<?php
$iYear = date('Y');

for ($i = 1; $i <= 12; $i++) {
    echo $iNumDaysInMonth = date('t', mktime(0, 0, 0, $i, 1, $iYear));

    for ($j = 1; $j <= $iNumDaysInMonth; $j++) {
        echo $iDayNum = date('N', mktime(0, 0, 0, $i, $j, $iYear));

        if ($iDayNum == 3) {
            // wednesday
        } elseif ($iDayNum == 5) {
            // friday
        } elseif ($iDayNum == 1) {
            // monday
        }
    }
}

function periode($var, $i2)
{
    if ($var == '1') {
        return '+' . $i2 . ' day';
    } else if ($var == '2') {
        return '+' . $i2 . ' week';
    } else if ($var == '3') {
        return '+' . $i2 . ' month';
    }
}

$current_date = date('Y-m-d');
echo date('Y-m-d', strtotime(periode(1, 1), strtotime($current_date)));
echo '<br />' . date('Y-m-d', strtotime(periode(2, 2), strtotime($current_date)));
echo '<br />' . date('Y-m-d', strtotime(periode(3, 1), strtotime($current_date)));
