#!/bin/sh

## SPDX-FileCopyrightText: 2023 Benjamin Grande M. S. <ben.grande.b@gmail.com>
##
## SPDX-License-Identifier: AGPL-3.0-or-later

## Detect if program exists, fail otherwise.
## With the option '-s', it prints the path to the utility that exists.
## Usage: has program
## Usage: has -s program alternative
## Example: has vim
## Example: has -s vim vim.tiny vi
set -eu

## The 'command' program fails to detect builtin programs.
has_cmd="command -v"
command -v which >/dev/null 2>&1 && has_cmd="which"
action=""

test -n "${1-}" || exit 1
case "$1" in
  -s) action=show; shift; test -n "${1-}" || exit 1;;
  "") printf '%s\n' "Argument required" >&2; exit 1;;
  *) ;;
esac

for prog in "${@}"; do
  cmd="$(${has_cmd} "${prog}" 2>/dev/null)" || continue
  test -x "${cmd}" || continue

  case "${action-}" in
    show) printf '%s\n' "${cmd}"; unset cmd; exit 0;;
    *) exit 0;;
  esac
done

exit 1