function calcDay($input)
{
$month_conversion_array = array(6, 2, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4);
$month_date_year_array = explode("-", $input);
$month_for_conversion = intval($month_date_year_array[1]);
$month_for_conversion--;
if (DayCalc::leapYear($month_date_year_array[0])) {
$month_conversion_array[0] = 5;
$month_conversion_array[1] = 1;
}
$day_code = $month_date_year_array[2];
$day_code = intval($day_code);
$month_code = $month_conversion_array[$month_for_conversion];
$year_for_conversion = $month_date_year_array[0];
$year_pattern = 0;
if ($year_for_conversion < 1600 || $year_for_conversion >= 2400) {
return "Error. Please enter a date range from 1/1/1600 to 12/31/2399";
} else {
if ($year_for_conversion >= 2300 && $year_for_conversion <= 2399) {
$year_for_conversion -= 300;
$year_pattern = 1;
} else {
if ($year_for_conversion >= 2200 && $year_for_conversion <= 2299) {
$year_for_conversion -= 200;
$year_pattern = 3;
} else {
if ($year_for_conversion >= 2100 && $year_for_conversion <= 2199) {
$year_for_conversion -= 100;
$year_pattern = 5;
} else {
if ($year_for_conversion >= 2000 && $year_for_conversion <= 2099) {
$year_for_conversion -= 0;
$year_pattern = 0;
} else {
if ($year_for_conversion >= 1900 && $year_for_conversion <= 1999) {
$year_for_conversion += 100;
$year_pattern = 1;
} else {
if ($year_for_conversion >= 1800 && $year_for_conversion <= 1899) {
$year_for_conversion += 200;
$year_pattern = 3;
} else {
if ($year_for_conversion >= 1700 && $year_for_conversion <= 1799) {
$year_for_conversion += 300;
$year_pattern = 5;
} else {
if ($year_for_conversion >= 1600 && $year_for_conversion <= 1699) {
$year_for_conversion += 400;
$year_pattern = 0;
} else {
return "what?";
}
}
}
}
}
}
}
}
}
$day_of_week_array = array("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday");
$year_code = (floor($year_for_conversion - 2000) / 4 + ($year_for_conversion - 2000)) % 7;
//2099 - floor(99 / 4) = 24; 24 + 99 = 123; 123 % 7 = 4
$year_code += $year_pattern;
$day_of_week_element = $month_code + $day_code + $year_code;
while ($day_of_week_element > 6) {
$day_of_week_element -= 7;
if ($day_of_week_element < 0) {
return "less than 0";
}
}
return $day_of_week_array[$day_of_week_element];
}
