path: root/modules/block/block.module

<?php
// $Id$

/**
 * @file
 * Controls the boxes that are displayed around the main content.
 */

/**
 * Denotes that a block is not enabled in any region and should not
 * be shown.
 */
define('BLOCK_REGION_NONE', -1);

/**
 * Constants defining cache granularity for blocks.
 *
 * Modules specify the caching patterns for their blocks using binary
 * combinations of these constants in their hook_block(op 'list'):
 *   $block[delta]['cache'] = BLOCK_CACHE_PER_ROLE | BLOCK_CACHE_PER_PAGE;
 * BLOCK_CACHE_PER_ROLE is used as a default when no caching pattern is
 * specified.
 *
 * The block cache is cleared in cache_clear_all(), and uses the same clearing
 * policy than page cache (node, comment, user, taxonomy added or updated...).
 * Blocks requiring more fine-grained clearing might consider disabling the
 * built-in block cache (BLOCK_NO_CACHE) and roll their own.
 *
 * Note that user 1 is excluded from block caching.
 */

/**
 * The block should not get cached. This setting should be used:
 * - for simple blocks (notably those that do not perform any db query),
 * where querying the db cache would be more expensive than directly generating
 * the content.
 * - for blocks that change too frequently.
 */
define('BLOCK_NO_CACHE', -1);

/**
* The block can change depending on the roles the user viewing the page belongs to.
* This is the default setting, used when the block does not specify anything.
*/
define('BLOCK_CACHE_PER_ROLE', 0x0001);

/**
* The block can change depending on the user viewing the page.
* This setting can be resource-consuming for sites with large number of users,
* and thus should only be used when BLOCK_CACHE_PER_ROLE is not sufficient.
*/
define('BLOCK_CACHE_PER_USER', 0x0002);

/**
* The block can change depending on the page being viewed.
*/
define('BLOCK_CACHE_PER_PAGE', 0x0004);

/**
 * The block is the same for every user on every page where it is visible.
 */
define('BLOCK_CACHE_GLOBAL', 0x0008);

/**
 * Implementation of hook_help().
 */
function block_help($path, $arg) {
  switch ($path) {
    case 'admin/help#block':
      $output = '<p>'. t('Blocks are boxes of content that may be rendered into certain regions of your web pages, for example, into sidebars. Blocks are usually generated automatically by modules (e.g., Recent Forum Topics), but administrators can also define custom blocks.') .'</p>';
      $output .= '<p>'. t('The region each block appears in depends on both which theme you are using (some themes allow greater control over block placement than others), and on the settings in the block administration section.') .'</p>';
      $output .= '<p>'. t('The block administration screen lets you specify the vertical placement of the blocks within a region. You do this by assigning a weight to each block. Lighter blocks (those having a smaller weight) "float up" towards the top of the region; heavier ones "sink".') .'</p>';
      $output .= t("<p>A block's visibility depends on:</p>
<ul>
<li>Its region placement. Blocks with no region assigned to them are never shown.</li>
<li>Its throttle checkbox when throttle module is enabled. Throttled blocks are hidden during high server loads.</li>
<li>Its page visibility settings. Blocks can be configured to be visible/hidden on certain pages.</li>
<li>Its custom visibility settings. Blocks can be configured to be visible only when specific conditions are true.</li>
<li>Its user visibility settings. Administrators can choose to let users decide whether to show/hide certain blocks.</li>
<li>Its user-role visibility settings. Administrators can choose to let blocks be visible only for certain user roles.</li>
<li>Its function. Some dynamic blocks, such as those generated by modules, will be displayed only on certain pages.</li>
</ul>
");
      $output .= '<h3>'. t('Module blocks') .'</h3>';
      $output .= '<p>'. t('Some modules generate blocks that become available when the modules are enabled. These blocks can be administered via the <a href="@admin-block">blocks administration page</a>.</p>', array('@admin-block' => url('admin/build/block'))) .'</p>';
      $output .= '<h3>'. t('Administrator defined blocks') .'</h3>';
      $output .= '<p>'. t('Administrators can also define custom blocks. These blocks consist of a title, a description, and a body which can be as long as you wish. Block content can be in any of the input formats supported for other content.') .'</p>';
      $output .= '<p>'. t('For more information please read the configuration and customization handbook <a href="@block">Block page</a>.', array('@block' => 'http://drupal.org/handbook/modules/block/')) .'</p>';
      return $output;
    case 'admin/build/block':
      return t('<p>Blocks are boxes of content that may be rendered into certain regions of your web pages, for example, into sidebars. They are usually generated automatically by modules, but administrators can create blocks manually.</p>
<p>Only enabled blocks are shown. You can position blocks by specifying which area of the page they should appear in (e.g., a sidebar).  Highlighted labels on this page show the regions into which blocks can be rendered. You can specify where within a region a block will appear by adjusting its weight.</p>
<p>If you want certain blocks to disable themselves temporarily during high server loads, check the "Throttle" box. You can configure the auto-throttle on the <a href="@throttle">throttle configuration page</a> after having enabled the throttle module.</p>
<p>You can configure the behaviour of each block (for example, specifying on which pages and for what users it will appear) by clicking the "configure" link for each block.</p>', array('@throttle' => url('admin/settings/throttle')));
    case 'admin/build/block/add':
      return '<p>'. t('Here you can create a new block. Once you have created this block you must make it active and give it a place on the page using <a href="@overview">blocks</a>. The description is used in the "block" column on the <a href="@overview">blocks</a> page.', array('@overview' => url('admin/build/block'))) .'</p>';
  }
}

/**
 * Implementation of hook_theme()
 */
function block_theme() {
  return array(
    'block_admin_display' => array(
      'file' => 'block-admin-display',
      'arguments' => array('form' => NULL),
    ),
  );
}

/**
 * Process variables for block-admin-display.tpl.php.
 *
 * The $variables array contains the following arguments:
 * - $form
 *
 * @see block-admin-display.tpl.php
 * @see theme_block_admin_display()
 */
function template_preprocess_block_admin_display(&$variables) {
  global $theme_key;

  $variables['throttle'] = module_exists('throttle');
  $block_regions = system_region_list($theme_key);

  // Highlight regions on page to provide visual reference.
  foreach ($block_regions as $key => $value) {
    drupal_set_content($key, '<div class="block-region">'. $value .'</div>');
  }

  // Setup to track previous region in loop.
  $last_region = '';
  foreach (element_children($variables['form']) as $i) {
    $block = &$variables['form'][$i];

    // Only take form elements that are blocks.
    if (isset($block['info'])) {
      // Fetch region for current block.
      $region = $block['region']['#default_value'];

      // Track first block listing to insert region header inside block_admin_display.tpl.php.
      $is_region_first = FALSE;
      if ($last_region != $region) {
        $is_region_first = TRUE;
        // Set region title. Block regions already translated.
        if ($region != BLOCK_REGION_NONE) {
          $region_title = drupal_ucfirst($block_regions[$region]);
        }
        else {
          $region_title = t('Disabled');
        }
      }

      $variables['block_listing'][$i]->is_region_first = $is_region_first;
      $variables['block_listing'][$i]->region_title = $region_title;
      $variables['block_listing'][$i]->block_title =  drupal_render($block['info']);
      $variables['block_listing'][$i]->region_select = drupal_render($block['region']) . drupal_render($block['theme']);
      $variables['block_listing'][$i]->weight_select = drupal_render($block['weight']);
      $variables['block_listing'][$i]->throttle_check = $variables['throttle'] ? drupal_render($block['throttle']) : '';
      $variables['block_listing'][$i]->configure_link = drupal_render($block['configure']);
      $variables['block_listing'][$i]->delete_link = !empty($block['delete']) ? drupal_render($block['delete']) : '';

      $last_region = $region;
    }
  }

  $variables['form_submit'] = drupal_render($variables['form']);
}

/**
 * Implementation of hook_perm().
 */
function block_perm() {
  return array('administer blocks', 'use PHP for block visibility');
}

/**
 * Implementation of hook_menu().
 */
function block_menu() {
  $items['admin/build/block'] = array(
    'title' => 'Blocks',
    'description' => 'Configure what block content appears in your site\'s sidebars and other regions.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('block_admin_display'),
    'access arguments' => array('administer blocks'),
    'file' => 'block.admin.inc',
  );
  $items['admin/build/block/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/build/block/configure'] = array(
    'title' => 'Configure block',
    'page arguments' => array('block_admin_configure'),
    'type' => MENU_CALLBACK,
    'file' => 'block.admin.inc',
  );
  $items['admin/build/block/delete'] = array(
    'title' => 'Delete block',
    'page arguments' => array('block_box_delete'),
    'type' => MENU_CALLBACK,
    'file' => 'block.admin.inc',
  );
  $items['admin/build/block/add'] = array(
    'title' => 'Add block',
    'page arguments' => array('block_add_block_form'),
    'type' => MENU_LOCAL_TASK,
    'file' => 'block.admin.inc',
  );
  $default = variable_get('theme_default', 'garland');
  foreach (list_themes() as $key => $theme) {
    $items['admin/build/block/list/'. $key] = array(
      'title' => check_plain($theme->info['name']),
      'page arguments' => array('block_admin_display', $key),
      'type' => $key == $default ? MENU_DEFAULT_LOCAL_TASK : MENU_LOCAL_TASK,
      'weight' => $key == $default ? -10 : 0,
      'file' => 'block.admin.inc',
    );
  }
  return $items;
}

/**
 * Implementation of hook_block().
 *
 * Generates the administrator-defined blocks for display.
 */
function block_block($op = 'list', $delta = 0, $edit = array()) {
  switch ($op) {
    case 'list':
      $blocks = array();

      $result = db_query('SELECT bid, info FROM {boxes} ORDER BY info');
      while ($block = db_fetch_object($result)) {
        $blocks[$block->bid]['info'] = $block->info;
        // Not worth caching.
        $blocks[$block->bid]['cache'] = BLOCK_NO_CACHE;
      }
      return $blocks;

    case 'configure':
      $box = array('format' => FILTER_FORMAT_DEFAULT);
      if ($delta) {
        $box = block_box_get($delta);
      }
      if (filter_access($box['format'])) {
        return block_box_form($box);
      }
      break;

    case 'save':
      block_box_save($edit, $delta);
      break;

    case 'view':
      $block = db_fetch_object(db_query('SELECT body, format FROM {boxes} WHERE bid = %d', $delta));
      $data['content'] = check_markup($block->body, $block->format, FALSE);
      return $data;
  }
}

/**
 * Update the 'blocks' DB table with the blocks currently exported by modules.
 *
 * @return
 *   Blocks currently exported by modules.
 */
function _block_rehash() {
  global $theme_key;

  init_theme();

  $result = db_query("SELECT * FROM {blocks} WHERE theme = '%s'", $theme_key);
  while ($old_block = db_fetch_object($result)) {
    $old_blocks[$old_block->module][$old_block->delta] = $old_block;
  }

  $blocks = array();

  foreach (module_list() as $module) {
    $module_blocks = module_invoke($module, 'block', 'list');
    if ($module_blocks) {
      foreach ($module_blocks as $delta => $block) {
        $block['module'] = $module;
        $block['delta']  = $delta;
        // If no cache pattern is specified, we use PER_ROLE as a default.
        $block['cache'] = isset($block['cache']) ? $block['cache'] : BLOCK_CACHE_PER_ROLE;
        // If previously written to database, load values.
        if (!empty($old_blocks[$module][$delta])) {
          $block['status'] = $old_blocks[$module][$delta]->status;
          $block['weight'] = $old_blocks[$module][$delta]->weight;
          $block['region'] = $old_blocks[$module][$delta]->region;
          $block['visibility'] = $old_blocks[$module][$delta]->visibility;
          $block['pages'] = $old_blocks[$module][$delta]->pages;
          $block['custom'] = $old_blocks[$module][$delta]->custom;
          $block['throttle'] = $old_blocks[$module][$delta]->throttle;
          $block['title'] = $old_blocks[$module][$delta]->title;
        }
        // Otherwise, use any set values, or else substitute defaults.
        else {
          $properties = array('status' => 0, 'weight' => 0, 'region' => 'left', 'pages' => '', 'custom' => 0, 'title' => '');
          foreach ($properties as $property => $default) {
            if (!isset($block[$property])) {
              $block[$property] = $default;
            }
          }
        }

        $blocks[] = $block;
      }
    }
  }

  db_lock_table('blocks');
  // Remove all blocks from table.
  db_query("DELETE FROM {blocks} WHERE theme = '%s'", $theme_key);

  // Reinsert new set of blocks into table.
  foreach ($blocks as $block) {
    $block += array(
      'visibility' => NULL,
      'throttle' => NULL,
    );
    db_query("INSERT INTO {blocks} (module, delta, theme, status, weight, region, visibility, pages, custom, throttle, title, cache) VALUES ('%s', '%s', '%s', %d, %d, '%s', %d, '%s', %d, %d, '%s', %d)", $block['module'], $block['delta'], $theme_key, $block['status'], $block['weight'], $block['region'], $block['visibility'], $block['pages'], $block['custom'], $block['throttle'], $block['title'], $block['cache']);
  }
  db_unlock_tables();

  return $blocks;
}

function block_box_get($bid) {
  return db_fetch_array(db_query("SELECT bx.*, bl.title FROM {boxes} bx INNER JOIN {blocks} bl ON bx.bid = bl.delta WHERE bl.module = 'block' AND bx.bid = %d", $bid));
}

/**
 * Define the custom block form.
 */
function block_box_form($edit = array()) {
  $edit += array(
    'info' => '',
    'body' => '',
  );
  $form['info'] = array(
    '#type' => 'textfield',
    '#title' => t('Block description'),
    '#default_value' => $edit['info'],
    '#maxlength' => 64,
    '#description' => t('A brief description of your block. Used on the <a href="@overview">block overview page</a>.', array('@overview' => url('admin/build/block'))),
    '#required' => TRUE,
    '#weight' => -19,
  );
  $form['body_field']['#weight'] = -17;
  $form['body_field']['body'] = array(
    '#type' => 'textarea',
    '#title' => t('Block body'),
    '#default_value' => $edit['body'],
    '#rows' => 15,
    '#description' => t('The content of the block as shown to the user.'),
    '#weight' => -17,
  );
  if (!isset($edit['format'])) {
    $edit['format'] = FILTER_FORMAT_DEFAULT;
  }
  $form['body_field']['format'] = filter_form($edit['format'], -16);

  return $form;
}

function block_box_save($edit, $delta) {
  if (!filter_access($edit['format'])) {
    $edit['format'] = FILTER_FORMAT_DEFAULT;
  }

  db_query("UPDATE {boxes} SET body = '%s', info = '%s', format = %d WHERE bid = %d", $edit['body'], $edit['info'], $edit['format'], $delta);

  return TRUE;
}

/**
 * Implementation of hook_user().
 *
 * Allow users to decide which custom blocks to display when they visit
 * the site.
 */
function block_user($type, $edit, &$user, $category = NULL) {
  global $user;
  switch ($type) {
    case 'form':
      if ($category == 'account') {
        $result = db_query("SELECT DISTINCT b.* FROM {blocks} b LEFT JOIN {blocks_roles} r ON b.module = r.module AND b.delta = r.delta WHERE b.status = 1 AND b.custom != 0 AND (r.rid IN (%s) OR r.rid IS NULL) ORDER BY b.weight, b.module", implode(',', array_keys($user->roles)));
        $form['block'] = array('#type' => 'fieldset', '#title' => t('Block configuration'), '#weight' => 3, '#collapsible' => TRUE, '#tree' => TRUE);
        while ($block = db_fetch_object($result)) {
          $data = module_invoke($block->module, 'block', 'list');
          if ($data[$block->delta]['info']) {
            $return = TRUE;
            $form['block'][$block->module][$block->delta] = array('#type' => 'checkbox', '#title' => check_plain($data[$block->delta]['info']), '#default_value' => isset($user->block[$block->module][$block->delta]) ? $user->block[$block->module][$block->delta] : ($block->custom == 1));
          }
        }

        if (!empty($return)) {
          return $form;
        }
      }

      break;
    case 'validate':
      if (empty($edit['block'])) {
        $edit['block'] = array();
      }
      return $edit;
  }
}

/**
 * Return all blocks in the specified region for the current user.
 *
 * @param $region
 *   The name of a region.
 *
 * @return
 *   An array of block objects, indexed with <i>module</i>_<i>delta</i>.
 *   If you are displaying your blocks in one or two sidebars, you may check
 *   whether this array is empty to see how many columns are going to be
 *   displayed.
 *
 * @todo
 *   Add a proper primary key (bid) to the blocks table so we don't have
 *   to mess around with this <i>module</i>_<i>delta</i> construct.
 *   Currently, the blocks table has no primary key defined!
 */
function block_list($region) {
  global $user, $theme_key;

  static $blocks = array();

  if (!count($blocks)) {
    $result = db_query(db_rewrite_sql("SELECT DISTINCT b.* FROM {blocks} b LEFT JOIN {blocks_roles} r ON b.module = r.module AND b.delta = r.delta WHERE b.theme = '%s' AND b.status = 1 AND (r.rid IN (%s) OR r.rid IS NULL) ORDER BY b.region, b.weight, b.module", 'b', 'bid'), $theme_key, implode(',', array_keys($user->roles)));
    while ($block = db_fetch_object($result)) {
      if (!isset($blocks[$block->region])) {
        $blocks[$block->region] = array();
      }
      // Use the user's block visibility setting, if necessary
      if ($block->custom != 0) {
        if ($user->uid && isset($user->block[$block->module][$block->delta])) {
          $enabled = $user->block[$block->module][$block->delta];
        }
        else {
          $enabled = ($block->custom == 1);
        }
      }
      else {
        $enabled = TRUE;
      }

      // Match path if necessary
      if ($block->pages) {
        if ($block->visibility < 2) {
          $path = drupal_get_path_alias($_GET['q']);
          $regexp = '/^('. preg_replace(array('/(\r\n?|\n)/', '/\\\\\*/', '/(^|\|)\\\\<front\\\\>($|\|)/'), array('|', '.*', '\1'. preg_quote(variable_get('site_frontpage', 'node'), '/') .'\2'), preg_quote($block->pages, '/')) .')$/';
          // Compare with the internal and path alias (if any).
          $page_match = preg_match($regexp, $path);
          if ($path != $_GET['q']) {
            $page_match = $page_match || preg_match($regexp, $_GET['q']);
          }
          // When $block->visibility has a value of 0, the block is displayed on
          // all pages except those listed in $block->pages. When set to 1, it
          // is displayed only on those pages listed in $block->pages.
          $page_match = !($block->visibility xor $page_match);
        }
        else {
          $page_match = drupal_eval($block->pages);
        }
      }
      else {
        $page_match = TRUE;
      }

      if ($enabled && $page_match) {
        // Check the current throttle status and see if block should be displayed
        // based on server load.
        if (!($block->throttle && (module_invoke('throttle', 'status') > 0))) {
          // Try fetching the block from cache. Block caching is not compatible with
          // node_access modules. We also preserve the submission of forms in blocks,
          // by fetching from cache only if the request method is 'GET'.
          if (!count(module_implements('node_grants')) && $_SERVER['REQUEST_METHOD'] == 'GET' && ($cid = _block_get_cache_id($block)) && ($cache = cache_get($cid, 'cache_block'))) {
            $array = $cache->data;
          }
          else {
            $array = module_invoke($block->module, 'block', 'view', $block->delta);
            if (isset($cid)) {
              cache_set($cid, $array, 'cache_block', CACHE_TEMPORARY);
            }
          }

          if (isset($array) && is_array($array)) {
            foreach ($array as $k => $v) {
              $block->$k = $v;
            }
          }
        }
        if (isset($block->content) && $block->content) {
          // Override default block title if a custom display title is present.
          if ($block->title) {
            // Check plain here to allow module generated titles to keep any markup.
            $block->subject = $block->title == '<none>' ? '' : check_plain($block->title);
          }
          $blocks[$block->region]["{$block->module}_{$block->delta}"] = $block;
        }
      }
    }
  }
  // Create an empty array if there were no entries
  if (!isset($blocks[$region])) {
    $blocks[$region] = array();
  }
  return $blocks[$region];
}

/**
 * Assemble the cache_id to use for a given block.
 *
 * The cache_id string reflects the viewing context for the current block
 * instance, obtained by concatenating the relevant context information
 * (user, page, ...) according to the block's cache settings (BLOCK_CACHE_*
 * constants). Two block instances can use the same cached content when
 * they share the same cache_id.
 *
 * Theme and language contexts are automatically differenciated.
 *
 * @param $block
 * @return
 *   The string used as cache_id for the block.
 */
function _block_get_cache_id($block) {
  global $theme, $base_root, $user;

  // User 1 being out of the regular 'roles define permissions' schema,
  // it brings too many chances of having unwanted output get in the cache
  // and later be served to other users. We therefore exclude user 1 from
  // block caching.
  if (variable_get('block_cache', 0) && $block->cache != BLOCK_NO_CACHE && $user->uid != 1) {
    $cid_parts = array();

    // Start with common sub-patterns: block identification, theme, language.
    $cid_parts[] = $block->module;
    $cid_parts[] = $block->delta;
    $cid_parts[] = $theme;
    if (module_exists('locale')) {
      global $language;
      $cid_parts[] = $language->language;
    }

    // 'PER_ROLE' and 'PER_USER' are mutually exclusive. 'PER_USER' can be a
    // resource drag for sites with many users, so when a module is being
    // equivocal, we favor the less expensive 'PER_ROLE' pattern.
    if ($block->cache & BLOCK_CACHE_PER_ROLE) {
      $cid_parts[] = 'r.'. implode(',', array_keys($user->roles));
    }
    elseif ($block->cache & BLOCK_CACHE_PER_USER) {
      $cid_parts[] = "u.$user->uid";
    }

    if ($block->cache & BLOCK_CACHE_PER_PAGE) {
      $cid_parts[] = $base_root . request_uri();
    }

    return implode(':', $cid_parts);
  }
}