$ git clone -q https://github.com/biox/pa.git
$ cd pa/contrib
$ ls -1 -p
pa-bemenu
pa-completion.bash
pa-completion.fish
pa-dmenu
pa-fuzzel
pa-pass
pa-rekey
pa-rofi
pa-ssg
pa-urn
pa-wmenu
$ nl -b a -s ' ' -w 3 pa-completion.bash

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14

_pa() {
    [[ $COMP_CWORD -ne 2 ]] && return

    names=()

    while read -r name; do names+=("${name@Q}"); done < <(case "${COMP_WORDS[1]}" in
        [des]*) pa l ;;
        l*) pa l | sed 's/[^/]\+$//' | grep '/$' | sort -u ;;
        esac)

    mapfile -t COMPREPLY < <(compgen -W "${names[*]}" -- "${COMP_WORDS[2]}")
}

complete -o filenames -F _pa pa