<?php

// express a time difference in readable form
//
function time_diff_str($t1, $t2) {
    if (!$t1 || !$t2) return "---";
    $diff = $t2 - $t1;
    $x = "";
    if ($diff > 3600*24) {
        $n = (int) ($diff/(3600*24));
        if ($n == 1) {
            $x .= "1 day ";
        } else {
            $x .= "$n days ";
        }
        $diff -= $n*3600*24;
    }
    if ($diff > 3600) {
        $n = (int) ($diff/3600);
        if ($n == 1) {
            $x .= "1h ";
        } else {
            $x .= $n."h ";
        }
        $diff -= $n*3600;
    }
    $n = (int) ($diff/60);
    if ($n == 1) {
        $x .= "1m ";
    } else {
        $x .= $n."m";
    }
    return $x." ago";
}
?>