/**
 * Format a timestamp to display its age (5 days ago,in 3 days,etc.).
 *
 * @param   int     $timestamp
 * @param   int     $now
 * @return  string
 */
function timetostr($timestamp,$now = null) {
    $age = ($now ?: time()) - $timestamp;
    $future = ($age < 0);
    $age = abs($age);

    $age = (int)($age / 60);        // minutes ago
    if ($age == 0) return $future ? "momentarily" : "just now";

    $scales = [
        ["minute","minutes",60],["hour","hours",24],["day","days",7],["week","weeks",4.348214286],// average with leap year every 4 years
        ["month","months",12],["year","years",10],["decade","decades",["century","centuries",1000],["millenium","millenia",PHP_INT_MAX]
    ];

    foreach ($scales as list($singular,$plural,$factor)) {
        if ($age == 0)
            return $future
                ? "in less than 1 $singular"
                : "less than 1 $singular ago";
        if ($age == 1)
            return $future
                ? "in 1 $singular"
                : "1 $singular ago";
        if ($age < $factor)
            return $future
                ? "in $age $plural"
                : "$age $plural ago";
        $age = (int)($age / $factor);
    }
}