refactor_1_solution.php

<?php

  // Before:

  function getStartDate() {
    return preg_match("/^\d\d\d\d-\d\d-\d\d$/", $_GET['dStartDate'])	? $_GET['dStartDate']	: date("Y-m-d", time() - 60 * 60 * 24 * 7);
  }

  function getEndDate() {
    return preg_match("/^\d\d\d\d-\d\d-\d\d$/", $_GET['dEndDate'])	? $_GET['dEndDate']		: date("Y-m-d");
  }
  
  // After:

  function getStartDate() {
		return normalizedDate($_GET['dStartDate'], time() - 60 * 60 * 24 * 7);
	}

	function getEndDate() {
		return normalizedDate($_GET['dEndDate'], time());
	}

	function normalizedDate($dateString, $defaultTimestamp) {
		return isProperlyFormattedDate($dateString)	? $dateString : formatDate($defaultTimestamp);
	}

	function isProperlyFormattedDate($dateString) {
		return preg_match("/^\d\d\d\d-\d\d-\d\d$/", $dateString);
	}

	function formatDate($timestamp) {
		return date("Y-m-d", $timestamp);
	}