#!/bin/zsh
local bottom=0 strip=0 opt=
while getopts 'fsh' opt; do
    case $opt in
    f) bottom=1;; # align with bottom of terminal
    s) strip=1;; # strip last character assuming it's a newline
    ?) echo -E "usage: $0 [-fs] {period} {program}"
       [ $opt = h ] && return 0 || return 1;;
    esac
done
shift $((OPTIND-1))

local time=$1
local cmd=$2

function _monclear() {
    [ $bottom -eq 1 ] && printf ${(l:$((LINES*2))::\n:)}
}
function _monfit() {
    if [ $strip -eq 1 ]; then
        tail -$((LINES)) | head -c-1
    else
        tail -$((LINES-1))
    fi
}

local stop=0
trap stop=1 INT
echo -en "\e[H\e[2J"
while [ $stop -eq 0 ]; do
    echo -en "\e[1J\e[H"
    { _monclear; $cmd 2>&1 } | fold -w $COLUMNS | _monfit
    sleep $time || break
done