// Copyright © 2017-2018 Mikael Berthe <mikael@lilotux.net>
//
// Licensed under the MIT license.
// Please see the LICENSE file is this directory.

package cmd

import (
	"bytes"
	"io"
	"os"
	"strings"

	"github.com/spf13/cobra"
)

var completionCmd = &cobra.Command{
	Use:       "completion bash|zsh",
	Short:     "Generate shell completion",
	ValidArgs: []string{"bash", "zsh"},
	Run: func(cmd *cobra.Command, args []string) {
		if len(args) < 1 {
			errPrint("Please specify your shell")
			os.Exit(1)
		}

		switch args[0] {
		case "bash":
			if err := runCompletionBash(os.Stdout, RootCmd); err != nil {
				errPrint("Error: %s", err.Error())
				os.Exit(1)
			}
		case "zsh":
			if err := runCompletionZsh(os.Stdout, RootCmd); err != nil {
				errPrint("Error: %s", err.Error())
				os.Exit(1)
			}
		default:
			errPrint("Only bash is supported at the moment")
			os.Exit(1)
		}
	},
}

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

func runCompletionBash(out io.Writer, c *cobra.Command) error {
	return c.GenBashCompletion(out)
}

// Many thanks to the Kubernetes project for this one!
func runCompletionZsh(out io.Writer, c *cobra.Command) error {
	const zshInitialization = `# Copyright 2016 The Kubernetes 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.

__madonctl_bash_source() {
	alias shopt=':'
	alias _expand=_bash_expand
	alias _complete=_bash_comp
	emulate -L sh
	setopt kshglob noshglob braceexpand

	source "$@"
}

__madonctl_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 [ "$1" = "__madonctl_compopt" ]; then
			echo builtin
			return 0
		fi
	fi
	type "$@"
}

__madonctl_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
}

__madonctl_compopt() {
	true # don't do anything. Not supported by bashcompinit in zsh
}

__madonctl_declare() {
	if [ "$1" == "-F" ]; then
		whence -w "$@"
	else
		builtin declare "$@"
	fi
}

__madonctl_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
}

__madonctl_get_comp_words_by_ref() {
	cur="${COMP_WORDS[COMP_CWORD]}"
	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
	words=("${COMP_WORDS[@]}")
	cword=("${COMP_CWORD[@]}")
}

__madonctl_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}\" = *.$1 || -d \"\${w}\" ]]"; then
			qw="$(__madonctl_quote "${w}")"
			if [ -d "${w}" ]; then
				COMPREPLY+=("${qw}/")
			else
				COMPREPLY+=("${qw}")
			fi
		fi
	done
}

__madonctl_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

__madonctl_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}/__madonctl_filedir/g" \
	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__madonctl_get_comp_words_by_ref/g" \
	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__madonctl_ltrim_colon_completions/g" \
	-e "s/${LWORD}compgen${RWORD}/__madonctl_compgen/g" \
	-e "s/${LWORD}compopt${RWORD}/__madonctl_compopt/g" \
	-e "s/${LWORD}declare${RWORD}/__madonctl_declare/g" \
	-e "s/\\\$(type${RWORD}/\$(__madonctl_type/g" \
	<<'BASH_COMPLETION_EOF'
`

	const zshTail = `
BASH_COMPLETION_EOF
}

__madonctl_bash_source <(__madonctl_convert_bash_to_zsh)
`

	buf := new(bytes.Buffer)
	out.Write([]byte(zshInitialization))
	err := c.GenBashCompletion(buf)
	script := strings.Replace(buf.String(), "flaghash[${flagname}]", `flaghash[workaround]`, -1)
	out.Write([]byte(script))
	out.Write([]byte(zshTail))
	return err
}