// Copyright 2020 Lingfei Kong <colin404@foxmail.com>. All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.

// Package completion output shell completion code for the specified shell (bash or zsh).
package completion

import (
	"bytes"
	"io"

	"github.com/spf13/cobra"

	cmdutil "github.com/marmotedu/iam/internal/iamctl/cmd/util"
	"github.com/marmotedu/iam/internal/iamctl/util/templates"
)

const defaultBoilerPlate = `
# Copyright 2020 Lingfei Kong <colin404@foxmail.com>. All rights reserved.    
# Use of this source code is governed by a MIT style    
# license that can be found in the LICENSE file.
`

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

		Detailed instructions on how to do this are available here:
		http://github.com/marmotedu/iam/docs/installation/iamctl.md#enabling-shell-autocompletion

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

	completionExample = templates.Examples(`
		# 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 iamctl 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
		    iamctl completion bash > $(brew --prefix)/etc/bash_completion.d/iamctl


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

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

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

// NewCmdCompletion creates the `completion` command.
func NewCmdCompletion(out io.Writer, boilerPlate string) *cobra.Command {
	shells := []string{}
	for s := range completionShells {
		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:                  completionLong,
		Example:               completionExample,
		Run: func(cmd *cobra.Command, args []string) {
			err := RunCompletion(out, boilerPlate, cmd, args)
			cmdutil.CheckErr(err)
		},
		ValidArgs: shells,
	}

	return cmd
}

// RunCompletion checks given arguments and executes command.
func RunCompletion(out io.Writer, boilerPlate string, 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 := completionShells[args[0]]
	if !found {
		return cmdutil.UsageErrorf(cmd, "Unsupported shell type %q.", args[0])
	}

	return run(out, boilerPlate, cmd.Parent())
}

func runCompletionBash(out io.Writer, boilerPlate string, iamctl *cobra.Command) error {
	if len(boilerPlate) == 0 {
		boilerPlate = defaultBoilerPlate
	}

	if _, err := out.Write([]byte(boilerPlate)); err != nil {
		return err
	}

	return iamctl.GenBashCompletion(out)
}

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

	if _, err := out.Write([]byte(zshHead)); err != nil {
		return err
	}

	if len(boilerPlate) == 0 {
		boilerPlate = defaultBoilerPlate
	}

	if _, err := out.Write([]byte(boilerPlate)); err != nil {
		return err
	}

	zshInitialization := `
__iamctl_bash_source() {
	alias shopt=':'
	emulate -L sh
	setopt kshglob noshglob braceexpand

	source "$@"
}

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

__iamctl_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
}

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

__iamctl_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
}

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

__iamctl_filedir() {
	# Don't need to do anything here.
	# Otherwise we will get trailing space without "compopt -o nospace"
	true
}

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

__iamctl_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}/__iamctl_filedir/g" \
	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__iamctl_get_comp_words_by_ref/g" \
	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__iamctl_ltrim_colon_completions/g" \
	-e "s/${LWORD}compgen${RWORD}/__iamctl_compgen/g" \
	-e "s/${LWORD}compopt${RWORD}/__iamctl_compopt/g" \
	-e "s/${LWORD}declare${RWORD}/builtin declare/g" \
	-e "s/\\\$(type${RWORD}/\$(__iamctl_type/g" \
	<<'BASH_COMPLETION_EOF'
`
	if _, err := out.Write([]byte(zshInitialization)); err != nil {
		return err
	}

	buf := new(bytes.Buffer)
	if err := iamctl.GenBashCompletion(buf); err != nil {
		return err
	}

	if _, err := out.Write(buf.Bytes()); err != nil {
		return err
	}

	zshTail := `
BASH_COMPLETION_EOF
}

__iamctl_bash_source <(__iamctl_convert_bash_to_zsh)
`
	if _, err := out.Write([]byte(zshTail)); err != nil {
		return err
	}

	return nil
}
