/**

 * \brief

 *   Get a school-specific information page.

 *

 * Each school may define a function called

 * <school_id>_instructions_html(). This is the wrapper which retrieves a

 * specific school's info HTML. It is recommended that instructions

 * about using the school's registration system in conjunction with

 * slate_permutate be placed in the instructions_html.

 *

 * \param $school

 *   A school handle obtained from school_load() or

 *   school_load_guess().

 * \return

 *   An HTML fragment of the school's information or NULL if the

 *   school either doesn't have any such information or if the school

 *   handle is invalid.

 */

function school_instructions_html($school)

{

  global $school_default_school;

  if (empty($school) || empty($school['id']))

    /*

     * Invalid param deserves a NULL :-p. Really, this invalid param

     * handling shouldn't be needed...

     */

    return NULL;

  $school_instructions_html = $school['id'] . '_instructions_html';

  if (!function_exists($school_instructions_html))

    {

      /* load the default school's _instructions_html() function */

      if ($school_default_school === NULL)

	$school_default_school = school_load('default');

      /* ``hacky'', but preferable to recursion: */

      $school_instructions_html = 'default' . '_instructions_html';

      /* be 503-safe */

      if (!function_exists($school_instructions_html))

	return NULL;

    }

  return $school_instructions_html();

}

/**

 * \brief

 *   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 (empty($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']];

  $semester = NULL;

  foreach ($semesters as $semester)

    {

    }

  return $semester;

}

/**

 * \brief

 *   Return an array of default classes for a particular school.

 *

 * \param $school

 *   The school's handle.

 */

function school_default_courses($school)

{

  $school_default_courses = $school['id'] . '_default_courses';

  if (function_exists($school_default_courses))

    {

      require_once(dirname(__FILE__) . DIRECTORY_SEPARATOR . 'class.course.inc');

      return $school_default_courses();

    }

  return array();

}

/**

 * \brief

 *   Return an example course id for the school.

 *

 * Each school may specify an example course ID by placing a key

 * called 'example_course_id' into the array returned by its

 * <school_id>_info() function. See school_load().

 *

 * \param $school

 *   The school's handle.

 * \return

 *   A string containing a representative example of a course ID for

 *   the given school.

 */

function school_example_course_id(array $school)

{

  return $school['example_course_id'];

}

/**

 * \brief

 *   Determine if a school has crawler data stored.

 *

 * \param $school

 *   The which should be checked.

 */

function school_has_auto(array $school)

{

  return isset($school['crawled']) && $school['crawled'];

}

/**

 * \brief

 *   Used to load the school cache.

 *

 * \return

 *   The cache array or NULL if the cache couldn't be loaded.

 */

function _school_cache_load()

{

  static $cache = NULL;

  if ($cache != NULL)

    return $cache;

  $cache_file_name = dirname(__FILE__) . DIRECTORY_SEPARATOR . '..'

    . DIRECTORY_SEPARATOR . 'cache' . DIRECTORY_SEPARATOR . 'schools';

  $cache_serialized = @file_get_contents($cache_file_name);

  if (!empty($cache_serialized))

    $cache = unserialize($cache_serialized);

  return $cache;

}