$semester = school_semester_guess($school);

$cache_dir = dirname(__FILE__) . DIRECTORY_SEPARATOR . 'cache' . DIRECTORY_SEPARATOR . 'auto'

  . DIRECTORY_SEPARATOR . $school['id'] . DIRECTORY_SEPARATOR . $semester['id'] . DIRECTORY_SEPARATOR;

	      if (!mkdir($cache_auto_school_dir_name, 0755, TRUE))

	  $semesters = array();

	  $semester_weights = 0;

	  /*

	   * Try to presort the semesters into the proper order based

	   * on time_start/time_end. We want the older semesters to be

	   * nearer to the end of the list. This way, the crawler

	   * doesn't have to decide how to sort the semesters itself:

	   */

	  usort($semesters, function ($sem_a, $sem_b)

		{

		  return $sem_a->time_start_get() - $sem_b->time_start_get();

		});

	  foreach ($school['crawled_semesters'] as $semester)

	    {

	      $semesters[$semester->id()] = array(

						  'id' => $semester->id(),

						  'time_start' => $semester->time_start_get(),

						  'time_end' => $semester->time_end_get(),

						  'weight' => $semester_weights ++,

						  'name' => $semester->name_get(),

						  );

	      $cache_auto_school_semester_dir_name = $cache_auto_school_dir_name . $semester->id() . DIRECTORY_SEPARATOR;

	      if (!is_dir($cache_auto_school_semester_dir_name))

		{

		  if (!mkdir($cache_auto_school_semester_dir_name, 0755, TRUE))

		    error_log('Unable to create needed directory: `' . $cache_auto_school_semester_dir_name . '\'');

		}

	      $dept_file = fopen($cache_auto_school_semester_dir_name . '-depts', 'wb');

		  $classes_file = fopen($cache_auto_school_semester_dir_name . $department . '.sects', 'wb');

		      if (!is_dir($cache_auto_school_semester_dir_name . $department))

			mkdir($cache_auto_school_semester_dir_name . $department);

		      $class_file = fopen($cache_auto_school_semester_dir_name . $department . DIRECTORY_SEPARATOR . $class, 'wb');

	    } /* foreach ( => $semester) */

	  /*

	   * Store/cache the semester metadata:

	   */

	  $semesters_file = fopen($cache_auto_school_dir_name . '-semesters', 'wb');

	  fwrite($semesters_file, serialize($semesters));

	  fclose($semesters_file);

 * <school_id>_crawl(array &$semesters, $verbosity = 1) must be

 * defined. It must accept at least one argument, the array to be

 * filled with Semester objects. It must populate this array with

 * individual Semester objects and fill those with Course objects and

 * populate those courses with the sections with as much detail as

 * possible. This function may return 1 to indicate an error must

 * return 0 to indicate success.

 * If the crawling is successful, a 'crawled' key is added to the

function school_crawl(array &$school, $verbosity = 1)

  $semesters = array();

  $ret = $school_crawl_func($semesters, $verbosity);

  $school['crawled_semesters'] = $semesters;

	  school_crawl($school, $verbosity);

    $this->semester = school_semester_guess($this->school);

  	 '            <span id="menu">' . PHP_EOL

      . '              Profile: '.$this->school['name'].' <a href="input.php?selectschool=1">(change)</a>' . PHP_EOL;

    if ($this->semester !== NULL)

      echo  '             Semester: ' . $this->semester['name'] . '<a href="input.php?selectsemester=1">(change)</a>' . PHP_EOL;

    echo '            </span>'. PHP_EOL .

   *   Display a list of semesters the user might be interested in.

   * \param $linkto

   *   The link to which a &semester= or ?semester= query string

   *   should be appended.

   */

  public function showSemesters($linkto = 'input.php')

  {

    if (strpos($linkto, '?'))

      $linkto .= '&';

    else

      $linkto .= '?';

    /*

     * We can pre-htmlentities() $linkto because we're only appending

     * a safe string.

     */

    $linkto = htmlentities($linkto . 'semester=');

    $time = time();

    echo "    <p>\n";

    echo "      <ul>\n";

    foreach (school_semesters($this->school) as $semester)

      {

	$text_extra = array();

	$class_extra = '';

	if ($semester['id'] == $this->semester['id'])

	  {

	    $class_extra = ' highlight';

	    $text_extra[] = 'selected';

	  }

	if ($semester['time_start'] < $time && $semester['time_end'] > $time)

	  $text_extra[] = 'current';

	$text_extra = implode($text_extra, ', ');

	if (strlen($text_extra))

	  $text_extra = ' (' . $text_extra . ')';

	echo '        <li class="semester' . $class_extra . '"><a href="' . $linkto . $semester['id'] . '">' . htmlentities($semester['name']) . '</a>' . $text_extra . "</li>\n";

      }

    echo "      </ul>\n";

    echo "    </p>\n";

  }

  /**

   * \brief

   *   The Summer season.

   */

  const SEASON_SUMMER = 'summer';

  /**

   * \brief

   *   The season of this semester. Please use the constants

   *   Semester::SEASON_FALL, Semester::SEASON_SPRING, or

   *   Semester::SEASON_SUMMER if possible.

   * \param $time_start

   *   Specify a timestamp which roughly estimates when this semester

   *   starts to aid the algorithm for guessing the current

   *   semester. See Semester::time_start_set(), which may be used

   *   instead of this parameter

   * \param $time_end

   *   This may be specified now or via Semester::time_end_set().

  function __construct($year, $season, $time_start = 0, $time_end = 0)

    $this->time_start = 0;

    $this->time_end = 0;

    if (strlen($year) != 4 || !is_numeric($year))

   *   Update the time_end.

   *

   * The time_end is a unix timestamp roughly estimating the time at

   * which a semester starts. It is used when guessing what semester a

   * user is interested in.

   *

   * \param $time_end

   *   The new time_end.

   */

  public function time_end_set($time_end)

  {

    $this->time_end = $time_end;

  }

  /**

   * \brief

   *   Set the time_end only if it would make the semester end later.

   *

   * Useful for crawler scripts incrementally guessing the endtime of

   * a semester.

   *

   * \param $time_end

   *   The new time_end to consider.

   */

  public function time_end_set_test($time_end)

  {

    if ($time_end && $time_end > $this->time_end)

      $this->time_end_set($time_end);

  }

  public function time_end_get()

  {

    return $this->time_end;

  }

  /**

   * \brief

   *   Update the time_start.

   *

   * The time_start is a unix timestamp roughly estimating the time at

   * which a semester starts. It is used when guessing what semester a

   * user is interested in.

   *

   * \param $time_start

   *   The new time_start.

   */

  public function time_start_set($time_start)

  {

    $this->time_start = $time_start;

  }

  /**

   * \brief

   *   Only update the time_start if the time_start isn't yet set or

   *   if the given time_start is earlier than the stored one.

   *

   * This should allow crawlers to easily accumulate proper time_start

   * and time_end values, see Semester::time_end_set_test();

   *

   * \param $time_start

   *   The new estimation of the semester's start.

   */

  public function time_start_set_test($time_start)

  {

    if ($time_start &&

	(!$this->time_start || $time_start < $this->time_start))

      $this->time_start_set($time_start);

  }

  public function time_start_get()

  {

    return $this->time_start;

  }

  /**

   * \brief

   *   Get a semester's friendly name:

   *

   * \return

   *   A string, the semester's friendly name.

   */

  public function name_get()

  {

    return ucfirst($this->season_get()) . ' ' . $this->year_get();

  }

  /**

   * \brief

   *   Return an identification string for this semester.

   *

   * Hopefully this identification string should be unique. Also, this

   * identification string is filesystem-safe.

   *

   * \return

   *   A string which may be used in paths or to uniquely identify

   *   this semester in the context of its school.

   */

  public function id()

  {

    return $this->year_get() . '_' . $this->season_get();

  }

  /**

   * \brief

    return array(self::SEASON_SPRING, self::SEASON_SUMMER, self::SEASON_FALL);

 *   Equivalent of mktime() except that it accepts strptime()'s output

 *   format as an input.

 *

 * \param $tm

 *   An array formatted as the output of strptime().

 * \return

 *   A unix timestamp.

 */

function school_crawl_mktime(array $tm)

{

  return mktime($tm['tm_hour'], $tm['tm_min'], $tm['tm_sec'],

		$tm['tm_mon'] + 1, $tm['tm_mday'], $tm['tm_year'] + 1900);

}

/**

 * \brief

 * - id: The school's ID.

  $school_file_name_base = dirname(dirname(__FILE__)) . DIRECTORY_SEPARATOR . 'school.d' . DIRECTORY_SEPARATOR;

    {

      $school_semesters_filename = dirname(dirname(__FILE__)) . DIRECTORY_SEPARATOR . 'cache'

	. DIRECTORY_SEPARATOR . 'auto' . DIRECTORY_SEPARATOR . $school['id']

	. DIRECTORY_SEPARATOR . '-semesters';

      if (file_exists($school_semesters_filename))

	$school['semesters'] = unserialize(file_get_contents($school_semesters_filename));

      else

	$school['semesters'] = array();

    }

 *   Return information about available semesters.

 *

 * \param $school

 *   The school.

 * \return

 *   An array with keys being semester IDs ordered by weights with

 *   lowest first and keys of 'id' (the semester's ID), 'name' (the

 *   friendly name), and 'weight' (lower numbers mean these semesters

 *   should be earlier, may be positive or negative). 'time_start',

 *   'time_end' are unix timestamps estimating the begin and end point

 *   of each semester.

 */

function school_semesters(array $school)

{

  if (!$school['crawled'])

    return array();

  return $school['semesters'];

}

/**

 * \brief

 *   Return the semester which either the user has selected or which

 *   makes the most sense.

 *

 * \param $school

 *   The school for which a semester should be guessed.

 * \return

 *   An array with the keys 'id', 'name', and 'weight' corresponding

 *   to the same keys in the arrays returned by school_semesters() or

 *   NULL if no semester can be found.

 */

function school_semester_guess(array $school)

{

  $semesters = school_semesters($school);

  if (!empty($_REQUEST['semester'])

      && isset($semesters[$_REQUEST['semester']]))

    {

      $semester = $semesters[$_REQUEST['semester']];

      $_SESSION['semester'] = $semester['id'];

      return $semester;

    }

  if (!empty($_SESSION['semester'])

      && isset($semesters[$_SESSION['semester']]))

      return $semesters[$_SESSION['semester']];

  $time = time();

  $next_semester = FALSE;

  $semester = NULL;

  foreach ($semesters as $semester)

    {

      if ($next_semester)

	return $semester;

      if ($semester['time_start'] < $time)

	$next_semester = TRUE;

    }

  return $semester;

}

/**

 * \brief

if (!empty($_REQUEST['selectsemester']))

  {

?>

<h2>Semester Selection</h2>

<p>

  Choose the semester for which you wish you make a schedule from the

  list below. If any semester is missing, please <a

  href="feedback.php?feedback=My+school+is+missing+the+&lt;semester+name&gt;+semester.">let us know</a>.

</p>

<?php

  $inputPage->showSemesters();

  $inputPage->foot();

  exit;

  }

 * \param $semesters

 *   An array to be filled with Semester objects which I should

 *   populate.

function calvin_crawl(array &$semesters, $verbosity = 1)

	  || !$semester_node->hasAttribute('value')

	  || !strlen($semester_node->getAttribute('value')))

  $semester_strs = array_reverse($semester_strs, TRUE);

  if ($verbosity > 4)

    fprintf(STDERR, "Available semesters: %s\n", implode($semester_strs, ', '));

  $semester_start_uri = $uri;

  $season_map = array(

		      'FA' => Semester::SEASON_FALL,

		      'IN' => 'interim',

		      'SP' => Semester::SEASON_SPRING,

		      'MA' => 'may',

		      /* I don't know if SU is a valid Calvin Smester ID or not */

		      'SU' => Semester::SEASON_SUMMER);

  foreach ($semester_strs as $semester_str => $semester_info)

    {

      if (empty($season_map[substr($semester_str, 3)]))

	{

	  fprintf(STDERR, "Warning: Unknown semester identification chars: %s. Skipping this semester.\n",

		  $semester_str);

	  continue;

	}

      $season = $season_map[substr($semester_str, 3)];

      $year_timespec = strptime(substr($semester_str, 0, 2), '%y');

      $year =  $year_timespec['tm_year'] + 1900;

      $semester = new Semester($year, $season);

      /* useful and necessary stats */

      $skipped_sections = array('incomplete meeting info' => 0, 'invalid meeting info format' => 0);

      $semester_start_min = 0;

      $semester_end_max = 0;

      $uri = $semester_start_uri;

      if ($verbosity)

	fprintf(STDERR, "Crawling semester %s->%s\n",

		$semester_str, $semester_info);

		 * Other form items we're not querying but which need

		 * to be sent blankly.

	  /*

	   * Try to update semester's longetivity stats to help the

	   * school_semester_guess() function:

	   */

	  $date_start_time = strptime($date_start, '%m/%d/%Y');

	  $date_end_time = strptime($date_end, '%m/%d/%Y');

	  if ($date_start_time !== FALSE)

	    {

	      $date_start_time = school_crawl_mktime($date_start_time);

	      if (!$semester_start_min || $semester_start_min > $date_start_time)

		$semester_start_min = $date_start_time;

	    }

	  if ($date_end_time !== FALSE)

	    {

	      $date_end_time = school_crawl_mktime($date_end_time);

	      if ($semester_end_max < $date_end_time)

		$semester_end_max = $date_end_time;

	    }

    $semester->time_end_set($semester_end_max);

    $semester->time_start_set($semester_start_min);

    $semesters[] = $semester;

    if ($verbosity)

      fprintf(STDERR, "\n");

    }

function ccbcmd_crawl(array &$semesters, $verbosity = 1)

  $semester_stage_uri = $uri;

  $semesters_post_save = school_crawl_form($semesters_form);

  foreach ($semesters_select_node->childNodes as $semesters_option_node)

    {

      $semester_text = $semesters_option_node->textContent;

      $semester_value = $semesters_option_node->getAttribute('value');

      if (empty($semester_value))

	/* skip the empty ``None'' semester */

	continue;

      if (stripos($semester_text, 'continuing') !== FALSE)

	/* skip the year-long semesters dedicated to continuing education */

	continue;

      $semester_text_parts = explode(' ', $semester_text);

      $semester_season = $semester_text_parts[0];

      $semester_year = $semester_text_parts[1];

      /* the college has two separate summer sessions, so distinguish between them */

      if (preg_match(';session ([0-9]+);i', $semester_text, $matches))

	$semester_season .= '_' . $matches[1];

      if ($verbosity)

	fprintf(STDERR, "Crawling semester %s:%s -> %s.\n", $semester_year, $semester_season, $semester_text);

      $semester = new Semester($semester_year, strtolower($semester_season));

  if ($verbosity > 1)

    fprintf(STDERR, "Found semester: %s=``%s''=``%s''.\n",

  	    $semester_value, $semester->id(), trim($semesters_option_node->textContent));

  /* load stored semester-page URI / form data */

  $semesters_post = $semesters_post_save;

  $uri = $semester_stage_uri;

			   'dates' => school_crawl_table_resolve_column($tr_header_node, 'sessiondates'),

	/* check if a semester's date range should be increased */

	$section_dates = $children->item($section_offsets['dates'])->textContent;

	if (preg_match(';^([0-9]+)/([0-9]+)-([0-9]+)/([0-9]+)$;', $section_dates, $section_dates_matches))

	  {

	    $semester->time_start_set_test(mktime(0, 0, 0, $section_dates_matches[1], $section_dates_matches[2], $semester->year_get()));