completion.go

/*
Copyright 2017 The Kedge Authors All rights reserved.

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 (
	"bytes"
	"fmt"
	"io"
	"os"

	log "github.com/Sirupsen/logrus"
	"github.com/spf13/cobra"
)

var completion = &cobra.Command{
	Use:   "completion SHELL",
	Short: "Output shell completion code",
	Long: `Generates shell completion code.

Auto completion supports both bash and zsh. Output is to STDOUT.

source <(kedge completion bash)
source <(kedge completion zsh)

Will load the shell completion code.
	`,

	RunE: func(cmd *cobra.Command, args []string) error {

		err := Generate(cmd, args)
		if err != nil {
			log.Fatalf("Error: %s", err)
		}

		return nil
	},
}

// Generate the the approriate autocompletion file
func Generate(cmd *cobra.Command, args []string) error {

	// Check the passed in arguments
	if len(args) == 0 {
		return fmt.Errorf("Shell not specified. ex. kedge completion [bash|zsh]")
	}
	if len(args) > 1 {
		return fmt.Errorf("Too many arguments. Expected only the shell type. ex. kedge completion [bash|zsh]")
	}
	shell := args[0]

	// Generate bash through cobra if selected
	if shell == "bash" {
		return cmd.Root().GenBashCompletion(os.Stdout)

		// Generate zsh with the appropriate conversion as well as bash inclusion
	} else if shell == "zsh" {
		return runCompletionZsh(os.Stdout, cmd.Root())

		// Else, return an error.
	} else {
		return fmt.Errorf("not a compatible shell, bash and zsh are only supported")
	}
}

func init() {
	RootCmd.AddCommand(completion)
}

/*
	This is copied from
	https://github.com/kubernetes/kubernetes/blob/ea18d5c32ee7c320fe96dda6b0c757476908e696/pkg/kubectl/cmd/completion.go
	in order to generate ZSH completion support.
*/
func runCompletionZsh(out io.Writer, kedge *cobra.Command) error {

	zshInitialization := `
__kedge_bash_source() {
	alias shopt=':'
	alias _expand=_bash_expand
	alias _complete=_bash_comp
	emulate -L sh
	setopt kshglob noshglob braceexpand
	source "$@"
}
__kedge_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 [ "$1" = "__kedge_compopt" ]; then
			echo builtin
			return 0
		fi
	fi
	type "$@"
}
__kedge_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
}
__kedge_compopt() {
	true # don't do anything. Not supported by bashcompinit in zsh
}
__kedge_declare() {
	if [ "$1" == "-F" ]; then
		whence -w "$@"
	else
		builtin declare "$@"
	fi
}
__kedge_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]#"$colon_word"}
		done
	fi
}
__kedge_get_comp_words_by_ref() {
	cur="${COMP_WORDS[COMP_CWORD]}"
	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
	words=("${COMP_WORDS[@]}")
	cword=("${COMP_CWORD[@]}")
}
__kedge_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}\" = *.$1 || -d \"\${w}\" ]]"; then
			qw="$(__kedge_quote "${w}")"
			if [ -d "${w}" ]; then
				COMPREPLY+=("${qw}/")
			else
				COMPREPLY+=("${qw}")
			fi
		fi
	done
}
__kedge_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
__kedge_convert_bash_to_zsh() {
	sed \
	-e 's/declare -F/whence -w/' \
	-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}/__kedge_filedir/g" \
	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__kedge_get_comp_words_by_ref/g" \
	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__kedge_ltrim_colon_completions/g" \
	-e "s/${LWORD}compgen${RWORD}/__kedge_compgen/g" \
	-e "s/${LWORD}compopt${RWORD}/__kedge_compopt/g" \
	-e "s/${LWORD}declare${RWORD}/__kedge_declare/g" \
	-e "s/\\\$(type${RWORD}/\$(__kedge_type/g" \
	<<'BASH_COMPLETION_EOF'
`
	out.Write([]byte(zshInitialization))

	buf := new(bytes.Buffer)
	kedge.GenBashCompletion(buf)
	out.Write(buf.Bytes())

	zshTail := `
BASH_COMPLETION_EOF
}
__kedge_bash_source <(__kedge_convert_bash_to_zsh)
`
	out.Write([]byte(zshTail))
	return nil
}