Add zsh completion and docs

cmd/minikube/cmd/completion.go

@@ -17,6 +17,7 @@ limitations under the License.
 package cmd
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"os"
@@ -27,20 +28,24 @@ import (
 )
 
 const longDescription = `
-	Outputs minikube shell completion for the given shell (bash)
+	Outputs minikube shell completion for the given shell (bash or zsh)
 
 	This depends on the bash-completion binary.  Example installation instructions:
 	OS X:
 		$ brew install bash-completion
 		$ source $(brew --prefix)/etc/bash_completion
-		$ minikube completion bash > ~/.minikube-completion
+		$ minikube completion bash > ~/.minikube-completion  # for bash users
+		$ minikube completion zsh > ~/.minikube-completion  # for zsh users
 		$ source ~/.minikube-completion
 	Ubuntu:
 		$ apt-get install bash-completion
 		$ source /etc/bash-completion
-		$ source <(minikube completion bash)
+		$ source <(minikube completion bash) # for bash users
+		$ source <(minikube completion bash) # for zsh users
 
 	Additionally, you may want to output the completion to a file and source in your .bashrc
+
+	Note for zsh users: [1] zsh completions are only supported in versions of zsh >= 5.2
 `
 
 const boilerPlate = `
@@ -61,21 +66,28 @@ const boilerPlate = `
 
 var completionCmd = &cobra.Command{
 	Use:   "completion SHELL",
-	Short: "Outputs minikube shell completion for the given shell (bash)",
+	Short: "Outputs minikube shell completion for the given shell (bash or zsh)",
 	Long:  longDescription,
 	Run: func(cmd *cobra.Command, args []string) {
 		if len(args) != 1 {
 			fmt.Println("Usage: minikube completion SHELL")
 			os.Exit(1)
 		}
-		if args[0] != "bash" {
+		if args[0] != "bash" && args[0] != "zsh" {
-			fmt.Println("Only bash is supported for minikube completion")
+			fmt.Println("Only bash and zsh are supported for minikube completion")
 			os.Exit(1)
+		} else if args[0] == "bash" {
+			err := GenerateBashCompletion(os.Stdout, cmd.Parent())
+			if err != nil {
+				cmdutil.MaybeReportErrorAndExit(err)
+			}
+		} else {
+			err := GenerateZshCompletion(os.Stdout, cmd.Parent())
+			if err != nil {
+				cmdutil.MaybeReportErrorAndExit(err)
+			}
 		}
-		err := GenerateBashCompletion(os.Stdout, cmd.Parent())
+
-		if err != nil {
-			cmdutil.MaybeReportErrorAndExit(err)
-		}
 	},
 }
 
@@ -93,6 +105,173 @@ func GenerateBashCompletion(w io.Writer, cmd *cobra.Command) error {
 	return nil
 }
 
+func GenerateZshCompletion(out io.Writer, cmd *cobra.Command) error {
+	zsh_initialization := `
+__minikube_bash_source() {
+	alias shopt=':'
+	alias _expand=_bash_expand
+	alias _complete=_bash_comp
+	emulate -L sh
+	setopt kshglob noshglob braceexpand
+	source "$@"
+}
+__minikube_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 [ "$1" = "__minikube_compopt" ]; then
+			echo builtin
+			return 0
+		fi
+	fi
+	type "$@"
+}
+__minikube_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}" = "$1"* ]]; then
+			echo "${w}"
+		fi
+	done
+}
+__minikube_compopt() {
+	true # don't do anything. Not supported by bashcompinit in zsh
+}
+__minikube_declare() {
+	if [ "$1" == "-F" ]; then
+		whence -w "$@"
+	else
+		builtin declare "$@"
+	fi
+}
+__minikube_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]#"$colon_word"}
+		done
+	fi
+}
+__minikube_get_comp_words_by_ref() {
+	cur="${COMP_WORDS[COMP_CWORD]}"
+	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
+	words=("${COMP_WORDS[@]}")
+	cword=("${COMP_CWORD[@]}")
+}
+__minikube_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}\" = *.$1 || -d \"\${w}\" ]]"; then
+			qw="$(__minikube_quote "${w}")"
+			if [ -d "${w}" ]; then
+				COMPREPLY+=("${qw}/")
+			else
+				COMPREPLY+=("${qw}")
+			fi
+		fi
+	done
+}
+__minikube_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; then
+	LWORD='\<'
+	RWORD='\>'
+fi
+__minikube_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}/__minikube_filedir/g" \
+	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__minikube_get_comp_words_by_ref/g" \
+	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__minikube_ltrim_colon_completions/g" \
+	-e "s/${LWORD}compgen${RWORD}/__minikube_compgen/g" \
+	-e "s/${LWORD}compopt${RWORD}/__minikube_compopt/g" \
+	-e "s/${LWORD}declare${RWORD}/__minikube_declare/g" \
+	-e "s/\\\$(type${RWORD}/\$(__minikube_type/g" \
+	<<'BASH_COMPLETION_EOF'
+`
+
+	_, err := out.Write([]byte(boilerPlate))
+	if err != nil {
+		return err
+	}
+
+	_, err = out.Write([]byte(zsh_initialization))
+	if err != nil {
+		return err
+	}
+
+	buf := new(bytes.Buffer)
+	err = cmd.GenBashCompletion(buf)
+	if err != nil {
+		return errors.Wrap(err, "Error generating zsh completion")
+	}
+	_, err = out.Write(buf.Bytes())
+	if err != nil {
+		return err
+	}
+
+	zsh_tail := `
+BASH_COMPLETION_EOF
+}
+__minikube_bash_source <(__minikube_convert_bash_to_zsh)
+`
+	_, err = out.Write([]byte(zsh_tail))
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func init() {
 	RootCmd.AddCommand(completionCmd)
 }