#!/bin/bash

################################################################
## @usage       telnet-wrapper.sh "uptime"
## @usage       telnet-wrapper.sh "ping -c1 10.0.0.2"
## @description Install Alpine packages and run telnet command
## @license     MIT
## @author      Dale Higgs <@dale3h>
################################################################

# Set these as needed
host="10.0.0.1"
username="Admin"
password="Admin"
cmd="$1"
logout="logout"

# You shouldn't need to edit anything below this line
if [[ -z "$cmd" ]]; then
  cmd="uptime"
fi

apk=$(command -v apk) || { echo "missing apk"; exit 0; }
expect=$(command -v expect)
telnet=$(command -v telnet)

if [[ -z "$expect" ]]; then
  $apk add --quiet --no-cache expect > /dev/null 2>&1
  expect=$(command -v expect)
  [[ -n "$expect" ]] || { echo "missing expect"; exit 0; }
fi

if [[ -z "$telnet" ]]; then
  $apk add --quiet --no-cache busybox-extras > /dev/null 2>&1
  telnet=$(command -v telnet)
  [[ -n "$telnet" ]] || { echo "missing telnet"; exit 0; }
fi

result=$(
/usr/bin/expect <<EOD
  set timeout 1
  log_user 0
  spawn -noecho telnet ${host}
  expect -re "login:\r"
  send "${username}\r"
  expect -re "Password:\r"
  send "${password}\r"
  expect -re "#"
  log_user 1
  send "echo START_OUTPUT; ${cmd}; echo END_OUTPUT\r"
  set timeout 10
  expect -re "#"
  send "${logout}\r"
  expect eof
EOD
)

echo "$result" | sed ':a;N;$!ba;s/.*START_OUTPUT\s\+\(.*\)\s\+END_OUTPUT.*/\1/g'