#!/usr/bin/env bash 
set -eu

DIR=$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)
MAC_ADDRESS_FILE=${DIR}/tinc-macaddr

has() {
  command -v "$1" >/dev/null 2>&1
}

die() {
  echo $1 &>2
  exit 1
}

set_mac() {
  local interface=$1
  local mac_address=$2
  if has ifconfig; then
    ifconfig "$interface" down
    if [[ "$OSTYPE" == "linux-gnu" ]]; then
      ifconfig "$interface" hw ether "$mac_address"
    else
      ifconfig "$interface" ether "$mac_address"
    fi
  elif has ip; then
    ip link set dev "$interface" down
    ip link set dev "$interface" address "$mac_address"
  else
    die "no suitable program found to configure the network interface, need iproute2 or ifconfig"
  fi
}

start_dhcp() {
  local interface=$1
  if has dhcpcd; then
    dhcpcd "$interface"
  elif has dhclient; then
    dhclient "$interface"
  elif [[ "$OSTYPE" == "darwin"* ]]; then # TODO
    untested
    ipconfig set "$interface" DHCP
  else
    die "no suitable dhcp program found, need dhcpcd or dhclient"
  fi
}

[ -z "${INTERFACE:-}" ] && die "no INTERFACE environment variable set"

if [ ! -f "$MAC_ADDRESS_FILE" ]; then
  die "${MAC_ADDRESS_FILE} does not exists. Generate it with ./tinc-generate-mac"
fi

read -r MAC_ADDRESS <"$MAC_ADDRESS_FILE"
set_mac "$INTERFACE" "$MAC_ADDRESS"

start_dhcp "$INTERFACE"