// Copyright 2019 PingCAP, Inc.
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.

package completion

import (
	"bytes"
	"io"

	"github.com/spf13/cobra"
	cmdutil "k8s.io/kubectl/pkg/cmd/util"
)

const (
	completionLongDesc = `
Output shell completion code for the specified shell (bash or zsh).
The shell code must be evaluated to provide interactive
completion of tkctl commands.  This can be done by sourcing it from
the .bash_profile.

Note for zsh users: [1] zsh completions are only supported in versions of zsh >= 5.2
`

	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
	## If tkctl is installed via homebrew, this should start working immediately.
	## If you've installed via other means, you may need add the completion to your completion directory
	    tkctl completion bash > $(brew --prefix)/etc/bash_completion.d/tkctl


	# 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.
	## Load the tkctl completion code for bash into the current shell
	    source <(tkctl completion bash)
	## Write bash completion code to a file and source if from .bash_profile
	    tkctl completion bash > ~/.kube/completion.bash.inc
	    printf "
	      # Kubectl shell completion
	      source '$HOME/.kube/completion.bash.inc'
	      " >> $HOME/.bash_profile
	    source $HOME/.bash_profile

	# Load the tkctl completion code for zsh[1] into the current shell
	    source <(tkctl completion zsh)
	# Set the tkctl completion code for zsh[1] to autoload on startup
	    tkctl completion zsh > "${fpath[1]}/_tkctl"
`
)

var (
	completion_shells = map[string]func(out io.Writer, cmd *cobra.Command) error{
		"bash": runCompletionBash,
		"zsh":  runCompletionZsh,
	}
)

func NewCmdCompletion(out io.Writer) *cobra.Command {
	shells := []string{}
	for s := range completion_shells {
		shells = append(shells, s)
	}

	cmd := &cobra.Command{
		Use:                   "completion SHELL",
		DisableFlagsInUseLine: true,
		Short:                 "Output shell completion code for the specified shell (bash or zsh)",
		Long:                  completionLongDesc,
		Example:               completionExample,
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(RunCompletion(out, cmd, args))
		},
		ValidArgs: shells,
	}

	return cmd
}

func RunCompletion(out io.Writer, cmd *cobra.Command, args []string) error {
	if len(args) == 0 {
		return cmdutil.UsageErrorf(cmd, "Shell not specified.")
	}
	if len(args) > 1 {
		return cmdutil.UsageErrorf(cmd, "Too many arguments. Expected only the shell type.")
	}
	run, found := completion_shells[args[0]]
	if !found {
		return cmdutil.UsageErrorf(cmd, "Unsupported shell type %q.", args[0])
	}

	return run(out, cmd.Root())
}

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

func runCompletionZsh(out io.Writer, tkctl *cobra.Command) error {
	zshHead := "#compdef tkctl\n"

	out.Write([]byte(zshHead))

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

	source "$@"
}

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

__tkctl_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
}

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

__tkctl_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
}

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

__tkctl_filedir() {
	local RET OLD_IFS w qw

	__tkctl_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="," __tkctl_debug "RET=${RET[@]} len=${#RET[@]}"

	for w in ${RET[@]}; do
		if [[ ! "${w}" = "${cur}"* ]]; then
			continue
		fi
		if eval "[[ \"\${w}\" = *.$1 || -d \"\${w}\" ]]"; then
			qw="$(__tkctl_quote "${w}")"
			if [ -d "${w}" ]; then
				COMPREPLY+=("${qw}/")
			else
				COMPREPLY+=("${qw}")
			fi
		fi
	done
}

__tkctl_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

__tkctl_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}/__tkctl_filedir/g" \
	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__tkctl_get_comp_words_by_ref/g" \
	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__tkctl_ltrim_colon_completions/g" \
	-e "s/${LWORD}compgen${RWORD}/__tkctl_compgen/g" \
	-e "s/${LWORD}compopt${RWORD}/__tkctl_compopt/g" \
	-e "s/${LWORD}declare${RWORD}/builtin declare/g" \
	-e "s/\\\$(type${RWORD}/\$(__tkctl_type/g" \
	<<'BASH_COMPLETION_EOF'
`
	out.Write([]byte(zshInitialization))

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

	zshTail := `
BASH_COMPLETION_EOF
}

__tkctl_bash_source <(__tkctl_convert_bash_to_zsh)
_complete tkctl 2>/dev/null
`
	out.Write([]byte(zshTail))
	return nil
}