Club Drupal

<?php

/**

 * @file

 * Controls the visual building blocks a page is constructed with.

 */

/**

 * Denotes that a block is not enabled in any region and should not be shown.

 */

define('BLOCK_REGION_NONE', -1);

/**

 * Users cannot control whether or not they see this block.

 */

define('BLOCK_CUSTOM_FIXED', 0);

/**

 * Shows this block by default, but lets individual users hide it.

 */

define('BLOCK_CUSTOM_ENABLED', 1);

/**

 * Hides this block by default but lets individual users show it.

 */

define('BLOCK_CUSTOM_DISABLED', 2);

/**

 * Shows this block on every page except the listed pages.

 */

define('BLOCK_VISIBILITY_NOTLISTED', 0);

/**

 * Shows this block on only the listed pages.

 */

define('BLOCK_VISIBILITY_LISTED', 1);

/**

 * Shows this block if the associated PHP code returns TRUE.

 */

define('BLOCK_VISIBILITY_PHP', 2);

/**

 * Implements hook_help().

 */

function block_help($path, $arg) {

  switch ($path) {

    case 'admin/help#block':

      $output = '';

      $output .= '<h3>' . t('About') . '</h3>';

      $output .= '<p>' . t('The Block module allows you to create boxes of content, which are rendered into an area, or region, of one or more pages of a website. The core Seven administration theme, for example, implements the regions "Content", "Help", "Dashboard main", and "Dashboard sidebar", and a block may appear in any one of these regions. The <a href="@blocks">Blocks administration page</a> provides a drag-and-drop interface for assigning a block to a region, and for controlling the order of blocks within regions. For more information, see the online handbook entry for <a href="@block">Block module</a>.', array('@block' => 'http://drupal.org/documentation/modules/block/', '@blocks' => url('admin/structure/block'))) . '</p>';

      $output .= '<h3>' . t('Uses') . '</h3>';

      $output .= '<dl>';

      $output .= '<dt>' . t('Positioning content') . '</dt>';

      $output .= '<dd>' . t('When working with blocks, remember that all themes do <em>not</em> implement the same regions, or display regions in the same way. Blocks are positioned on a per-theme basis. Users with the <em>Administer blocks</em> permission can disable blocks. Disabled blocks are listed on the <a href="@blocks">Blocks administration page</a>, but are not displayed in any region.', array('@block' => 'http://drupal.org/documentation/modules/block/', '@blocks' => url('admin/structure/block'))) . '</dd>';

      $output .= '<dt>' . t('Controlling visibility') . '</dt>';

      $output .= '<dd>' . t('Blocks can be configured to be visible only on certain pages, only to users of certain roles, or only on pages displaying certain <a href="@content-type">content types</a>. Administrators can also allow specific blocks to be enabled or disabled by users when they edit their <a href="@user">My account</a> page. Some dynamic blocks, such as those generated by modules, will be displayed only on certain pages.', array('@content-type' => url('admin/structure/types'), '@user' => url('user'))) . '</dd>';

      $output .= '<dt>' . t('Creating custom blocks') . '</dt>';

      $output .= '<dd>' . t('Users with the <em>Administer blocks</em> permission can <a href="@block-add">add custom blocks</a>, which are then listed on the <a href="@blocks">Blocks administration page</a>. Once created, custom blocks behave just like default and module-generated blocks.', array('@blocks' => url('admin/structure/block'), '@block-add' => url('admin/structure/block/add'))) . '</dd>';

      $output .= '</dl>';

      return $output;

    case 'admin/structure/block/add':

      return '<p>' . t('Use this page to create a new custom block.') . '</p>';

  }

  if ($arg[0] == 'admin' && $arg[1] == 'structure' && $arg['2'] == 'block' && (empty($arg[3]) || $arg[3] == 'list')) {

    $demo_theme = !empty($arg[4]) ? $arg[4] : variable_get('theme_default', 'bartik');

    $themes = list_themes();

    $output = '<p>' . t('This page provides a drag-and-drop interface for assigning a block to a region, and for controlling the order of blocks within regions. Since not all themes implement the same regions, or display regions in the same way, blocks are positioned on a per-theme basis. Remember that your changes will not be saved until you click the <em>Save blocks</em> button at the bottom of the page. Click the <em>configure</em> link next to each block to configure its specific title and visibility settings.') . '</p>';

    $output .= '<p>' . l(t('Demonstrate block regions (!theme)', array('!theme' => $themes[$demo_theme]->info['name'])), 'admin/structure/block/demo/' . $demo_theme) . '</p>';

    return $output;

  }

}

/**

 * Implements hook_theme().

 */

function block_theme() {

  return array(

    'block' => array(

      'render element' => 'elements',

      'template' => 'block',

    ),

    'block_admin_display_form' => array(

      'template' => 'block-admin-display-form',

      'file' => 'block.admin.inc',

      'render element' => 'form',

    ),

  );

}

/**

 * Implements hook_permission().

 */

function block_permission() {

  return array(

    'administer blocks' => array(

      'title' => t('Administer blocks'),

    ),

  );

}

/**

 * Implements hook_menu().

 */

function block_menu() {

  $default_theme = variable_get('theme_default', 'bartik');

  $items['admin/structure/block'] = array(

    'title' => 'Blocks',

    'description' => 'Configure what block content appears in your site\'s sidebars and other regions.',

    'page callback' => 'block_admin_display',

    'page arguments' => array($default_theme),

    'access arguments' => array('administer blocks'),

    'file' => 'block.admin.inc',

  );

  $items['admin/structure/block/manage/%/%'] = array(

    'title' => 'Configure block',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('block_admin_configure', 4, 5),

    'access arguments' => array('administer blocks'),

    'file' => 'block.admin.inc',

  );

  $items['admin/structure/block/manage/%/%/configure'] = array(

    'title' => 'Configure block',

    'type' => MENU_DEFAULT_LOCAL_TASK,

    'context' => MENU_CONTEXT_INLINE,

  );

  $items['admin/structure/block/manage/%/%/delete'] = array(

    'title' => 'Delete block',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('block_custom_block_delete', 4, 5),

    'access arguments' => array('administer blocks'),

    'type' => MENU_LOCAL_TASK,

    'context' => MENU_CONTEXT_NONE,

    'file' => 'block.admin.inc',

  );

  $items['admin/structure/block/add'] = array(

    'title' => 'Add block',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('block_add_block_form'),

    'access arguments' => array('administer blocks'),

    'type' => MENU_LOCAL_ACTION,

    'file' => 'block.admin.inc',

  );

  foreach (list_themes() as $key => $theme) {

    $items['admin/structure/block/list/' . $key] = array(

      'title' => $theme->info['name'],

      'page arguments' => array($key),

      'type' => $key == $default_theme ? MENU_DEFAULT_LOCAL_TASK : MENU_LOCAL_TASK,

      'weight' => $key == $default_theme ? -10 : 0,

      'access callback' => '_block_themes_access',

      'access arguments' => array($theme),

      'file' => 'block.admin.inc',

    );

    if ($key != $default_theme) {

      $items['admin/structure/block/list/' . $key . '/add'] = array(

        'title' => 'Add block',

        'page callback' => 'drupal_get_form',

        'page arguments' => array('block_add_block_form'),

        'access arguments' => array('administer blocks'),

        'type' => MENU_LOCAL_ACTION,

        'file' => 'block.admin.inc',

      );

    }

    $items['admin/structure/block/demo/' . $key] = array(

      'title' => $theme->info['name'],

      'page callback' => 'block_admin_demo',

      'page arguments' => array($key),

      'type' => MENU_CALLBACK,

      'access callback' => '_block_themes_access',

      'access arguments' => array($theme),

      'theme callback' => '_block_custom_theme',

      'theme arguments' => array($key),

      'file' => 'block.admin.inc',

    );

  }

  return $items;

}

/**

 * Menu item access callback - only admin or enabled themes can be accessed.

 */

function _block_themes_access($theme) {

  return user_access('administer blocks') && drupal_theme_access($theme);

}

/**

 * Theme callback for the block configuration pages.

 *

 * @param $theme

 *   The theme whose blocks are being configured. If not set, the default theme

 *   is assumed.

 *

 * @return

 *   The theme that should be used for the block configuration page, or NULL

 *   to indicate that the default theme should be used.

 */

function _block_custom_theme($theme = NULL) {

  // We return exactly what was passed in, to guarantee that the page will

  // always be displayed using the theme whose blocks are being configured.

  return $theme;

}

/**

 * Implements hook_block_info().

 */

function block_block_info() {

  $blocks = array();

  $result = db_query('SELECT bid, info FROM {block_custom} ORDER BY info');

  foreach ($result as $block) {

    $blocks[$block->bid]['info'] = $block->info;

    // Not worth caching.

    $blocks[$block->bid]['cache'] = DRUPAL_NO_CACHE;

  }

  return $blocks;

}

/**

 * Implements hook_block_configure().

 */

function block_block_configure($delta = 0) {

  if ($delta) {

    $custom_block = block_custom_block_get($delta);

  }

  else {

    $custom_block = array();

  }

  return block_custom_block_form($custom_block);

}

/**

 * Implements hook_block_save().

 */

function block_block_save($delta = 0, $edit = array()) {

  block_custom_block_save($edit, $delta);

}

/**

 * Implements hook_block_view().

 *

 * Generates the administrator-defined blocks for display.

 */

function block_block_view($delta = '') {

  $block = db_query('SELECT body, format FROM {block_custom} WHERE bid = :bid', array(':bid' => $delta))->fetchObject();

  $data['subject'] = NULL;

  $data['content'] = check_markup($block->body, $block->format, '', TRUE);

  return $data;

}

/**

 * Implements hook_page_build().

 *

 * Renders blocks into their regions.

 */

function block_page_build(&$page) {

  global $theme;

  // The theme system might not yet be initialized. We need $theme.

  drupal_theme_initialize();

  // Fetch a list of regions for the current theme.

  $all_regions = system_region_list($theme);

  $item = menu_get_item();

  if ($item['path'] != 'admin/structure/block/demo/' . $theme) {

    // Load all region content assigned via blocks.

    foreach (array_keys($all_regions) as $region) {

      // Assign blocks to region.

      if ($blocks = block_get_blocks_by_region($region)) {

        $page[$region] = $blocks;

      }

    }

    // Once we've finished attaching all blocks to the page, clear the static

    // cache to allow modules to alter the block list differently in different

    // contexts. For example, any code that triggers hook_page_build() more

    // than once in the same page request may need to alter the block list

    // differently each time, so that only certain parts of the page are

    // actually built. We do not clear the cache any earlier than this, though,

    // because it is used each time block_get_blocks_by_region() gets called

    // above.

    drupal_static_reset('block_list');

  }

  else {

    // Append region description if we are rendering the regions demo page.

    $item = menu_get_item();

    if ($item['path'] == 'admin/structure/block/demo/' . $theme) {

      $visible_regions = array_keys(system_region_list($theme, REGIONS_VISIBLE));

      foreach ($visible_regions as $region) {

        $description = '<div class="block-region">' . $all_regions[$region] . '</div>';

        $page[$region]['block_description'] = array(

          '#markup' => $description,

          '#weight' => 15,

        );

      }

      $page['page_top']['backlink'] = array(

        '#type' => 'link',

        '#title' => t('Exit block region demonstration'),

        '#href' => 'admin/structure/block' . (variable_get('theme_default', 'bartik') == $theme ? '' : '/list/' . $theme),

        // Add the "overlay-restore" class to indicate this link should restore

        // the context in which the region demonstration page was opened.

        '#options' => array('attributes' => array('class' => array('block-demo-backlink', 'overlay-restore'))),

        '#weight' => -10,

      );

    }

  }

}

/**

 * Gets a renderable array of a region containing all enabled blocks.

 *

 * @param $region

 *   The requested region.

 *

 * @return

 *   A renderable array of a region containing all enabled blocks.

 */

function block_get_blocks_by_region($region) {

  $build = array();

  if ($list = block_list($region)) {

    $build = _block_get_renderable_array($list);

  }

  return $build;

}

/**

 * Gets an array of blocks suitable for drupal_render().

 *

 * @param $list

 *   A list of blocks such as that returned by block_list().

 *

 * @return

 *   A renderable array.

 */

function _block_get_renderable_array($list = array()) {

  $weight = 0;

  $build = array();

  foreach ($list as $key => $block) {

    $build[$key] = $block->content;

    unset($block->content);

    // Add contextual links for this block; skip the main content block, since

    // contextual links are basically output as tabs/local tasks already. Also

    // skip the help block, since we assume that most users do not need or want

    // to perform contextual actions on the help block, and the links needlessly

    // draw attention on it.

    if ($key != 'system_main' && $key != 'system_help') {

      $build[$key]['#contextual_links']['block'] = array(

        'admin/structure/block/manage',

        array($block->module, $block->delta),

      );

    }

    $build[$key] += array(

      '#block' => $block,

      '#weight' => ++$weight,

    );

    $build[$key]['#theme_wrappers'][] = 'block';

  }

  $build['#sorted'] = TRUE;

  return $build;

}

/**

 * Updates the 'block' DB table with the blocks currently exported by modules.

 *

 * @param $theme

 *   The theme to rehash blocks for. If not provided, defaults to the currently

 *   used theme.

 *

 * @return

 *   Blocks currently exported by modules.

 */

function _block_rehash($theme = NULL) {

  global $theme_key;

  drupal_theme_initialize();

  if (!isset($theme)) {

    // If theme is not specifically set, rehash for the current theme.

    $theme = $theme_key;

  }

  $regions = system_region_list($theme);

  // These are the blocks the function will return.

  $blocks = array();

  // These are the blocks defined by code and modified by the database.

  $current_blocks = array();

  // These are {block}.bid values to be kept.

  $bids = array();

  $or = db_or();

  // Gather the blocks defined by modules.

  foreach (module_implements('block_info') as $module) {

    $module_blocks = module_invoke($module, 'block_info');

    $delta_list = array();

    foreach ($module_blocks as $delta => $block) {

      // Compile a condition to retrieve this block from the database.

      // Add identifiers.

      $delta_list[] = $delta;

      $block['module'] = $module;

      $block['delta'] = $delta;

      $block['theme'] = $theme;

      $current_blocks[$module][$delta] = $block;

    }

    if (!empty($delta_list)) {

      $condition = db_and()->condition('module', $module)->condition('delta', $delta_list);

      $or->condition($condition);

    }

  }

  // Save the blocks defined in code for alter context.

  $code_blocks = $current_blocks;

  $database_blocks = db_select('block', 'b', array('fetch' => PDO::FETCH_ASSOC))

    ->fields('b')

    ->condition($or)

    ->condition('theme', $theme)

    ->execute();

  $original_database_blocks = array();

  foreach ($database_blocks as $block) {

    $module = $block['module'];

    $delta = $block['delta'];

    $original_database_blocks[$module][$delta] = $block;

    // The cache mode can only by set from hook_block_info(), so that has

    // precedence over the database's value.

    if (isset($current_blocks[$module][$delta]['cache'])) {

      $block['cache'] = $current_blocks[$module][$delta]['cache'];

    }

    // Preserve info which is not in the database.

    $block['info'] = $current_blocks[$module][$delta]['info'];

    // Blocks stored in the database override the blocks defined in code.

    $current_blocks[$module][$delta] = $block;

    // Preserve this block.

    $bids[$block['bid']] = $block['bid'];

  }

  drupal_alter('block_info', $current_blocks, $theme, $code_blocks);

  foreach ($current_blocks as $module => $module_blocks) {

    foreach ($module_blocks as $delta => $block) {

      if (!isset($block['pages'])) {

        // {block}.pages is type 'text', so it cannot have a

        // default value, and not null, so we need to provide

        // value if the module did not.

        $block['pages']  = '';

      }

      // Make sure weight is set.

      if (!isset($block['weight'])) {

        $block['weight'] = 0;

      }

      if (!empty($block['region']) && $block['region'] != BLOCK_REGION_NONE && !isset($regions[$block['region']]) && $block['status'] == 1) {

        drupal_set_message(t('The block %info was assigned to the invalid region %region and has been disabled.', array('%info' => $block['info'], '%region' => $block['region'])), 'warning');

        // Disabled modules are moved into the BLOCK_REGION_NONE later so no

        // need to move the block to another region.

        $block['status'] = 0;

      }

      // Set region to none if not enabled and make sure status is set.

      if (empty($block['status'])) {

        $block['status'] = 0;

        $block['region'] = BLOCK_REGION_NONE;

      }

      // There is no point saving disabled blocks. Still, we need to save them

      // because the 'title' attribute is saved to the {blocks} table.

      if (isset($block['bid'])) {

        // If the block has a bid property, it comes from the database and

        // the record needs to be updated, so set the primary key to 'bid'

        // before passing to drupal_write_record().

        $primary_keys = array('bid');

        // Remove a block from the list of blocks to keep if it became disabled.

        unset($bids[$block['bid']]);

      }

      else {

        $primary_keys = array();

      }

      // If the block is new or differs from the original database block, save

      // it. To determine whether there was a change it is enough to examine

      // the values for the keys in the original database record as that

      // contained every database field.

      if (!$primary_keys || array_diff_assoc($original_database_blocks[$module][$delta], $block)) {

        drupal_write_record('block', $block, $primary_keys);

        // Make it possible to test this.

        $block['saved'] = TRUE;

      }

      // Add to the list of blocks we return.

      $blocks[] = $block;

    }

  }

  if ($bids) {

    // Remove disabled that are no longer defined by the code from the

    // database.

    db_delete('block')

      ->condition('bid', $bids, 'NOT IN')

      ->condition('theme', $theme)

      ->execute();

  }

  return $blocks;

}

/**

 * Returns information from database about a user-created (custom) block.

 *

 * @param $bid

 *   ID of the block to get information for.

 *

 * @return

 *   Associative array of information stored in the database for this block.

 *   Array keys:

 *   - bid: Block ID.

 *   - info: Block description.

 *   - body: Block contents.

 *   - format: Filter ID of the filter format for the body.

 */

function block_custom_block_get($bid) {

  return db_query("SELECT * FROM {block_custom} WHERE bid = :bid", array(':bid' => $bid))->fetchAssoc();

}

/**

 * Form constructor for the custom block form.

 *

 * @param $edit

 *   (optional) An associative array of information retrieved by

 *   block_custom_get_block() if an existing block is being edited, or an empty

 *   array otherwise. Defaults to array().

 *

 * @ingroup forms

 */

function block_custom_block_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">Blocks administration page</a>.', array('@overview' => url('admin/structure/block'))),

    '#required' => TRUE,

    '#weight' => -18,

  );

  $form['body_field']['#weight'] = -17;

  $form['body_field']['body'] = array(

    '#type' => 'text_format',

    '#title' => t('Block body'),

    '#default_value' => $edit['body'],

    '#format' => isset($edit['format']) ? $edit['format'] : NULL,

    '#rows' => 15,

    '#description' => t('The content of the block as shown to the user.'),

    '#required' => TRUE,

    '#weight' => -17,

  );

  return $form;

}

/**

 * Saves a user-created block in the database.

 *

 * @param $edit

 *   Associative array of fields to save. Array keys:

 *   - info: Block description.

 *   - body: Associative array of body value and format.  Array keys:

 *     - value: Block contents.

 *     - format: Filter ID of the filter format for the body.

 * @param $delta

 *   Block ID of the block to save.

 *

 * @return

 *   Always returns TRUE.

 */

function block_custom_block_save($edit, $delta) {

  db_update('block_custom')

    ->fields(array(

      'body' => $edit['body']['value'],

      'info' => $edit['info'],

      'format' => $edit['body']['format'],

    ))

    ->condition('bid', $delta)

    ->execute();

  return TRUE;

}

/**

 * Implements hook_form_FORM_ID_alter() for user_profile_form().

 */

function block_form_user_profile_form_alter(&$form, &$form_state) {

  if ($form['#user_category'] == 'account') {

    $account = $form['#user'];

    $rids = array_keys($account->roles);

    $result = db_query("SELECT DISTINCT b.* FROM {block} b LEFT JOIN {block_role} r ON b.module = r.module AND b.delta = r.delta WHERE b.status = 1 AND b.custom <> 0 AND (r.rid IN (:rids) OR r.rid IS NULL) ORDER BY b.weight, b.module", array(':rids' => $rids));

    $blocks = array();

    foreach ($result as $block) {

      $data = module_invoke($block->module, 'block_info');

      if ($data[$block->delta]['info']) {

        $blocks[$block->module][$block->delta] = array(

          '#type' => 'checkbox',

          '#title' => check_plain($data[$block->delta]['info']),

          '#default_value' => isset($account->data['block'][$block->module][$block->delta]) ? $account->data['block'][$block->module][$block->delta] : ($block->custom == 1),

        );

      }

    }

    // Only display the fieldset if there are any personalizable blocks.

    if ($blocks) {

      $form['block'] = array(

        '#type' => 'fieldset',

        '#title' => t('Personalize blocks'),

        '#description' => t('Blocks consist of content or information that complements the main content of the page. Enable or disable optional blocks using the checkboxes below.'),

        '#weight' => 3,

        '#collapsible' => TRUE,

        '#tree' => TRUE,

      );

      $form['block'] += $blocks;

    }

  }

}

/**

 * Implements hook_user_presave().

 */

function block_user_presave(&$edit, $account, $category) {

  if (isset($edit['block'])) {

    $edit['data']['block'] = $edit['block'];

  }

}

/**

 * Initializes blocks for enabled themes.

 *

 * @param $theme_list

 *   An array of theme names.

 */

function block_themes_enabled($theme_list) {

  foreach ($theme_list as $theme) {

    block_theme_initialize($theme);

  }

}

/**

 * Assigns an initial, default set of blocks for a theme.

 *

 * This function is called the first time a new theme is enabled. The new theme

 * gets a copy of the default theme's blocks, with the difference that if a

 * particular region isn't available in the new theme, the block is assigned

 * to the new theme's default region.

 *

 * @param $theme

 *   The name of a theme.

 */

function block_theme_initialize($theme) {

  // Initialize theme's blocks if none already registered.

  $has_blocks = (bool) db_query_range('SELECT 1 FROM {block} WHERE theme = :theme', 0, 1, array(':theme' => $theme))->fetchField();

  if (!$has_blocks) {

    $default_theme = variable_get('theme_default', 'bartik');

    // Apply only to new theme's visible regions.

    $regions = system_region_list($theme, REGIONS_VISIBLE);

    $result = db_query("SELECT * FROM {block} WHERE theme = :theme", array(':theme' => $default_theme), array('fetch' => PDO::FETCH_ASSOC));

    foreach ($result as $block) {

      // If the region isn't supported by the theme, assign the block to the

      // theme's default region.

      if ($block['status'] && !isset($regions[$block['region']])) {

        $block['region'] = system_default_region($theme);

      }

      $block['theme'] = $theme;

      unset($block['bid']);

      drupal_write_record('block', $block);

    }

  }

}

/**

 * Returns 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 the module name and block delta

 *   concatenated with an underscore, thus: MODULE_DELTA. 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

 *   Now that the block table has a primary key, we should use that as the

 *   array key instead of MODULE_DELTA.

 */

function block_list($region) {

  $blocks = &drupal_static(__FUNCTION__);

  if (!isset($blocks)) {

    $blocks = _block_load_blocks();

  }

  // Create an empty array if there are no entries.

  if (!isset($blocks[$region])) {

    $blocks[$region] = array();

  }

  else {

    $blocks[$region] = _block_render_blocks($blocks[$region]);

  }

  return $blocks[$region];

}

/**

 * Loads a block object from the database.

 *

 * This function returns the first block matching the module and delta

 * parameters, so it should not be used for theme-specific functionality.

 *

 * @param $module

 *   Name of the module that implements the block to load.

 * @param $delta

 *   Unique ID of the block within the context of $module. Pass NULL to return

 *   an empty block object for $module.

 *

 * @return

 *   A block object.

 */

function block_load($module, $delta) {

  if (isset($delta)) {

    $block = db_query('SELECT * FROM {block} WHERE module = :module AND delta = :delta', array(':module' => $module, ':delta' => $delta))->fetchObject();

  }

  // If the block does not exist in the database yet return a stub block

  // object.

  if (empty($block)) {

    $block = new stdClass();

    $block->module = $module;

    $block->delta = $delta;

  }

  return $block;

}

/**

 * Loads blocks' information from the database.

 *

 * @return

 *   An array of blocks grouped by region.

 */

function _block_load_blocks() {

  global $theme_key;

  $query = db_select('block', 'b');

  $result = $query

    ->fields('b')

    ->condition('b.theme', $theme_key)

    ->condition('b.status', 1)

    ->orderBy('b.region')

    ->orderBy('b.weight')

    ->orderBy('b.module')

    ->addTag('block_load')

    ->addTag('translatable')

    ->execute();

  $block_info = $result->fetchAllAssoc('bid');

  // Allow modules to modify the block list.

  drupal_alter('block_list', $block_info);

  $blocks = array();

  foreach ($block_info as $block) {

    $blocks[$block->region]["{$block->module}_{$block->delta}"] = $block;

  }

  return $blocks;

}

/**

 * Implements hook_block_list_alter().

 *

 * Checks the page, user role, and user-specific visibility settings.

 * Removes the block if the visibility conditions are not met.

 */

function block_block_list_alter(&$blocks) {

  global $user, $theme_key;

  // Build an array of roles for each block.

  $block_roles = array();

  $result = db_query('SELECT module, delta, rid FROM {block_role}');

  foreach ($result as $record) {

    $block_roles[$record->module][$record->delta][] = $record->rid;

  }

  foreach ($blocks as $key => $block) {

    if (!isset($block->theme) || !isset($block->status) || $block->theme != $theme_key || $block->status != 1) {

      // This block was added by a contrib module, leave it in the list.

      continue;

    }

    // If a block has no roles associated, it is displayed for every role.

    // For blocks with roles associated, if none of the user's roles matches

    // the settings from this block, remove it from the block list.

    if (isset($block_roles[$block->module][$block->delta]) && !array_intersect($block_roles[$block->module][$block->delta], array_keys($user->roles))) {

      // No match.

      unset($blocks[$key]);

      continue;

    }

    // Use the user's block visibility setting, if necessary.

    if ($block->custom != BLOCK_CUSTOM_FIXED) {

      if ($user->uid && isset($user->data['block'][$block->module][$block->delta])) {

        $enabled = $user->data['block'][$block->module][$block->delta];

      }

      else {

        $enabled = ($block->custom == BLOCK_CUSTOM_ENABLED);

      }

    }

    else {

      $enabled = TRUE;

    }

    // Limited visibility blocks must list at least one page.

    if ($block->visibility == BLOCK_VISIBILITY_LISTED && empty($block->pages)) {

      $enabled = FALSE;

    }

    if (!$enabled) {

      unset($blocks[$key]);

      continue;

    }

    // Match path if necessary.

    if ($block->pages) {

      // Convert path to lowercase. This allows comparison of the same path

      // with different case. Ex: /Page, /page, /PAGE.

      $pages = drupal_strtolower($block->pages);

      if ($block->visibility < BLOCK_VISIBILITY_PHP) {

        // Convert the Drupal path to lowercase.

        $path = drupal_strtolower(drupal_get_path_alias($_GET['q']));

        // Compare the lowercase internal and lowercase path alias (if any).

        $page_match = drupal_match_path($path, $pages);

        if ($path != $_GET['q']) {

          $page_match = $page_match || drupal_match_path($_GET['q'], $pages);

        }

        // When $block->visibility has a value of 0

        // (BLOCK_VISIBILITY_NOTLISTED), the block is displayed on all pages

        // except those listed in $block->pages. When set to 1

        // (BLOCK_VISIBILITY_LISTED), it is displayed only on those pages

        // listed in $block->pages.

        $page_match = !($block->visibility xor $page_match);

      }

      elseif (module_exists('php')) {

        $page_match = php_eval($block->pages);

      }

      else {

        $page_match = FALSE;

      }

    }

    else {

      $page_match = TRUE;

    }

    if (!$page_match) {

      unset($blocks[$key]);

    }

  }

}

/**

 * Render the content and subject for a set of blocks.

 *

 * @param $region_blocks

 *   An array of block objects such as returned for one region by

 *   _block_load_blocks().

 *

 * @return

 *   An array of visible blocks as expected by drupal_render().

 */

function _block_render_blocks($region_blocks) {

  $cacheable = TRUE;

  // We preserve the submission of forms in blocks, by fetching from cache only

  // if the request method is 'GET' (or 'HEAD').

  if ($_SERVER['REQUEST_METHOD'] != 'GET' && $_SERVER['REQUEST_METHOD'] != 'HEAD') {

    $cacheable = FALSE;

  }

  // Block caching is not usually compatible with node access modules, so by

  // default it is disabled when node access modules exist. However, it can be

  // allowed by using the variable 'block_cache_bypass_node_grants'.

  elseif (!variable_get('block_cache_bypass_node_grants', FALSE) && count(module_implements('node_grants'))) {

    $cacheable = FALSE;

  }

  // Proceed to loop over all blocks in order to compute their respective cache

  // identifiers; this allows us to do one single cache_get_multiple() call

  // instead of doing one cache_get() call per block.

  $cached_blocks = array();

  $cids = array();

  if ($cacheable) {

    foreach ($region_blocks as $key => $block) {

      if (!isset($block->content)) {

        if (($cid = _block_get_cache_id($block))) {

          $cids[$key] = $cid;

        }

      }

    }

    if ($cids) {

      // We cannot pass $cids in directly because cache_get_multiple() will

      // modify it, and we need to use it later on in this function.

      $cid_values = array_values($cids);

      $cached_blocks = cache_get_multiple($cid_values, 'cache_block');

    }

  }

  foreach ($region_blocks as $key => $block) {

    // Render the block content if it has not been created already.

    if (!isset($block->content)) {

      // Erase the block from the static array - we'll put it back if it has

      // content.

      unset($region_blocks[$key]);

      $cid = empty($cids[$key]) ? NULL : $cids[$key];

      // Try fetching the block from the previously loaded cache entries.

      if (isset($cached_blocks[$cid])) {

        $array = $cached_blocks[$cid]->data;

      }

      else {

        $array = module_invoke($block->module, 'block_view', $block->delta);

        // Valid PHP function names cannot contain hyphens.

        $delta = str_replace('-', '_', $block->delta);

        // Allow modules to modify the block before it is viewed, via either

        // hook_block_view_alter() or hook_block_view_MODULE_DELTA_alter().

        drupal_alter(array('block_view', "block_view_{$block->module}_{$delta}"), $array, $block);

        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) {

        // Normalize to the drupal_render() structure.

        if (is_string($block->content)) {

          $block->content = array('#markup' => $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);

        }

        if (!isset($block->subject)) {

          $block->subject = '';

        }

        $region_blocks["{$block->module}_{$block->delta}"] = $block;

      }

    }

  }

  return $region_blocks;

}

/**

 * 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 differentiated.

 *

 * @param $block

 *   The block to get the cache_id from.

 *

 * @return

 *   The string used as cache_id for the block.

 */

function _block_get_cache_id($block) {

  global $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', FALSE) && !in_array($block->cache, array(DRUPAL_NO_CACHE, DRUPAL_CACHE_CUSTOM)) && $user->uid != 1) {

    // Start with common sub-patterns: block identification, theme, language.

    $cid_parts[] = $block->module;

    $cid_parts[] = $block->delta;

    drupal_alter('block_cid_parts', $cid_parts, $block);

    $cid_parts = array_merge($cid_parts, drupal_render_cid_parts($block->cache));

    return implode(':', $cid_parts);

  }

}

/**

 * Implements hook_flush_caches().

 */

function block_flush_caches() {

  // Rehash blocks for active themes. We don't use list_themes() here,

  // because if MAINTENANCE_MODE is defined it skips reading the database,

  // and we can't tell which themes are active.

  $themes = db_query("SELECT name FROM {system} WHERE type = 'theme' AND status = 1");

  foreach ($themes as $theme) {

    _block_rehash($theme->name);

  }

  return array('cache_block');

}

/**

 * Processes variables for block.tpl.php.

 *

 * Prepares the values passed to the theme_block function to be passed

 * into a pluggable template engine. Uses block properties to generate a

 * series of template file suggestions. If none are found, the default

 * block.tpl.php is used.

 *

 * Most themes utilize their own copy of block.tpl.php. The default is located

 * inside "modules/block/block.tpl.php". Look in there for the full list of

 * variables.

 *

 * The $variables array contains the following arguments:

 * - $block

 *

 * @see block.tpl.php

 */

function template_preprocess_block(&$variables) {

  $block_counter = &drupal_static(__FUNCTION__, array());

  $variables['block'] = $variables['elements']['#block'];

  // All blocks get an independent counter for each region.

  if (!isset($block_counter[$variables['block']->region])) {

    $block_counter[$variables['block']->region] = 1;

  }

  // Same with zebra striping.

  $variables['block_zebra'] = ($block_counter[$variables['block']->region] % 2) ? 'odd' : 'even';

  $variables['block_id'] = $block_counter[$variables['block']->region]++;

  // Create the $content variable that templates expect.

  $variables['content'] = $variables['elements']['#children'];

  $variables['classes_array'][] = drupal_html_class('block-' . $variables['block']->module);

  $variables['theme_hook_suggestions'][] = 'block__' . $variables['block']->region;

  $variables['theme_hook_suggestions'][] = 'block__' . $variables['block']->module;

  // Hyphens (-) and underscores (_) play a special role in theme suggestions.

  // Theme suggestions should only contain underscores, because within

  // drupal_find_theme_templates(), underscores are converted to hyphens to

  // match template file names, and then converted back to underscores to match

  // pre-processing and other function names. So if your theme suggestion

  // contains a hyphen, it will end up as an underscore after this conversion,

  // and your function names won't be recognized. So, we need to convert

  // hyphens to underscores in block deltas for the theme suggestions.

  $variables['theme_hook_suggestions'][] = 'block__' . $variables['block']->module . '__' . strtr($variables['block']->delta, '-', '_');

  // Create a valid HTML ID and make sure it is unique.

  $variables['block_html_id'] = drupal_html_id('block-' . $variables['block']->module . '-' . $variables['block']->delta);

}

/**

 * Implements hook_user_role_delete().

 *

 * Removes deleted role from blocks that use it.

 */

function block_user_role_delete($role) {

  db_delete('block_role')

    ->condition('rid', $role->rid)

    ->execute();

}

/**

 * Implements hook_menu_delete().

 */

function block_menu_delete($menu) {

  db_delete('block')

    ->condition('module', 'menu')

    ->condition('delta', $menu['menu_name'])

    ->execute();

  db_delete('block_role')

    ->condition('module', 'menu')

    ->condition('delta', $menu['menu_name'])

    ->execute();

}

/**

 * Implements hook_form_FORM_ID_alter().

 */

function block_form_system_performance_settings_alter(&$form, &$form_state) {

  $disabled = (!variable_get('block_cache_bypass_node_grants', FALSE) && count(module_implements('node_grants')));

  $form['caching']['block_cache'] = array(

    '#type' => 'checkbox',

    '#title' => t('Cache blocks'),

    '#default_value' => variable_get('block_cache', FALSE),

    '#disabled' => $disabled,

    '#description' => $disabled ? t('Block caching is inactive because you have enabled modules defining content access restrictions.') : NULL,

    '#weight' => -1,

  );

}

/**

 * Implements hook_admin_paths().

 */

function block_admin_paths() {

  $paths = array(

    // Exclude the block demonstration page from admin (overlay) treatment.

    // This allows us to present this page in its true form, full page.

    'admin/structure/block/demo/*' => FALSE,

  );

  return $paths;

}

/**

 * Implements hook_modules_uninstalled().

 *

 * Cleans up {block} and {block_role} tables from modules' blocks.

 */

function block_modules_uninstalled($modules) {

  db_delete('block')

    ->condition('module', $modules, 'IN')

    ->execute();

  db_delete('block_role')

    ->condition('module', $modules, 'IN')

    ->execute();

}