# bash completion for GNU tar                              -*- shell-script -*-
#
# General info
# ============
#
# The "old" style arguments
# -------------------------
#
# We don't "advice" the old tar option format by default for GNU tar, example:
#
#   'tar czfT /tmp/archive.tar patterns.txt'
#
# We rather advice the 'tar -czf /tmp/archive.tar -T patterns.txt' format of
# arguments.  Though, if user starts the 'first' tar argument without leading
# dash, we treat the command line appropriately.
#
#
# long/short options origin
# -------------------------
#
# For GNU tar, everything is parsed from `tar --help` output so not so much
# per-distribution work should be needed.  The _comp_compgen_help does not seem
# to be good enough so parsed here directly.
#
#
# FIXME: --starting-file (-K) (should be matched for extraction only)
# FIXME: handle already used (at least short) options
# FIXME: Test-cases for make check.
#        - check for no global variable pollution
# FIXME: why PS4='$BASH_SOURCE:$LINENO: ' shows sometimes negative lines?
# FIXME: timeout on tarball listing
# FIXME: cache 'tar --help' parsing results into global variables
# FIXME: at least 'tar -<tab>' should show some helping text (apart from just
#        pure option advices)
# FIXME: short option completion should be more intuitive
#        - verbose mode option should be advised multiple times
#        - mode option should be advised only once
#        - format option should be advised only once
#        ...
#
# Tar files vs internal paths
# ===========================
#
# bash's programmable completion is limited in how it handles the list of
# possible completions it returns.
#
# Because the paths returned from within the tar file are likely not existing
# paths on the file system, `-o dirnames` must be passed to the `complete`
# built-in to make it treat them as such. However, then bash will append a
# space when completing on directories during pathname completion to the tar
# files themselves.
#
# It's more important to have proper completion of paths to tar files than it
# is to have completion for their contents, so this sacrifice was made and
# `-o filenames` is used with complete instead by default. Setting the
# `$BASH_COMPLETION_CMD_TAR_INTERNAL_PATHS` environment variable to a non-null
# value *before sourcing* this completion toggles that the other way around.

_comp_deprecate_var 2.12 \
    COMP_TAR_INTERNAL_PATHS BASH_COMPLETION_CMD_TAR_INTERNAL_PATHS

_comp_cmd_gtar__parse_help_opt()
{
    local opttype arg opt separator optvar
    opttype=long
    arg="$2"
    opt="$1"
    separator=" "

    case "$opt" in
        --*) ;;

        -\?)
            return
            ;;
        -*)
            opttype=short
            opt=${opt##-}
            separator=
            ;;
        *)
            echo "bash_completion: $FUNCNAME: unknown option $opt" >&2
            return 1
            ;;
    esac

    # Remove arguments.
    opt=${opt//\[*/}
    opt=${opt//=*/=}

    # Basic sanity.
    opt=${opt//\"*/}
    opt=${opt//\'*/}
    opt=${opt//\;*/}

    optvar=$opttype'_arg_'$arg

    eval "$optvar=\"\$$optvar$separator\"\"$opt\""
}

_comp_cmd_gtar__parse_help_line()
{
    local i
    local -a tmp
    while read -ra tmp; do
        for i in "${tmp[@]}"; do
            case "$i" in
                # regular options
                --* | -*)
                    _comp_cmd_gtar__parse_help_opt "$i" "$2"
                    ;;

                # end once there is single non-option word
                *)
                    break
                    ;;
            esac
        done
    done <<<"$1"
}

_comp_cmd_gtar__parse_help()
{
    local str line arg
    while IFS= read -r line; do
        # Ok, this requires some comment probably.  The GNU help output prints
        # options on lines beginning with spaces.  After that, there is one
        # or more options separated by ', ' separator string.  We are matching
        # like this then:  ^<spaces>(<separator>?<option>)+<whatever>$
        if [[ $line =~ ^[[:blank:]]{1,10}(((,[[:blank:]])?(--?([\]\[a-zA-Z0-9?=-]+))(,[[:space:]])?)+).*$ ]]; then

            line=${BASH_REMATCH[1]}
            str="${line//,/ }"

            # Detect that all options on this line accept arguments (and whether
            # the arguments are required or not).  Note that only long option
            # description in GNU help output mentions arguments.  So the $line
            # variable may contain e.g. '-X, --XXX[=NAME], -XXX2[=NAME]'.
            arg=none
            if [[ $line =~ --[A-Za-z0-9-]+(\[?)= ]]; then
                [[ ${BASH_REMATCH[1]} ]] && arg=opt || arg=req
            fi

            _comp_cmd_gtar__parse_help_line "$str" "$arg"
        fi
    done <<<"$(tar --help)"

    long_opts="\
        $long_arg_none        $long_arg_opt        $long_arg_req"

    short_opts="$short_arg_none$short_arg_opt$short_arg_req"
}

# Hack: parse --warning keywords from tar's error output
_comp_cmd_gtar__parse_warnings()
{
    local -a warnings=()
    local lines line
    _comp_split -l lines "$(LC_ALL=C exec tar --warning= 2>&1)"
    for line in "${line[@]}"; do
        if [[ $line =~ ^[[:blank:]]*-[[:blank:]]*[\`\']([a-zA-Z0-9-]+)\'$ ]]; then
            warnings+=("${BASH_REMATCH[1]}" "no-${BASH_REMATCH[1]}")
        fi
    done
    _comp_compgen -- -W '"${warnings[@]}"'
}

_comp_cmd_tar__parse_old_opt()
{
    local first_word char

    # current word is the first word
    [[ $cword -eq 1 && $cur && ${cur:0:1} != '-' ]] &&
        old_opt_progress=set

    # check that first argument does not begin with "-"
    first_word=${words[1]}
    [[ $first_word && ${first_word:0:1} != "-" ]] &&
        old_opt_used=set

    # parse the old option (if present) contents to allow later code expect
    # corresponding arguments
    if [[ $old_opt_used ]]; then
        char=${first_word:0:1}
        while [[ $char ]]; do
            if _comp_cmd_tar__is_argreq "$char"; then
                old_opt_parsed+=("$char")
            fi
            first_word=${first_word##"$char"}
            char=${first_word:0:1}
        done
    fi
}

# Make the analysis of whole command line.
_comp_cmd_tar__preparse_cmdline()
{
    local first_arg=set i modes="ctxurdA"

    shift # progname

    _comp_cmd_tar__parse_old_opt

    for i in "$@"; do
        case "$i" in
            --delete | --test-label)
                tar_mode=${i:2:100}
                tar_mode_arg=$i
                break
                ;;
            --*)
                # skip
                ;;
            -*[$modes]*)
                tar_mode=${i//[^$modes]/}
                tar_mode=${tar_mode:0:1}
                tar_mode_arg=$i
                break
                ;;
            *[$modes]*)
                # Only the first arg may be "MODE" without leading dash
                if [[ $first_arg ]]; then
                    tar_mode=${i//[^$modes]/}
                    tar_mode=${tar_mode:0:1}
                    tar_mode_arg=$i
                fi
                ;;
        esac
        first_arg=""
    done
}

# Generate completions for -f/--file.
_comp_cmd_tar__file_option()
{
    local ext="$1"

    case "$tar_mode" in
        c)
            # no need to advise user to re-write existing tarball
            _comp_compgen_filedir -d
            ;;
        *)
            _comp_compgen_filedir "$ext"
            ;;
    esac
}

# Returns truth if option requires argument.  No equal sign must be pasted.
# Accepts option in format: 'c', '-c', '--create'
_comp_cmd_tar__is_argreq()
{
    local opt
    opt=$1
    case "$opt" in
        -[A-Za-z0-9?])
            [[ $short_arg_req =~ ${opt##-} ]] && return 0
            ;;
        [A-Za-z0-9?])
            [[ $short_arg_req =~ ${opt} ]] && return 0
            ;;
        --*)
            [[ $long_arg_req =~ [[:blank:]]$opt=[[:blank:]] ]] && return 0
            ;;
    esac

    return 1
}

# Called only for short parameter
_comp_cmd_tar__mode()
{
    local short_modes rawopt generated \
        allshort_raw_unused allshort_raw \
        filler i

    short_modes="ctx"
    [[ ! $basic_tar ]] && short_modes="ctxurdA"

    # Remove prefix when needed
    rawopt=${cur#-}

    # -c -z -x ... => czx
    allshort_raw=${short_opts//[- ]/}

    # init the 'mode' option if no option is in ${cur}
    if [[ $tar_mode == none ]]; then

        # when user passed something like 'tar cf' do not put the '-' before
        filler=
        if [[ ! $cur && ! $basic_tar ]]; then
            filler=-
        fi

        generated=""
        for ((i = 0; 1; i++)); do
            local c="${short_modes:i:1}"
            [[ ! $c ]] && break
            generated+=" $filler$cur$c"
        done

        _comp_compgen -R -- -W "$generated"
        return 0
    fi

    # The last short option requires argument, like '-cf<TAB>'.  Cut the
    # completion here to enforce argument processing.
    if [[ ! $old_opt_progress ]] &&
        _comp_cmd_tar__is_argreq "${cur: -1}"; then
        COMPREPLY=("$cur") && return 0
    fi

    allshort_raw_unused=${allshort_raw//[$rawopt]/}
    if [[ $tar_mode != none ]]; then
        allshort_raw_unused=${allshort_raw_unused//[$short_modes]/}
    fi

    generated=
    for ((i = 0; 1; i++)); do
        local c="${allshort_raw_unused:i:1}"
        [[ ! $c ]] && break
        generated+=" $cur$c"
    done

    _comp_compgen -R -- -W "$generated"

    return 0
}

_comp_cmd_tar__gnu_long_options()
{
    local rv
    _comp_compgen -- -W "$long_opts"
    rv=$?
    [[ ${COMPREPLY-} == *= ]] && compopt -o nospace
    return $rv
}

_comp_cmd_tar__gnu_short_options()
{
    local generated short_mode_opts i c
    short_mode_opts="ctxurdA"
    generated=${short_opts//[$short_mode_opts]/}

    for ((i = 0; 1; i++)); do
        c="${allshort_raw_unused:i:1}"
        [[ ! $c ]] && break
        generated+=" $cur$c"
    done

    _comp_compgen -- -W "$generated"
}

_comp_cmd_tar__try_mode()
{
    case "$cur" in
        --*)
            # posix tar does not support long opts
            [[ $basic_tar ]] && return 0
            _comp_cmd_tar__gnu_long_options
            return $?
            ;;

        -*)
            # posix tar does not support short options
            [[ $basic_tar ]] && return 0

            _comp_cmd_tar__mode && return 0
            ;;

        *)
            if [[ $cword -eq 1 || $tar_mode == none ]]; then
                _comp_cmd_tar__mode && return 0
            fi
            ;;
    esac
    return 1
}

_comp_cmd_tar__adjust_PREV_from_old_option()
{
    # deal with old style arguments here
    # $ tar cfTC # expects this sequence of arguments:
    # $ tar cfTC ARCHIVE_FILE PATTERNS_FILE CHANGE_DIR
    if [[ $old_opt_used ]] && ((cword > 1 && cword < ${#old_opt_parsed[@]} + 2)); then
        # make e.g. 'C' option from 'cffCT'
        prev="-${old_opt_parsed[cword - 2]}"
    fi
}

_comp_cmd_tar__extract_like_mode()
{
    local i
    for i in x d t delete; do
        [[ $tar_mode == "$i" ]] && return 0
    done
    return 1
}

_comp_cmd_tar__try_list_archive()
{
    local tarball="" tarbin untar i

    _comp_cmd_tar__extract_like_mode || return 1

    # This all is just to approach directory completion from "virtual"
    # directory structure in tarball (for which the _comp_compgen_filedir is
    # unusable)

    set -- "${words[@]}"
    tarbin=$1
    untar="tf"
    shift

    for i in "$@"; do
        if [[ $i == *.$ext ]]; then
            tarball=$i
            break
        fi
    done
    if [[ $tarball ]]; then
        _comp_compgen -c "$(printf %q "$cur")" split -lo filenames -- "$(
            $tarbin $untar "$tarball" 2>/dev/null |
                while read -r line; do
                    printf "%q\n" "$line"
                done
        )"
        return 0
    fi
}

_comp_cmd_tar__cleanup_prev()
{
    if [[ $prev =~ ^-[a-zA-Z0-9?]*$ ]]; then
        # transform '-caf' ~> '-f'
        prev="-${prev: -1}"
    fi
}

_comp_cmd_tar__detect_ext()
{
    local tars='@(@(tar|spkg)?(.@(Z|[bgx]z|bz2|lz?(ma|o)|zst))|t@([abglx]z|b?(z)2|zst)|cbt|gem|xbps)'
    if [[ ${COMP_WORDS[0]} == ?(*/)bsdtar ]]; then
        # https://github.com/libarchive/libarchive/wiki/LibarchiveFormats
        tars=${tars/%\)/|pax|cpio|iso|zip|@(j|x)ar|mtree|a|7z|warc}
        if _comp_cmd_tar__extract_like_mode; then
            # read only
            tars+="|l@(ha|zh)|rar|cab)"
        else
            # write only
            tars+="|shar)"
        fi
    fi
    ext="$tars"

    case "$tar_mode_arg" in
        --*)
            # Should never happen?
            ;;
        ?(-)*[cr]*f)
            ext='@(tar|gem|spkg|cbt|xpbs)'
            case ${words[1]} in
                *a*) ext="$tars" ;;
                *z*) ext='t?(ar.)gz' ;;
                *Z*) ext='ta@(r.Z|z)' ;;
                *[jy]*) ext='t@(?(ar.)bz?(2)|b2)' ;;
                *J*) ext='t?(ar.)xz' ;;
            esac
            ;;
        +([^ZzJjy])f)
            # Pass through using defaults above
            ;;
        *[Zz]*f)
            ext='@(@(t?(ar.)|spkg.)@(gz|Z)|taz)'
            ;;
        *[jy]*f)
            ext='@(t?(ar.)bz?(2)|spkg|tb2)'
            ;;
        *[J]*f)
            ext='@(@(tar|spkg).@(lzma|xz)|t[lx]z)'
            ;;
    esac
}

_comp_cmd_tar__gnu()
{
    local long_opts short_opts basic_tar="" \
        long_arg_none="" long_arg_opt="" long_arg_req="" \
        short_arg_none="" short_arg_opt="" short_arg_req="" \
        tar_mode tar_mode_arg old_opt_progress="" \
        old_opt_used="" old_opt_parsed=()

    # Main mode, e.g. -x or -c (extract/creation)
    local tar_mode=none

    # The mode argument, e.g. -cpf or -c
    # FIXME: handle long options
    local tar_mode_arg=

    if [[ -v _comp_cmd_tar__debug ]]; then
        set -x
        local PS4='$BASH_SOURCE:$LINENO: '
    fi

    local cur prev words cword was_split comp_args

    _comp_initialize -s -- "$@" || return

    # Fill the {long,short}_{opts,arg*}
    _comp_cmd_gtar__parse_help

    _comp_cmd_tar__preparse_cmdline "${words[@]}"

    local ext

    _comp_cmd_tar__detect_ext

    while true; do # just-for-easy-break while, not looping
        _comp_cmd_tar__adjust_PREV_from_old_option
        _comp_cmd_tar__posix_prev_handle && break
        _comp_cmd_tar__cleanup_prev

        # Handle all options *REQUIRING* argument.  Optional arguments are up to
        # user (TODO: is there any sane way to deal with this?).  This case
        # statement successes only if there already is PREV.
        local noargopts='!(-*|*[TXgCFIfH]*)'
        # shellcheck disable=SC2254
        case $prev in
            --add-file | --exclude | --exclude-ignore | \
                --exclude-ignore-recursive | --exclude-tag | \
                --exclude-tag-all | --exclude-tag-under | --files-from | \
                --exclude-from | --listed-incremental | --group-map | \
                --mtime | --owner-map | --volno-file | --newer | \
                --after-date | --index-file | -${noargopts}[TXg])
                _comp_compgen_filedir
                break
                ;;
            --directory | -${noargopts}C)
                _comp_compgen_filedir -d
                break
                ;;
            --hole-detection)
                _comp_compgen -- -W 'raw seek'
                break
                ;;
            --to-command | --info-script | --new-volume-script | \
                --rmt-command | --rsh-command | --use-compress-program | \
                -${noargopts}[FI])
                _comp_compgen_commands
                break
                ;;
            --atime-preserve)
                _comp_compgen -- -W 'replace system'
                break
                ;;
            --group)
                _comp_compgen -- -g
                break
                ;;
            --owner)
                _comp_compgen -- -u
                break
                ;;
            --sort)
                _comp_compgen -- -W 'none name inode'
                break
                ;;
            --file | -${noargopts}f)
                _comp_cmd_tar__file_option "$ext"
                break
                ;;
            --format | -${noargopts}H)
                _comp_compgen -- -W 'gnu oldgnu pax posix ustar v7'
                break
                ;;
            --quoting-style)
                _comp_compgen -- -W 'literal shell shell-always shell-escape
                    shell-escape-always c c-maybe escape locale clocale'
                break
                ;;
            --totals)
                _comp_compgen -- -W 'SIGHUP SIGQUIT SIGINT SIGUSR1 SIGUSR2'
                break
                ;;
            --warning)
                _comp_cmd_gtar__parse_warnings
                break
                ;;
            --*)
                # parameter with required argument but no completion yet
                [[ " $long_arg_req " =~ \ $prev=\  ]] && break

                # parameter with optional argument passed with =, something like
                # --occurrence=*<TAB> which is not handled above
                [[ " $long_arg_opt " =~ \ $prev\  ]] && break

                # if there is some unknown option with '=', for example
                # (literally) user does --nonexistent=<TAB>, we do not want
                # continue also
                [[ $was_split ]] && break

                # Most probably, when code goes here, the PREV variable contains
                # some string from "$long_arg_none" and we want continue.
                ;;
            -${noargopts}[a-zA-Z0-9?])
                # argument required but no completion yet
                [[ $short_arg_req =~ ${prev##-} ]] && break
                ;;
        esac

        # safety belts
        case "$cur" in
            -[a-zA-Z0-9]=*)
                # e.g. 'tar -c -f=sth' does not what user could expect
                break
                ;;
        esac

        # Handle the main operational mode of tar.  We should do it as soon as
        # possible.
        _comp_cmd_tar__try_mode && break

        # handle others
        case "$cur" in
            --*)
                _comp_cmd_tar__gnu_long_options
                break
                ;;
            -*)
                # called only if it is *not* first parameter
                _comp_cmd_tar__gnu_short_options
                break
                ;;
        esac

        # the first argument must be "mode" argument or --param, if any of those
        # was truth - the 'break' statement would have been already called
        ((cword == 1)) && break

        _comp_cmd_tar__try_list_archive && break

        # file completion on relevant files
        if [[ $tar_mode != none ]]; then
            _comp_compgen_filedir
        fi

        break
    done # just-for-easy-break while

    if [[ -v _comp_cmd_tar__debug ]]; then
        set +x
    fi
}

_comp_cmd_tar__posix_prev_handle()
{
    case "$prev" in
        -f)
            _comp_cmd_tar__file_option "$ext"
            return 0
            ;;
        -b)
            return 0
            ;;
    esac

    return 1
}

_comp_cmd_tar__posix()
{
    local long_opts short_opts basic_tar=set \
        long_arg_none="" long_arg_opt long_arg_req="" \
        short_arg_none short_arg_opt short_arg_req \
        tar_mode tar_mode_arg old_opt_progress="" \
        old_opt_used=set old_opt_parsed=()

    # Main mode, e.g. -x or -c (extract/creation)
    local tar_mode=none

    # The mode argument, e.g. -cpf or -c
    local tar_mode_arg=

    local cur prev words cword was_split comp_args

    _comp_initialize -s -- "$@" || return

    tar_mode=none

    # relatively compatible modes are {c,t,x}
    # relatively compatible options {b,f,m,v,w}
    short_arg_req="fb"
    short_arg_none="wmv"
    short_opts="$short_arg_req$short_arg_none"

    _comp_cmd_tar__preparse_cmdline "${words[@]}"

    local ext

    _comp_cmd_tar__detect_ext

    _comp_cmd_tar__adjust_PREV_from_old_option

    _comp_cmd_tar__posix_prev_handle && return

    _comp_cmd_tar__try_mode && return

    _comp_cmd_tar__try_list_archive && return

    # file completion on relevant files
    _comp_compgen_filedir
}

_comp_cmd_tar()
{
    local cmd=${COMP_WORDS[0]} func line
    line="$("$cmd" --version 2>/dev/null)"
    case "$line" in
        *GNU*)
            func=_comp_cmd_tar__gnu
            ;;
        *)
            func=_comp_cmd_tar__posix
            ;;
    esac
    $func "$@"

    # Install real completion for subsequent completions
    if [[ ${BASH_COMPLETION_CMD_TAR_INTERNAL_PATHS-} ]]; then
        complete -F $func -o dirnames tar
    else
        complete -F $func tar
    fi
    unset -f "$FUNCNAME"
}

if [[ ${BASH_COMPLETION_CMD_TAR_INTERNAL_PATHS-} ]]; then
    complete -F _comp_cmd_tar -o dirnames tar
    complete -F _comp_cmd_tar__gnu -o dirnames gtar
    complete -F _comp_cmd_tar__posix -o dirnames bsdtar
    complete -F _comp_cmd_tar__posix -o dirnames star
else
    complete -F _comp_cmd_tar tar
    complete -F _comp_cmd_tar__gnu gtar
    complete -F _comp_cmd_tar__posix bsdtar
    complete -F _comp_cmd_tar__posix star
fi

# ex: filetype=sh