#!/bin/bash
# this file is meant to be sourced, not executed directly

# if destination argument is not provided, fail
if [[ $# -lt 1 ]]; then
    echo "$(basename $BASH_SOURCE): error: no destination provided!" >&2
    return 1
elif [[ $# -gt 1 ]]; then
    echo "$(basename $BASH_SOURCE): error: too many arguments!" >&2
    return 1
fi

# provide sshp command for executing commands on remote computer
sshp() {
    echo "$@" >&$_sshp_in
    echo "echo EOF" >&$_sshp_in
    sed '/EOF/Q' <$_sshp_out
}

# assign dest to variable
_sshp_dest=$1
# create temporary directory
_sshp_tmpdir=$(mktemp -d)
mkfifo $tempdir/in $tempdir/out
_sshp_out=$_sshp_tmpdir/out
# assign input to a file descriptor so it doesn't get closed
exec {_sshp_in}<>$tempdir/in
# trap exit to do cleanup
trap "{ exec {_sshp_in}>&-; ssh -O exit -S $_sshp_tmpdir/ssh $_sshp_dest &>/dev/null; rm -rf $tempdir; }" EXIT
# login with master so ssh can ask password if necessary
ssh -M -Nf -S $tempdir/ssh $_sshp_dest
# login with redirection for the persistent connection
ssh -S $tempdir/ssh medusa 0<&$_sshp_in 1>$_sshp_out 2>$_sshp_out &
# clear output 
sshp true &> /dev/null
# ask for password and run sudo so password can be cached
(printf "[sudo] password for $(remote echo \$USER)@$(remote hostname): "
 read -s password
 printf '\n'
 echo "sudo -S true" >&3
 echo $password >&3)
# clear output
sshp true &> /dev/null