#!/bin/sh

## SPDX-FileCopyrightText: 2018 - 2025 The Qubes OS Project <https://www.qubes-os.org>
## SPDX-FileCopyrightText: 2025 Benjamin Grande M. S. <ben.grande.b@gmail.com>
##
## SPDX-License-Identifier: AGPL-3.0-or-later

## Debian has x-terminal-emulator to set default one.
## Qubes has qubes-run-terminal to get beginner friendly one.
## Most OSes do not have a wrapper, create one.

set -eu

has(){
  if ! command -v "${1}" >/dev/null; then
    if test "${DEBUG-}" = "1"; then
      printf '%s\n' "debug: command not found: ${prog}" >&2
    fi
    return 1
  fi
}

exec_has(){
  prog="${1}"
  shift
  # shellcheck disable=SC2310
  if has "${prog}"; then
    if test "${DEBUG-}" = "1"; then
      printf '%s\n' "debug: executing: ${prog} ${*}" >&2
    fi
    exec "${prog}" "${@}"
  fi
}

run_term_gnome(){
  case "${1}" in
    gnome-terminal) ghelp="$("${1}" --help-terminal-options)";;
    kgx) ghelp="$("${1}" --help)";;
    *) printf '%s\n' "error: unsupported GNOME terminal" >&2; exit 1;;
  esac
  case "${ghelp}" in
    *--wait\ *) exec "${1}" --wait "${@}";;
    *) exec "${1}" "${@}";;
  esac
}

run(){
  case "${wanted_program}" in
    terminal) env_prog="${TERMINAL:-}";;
    file-manager) env_prog="${FILE_MANAGER:-}";;
    browser) env_prog="${BROWSER:-}";;
    mail) env_prog="${MAIL_USER_AGENT:-}";;
    *) printf '%s\n' "error: invalid program type ${wanted_program}"; exit 1;;
  esac
  for prog in "${env_prog}" ${programs}; do
    # shellcheck disable=SC2310
    has "${prog}" || continue
    case "${wanted_program}" in
      terminal)
        case "${prog}" in
          gnome-terminal|kgx) run_term_gnome "${prog}" "${@}";;
          *);;
        esac
        ;;
      file-manager)
        ## Required by 'xdg-open'.
        if test "${#}" = "0"; then
          set -- .
        fi
        ;;
      browser)
        if test "${prog}" = "xdg-open" && test "${#}" = "0"; then
          continue
        fi
        ;;
      *);;
    esac
    exec_has "${prog}" "${@}"
  done
  printf '%s\n' "error: no ${wanted_program} program found" >&2
  exit 1
}

usage(){
  case "${wanted_program}" in
    terminal) set -- "\$TERMINAL";;
    file-manager) set -- "\$FILE_MANAGER";;
    browser) set -- "\$BROWSER";;
    mail) set -- "\$MAIL_USER_AGENT";;
    *) printf '%s\n' "error: invalid program type ${wanted_program}"; exit 1;;
  esac
  set -- "${@}" "${programs}"
  printf '%s\n' "Usage: ${0##*/} [ARGS...]
Action: Run the first ${wanted_program} found with the arguments provided.
Order: ${*}" >&2
  exit 1
}

terminals="x-terminal-emulator ptyxis gnome-terminal kgx
xfce4-terminal konsole termit terminator Eterm aterm roxterm termite
lxterminal mate-terminal terminology st urxvt rxvt lxterm xterm"
file_managers="xdg-open thunar nautilus caja"
browsers="xdg-open chrome chromium mullvad-browser firefox
firefox-esr w3m elinks links lynx"
mail_user_agents="thunderbird mutt"

wanted_program="${0##*/run-}"
case "${wanted_program}" in
  terminal) programs="${terminals}";;
  file-manager) programs="${file_managers}";;
  browser) programs="${browsers}";;
  mail) programs="${mail_user_agents}";;
  *) printf '%s\n' "error: invalid script name: ${0##*/}"; exit 1;;
esac
case "${1:-}" in
  -\?|--?help|help) usage;;
  "");;
  *);;
esac

run "${@}"