bash_completion_example.sh

#!/usr/bin/env bash

HILL1_UPDATE_HOST_SSHT_ADDR="ssh -t user@demo1"
HILL2_UPDATE_HOST_SSHT_ADDR="ssh -t user@demo2"
HILL3_UPDATE_HOST_SSHT_ADDR="ssh -t user@ci ssh -t user@demo3"
HILLS="HILL1 HILL2 HILL3"
TARGET_HOSTS="host1 host2 host3"

_SSHTargetHostCompletion () {
  options_1=${HILLS}
  options_2=${TARGET_HOSTS}
  options_3=""
  __CompliteSerial
}

__CompliteSerial () {
  COMPREPLY=();
  eval "options=\${options_${COMP_CWORD}}"
  cur=${COMP_WORDS[COMP_CWORD]}
  COMPREPLY=($(compgen -W "${options} " -- ${cur}))
  return 0
}

complete -F _SSHTargetHostCompletion   SSHTargetHost

# SSHTargetHost HILL2
# SSHTargetHost HILL2 host1
SSHTargetHost () {
  eval "update_host_ssh_addr=\${$1_UPDATE_HOST_SSHT_ADDR}"
  if [ "$2" != "" ]; then
    ${update_host_ssh_addr} ssh -t $2
  else
    ${update_host_ssh_addr}
  fi
}