<?php

/**

 * @file

 * Functions to aid in presenting database results as a set of pages.

 */

/**

 * Query extender for pager queries.

 *

 * This is the "default" pager mechanism.  It creates a paged query with a fixed

 * number of entries per page.

 */

class PagerDefault extends SelectQueryExtender {

  /**

   * The highest element we've autogenerated so far.

   *

   * @var int

   */

  static $maxElement = 0;

  /**

   * The number of elements per page to allow.

   *

   * @var int

   */

  protected $limit = 10;

  /**

   * The unique ID of this pager on this page.

   *

   * @var int

   */

  protected $element = NULL;

  /**

   * The count query that will be used for this pager.

   *

   * @var SelectQueryInterface

   */

  protected $customCountQuery = FALSE;

  public function __construct(SelectQueryInterface $query, DatabaseConnection $connection) {

    parent::__construct($query, $connection);

    // Add pager tag. Do this here to ensure that it is always added before

    // preExecute() is called.

    $this->addTag('pager');

  }

  /**

   * Override the execute method.

   *

   * Before we run the query, we need to add pager-based range() instructions

   * to it.

   */

  public function execute() {

    // Add convenience tag to mark that this is an extended query. We have to

    // do this in the constructor to ensure that it is set before preExecute()

    // gets called.

    if (!$this->preExecute($this)) {

      return NULL;

    }

    // A NULL limit is the "kill switch" for pager queries.

    if (empty($this->limit)) {

      return;

    }

    $this->ensureElement();

    $total_items = $this->getCountQuery()->execute()->fetchField();

    $current_page = pager_default_initialize($total_items, $this->limit, $this->element);

    $this->range($current_page * $this->limit, $this->limit);

    // Now that we've added our pager-based range instructions, run the query normally.

    return $this->query->execute();

  }

  /**

   * Ensure that there is an element associated with this query.

   * If an element was not specified previously, then the value of the

   * $maxElement counter is taken, after which the counter is incremented.

   *

   * After running this method, access $this->element to get the element for this

   * query.

   */

  protected function ensureElement() {

    if (!isset($this->element)) {

      $this->element = self::$maxElement++;

    }

  }

  /**

   * Specify the count query object to use for this pager.

   *

   * You will rarely need to specify a count query directly.  If not specified,

   * one is generated off of the pager query itself.

   *

   * @param SelectQueryInterface $query

   *   The count query object.  It must return a single row with a single column,

   *   which is the total number of records.

   */

  public function setCountQuery(SelectQueryInterface $query) {

    $this->customCountQuery = $query;

  }

  /**

   * Retrieve the count query for this pager.

   *

   * The count query may be specified manually or, by default, taken from the

   * query we are extending.

   *

   * @return SelectQueryInterface

   *   A count query object.

   */

  public function getCountQuery() {

    if ($this->customCountQuery) {

      return $this->customCountQuery;

    }

    else {

      return $this->query->countQuery();

    }

  }

  /**

   * Specify the maximum number of elements per page for this query.

   *

   * The default if not specified is 10 items per page.

   *

   * @param $limit

   *   An integer specifying the number of elements per page.  If passed a false

   *   value (FALSE, 0, NULL), the pager is disabled.

   */

  public function limit($limit = 10) {

    $this->limit = $limit;

    return $this;

  }

  /**

   * Specify the element ID for this pager query.

   *

   * The element is used to differentiate different pager queries on the same

   * page so that they may be operated independently.  If you do not specify an

   * element, every pager query on the page will get a unique element.  If for

   * whatever reason you want to explicitly define an element for a given query,

   * you may do so here.

   *

   * Setting the element here also increments the static $maxElement counter,

   * which is used for determining the $element when there's none specified.

   *

   * Note that no collision detection is done when setting an element ID

   * explicitly, so it is possible for two pagers to end up using the same ID

   * if both are set explicitly.

   *

   * @param $element

   */

  public function element($element) {

    $this->element = $element;

    if ($element >= self::$maxElement) {

      self::$maxElement = $element + 1;

    }

    return $this;

  }

}

/**

 * Returns the current page being requested for display within a pager.

 *

 * @param $element

 *  An optional integer to distinguish between multiple pagers on one page.

 *

 * @return

 *  The number of the current requested page, within the pager represented by

 *  $element. This is determined from the URL query parameter $_GET['page'], or

 *  0 by default. Note that this number may differ from the actual page being

 *  displayed. For example, if a search for "example text" brings up three

 *  pages of results, but a users visits search/node/example+text?page=10, this

 *  function will return 10, even though the default pager implementation

 *  adjusts for this and still displays the third page of search results at

 *  that URL.

 *

 * @see pager_default_initialize()

 */

function pager_find_page($element = 0) {

  $page = isset($_GET['page']) ? $_GET['page'] : '';

  $page_array = explode(',', $page);

  if (!isset($page_array[$element])) {

    $page_array[$element] = 0;

  }

  return (int) $page_array[$element];

}

/**

 * Initializes a pager for theme('pager').

 *

 * This function sets up the necessary global variables so that future calls

 * to theme('pager') will render a pager that correctly corresponds to the

 * items being displayed.

 *

 * If the items being displayed result from a database query performed using

 * Drupal's database API, and if you have control over the construction of the

 * database query, you do not need to call this function directly; instead, you

 * can simply extend the query object with the 'PagerDefault' extender before

 * executing it. For example:

 * @code

 *   $query = db_select('some_table')->extend('PagerDefault');

 * @endcode

 *

 * However, if you are using a different method for generating the items to be

 * paged through, then you should call this function in preparation.

 *

 * The following example shows how this function can be used in a page callback

 * that invokes an external datastore with an SQL-like syntax:

 * @code

 *   // First find the total number of items and initialize the pager.

 *   $where = "status = 1";

 *   $total = mymodule_select("SELECT COUNT(*) FROM data " . $where)->result();

 *   $num_per_page = variable_get('mymodule_num_per_page', 10);

 *   $page = pager_default_initialize($total, $num_per_page);

 *

 *   // Next, retrieve and display the items for the current page.

 *   $offset = $num_per_page * $page;

 *   $result = mymodule_select("SELECT * FROM data " . $where . " LIMIT %d, %d", $offset, $num_per_page)->fetchAll();

 *   $output = theme('mymodule_results', array('result' => $result));

 *

 *   // Finally, display the pager controls, and return.

 *   $output .= theme('pager');

 *   return $output;

 * @endcode

 *

 * A second example involves a page callback that invokes an external search

 * service where the total number of matching results is provided as part of

 * the returned set (so that we do not need a separate query in order to obtain

 * this information). Here, we call pager_find_page() to calculate the desired

 * offset before the search is invoked:

 * @code

 *   // Perform the query, using the requested offset from pager_find_page().

 *   // This comes from a URL parameter, so here we are assuming that the URL

 *   // parameter corresponds to an actual page of results that will exist

 *   // within the set.

 *   $page = pager_find_page();

 *   $num_per_page = variable_get('mymodule_num_per_page', 10);

 *   $offset = $num_per_page * $page;

 *   $result = mymodule_remote_search($keywords, $offset, $num_per_page);

 *

 *   // Now that we have the total number of results, initialize the pager.

 *   pager_default_initialize($result->total, $num_per_page);

 *

 *   // Display the search results.

 *   $output = theme('search_results', array('results' => $result->data, 'type' => 'remote'));

 *

 *   // Finally, display the pager controls, and return.

 *   $output .= theme('pager');

 *   return $output;

 * @endcode

 *

 * @param $total

 *  The total number of items to be paged.

 * @param $limit

 *  The number of items the calling code will display per page.

 * @param $element

 *  An optional integer to distinguish between multiple pagers on one page.

 *

 * @return

 *   The number of the current page, within the pager represented by $element.

 *   This is determined from the URL query parameter $_GET['page'], or 0 by

 *   default. However, if a page that does not correspond to the actual range

 *   of the result set was requested, this function will return the closest

 *   page actually within the result set.

 */

function pager_default_initialize($total, $limit, $element = 0) {

  global $pager_page_array, $pager_total, $pager_total_items, $pager_limits;

  $page = pager_find_page($element);

  // We calculate the total of pages as ceil(items / limit).

  $pager_total_items[$element] = $total;

  $pager_total[$element] = ceil($pager_total_items[$element] / $limit);

  $pager_page_array[$element] = max(0, min($page, ((int) $pager_total[$element]) - 1));

  $pager_limits[$element] = $limit;

  return $pager_page_array[$element];

}

/**

 * Compose a URL query parameter array for pager links.

 *

 * @return

 *   A URL query parameter array that consists of all components of the current

 *   page request except for those pertaining to paging.

 */

function pager_get_query_parameters() {

  $query = &drupal_static(__FUNCTION__);

  if (!isset($query)) {

    $query = drupal_get_query_parameters($_GET, array('q', 'page'));

  }

  return $query;

}

/**

 * Returns HTML for a query pager.

 *

 * Menu callbacks that display paged query results should call theme('pager') to

 * retrieve a pager control so that users can view other results. Format a list

 * of nearby pages with additional query results.

 *

 * @param $variables

 *   An associative array containing:

 *   - tags: An array of labels for the controls in the pager.

 *   - element: An optional integer to distinguish between multiple pagers on

 *     one page.

 *   - parameters: An associative array of query string parameters to append to

 *     the pager links.

 *   - quantity: The number of pages in the list.

 *

 * @ingroup themeable

 */

function theme_pager($variables) {

  $tags = $variables['tags'];

  $element = $variables['element'];

  $parameters = $variables['parameters'];

  $quantity = $variables['quantity'];

  global $pager_page_array, $pager_total;

  // Calculate various markers within this pager piece:

  // Middle is used to "center" pages around the current page.

  $pager_middle = ceil($quantity / 2);

  // current is the page we are currently paged to

  $pager_current = $pager_page_array[$element] + 1;

  // first is the first page listed by this pager piece (re quantity)

  $pager_first = $pager_current - $pager_middle + 1;

  // last is the last page listed by this pager piece (re quantity)

  $pager_last = $pager_current + $quantity - $pager_middle;

  // max is the maximum page number

  $pager_max = $pager_total[$element];

  // End of marker calculations.

  // Prepare for generation loop.

  $i = $pager_first;

  if ($pager_last > $pager_max) {

    // Adjust "center" if at end of query.

    $i = $i + ($pager_max - $pager_last);

    $pager_last = $pager_max;

  }

  if ($i <= 0) {

    // Adjust "center" if at start of query.

    $pager_last = $pager_last + (1 - $i);

    $i = 1;

  }

  // End of generation loop preparation.

  $li_first = theme('pager_first', array('text' => (isset($tags[0]) ? $tags[0] : t('« first')), 'element' => $element, 'parameters' => $parameters));

  $li_previous = theme('pager_previous', array('text' => (isset($tags[1]) ? $tags[1] : t('‹ previous')), 'element' => $element, 'interval' => 1, 'parameters' => $parameters));

  $li_next = theme('pager_next', array('text' => (isset($tags[3]) ? $tags[3] : t('next ›')), 'element' => $element, 'interval' => 1, 'parameters' => $parameters));

  $li_last = theme('pager_last', array('text' => (isset($tags[4]) ? $tags[4] : t('last »')), 'element' => $element, 'parameters' => $parameters));

  if ($pager_total[$element] > 1) {

    if ($li_first) {

      $items[] = array(

        'class' => array('pager-first'),

        'data' => $li_first,

      );

    }

    if ($li_previous) {

      $items[] = array(

        'class' => array('pager-previous'),

        'data' => $li_previous,

      );

    }

    // When there is more than one page, create the pager list.

    if ($i != $pager_max) {

      if ($i > 1) {

        $items[] = array(

          'class' => array('pager-ellipsis'),

          'data' => '…',

        );

      }

      // Now generate the actual pager piece.

      for (; $i <= $pager_last && $i <= $pager_max; $i++) {

        if ($i < $pager_current) {

          $items[] = array(

            'class' => array('pager-item'),

            'data' => theme('pager_previous', array('text' => $i, 'element' => $element, 'interval' => ($pager_current - $i), 'parameters' => $parameters)),

          );

        }

        if ($i == $pager_current) {

          $items[] = array(

            'class' => array('pager-current'),

            'data' => $i,

          );

        }

        if ($i > $pager_current) {

          $items[] = array(

            'class' => array('pager-item'),

            'data' => theme('pager_next', array('text' => $i, 'element' => $element, 'interval' => ($i - $pager_current), 'parameters' => $parameters)),

          );

        }

      }

      if ($i < $pager_max) {

        $items[] = array(

          'class' => array('pager-ellipsis'),

          'data' => '…',

        );

      }

    }

    // End generation.

    if ($li_next) {

      $items[] = array(

        'class' => array('pager-next'),

        'data' => $li_next,

      );

    }

    if ($li_last) {

      $items[] = array(

        'class' => array('pager-last'),

        'data' => $li_last,

      );

    }

    return '<h2 class="element-invisible">' . t('Pages') . '</h2>' . theme('item_list', array(

      'items' => $items,

      'attributes' => array('class' => array('pager')),

    ));

  }

}

/**

 * @defgroup pagerpieces Pager pieces

 * @{

 * Theme functions for customizing pager elements.

 *

 * Note that you should NOT modify this file to customize your pager.

 */

/**

 * Returns HTML for the "first page" link in a query pager.

 *

 * @param $variables

 *   An associative array containing:

 *   - text: The name (or image) of the link.

 *   - element: An optional integer to distinguish between multiple pagers on