Add a command to generate completion scripts

USAGE.md

@@ -683,12 +683,10 @@ Further config:
 
 ## Shell completion
 
-You can generate shell completions for
- - bash: `eval "$(curl -fs https://raw.githubusercontent.com/99designs/aws-vault/master/contrib/completions/bash/aws-vault.bash)"`
- - zsh: `eval "$(curl -fs https://raw.githubusercontent.com/99designs/aws-vault/master/contrib/completions/zsh/aws-vault.zsh)"`
- - fish: `eval "$(curl -fs https://raw.githubusercontent.com/99designs/aws-vault/master/contrib/completions/fish/aws-vault.fish)"`
-
-Find the completion scripts at [contrib/completions](contrib/completions).
+You can generate shell completions for `bash`, `zsh` and `fish`:
+  - bash: `eval "$(aws-vault completion bash)"`
+  - zsh: `eval "$(aws-vault completion zsh)"`
+  - fish: `eval "$(aws-vault completion fish)"`
 
 
 ## Desktop apps

cli/completion-scripts/aws-vault.bash

@@ -0,0 +1,17 @@
+_aws-vault_bash_autocomplete() {
+    local i cur prev opts base
+
+    for (( i=1; i < COMP_CWORD; i++ )); do
+        if [[ ${COMP_WORDS[i]} == -- ]]; then
+            _command_offset $i+1
+            return
+        fi
+    done
+
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    opts=$( ${COMP_WORDS[0]} --completion-bash "${COMP_WORDS[@]:1:$COMP_CWORD}" )
+    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
+    return 0
+}
+complete -F _aws-vault_bash_autocomplete -o default aws-vault

cli/completion-scripts/aws-vault.fish

@@ -0,0 +1,24 @@
+if status --is-interactive
+  complete -ec aws-vault
+
+  # switch based on seeing a `--`
+  complete -c aws-vault -n 'not __fish_aws_vault_is_commandline' -xa '(__fish_aws_vault_complete_arg)'
+  complete -c aws-vault -n '__fish_aws_vault_is_commandline' -xa '(__fish_aws_vault_complete_commandline)'
+
+  function __fish_aws_vault_is_commandline
+    string match -q -r '^--$' -- (commandline -opc)
+  end
+
+  function __fish_aws_vault_complete_arg
+    set -l parts (commandline -opc)
+    set -e parts[1]
+
+    aws-vault --completion-bash $parts
+  end
+
+  function __fish_aws_vault_complete_commandline
+    set -l parts (string split --max 1 '--' -- (commandline -pc))
+
+    complete "-C$parts[2]"
+  end
+end

cli/completion-scripts/aws-vault.zsh

@@ -0,0 +1,24 @@
+#compdef aws-vault
+
+_aws-vault() {
+    local i
+    for (( i=2; i < CURRENT; i++ )); do
+        if [[ ${words[i]} == -- ]]; then
+            shift $i words
+            (( CURRENT -= i ))
+            _normal
+            return
+        fi
+    done
+
+    local matches=($(${words[1]} --completion-bash ${(@)words[2,$CURRENT]}))
+    compadd -a matches
+
+    if [[ $compstate[nmatches] -eq 0 && $words[$CURRENT] != -* ]]; then
+        _files
+    fi
+}
+
+if [[ "$(basename -- ${(%):-%x})" != "_aws-vault" ]]; then
+    compdef _aws-vault aws-vault
+fi

cli/completion.go

@@ -0,0 +1,72 @@
+package cli
+
+import (
+	"embed"
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/alecthomas/kingpin/v2"
+)
+
+//go:embed completion-scripts/aws-vault.*
+var completionScripts embed.FS
+
+type CompletionCommandInput struct {
+	Shell string
+}
+
+var completionScriptPrinter io.Writer = os.Stdout
+
+func ConfigureCompletionCommand(app *kingpin.Application) {
+	var input CompletionCommandInput
+
+	supportedShells, err := completionSupportedShells()
+	if err != nil {
+		panic(err)
+	}
+
+	cmd := app.Command(
+		"completion",
+		"Output shell completion script. To be used with `eval $(aws-vault completion SHELL)`.",
+	)
+
+	shellArgHelp := fmt.Sprintf("Shell to get completion script for [ %s ]", strings.Join(supportedShells, " "))
+	cmd.Arg("shell", shellArgHelp).
+		Required().
+		Envar("SHELL").
+		HintOptions(supportedShells...).
+		StringVar(&input.Shell)
+
+	cmd.Action(func(c *kingpin.ParseContext) error {
+		shell := path.Base(input.Shell) // strip any path (useful for $SHELL, doesn't hurt for other cases)
+
+		completionScript, err := completionScripts.ReadFile(fmt.Sprintf("completion-scripts/aws-vault.%s", shell))
+		if err != nil {
+			return fmt.Errorf("unknown shell: %s", input.Shell)
+		}
+
+		_, err = fmt.Fprint(completionScriptPrinter, string(completionScript))
+		if err != nil {
+			return fmt.Errorf("failed to print completion script: %w", err)
+		}
+
+		return nil
+	})
+}
+
+// completionSupportedShells returns a list of shells with available completions.
+// The list is generated from the embedded completion scripts.
+func completionSupportedShells() ([]string, error) {
+	scripts, err := completionScripts.ReadDir("completion-scripts")
+	if err != nil {
+		return nil, fmt.Errorf("failed to read completion scripts: %w", err)
+	}
+	var shells []string
+	for _, f := range scripts {
+		shells = append(shells, strings.Split(path.Ext(f.Name()), ".")[1])
+	}
+	return shells, nil
+}

cli/completion_test.go

@@ -0,0 +1,138 @@
+package cli
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/alecthomas/kingpin/v2"
+)
+
+type shellTestDataItem struct {
+	shellName        string
+	shellPath        string
+	completionScript string
+}
+
+func TestConfigureCompletionCommand(t *testing.T) {
+	app := kingpin.New("test", "")
+	ConfigureCompletionCommand(app)
+
+	shellsAndCompletionScripts, err := getShellsAndCompletionScripts()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(shellsAndCompletionScripts) == 0 {
+		t.Fatal("no shells found")
+	}
+
+	invalidShellTestDataItem := shellTestDataItem{
+		shellName: "invalid",
+		shellPath: "/bin/invalid",
+	}
+	for _, tt := range shellsAndCompletionScripts {
+		if tt.shellName == invalidShellTestDataItem.shellName {
+			t.Fatalf("invalidShellTestDataItem.shellName (%s) is actually a valid shell name", invalidShellTestDataItem.shellName)
+		}
+	}
+
+	// Test shell argument
+	t.Run("arg", func(t *testing.T) {
+		for _, tt := range shellsAndCompletionScripts {
+			t.Run(tt.shellName, func(t *testing.T) {
+				var buf bytes.Buffer
+				completionScriptPrinter = &buf
+
+				_, err := app.Parse([]string{"completion", tt.shellName})
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+
+				got := buf.String()
+				if got != tt.completionScript {
+					t.Errorf("got %q; want %q", got, tt.completionScript)
+				}
+			})
+		}
+
+		t.Run(invalidShellTestDataItem.shellName, func(t *testing.T) {
+			var buf bytes.Buffer
+			app.UsageWriter(&buf)
+
+			_, err := app.Parse([]string{"completion", "invalid"})
+
+			if err == nil {
+				t.Fatal("expected error, but didn't get one")
+			}
+
+			want := fmt.Sprintf("unknown shell: %s", invalidShellTestDataItem.shellName)
+			if err.Error() != want {
+				t.Errorf("got error(%q); want error(%q)", err.Error(), want)
+			}
+		})
+	})
+
+	// Test $SHELL envar
+	t.Run("envar", func(t *testing.T) {
+		for _, tt := range shellsAndCompletionScripts {
+			t.Run(tt.shellName, func(t *testing.T) {
+				var buf bytes.Buffer
+				completionScriptPrinter = &buf
+
+				os.Setenv("SHELL", tt.shellPath)
+
+				_, err := app.Parse([]string{"completion"})
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+
+				got := buf.String()
+				if got != tt.completionScript {
+					t.Errorf("got %q; want %q", got, tt.completionScript)
+				}
+			})
+		}
+
+		t.Run(invalidShellTestDataItem.shellName, func(t *testing.T) {
+			var buf bytes.Buffer
+			app.UsageWriter(&buf)
+
+			os.Setenv("SHELL", invalidShellTestDataItem.shellPath)
+
+			_, err := app.Parse([]string{"completion"})
+			if err == nil {
+				t.Fatal("expected error, but didn't get one")
+			}
+
+			want := fmt.Sprintf("unknown shell: %s", invalidShellTestDataItem.shellPath)
+			if err.Error() != want {
+				t.Errorf("got error(%q); want error(%q)", err.Error(), want)
+			}
+		})
+	})
+}
+
+func getShellsAndCompletionScripts() ([]shellTestDataItem, error) {
+	shells, err := completionSupportedShells()
+	if err != nil {
+		return nil, err
+	}
+
+	var shellsAndValues []shellTestDataItem
+	for _, shell := range shells {
+		completionScript, err := completionScripts.ReadFile(fmt.Sprintf("completion-scripts/aws-vault.%s", shell))
+		if err != nil {
+			return nil, err
+		}
+		shellsAndValues = append(
+			shellsAndValues,
+			shellTestDataItem{
+				shellName:        shell,
+				shellPath:        fmt.Sprintf("/bin/%s", shell),
+				completionScript: string(completionScript),
+			},
+		)
+	}
+	return shellsAndValues, nil
+}

contrib/completions/bash/aws-vault.bash

@@ -0,0 +1 @@
+../../../cli/completion-scripts/aws-vault.bash

contrib/completions/fish/aws-vault.fish

@@ -0,0 +1 @@
+../../../cli/completion-scripts/aws-vault.fish

contrib/completions/zsh/aws-vault.zsh

@@ -0,0 +1 @@
+../../../cli/completion-scripts/aws-vault.zsh

main.go

@@ -24,6 +24,7 @@ func main() {
 	cli.ConfigureClearCommand(app, a)
 	cli.ConfigureLoginCommand(app, a)
 	cli.ConfigureProxyCommand(app)
+	cli.ConfigureCompletionCommand(app)
 
 	kingpin.MustParse(app.Parse(os.Args[1:]))
 }