#!/usr/bin/env bash

## CONSTANTS

## FUNCTIONS

function upgrade {
  echo UPGRADE
  if sudo -E "$MIAOU_BASH_DIR"/bin/miaou-bash none 3>&1; then
    echo FAILURE $?
  fi
}

function assert_supported_distro {
  if ! grep -E '^ID=debian|^ID_LIKE=debian' /etc/os-release &&
    ! grep -E '^ID=arch|^ID_LIKE=arch' /etc/os-release; then
    local distro
    distro=$(grep -oP '^ID=\K(.*)' /etc/os-release)
    >&2 echo "unsupported GNU/Linux distribution: $distro"
    >&2 echo 'only debian-like OR arch-like currently supported'
    return 10
  fi
}

function assert_bash {
  if [[ $(basename "$SHELL") != 'bash' ]]; then
    >&2 echo "MIAOU ERROR: you are running on SHELL=$SHELL rather than 'bash'!"
    return 11
  fi
}

function sudo_root {
  if [[ "$UID" -ne 0 ]] && ! sudo -vp 'SUDO privilege required: '; then
    >&2 echo "canceled"
    return 12
  fi
}
## MAIN

set -Eeuo pipefail
if assert_supported_distro && assert_bash && sudo_root; then
  if [[ ! -v MIAOU_BASH_DIR ]]; then
    MIAOU_BASH_DIR=/opt/miaou-bash
    export MIAOU_BASH_DIR
  fi
  upgrade
else
  >&2 echo "MIAOU_BASH_ERROR: requirements failure"
fi