<?php
  require('global-php.php');
  $verbindung = database_connection($lang_database_failure[$language]);
  $PHP_AUTH_USER = $_SERVER["PHP_AUTH_USER"];
  $PHP_AUTH_PW = $_SERVER["PHP_AUTH_PW"];
  $ergebnis = db_exec($verbindung,
			"SELECT * FROM staff_authorization,superuser "
				. "WHERE superuser.account"
				. "=staff_authorization.id "
				. "AND "
				. login_query_clauses(
					$PHP_AUTH_USER,
					$PHP_AUTH_PW)
				. ";");
  if (pg_numrows($ergebnis) < 1) {
    header('WWW-Authenticate: Basic realm="Kursverwaltung"');
    header("HTTP/1.0 401 Unauthorized");
    echo $lang_authentication_failure[$language];
    db_close($verbindung);
    exit;
  }
  $direction = $_REQUEST["direction"];
  if ($direction == "up") {
    $ahead = "<";
    $behind = ">";
    $forward = "-";
    $backward = "+";
    $nearest_ahead = "max";
  } else {
    $ahead = ">";
    $behind = "<";
    $forward = "+";
    $backward = "-";
    $nearest_ahead = "min";
  }
  $course = intval($_REQUEST["course"]);
  $course_period = option_value($course_period_option);
  db_exec($verbindung, "START TRANSACTION;");
  db_exec($verbindung, "LOCK TABLE $course_date;");
  $ergebnis = db_exec($verbindung, "SELECT category FROM $course_date,course "
  					. "WHERE $course_date.id=$course "
					. "AND course=course.id;");
  $category = pg_result($ergebnis,0,0);
  $ergebnis = db_exec($verbindung,
  			"SELECT $nearest_ahead($course_date.position),"
			. "this_one.position "
  			. "FROM $course_date,course,"
			. "$course_date AS this_one "
			. "WHERE course_period=$course_period "
			. "AND $course_date.course=course.id "
			. "AND this_one.id=$course "
			. "AND category=$category "
			. "AND $course_date.position $ahead this_one.position "
			. "GROUP BY this_one.position;");
  if (pg_numrows($ergebnis) > 0) {
    $next_position = pg_result($ergebnis,0,0);
    $this_position = pg_result($ergebnis,0,1);
    $ergebnis = db_exec($verbindung,
  			"UPDATE $course_date SET position=-1 "
			. "WHERE position=$next_position;");
    $ergebnis = db_exec($verbindung,
  			"UPDATE $course_date SET position=$next_position "
			. "WHERE position=$this_position;");
    $ergebnis = db_exec($verbindung,
  			"UPDATE $course_date SET position=$this_position "
			. "WHERE position=-1;");
  }
  $ergebnis = db_exec($verbindung, "COMMIT;");
  db_close($verbindung);
?>