckErr(cmd.Root().GenBashCompletion(os.Stdout))
+				case "zsh":
+					cobra.CheckErr(cmd.Root().GenZshCompletion(os.Stdout))
+				case "fish":
+					cobra.CheckErr(cmd.Root().GenFishCompletion(os.Stdout, true))
+				case "powershell":
+					cobra.CheckErr(cmd.Root().GenPowerShellCompletionWithDesc(os.Stdout))
+				}
+			},
+		},
+	}
+}
diff --git a/cmd/root.go b/cmd/root.go
index 379e1c1..fb34032 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -52,6 +52,7 @@ func init() {
 	rootCmd.AddCommand(newMessageCmd().cmd)
 	rootCmd.AddCommand(newMessageAttemptCmd().cmd)
 	rootCmd.AddCommand(newVerifyCmd().cmd)
+	rootCmd.AddCommand(newCompletionCmd().cmd)
 }
 
 // initConfig reads in config file and ENV variables if set.
diff --git a/validators/validators.go b/validators/validators.go
index 76090be..d86b7cb 100644
--- a/validators/validators.go
+++ b/validators/validators.go
@@ -37,17 +37,30 @@ func RangeArgs(min int, max int) cobra.PositionalArgs {
 func ExactArgs(n int) cobra.PositionalArgs {
 	return func(cmd *cobra.Command, args []string) error {
 		if len(args) != n {
-			msg := "`%s`requires %d args, received %d. Run `%s --help` for usage information."
 			if n == 1 {
-				msg = "`%s`requires 1 arg, received %d. Run `%s --help` for usage information."
+				return fmt.Errorf("`%s` requires 1 arg, received %d. Run `%s --help` for usage information.",
+					cmd.CommandPath(),
+					len(args),
+					cmd.CommandPath(),
+				)
+			} else {
+				return fmt.Errorf("`%s` requires %d args, received %d. Run `%s --help` for usage information.",
+					cmd.CommandPath(),
+					n,
+					len(args),
+					cmd.CommandPath(),
+				)
 			}
-			return fmt.Errorf(msg,
-				cmd.CommandPath(),
-				n,
-				len(args),
-				cmd.CommandPath(),
-			)
 		}
 		return nil
 	}
 }
+
+func ExactValidArgs(n int) cobra.PositionalArgs {
+	return func(cmd *cobra.Command, args []string) error {
+		if err := ExactArgs(n)(cmd, args); err != nil {
+			return err
+		}
+		return cobra.OnlyValidArgs(cmd, args)
+	}
+}