Question

I have a function that accepts ($year, $month = null, $day = null)

Essentially a year always has to be passed in, but the month and day are optional.
If they are not passed in then it sets the range to the biggest possible.

so: call | result

(2012, 08, 15) | ['2012-08-15', '2012-08-15']  
(2012, 08)     | ['2012-08-01', '2012-08-31']
(2012, 02)     | ['2012-02-01', '2012-02-29']
(2012)         | ['2012-01-01', '2012-12-31']
()             | false

I have the below code, however to me it seems needlessly complex, can anyone think of a better version?

if (!is_null($year)) {

  //year
  $from = $year . '-';
  $to   = $year . '-';

  //month
  if (!is_null($month)) {
    $from .= sprintf('%02d', $month) . '-';
    $to   .= sprintf('%02d', $month) . '-';

    //day
    if (!is_null($day)) {
      $from .= sprintf('%02d', $day);
      $to   .= sprintf('%02d', $day);
    } else {
      $from .= '01';
      $to   .= sprintf('%02d', cal_days_in_month(CAL_GREGORIAN, $month, $year));
    }

  } else {
    $from .= '01-31';
    $to   .= '12-31';
  }
  return array($from, $to);
}
return false;

Answer 1

First of all I would change the design a little so that the usage is more easy:

function my_func_your_func_date_func($year, $month = null, $day = null)
{
    if (NULL === $year)
        return false;

    $mask = '%04d-%02d-%02d';
    $from = vsprintf($mask, date_pad_first($year, $month, $day));
    $to   = vsprintf($mask, date_pad_last($year, $month, $day));

    return array($from, $to);
}

And then these helper functions:

function date_pad_first($year, $month = NULL, $day = NULL)
{
    if (NULL === $month)
        $month = 1;

    if (NULL === $day)
        $day = 1;

    return array($year, $month, $day);
}

function date_pad_last($year, $month = NULL, $day = NULL)
{
    if (NULL === $month)
        $month = 12;

    if (NULL === $day)
        $day = cal_days_in_month(CAL_GREGORIAN, $month, $year);

    return array($year, $month, $day);
}

I then might want to extract the differences between these two pretty similar looking functions and parametrice it but I am not sure.

---

If you prefer to have it within one function (and with a little different semantics resetting the $day if $month is not set), this needs the branching with an if:

function my_func_your_func_date_func($year, $month = null, $day = null)
{
    if (NULL === $year)
        return false;

    $from[-1] = $year;
    $to = $from;

    if (NULL === $month) {
        $from += [1, 1];
        $to += [12, 31];
    } else {
        $from[2] += [$month, 1];
        $to[2] += [$month, cal_days_in_month(CAL_GREGORIAN, $month, $year)];
    }

    $mask = '%04d-%02d-%02d';
    return array(
        vsprintf($mask, $from),
        vsprintf($mask, $to)
    );
}

This function would also not work if there will be one December in time which has less or more than 31 days.