# GNU Guix --- Functional package management for GNU
# Copyright © 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
#
# This file is part of GNU Guix.
#
# GNU Guix is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or (at
# your option) any later version.
#
# GNU Guix is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

# Bash completion for Guix commands.

declare _guix_available_packages

_guix_complete_subcommand ()
{
    local command="${COMP_WORDS[1]}"
    local subcommands="$(${COMP_WORDS[0]} $command --help 2> /dev/null \
                         | grep '^   [a-z]' \
                         | sed -e's/^ \+\([a-z-]\+\).*$/\1/g')"
    COMPREPLY=($(compgen -W "$subcommands" -- "${COMP_WORDS[$COMP_CWORD]}"))
}

_guix_complete_available_package ()
{
    local prefix="$1"
    if [ -z "$_guix_available_packages" ]
    then
	# Cache the complete list because it rarely changes and makes
	# completion much faster.
	_guix_available_packages="$(${COMP_WORDS[0]} package -A 2> /dev/null \
                                    | cut -f1)"
    fi
    COMPREPLY=($(compgen -W "$_guix_available_packages" -- "$prefix"))
}

_guix_complete_installed_package ()
{
    # Here we do not cache the list of installed packages because that
    # may change over time and the list is relatively small anyway.
    local prefix="$1"
    local packages="$(${COMP_WORDS[0]} package -I "^$prefix" 2> /dev/null \
                      | cut -f1)"
    COMPREPLY=($(compgen -W "$packages" -- "$prefix"))
}

_guix_complete_option ()
{
    local subcommand
    case "${COMP_WORDS[2]}" in
	-*)     subcommand="";;
	[a-z]*) subcommand="${COMP_WORDS[2]}";;
    esac
    local options="$(${COMP_WORDS[0]} ${COMP_WORDS[1]} $subcommand --help 2> /dev/null \
                            | grep '^  \+-' \
                            | sed -e's/^.*--\([a-zA-Z0-9_-]\+\)\(=\?\).*/--\1\2/g')"
    compopt -o nospace
    COMPREPLY=($(compgen -W "$options" -- "${COMP_WORDS[${#COMP_WORDS[*]} - 1]}"))
}

_guix_is_command ()
{
    local word
    local result="false"
    for word in ${COMP_WORDS[*]}
    do
	if [ "$word" = "$1" ]
	then
	    result=true
	    break
	fi
    done
    $result
}

_guix_is_removing ()
{
    local word
    local result="false"
    for word in ${COMP_WORDS[*]}
    do
	case "$word" in
	    --remove|--remove=*|-r)
		result=true
		break
		;;
	esac
    done
    $result
}

_guix_is_dash_L ()
{
    [ "${COMP_WORDS[$COMP_CWORD - 1]}" = "-L" ] \
	|| { case "${COMP_WORDS[$COMP_CWORD]}" in
		 --load-path=*) true;;
		 *)             false;;
	     esac }
}

_guix_complete_file ()
{
    # Let Readline complete file names.
    compopt -o default
    COMPREPLY=()
}

_guix_complete_pid ()
{
    local pids="$(cd /proc; echo [0-9]*)"
    COMPREPLY=($(compgen -W "$pids" -- "$1"))
}

declare _guix_subcommands

_guix_complete ()
{
    local word_count=${#COMP_WORDS[*]}
    local word_at_point="${COMP_WORDS[$COMP_CWORD]}"

    if [ "$COMP_CWORD" -gt 1 ]
    then
	case "$word_at_point" in
	    -*)
		_guix_complete_option "$word_at_point"
		return
		;;
	esac
    fi

    case $COMP_CWORD in
	1)
	    if [ -z "$_guix_subcommands" ]
	    then
		# Cache the list of subcommands to speed things up.
		_guix_subcommands="$(guix --help 2> /dev/null \
                                     | grep '^  ' | cut -c 2-)"
	    fi
	    COMPREPLY=($(compgen -W "$_guix_subcommands" -- "$word_at_point"))
	    ;;
	*)
	    if _guix_is_command "package"
	    then
		if _guix_is_dash_L
		then
		    _guix_complete_file
		elif _guix_is_removing
		then
		    _guix_complete_installed_package "$word_at_point"
		else
		    _guix_complete_available_package "$word_at_point"
		fi
	    elif _guix_is_command "download"
	    then
		 _guix_complete_file
	    elif _guix_is_command "system"
	    then
		case $COMP_CWORD in
		    2) _guix_complete_subcommand;;
		    *) _guix_complete_file;; # TODO: restrict to *.scm
		esac
	    elif _guix_is_command "container"
	    then
		case $COMP_CWORD in
		    2) _guix_complete_subcommand;;
		    3) _guix_complete_pid "$word_at_point";;
		    *) _guix_complete_file;;
		esac
	    elif _guix_is_command "import"
	    then
		_guix_complete_subcommand
	    elif _guix_is_command "hash" || _guix_is_command "gc"
	    then
		_guix_complete_file
	    else
		_guix_complete_available_package "$word_at_point"
	    fi
	    ;;
    esac
}

complete -F _guix_complete guix
