gstreamer-completion

# Bash tab-completion for GStreamer.                      -*- shell-script -*-
# Put this in /etc/bash_completion.d/
# https://raw.githubusercontent.com/drothlis/gstreamer/bash-completion-master/tools/gstreamer-completion

_gst_inspect() {
    local _gst_version=1.0
    local cur cword prev words
    _gst_init_completion
    [[ "$cur" == "=" ]] && cur=
    [[ "$cur" =~ -.*=*$ ]] && prev="${cur%%=*}" cur="${cur#*=}"

    _gst_common_options || return

    COMPREPLY=( $(compgen \
        -W "$(_gst_parse_help gst-inspect-$_gst_version) \
            $(_gst_plugins) $(_gst_elements)" \
        -- "$cur") )
    [[ $COMPREPLY == *= ]] && compopt -o nospace 2>/dev/null
} &&
complete -F _gst_inspect gst-inspect-1.0

_gst_launch() {
    local _gst_version=1.0
    local cur cword prev words
    _gst_init_completion
    local curtype option element property
    _gst_launch_parse
    _gst_common_options || return

    COMPREPLY=( $(_gst_launch_compgen) )
    [[ $COMPREPLY == *= ]] && compopt -o nospace 2>/dev/null
} &&
complete -o default -F _gst_launch gst-launch-1.0

_gst_common_options() {
    if [[ -n "$curtype" ]]; then  # Called from _gst_launch
        [[ $curtype == optionval ]] || return 0
    else  # Called from _gst_inspect
        local option="$prev"
    fi

    case "$option" in
        --gst-debug-level)
                COMPREPLY=( $(compgen -W "0 1 2 3 4 5" -- "$cur") );;
        --gst-debug) # TODO: comma-separated list of category_name:level pairs.
                ;;
        --gst-plugin-path) # TODO: support multiple (colon-separated) paths.
                COMPREPLY=( $(compgen -d -- "$cur") );;
        --gst-plugin-load) # TODO: comma-separated list of plugins (files?).
                ;;
        *) return 0;;
    esac
    return 1  # No need to attempt further completions.
}

_gst_launch_compgen() {
    case $curtype in
        option)
            compgen \
                -W "$(_gst_parse_help gst-launch-$_gst_version)" \
                -- "$cur" ;;
        element)
            compgen -W "$(_gst_elements)" -- "$cur" ;;
        option-or-element)
            compgen \
                -W "$(_gst_parse_help gst-launch-$_gst_version) \
                    $(_gst_elements)" \
                -- "$cur" ;;
        optionval)
            case "$option" in
                -o|--output) compgen -f -- "$cur" ;;
                --exclude) ;; # TODO: comma-separated list of status information types.
            esac ;;
        \!)
            compgen -W '!' -- "$cur" ;;
        property)
            compgen -W "$(_gst_properties $element) ! " -- "$cur" ;;
        propertyval)
            compgen -W "$(_gst_property_values $element $property)" -- "$cur" ;;
    esac
}

_gst_plugins() {
    gst-inspect-$_gst_version 2>/dev/null |
    grep -v 'Total count' |
    awk -F': +' '{print $1}' |
    uniq
}

_gst_elements() {
    gst-inspect-$_gst_version 2>/dev/null |
    grep -v 'Total count' |
    awk -F': +' '{print $2}'
}

_gst_properties() {
    local element="$1"
    gst-inspect-$_gst_version "$element" 2>/dev/null |
    sed -n '/^Element Properties:$/,$ p' |
    awk '/^  [a-z]/ { print $1 "=" }'
}

_gst_property_values() {
    local element=$1 property=$2
    gst-inspect-$_gst_version $element 2>/dev/null |
    awk "
        /^Element Properties:\$/        { inproperties = 1; next; }
        inproperties && /^  $property / { inproperty = 1; next; }
        inproperty && /^ *Boolean/      { printf \"true\nfalse\n\"; exit; }
        inproperty && /^ *Enum/         { inenum = 1; next; }
        inenum && /^ *\([0-9]+\): /     { print \$2; next; }
        inproperty && /^  [a-z]/        { exit; }"
}

# Walks over $words, sets $curtype to the string:
#
#   'option' if $cur is an option or flag like "-a" or "--abc".
#   'optionval' if $cur is the value of an option
#               (which will be set in $option).
#   'element' if $cur is a GStreamer element name.
#   '!' if $cur is '!'.
#   'property' if $cur is the name of a property of a GStreamer element
#               (which will be set in $element).
#   'propertyval' if $cur is the value of an element's property
#               (which will be set in $element and $property, respectively).
#
# ($cur is the word currently being completed.)
#
# Before calling this function make sure that $curtype, $option, $element and
# $property are local, and that $cur, $cword and $words have been initialised.
#
# See test cases in tests/misc/test-gstreamer-completion.sh in the
# gstreamer source repository.
#
_gst_launch_parse() {
    local i next state
    curtype= i=1 state=start
    while [[ $i -le $cword ]]; do
        next="${words[i]}"
        # Note that COMP_WORDBREAKS by default includes "=" and ":".
        case "$state,$next" in
            start,-*=*) curtype=optionval option="${next%%=*}" state=start;;
            start,-*) curtype=option option="$next" state=option;;
            start,) curtype=option-or-element;;
            start,*) curtype=element element="$next" state=element;;
            option,=) curtype=optionval state=option=;;
            option,*) _gst_takes_arg "$option" &&
                            curtype=optionval state=start ||
                        # re-evaluate without incrementing i:
                        { curtype= state=start; continue; }
                      ;;
            option=,*) curtype=optionval state=start;;
            element,\!) curtype='!' state='!';;
            \!,*) curtype=element element="$next" state=element;;
            element,*=)
                curtype=propertyval property="${next%=}" state=property=;;
            element,*=*)
                curtype=propertyval property="${next%%=*}" state=element;;
            element,*) curtype=property property="$next" state=property;;
            property,=) curtype=propertyval state=property=;;
            property=,*) curtype=propertyval state=element;;
        esac
        i=$((i + 1))
    done
    cur="${cur#*=}"
}

_gst_takes_arg() {
    case "$1" in
        -o|--output|--gst-debug-level|--gst-debug) true;;
        --gst-plugin-path|--gst-plugin-load|--exclude) true;;
        *) false;;
    esac
}

_gst_parse_help() {
    $1 --help-all 2>&1 | grep -Eo -e '--[a-z-]+'
}

_gst_init_completion() {
    if type _get_comp_words_by_ref &>/dev/null; then
        # Available since bash-completion 1.2
        _get_comp_words_by_ref cur cword prev words
    else
        # bash-completion not installed or too old. Use bash's raw facilities.
        # This won't complete properly if the cursor is in the middle of a
        # word.
        cur="${COMP_WORDS[COMP_CWORD]}"
        prev="${COMP_WORDS[COMP_CWORD-1]}"
        cword=$COMP_CWORD
        words=("${COMP_WORDS[@]}")
    fi
}