nnn/plugins/xdgdefault

#!/usr/bin/env sh

# Description: Sets the xdg-open's default application for the current entry's file
#              type. ${XDG_DATA_DIRS} and ${XDG_DATA_HOME} are set to the recommended
#              defaults if unset, as specified in XDG Base Directory Specification
#              - http://specifications.freedesktop.org/basedir-spec/.
#
# Dependencies: xdg-utils, fzf or dmenu (GUI)
#
# Shell: POSIX compliant
# Author: lwnctd

# set to 1 to enable GUI apps
GUI="${GUI:-0}"

if [ "$GUI" -ne 0 ] && command -v dmenu >/dev/null 2>& 1; then
  menu="dmenu -l 7"
elif command -v fzf > /dev/null 2>& 1; then
  menu="fzf -e --tiebreak=begin"
fi

if [ -z "$1" ] || [ -z "$menu" ] > /dev/null 2>& 1; then
    exit 1
fi

ftype=$(xdg-mime query filetype "$2/$1")

if [ -z "$ftype" ]; then
    exit 1
fi

dirs=${XDG_DATA_DIRS:-/usr/local/share:/usr/share}
dirs=${dirs}:${XDG_DATA_HOME:-$HOME/.local/share}:

while [ -n "$dirs" ]; do
    d=${dirs%%:*}
    if [ -n "$d" ] && [ -d "$d"/applications ]; then
        set -- "$@" "$d"/applications
    fi
    dirs=${dirs#*:}
done

app=$(find "$@" -iname '*.desktop' -exec grep '^Name=' {} + \
    | sort -u -t ':' -k 1,1 \
    | sed -E 's;.+/(.+desktop):Name=(.+);\2:\1;' \
    | sort -t ':' -k 1,1 \
    | column -t -s ':' -o "$(printf '\t')" \
    | $menu \
    | cut -f 2)

if [ -n "$app" ]; then
    xdg-mime default "$app" "$ftype"
fi