Add autocomplete for bash and zsh in lokoctl

Fixes #18

Signed-off-by: knrt10 <kautilya@kinvolk.io>

cli/cmd/completion.go

@@ -0,0 +1,294 @@
+// Copyright 2020 The Lokomotive Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+const completionDesc = `
+Generate autocompletion script for lokoctl for the specified shell (bash or zsh).
+`
+
+const completionExample = `
+		# Installing bash completion on macOS using homebrew
+		## If running Bash 3.2 included with macOS
+		    brew install bash-completion
+		## or, if running Bash 4.1+
+		    brew install bash-completion@2
+		## You need to add the completion to your completion directory
+		    lokoctl completion bash > /usr/local/etc/bash_completion.d/lokoctl && exec $SHELL
+		
+		# Installing bash completion on Linux
+		## If bash-completion is not installed on Linux, please install the 'bash-completion' package
+		## via your distribution's package manager.
+		## You need to add the completion to your completion directory
+		    lokoctl completion bash > /etc/bash_completion.d/lokoctl && exec $SHELL
+
+		## Load the lokoctl completion code for bash into the current shell
+		    source <(lokoctl completion bash)
+		# Load the lokoctl completion code for zsh into the current shell
+		    source <(lokoctl completion zsh)
+
+		# Set the lokoctl completion code for zsh to autoload on startup
+		    lokoctl completion zsh > "${fpath[1]}/_lokoctl" && exec $SHELL`
+
+const bashCompDesc = `
+Generate the autocompletion script for lokoctl for the bash shell.
+
+To load completions in your current shell session:
+$ source <(lokoctl completion bash)
+
+To load completions for every new session, execute once:
+Linux:
+  $ lokoctl completion bash > /etc/bash_completion.d/lokoctl && exec $SHELL
+MacOS:
+  $ lokoctl completion bash > /usr/local/etc/bash_completion.d/lokoctl && exec $SHELL
+`
+
+const zshCompDesc = `
+Generate the autocompletion script for lokoctl for the zsh shell.
+
+To load completions in your current shell session:
+$ source <(lokoctl completion zsh)
+
+To load completions for every new session, execute once:
+$ lokoctl completion zsh > "${fpath[1]}/_lokoctl" && exec $SHELL
+`
+
+const zshInitialization = `#compdef lokoctl
+__lokoctl_bash_source() {
+	alias shopt=':'
+	alias _expand=_bash_expand
+	alias _complete=_bash_comp
+	emulate -L sh
+	setopt kshglob noshglob braceexpand
+	source "$@"
+}
+__lokoctl_type() {
+	# -t is not supported by zsh
+	if [ "$1" == "-t" ]; then
+		shift
+		# fake Bash 4 to disable "complete -o nospace". Instead
+		# "compopt +-o nospace" is used in the code to toggle trailing
+		# spaces. We don't support that, but leave trailing spaces on
+		# all the time
+		if [ "$1" = "__lokoctl_compopt" ]; then
+			echo builtin
+			return 0
+		fi
+	fi
+	type "$@"
+}
+__lokoctl_compgen() {
+	local completions w
+	completions=( $(compgen "$@") ) || return $?
+	# filter by given word as prefix
+	while [[ "$1" = -* && "$1" != -- ]]; do
+		shift
+		shift
+	done
+	if [[ "$1" == -- ]]; then
+		shift
+	fi
+	for w in "${completions[@]}"; do
+		if [[ "${w}" = "$1"* ]]; then
+			# Use printf instead of echo because it is possible that
+			# the value to print is -n, which would be interpreted
+			# as a flag to echo
+			printf "%s\n" "${w}"
+		fi
+	done
+}
+__lokoctl_compopt() {
+	true # don't do anything. Not supported by bashcompinit in zsh
+}
+__lokoctl_ltrim_colon_completions()
+{
+	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
+		# Remove colon-word prefix from COMPREPLY items
+		local colon_word=${1%${1##*:}}
+		local i=${#COMPREPLY[*]}
+		while [[ $((--i)) -ge 0 ]]; do
+			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}
+		done
+	fi
+}
+__lokoctl_get_comp_words_by_ref() {
+	cur="${COMP_WORDS[COMP_CWORD]}"
+	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
+	words=("${COMP_WORDS[@]}")
+	cword=("${COMP_CWORD[@]}")
+}
+__lokoctl_filedir() {
+	local RET OLD_IFS w qw
+	__debug "_filedir $@ cur=$cur"
+	if [[ "$1" = \~* ]]; then
+		# somehow does not work. Maybe, zsh does not call this at all
+		eval echo "$1"
+		return 0
+	fi
+	OLD_IFS="$IFS"
+	IFS=$'\n'
+	if [ "$1" = "-d" ]; then
+		shift
+		RET=( $(compgen -d) )
+	else
+		RET=( $(compgen -f) )
+	fi
+	IFS="$OLD_IFS"
+	IFS="," __debug "RET=${RET[@]} len=${#RET[@]}"
+	for w in ${RET[@]}; do
+		if [[ ! "${w}" = "${cur}"* ]]; then
+			continue
+		fi
+		if eval "[[ \"\${w}\" = *.$1 || -d \"\${w}\" ]]"; then
+			qw="$(__lokoctl_quote "${w}")"
+			if [ -d "${w}" ]; then
+				COMPREPLY+=("${qw}/")
+			else
+				COMPREPLY+=("${qw}")
+			fi
+		fi
+	done
+}
+__lokoctl_quote() {
+	if [[ $1 == \'* || $1 == \"* ]]; then
+		# Leave out first character
+		printf %q "${1:1}"
+	else
+		printf %q "$1"
+	fi
+}
+autoload -U +X bashcompinit && bashcompinit
+# use word boundary patterns for BSD or GNU sed
+LWORD='[[:<:]]'
+RWORD='[[:>:]]'
+if sed --help 2>&1 | grep -q 'GNU\|BusyBox'; then
+	LWORD='\<'
+	RWORD='\>'
+fi
+__lokoctl_convert_bash_to_zsh() {
+	sed \
+	-e 's/declare -F/whence -w/' \
+	-e 's/_get_comp_words_by_ref "\$@"/_get_comp_words_by_ref "\$*"/' \
+	-e 's/local \([a-zA-Z0-9_]*\)=/local \1; \1=/' \
+	-e 's/flags+=("\(--.*\)=")/flags+=("\1"); two_word_flags+=("\1")/' \
+	-e 's/must_have_one_flag+=("\(--.*\)=")/must_have_one_flag+=("\1")/' \
+	-e "s/${LWORD}_filedir${RWORD}/__lokoctl_filedir/g" \
+	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__lokoctl_get_comp_words_by_ref/g" \
+	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__lokoctl_ltrim_colon_completions/g" \
+	-e "s/${LWORD}compgen${RWORD}/__lokoctl_compgen/g" \
+	-e "s/${LWORD}compopt${RWORD}/__lokoctl_compopt/g" \
+	-e "s/${LWORD}declare${RWORD}/builtin declare/g" \
+	-e "s/\\\$(type${RWORD}/\$(__lokoctl_type/g" \
+	-e 's/aliashash\["\(.\{1,\}\)"\]/aliashash[\1]/g' \
+	-e 's/FUNCNAME/funcstack/g' \
+	<<'BASH_COMPLETION_EOF'
+`
+
+const zshTail = `
+BASH_COMPLETION_EOF
+}
+__lokoctl_bash_source <(__lokoctl_convert_bash_to_zsh)
+`
+
+func newCompletionCmd(out io.Writer) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:               "completion",
+		Short:             "Generate autocompletion script for the specified shell",
+		Long:              completionDesc,
+		Example:           completionExample,
+		Args:              NoArgs,
+		ValidArgsFunction: noCompletions, // Disable file completion.
+	}
+
+	bash := &cobra.Command{
+		Use:                   "bash",
+		Short:                 "Generate autocompletion script for bash",
+		Long:                  bashCompDesc,
+		Args:                  NoArgs,
+		DisableFlagsInUseLine: true,
+		ValidArgsFunction:     noCompletions,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runCompletionBash(out, cmd)
+		},
+	}
+
+	zsh := &cobra.Command{
+		Use:                   "zsh",
+		Short:                 "Generate autocompletion script for zsh",
+		Long:                  zshCompDesc,
+		Args:                  NoArgs,
+		DisableFlagsInUseLine: true,
+		ValidArgsFunction:     noCompletions,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runCompletionZsh(out, cmd)
+		},
+	}
+
+	cmd.AddCommand(bash, zsh)
+
+	return cmd
+}
+
+func runCompletionBash(out io.Writer, cmd *cobra.Command) error {
+	return cmd.Root().GenBashCompletion(out)
+}
+
+func runCompletionZsh(out io.Writer, cmd *cobra.Command) error {
+	_, err := out.Write([]byte(zshInitialization))
+	if err != nil {
+		return fmt.Errorf("writing zsh initialization: %w", err)
+	}
+
+	err = runCompletionBash(out, cmd)
+	if err != nil {
+		return fmt.Errorf("running bash completion: %w", err)
+	}
+
+	_, err = out.Write([]byte(zshTail))
+	if err != nil {
+		return fmt.Errorf("writing zsh tail: %w", err)
+	}
+
+	return nil
+}
+
+// noCompletions is used to disable file completion.
+func noCompletions(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	return nil, cobra.ShellCompDirectiveNoFileComp
+}
+
+// NoArgs returns an error if any args are included.
+func NoArgs(cmd *cobra.Command, args []string) error {
+	if len(args) > 0 {
+		return fmt.Errorf(
+			"%q accepts no arguments\n\nUsage:  %s",
+			cmd.CommandPath(),
+			cmd.UseLine(),
+		)
+	}
+
+	return nil
+}
+
+func init() { //nolint:gochecknoinits
+	RootCmd.AddCommand(newCompletionCmd(os.Stdout))
+}

cli/cmd/component-apply.go

@@ -32,6 +32,13 @@ var componentApplyCmd = &cobra.Command{
 Deploys a component if not yet present, otherwise updates it.
 When run with no arguments, all components listed in the configuration are applied.`,
 	Run: runApply,
+	ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		if len(args) != 0 {
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+
+		return components.ListNames(), cobra.ShellCompDirectiveNoFileComp
+	},
 }
 
 func init() {

cli/cmd/component-delete.go

@@ -31,6 +31,13 @@ var componentDeleteCmd = &cobra.Command{
 	Long: `Delete a component.
 When run with no arguments, all components listed in the configuration are deleted.`,
 	Run: runDelete,
+	ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		if len(args) != 0 {
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+
+		return components.ListNames(), cobra.ShellCompDirectiveNoFileComp
+	},
 }
 
 var deleteNamespace bool