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<?php

/**

 * @file

 *

 * Contains code related to the ctools system of 'context'.

 *

 * Context, originally from Panels, is a method of packaging objects into

 * a more generic bundle and providing a plugin system so that a UI can

 * take advantage of them. The idea is that the context objects

 * represent 'the context' that a given operation (usually a page view)

 * is operating in or on.

 *

 * For example, when viewing a page, the 'context' is a node object. When

 * viewing a user, the 'context' is a user object. Contexts can also

 * have related contexts. For example, when viewing a 'node' you may need

 * to know something about the node author. Therefore, the node author

 * is a related context.

 */

/**

 * The context object is largely a wrapper around some other object, with

 * an interface to finding out what is contained and getting to both

 * the object and information about the object.

 *

 * Each context object has its own information, but some things are very

 * common, such as titles, data, keywords, etc. In particulare, the 'type'

 * of the context is important.

 */

class ctools_context {

  var $type = NULL;

  var $data = NULL;

  // The title of this object.

  var $title = '';

  // The title of the page if this object exists

  var $page_title = '';

  // The identifier (in the UI) of this object

  var $identifier = '';

  var $argument = NULL;

  var $keyword = '';

  var $original_argument = NULL;

  var $restrictions = array();

  var $empty = FALSE;

  function ctools_context($type = 'none', $data = NULL) {

    $this->type  = $type;

    $this->data  = $data;

    $this->title = t('Unknown context');

  }

  function is_type($type) {

    if ($type == 'any' || $this->type == 'any') {

      return TRUE;

    }

    $a = is_array($type) ? $type : array($type);

    $b = is_array($this->type) ? $this->type : array($this->type);

    return (bool) array_intersect($a, $b);

  }

  function get_argument() {

    return $this->argument;

  }

  function get_original_argument() {

    if (!is_null($this->original_argument)) {

      return $this->original_argument;

    }

    return $this->argument;

  }

  function get_keyword() {

    return $this->keyword;

  }

  function get_identifier() {

    return $this->identifier;

  }

  function get_title() {

    return $this->title;

  }

  function get_page_title() {

    return $this->page_title;

  }

}

/**

 * Used to create a method of comparing if a list of contexts

 * match a required context type.

 */

class ctools_context_required {

  var $keywords = '';

  /**

   * If set, the title will be used in the selector to identify

   * the context. This is very useful when multiple contexts

   * are required to inform the user will be used for what.

   */

  var $title = NULL;

  /**

   * Test to see if this context is required.

   */

  var $required = TRUE;

  /**

   * If TRUE, skip the check in ctools_context_required::select()

   * for contexts whose names may have changed.

   */

  var $skip_name_check = FALSE;

  /**

   *

   * @param $title

   *   The first parameter should be the 'title' of the context for use

   *   in UYI selectors when multiple contexts qualify.

   * @param ...

   *   One or more keywords to use for matching which contexts are allowed.

   */

  function ctools_context_required($title) {

    $args = func_get_args();

    $this->title = array_shift($args);

    // If we have a boolean value at the end for $skip_name_check, store it

    if (is_bool(end($args))) {

      $this->skip_name_check = array_pop($args);

    }

    // If we were given restrictions at the end, store them.

    if (count($args) > 1 && is_array(end($args))) {

      $this->restrictions = array_pop($args);

    }

    if (count($args) == 1) {

      $args = array_shift($args);

    }

    $this->keywords = $args;

  }

  function filter($contexts) {

    $result = array();

    // See which of these contexts are valid

    foreach ((array) $contexts as $cid => $context) {

      if ($context->is_type($this->keywords)) {

        // Compare to see if our contexts were met.

        if (!empty($this->restrictions) && !empty($context->restrictions)) {

          foreach ($this->restrictions as $key => $values) {

            // If we have a restriction, the context must either not have that

            // restriction listed, which means we simply don't know what it is,

            // or there must be an intersection of the restricted values on

            // both sides.

            if (!is_array($values)) {

              $values = array($values);

            }

            if (!empty($context->restrictions[$key]) && !array_intersect($values, $context->restrictions[$key])) {

              continue 2;

            }

          }

        }

        $result[$cid] = $context;

      }

    }

    return $result;

  }

  function select($contexts, $context) {

    if (!is_array($contexts)) {

      $contexts = array($contexts);

    }

    // If we had requested a $context but that $context doesn't exist

    // in our context list, there is a good chance that what happened

    // is our context IDs changed. See if there's another context

    // that satisfies our requirements.

    if (!$this->skip_name_check && !empty($context) && !isset($contexts[$context])) {

      $choices = $this->filter($contexts);

      // If we got a hit, take the first one that matches.

      if ($choices) {

        $keys = array_keys($choices);

        $context = reset($keys);

      }

    }

    if (empty($context) || empty($contexts[$context])) {

      return FALSE;

    }

    return $contexts[$context];

  }

}

/**

 * Used to compare to see if a list of contexts match an optional context. This

 * can produce empty contexts to use as placeholders.

 */

class ctools_context_optional extends ctools_context_required {

  var $required = FALSE;

  function ctools_context_optional() {

    $args = func_get_args();

    call_user_func_array(array($this, 'ctools_context_required'), $args);

  }

  /**

   * Add the 'empty' context which is possible for optional

   */

  function add_empty(&$contexts) {

    $context = new ctools_context('any');

    $context->title      = t('No context');

    $context->identifier = t('No context');

    $contexts = array_merge(array('empty' => $context), $contexts);

  }

  function filter($contexts) {

    $this->add_empty($contexts);

    return parent::filter($contexts);

  }

  function select($contexts, $context) {

    $this->add_empty($contexts);

    if (empty($context)) {

      return $contexts['empty'];

    }

    $result = parent::select($contexts, $context);

    // Don't flip out if it can't find the context; this is optional, put

    // in an empty.

    if ($result == FALSE) {

      $result = $contexts['empty'];

    }

    return $result;

  }

}

/**

 * Return a keyed array of context that match the given 'required context'

 * filters.

 *

 * Functions or systems that require contexts of a particular type provide a

 * ctools_context_required or ctools_context_optional object. This function

 * examines that object and an array of contexts to determine which contexts

 * match the filter.

 *

 * Since multiple contexts can be required, this function will accept either

 * an array of all required contexts, or just a single required context object.

 *

 * @param $contexts

 *   A keyed array of all available contexts.

 * @param $required

 *   A ctools_context_required or ctools_context_optional object, or an array

 *   of such objects.

 *

 * @return

 *   A keyed array of contexts that match the filter.

 */

function ctools_context_filter($contexts, $required) {

  if (is_array($required)) {

    $result = array();

    foreach ($required as $r) {

      $result = array_merge($result, _ctools_context_filter($contexts, $r));

    }

    return $result;

  }

  return _ctools_context_filter($contexts, $required);

}

function _ctools_context_filter($contexts, $required) {

  $result = array();

  if (is_object($required)) {

    $result = $required->filter($contexts);

  }

  return $result;

}

/**

 * Create a select box to choose possible contexts.

 *

 * This only creates a selector if there is actually a choice; if there

 * is only one possible context, that one is silently assigned.

 *

 * If an array of required contexts is provided, one selector will be

 * provided for each context.

 *

 * @param $contexts

 *   A keyed array of all available contexts.

 * @param $required

 *   The required context object or array of objects.

 *

 * @return

 *   A form element, or NULL if there are no contexts that satisfy the

 *   requirements.

 */

function ctools_context_selector($contexts, $required, $default) {

  if (is_array($required)) {

    $result = array('#tree' => TRUE);

    $count = 1;

    foreach ($required as $id => $r) {

      $result[] = _ctools_context_selector($contexts, $r, isset($default[$id]) ? $default[$id] : '', $count++);

    }

    return $result;

  }

  return _ctools_context_selector($contexts, $required, $default);

}

function _ctools_context_selector($contexts, $required, $default, $num = 0) {

  $filtered = ctools_context_filter($contexts, $required);

  $count = count($filtered);

  $form = array();

  if ($count >= 1) {

    // If there's more than one to choose from, create a select widget.

    foreach ($filtered as $cid => $context) {

      $options[$cid] = $context->get_identifier();

    }

    if (!empty($required->title)) {

      $title = $required->title;

    }

    else {

      $title = $num ? t('Context %count', array('%count' => $num)) : t('Context');

    }

    return array(

      '#type' => 'select',

      '#options' => $options,

      '#title' => $title,

      '#default_value' => $default,

    );

  }

}

/**

 * Are there enough contexts for a plugin?

 *

 * Some plugins can have a 'required contexts' item which can either

 * be a context requirement object or an array of them. When contexts

 * are required, items that do not have enough contexts should not

 * appear. This tests an item to see if it has enough contexts

 * to actually appear.

 *

 * @param $contexts

 *   A keyed array of all available contexts.

 * @param $required

 *   The required context object or array of objects.

 *

 * @return

 *   TRUE if there are enough contexts, FALSE if there are not.

 */

function ctools_context_match_requirements($contexts, $required) {

  if (!is_array($required)) {

    $required = array($required);

  }

  // Get the keys to avoid bugs in PHP 5.0.8 with keys and loops.

  // And use it to remove optional contexts.

  $keys = array_keys($required);

  foreach ($keys as $key) {

    if (empty($required[$key]->required)) {

      unset($required[$key]);

    }

  }

  $count = count($required);

  return (count(ctools_context_filter($contexts, $required)) >= $count);

}

/**

 * Create a select box to choose possible contexts.

 *

 * This only creates a selector if there is actually a choice; if there

 * is only one possible context, that one is silently assigned.

 *

 * If an array of required contexts is provided, one selector will be

 * provided for each context.

 *

 * @param $contexts

 *   A keyed array of all available contexts.

 * @param $required

 *   The required context object or array of objects.

 *

 * @return

 *   A form element, or NULL if there are no contexts that satisfy the

 *   requirements.

 */

function ctools_context_converter_selector($contexts, $required, $default) {

  if (is_array($required)) {

    $result = array('#tree' => TRUE);

    $count = 1;

    foreach ($required as $id => $r) {

      $result[] = _ctools_context_converter_selector($contexts, $r, isset($default[$id]) ? $default[$id] : '', $count++);

    }

    return $result;

  }

  return _ctools_context_converter_selector($contexts, $required, $default);

}

function _ctools_context_converter_selector($contexts, $required, $default, $num = 0) {

  $filtered = ctools_context_filter($contexts, $required);

  $count = count($filtered);

  $form = array();

  if ($count > 1) {

    // If there's more than one to choose from, create a select widget.

    $options = array();

    foreach ($filtered as $cid => $context) {

      if ($context->type == 'any') {

        $options[''] = t('No context');

        continue;

      }

      $key = $context->get_identifier();

      if ($converters = ctools_context_get_converters($cid . '.', $context)) {

        $options[$key] = $converters;

      }

    }

    if (empty($options)) {

      return array(

        '#type' => 'value',

        '#value' => 'any',

      );

    }

    if (!empty($required->title)) {

      $title = $required->title;

    }

    else {

      $title = $num ? t('Context %count', array('%count' => $num)) : t('Context');

    }

    return array(

      '#type' => 'select',

      '#options' => $options,

      '#title' => $title,

      '#description' => t('Please choose which context and how you would like it converted.'),

      '#default_value' => $default,

    );

  }

}

/**

 * Get a list of converters available for a given context.

 */

function ctools_context_get_converters($cid, $context) {

  if (empty($context->plugin)) {

    return array();

  }

  return _ctools_context_get_converters($cid, $context->plugin);

}

/**

 * Get a list of converters available for a given context.

 */

function _ctools_context_get_converters($id, $plugin_name) {

  $plugin = ctools_get_context($plugin_name);

  if (empty($plugin['convert list'])) {

    return array();

  }

  $converters = array();

  if (is_array($plugin['convert list'])) {

    $converters = $plugin['convert list'];

  }

  else if ($function = ctools_plugin_get_function($plugin, 'convert list')) {

    $converters = (array) $function($plugin);

  }

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

    $function = $module . '_ctools_context_convert_list_alter';

    $function($plugin, $converters);

  }

  // Now, change them all to include the plugin:

  $return = array();

  foreach ($converters as $key => $title) {

    $return[$id . $key] = $title;

  }

  natcasesort($return);

  return $return;

}

/**

 * Get a list of all contexts + converters available.

 */

function ctools_context_get_all_converters() {

  $contexts = ctools_get_contexts();

  $converters = array();

  foreach ($contexts as $name => $context) {

    if (empty($context['no required context ui'])) {

      $context_converters = _ctools_context_get_converters($name . '.', $name);

      if ($context_converters) {

        $converters[$context['title']] = $context_converters;

      }

    }

  }

  return $converters;

}

/**

 * Let the context convert an argument based upon the converter that was given.

 *

 * @param $context

 *   The context object

 * @param $converter

 *   The converter to use, which should be a string provided by the converter list.

 * @param $converter_options

 *   A n array of options to pass on to the generation function. For contexts

 *   that use token module, of particular use is 'sanitize' => FALSE which can

 *   get raw tokens. This should ONLY be used in values that will later be

 *   treated as unsafe user input since these values are by themselves unsafe.

 *   It is particularly useful to get raw values from Field API.

 */

function ctools_context_convert_context($context, $converter, $converter_options = array()) {

  // Contexts without plugins might be optional placeholders.

  if (empty($context->plugin)) {

    return;

  }

  $value = $context->argument;

  $plugin = ctools_get_context($context->plugin);

  if ($function = ctools_plugin_get_function($plugin, 'convert')) {

    $value = $function($context, $converter, $converter_options);

  }

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

    $function = $module . '_ctools_context_converter_alter';

    $function($context, $converter, $value, $converter_options);

  }

  return $value;

}

/**

 * Choose a context or contexts based upon the selection made via

 * ctools_context_filter.

 *

 * @param $contexts

 *   A keyed array of all available contexts

 * @param $required

 *   The required context object provided by the plugin

 * @param $context

 *   The selection made using ctools_context_selector

 */

function ctools_context_select($contexts, $required, $context) {

  if (is_array($required)) {

    $result = array();

    foreach ($required as $id => $r) {

      if (empty($required[$id])) {

        continue;

      }

      if (($result[] = _ctools_context_select($contexts, $r, $context[$id])) === FALSE) {

        return FALSE;

      }

    }

    return $result;

  }

  return _ctools_context_select($contexts, $required, $context);

}

function _ctools_context_select($contexts, $required, $context) {

  if (!is_object($required)) {

    return FALSE;

  }

  return $required->select($contexts, $context);

}

/**

 * Create a new context object.

 *

 * @param $type

 *   The type of context to create; this loads a plugin.

 * @param $data

 *   The data to put into the context.

 * @param $empty

 *   Whether or not this context is specifically empty.

 * @param $conf

 *   A configuration structure if this context was created via UI.

 *

 * @return

 *   A $context or NULL if one could not be created.

 */

function ctools_context_create($type, $data = NULL, $conf = FALSE) {

  ctools_include('plugins');

  $plugin = ctools_get_context($type);

  if ($function = ctools_plugin_get_function($plugin, 'context')) {

    return $function(FALSE, $data, $conf, $plugin);

  }

}

/**

 * Create an empty context object.

 *

 * Empty context objects are primarily used as placeholders in the UI where

 * the actual contents of a context object may not be known. It may have

 * additional text embedded to give the user clues as to how the context

 * is used.

 *

 * @param $type

 *   The type of context to create; this loads a plugin.

 *

 * @return

 *   A $context or NULL if one could not be created.

 */

function ctools_context_create_empty($type) {

  $plugin = ctools_get_context($type);

  if ($function = ctools_plugin_get_function($plugin, 'context')) {

    $context = $function(TRUE, NULL, FALSE, $plugin);

    if (is_object($context)) {

      $context->empty = TRUE;

    }

    return $context;

  }

}

/**

 * Perform keyword and context substitutions.

 */

function ctools_context_keyword_substitute($string, $keywords, $contexts, $converter_options = array()) {

  // Ensure a default keyword exists:

  $keywords['%%'] = '%';

  // Match contexts to the base keywords:

  $context_keywords = array();

  foreach ($contexts as $context) {

    if (isset($context->keyword)) {

      $context_keywords[$context->keyword] = $context;

    }

  }

  // Look for context matches we we only have to convert known matches.

  $matches = array();

  if (preg_match_all('/%(%|[a-zA-Z0-9_-]+(?:\:[a-zA-Z0-9_-]+)*)/us', $string, $matches)) {

    foreach ($matches[1] as $keyword) {

      // Ignore anything it finds with %%.

      if ($keyword[0] == '%') {

        continue;

      }

      // If the keyword is already set by something passed in, don't try to

      // overwrite it.

      if (!empty($keywords['%' . $keyword])) {

        continue;

      }

      // Figure out our keyword and converter, if specified.

      if (strpos($keyword, ':')) {

        list($context, $converter) = explode(':', $keyword, 2);

      }

      else {

        $context = $keyword;

        if (isset($context_keywords[$keyword])) {

          $plugin = ctools_get_context($context_keywords[$context]->plugin);

          // Fall back to a default converter, if specified.

          if ($plugin && !empty($plugin['convert default'])) {

            $converter = $plugin['convert default'];

          }

        }

      }

      if (empty($context_keywords[$context]) || !empty($context_keywords[$context]->empty)) {

        $keywords['%' . $keyword] = '';

      }

      else if (!empty($converter)) {

        $keywords['%' . $keyword] = ctools_context_convert_context($context_keywords[$context], $converter, $converter_options);

      }

      else {

        $keywords['%' . $keyword] = $context_keywords[$keyword]->title;

      }

    }

  }

  return strtr($string, $keywords);

}

/**

 * Determine a unique context ID for a context

 *

 * Often contexts of many different types will be placed into a list. This

 * ensures that even though contexts of multiple types may share IDs, they

 * are unique in the final list.

 */

function ctools_context_id($context, $type = 'context') {

  if (!$context['id']) {

    $context['id'] = 1;

  }

  return $type . '_' . $context['name'] . '_' . $context['id'];

}

/**

 * Get the next id available given a list of already existing objects.

 *

 * This finds the next id available for the named object.

 *

 * @param $objects

 *   A list of context descriptor objects, i.e, arguments, relationships, contexts, etc.

 * @param $name

 *   The name being used.

 */

function ctools_context_next_id($objects, $name) {

  $id = 0;

  // Figure out which instance of this argument we're creating

  if (!$objects) {

    return $id + 1;

  }

  foreach ($objects as $object) {

    if (isset($object['name']) && $object['name'] == $name) {

      if ($object['id'] > $id) {

        $id = $object['id'];

      }

    }

  }

  return $id + 1;

}

// ---------------------------------------------------------------------------

// Functions related to contexts from arguments.

/**

 * Fetch metadata on a specific argument plugin.

 *

 * @param $argument

 *   Name of an argument plugin.

 *

 * @return

 *   An array with information about the requested argument plugin.

 */

function ctools_get_argument($argument) {

  ctools_include('plugins');

  return ctools_get_plugins('ctools', 'arguments', $argument);

}

/**

 * Fetch metadata for all argument plugins.

 *

 * @return

 *   An array of arrays with information about all available argument plugins.

 */

function ctools_get_arguments() {

  ctools_include('plugins');

  return ctools_get_plugins('ctools', 'arguments');

}

/**

 * Get a context from an argument.

 *

 * @param $argument

 *   The configuration of an argument. It must contain the following data:

 *   - name: The name of the argument plugin being used.

 *   - argument_settings: The configuration based upon the plugin forms.

 *   - identifier: The human readable identifier for this argument, usually

 *     defined by the UI.

 *   - keyword: The keyword used for this argument for substitutions.

 *

 * @param $arg

 *   The actual argument received. This is expected to be a string from a URL but

 *   this does not have to be the only source of arguments.

 * @param $empty

 *   If true, the $arg will not be used to load the context. Instead, an empty

 *   placeholder context will be loaded.

 *

 * @return

 *   A context object if one can be loaded.

 */

function ctools_context_get_context_from_argument($argument, $arg, $empty = FALSE) {

  ctools_include('plugins');

  if (empty($argument['name'])) {

    return;

  }

  if ($function = ctools_plugin_load_function('ctools', 'arguments', $argument['name'], 'context')) {

    // Backward compatibility: Merge old style settings into new style:

    if (!empty($argument['settings'])) {

      $argument += $argument['settings'];

      unset($argument['settings']);

    }

    $context = $function($arg, $argument, $empty);

    if (is_object($context)) {

      $context->identifier = $argument['identifier'];

      $context->page_title = isset($argument['title']) ? $argument['title'] : '';

      $context->keyword    = $argument['keyword'];

      $context->id         = ctools_context_id($argument, 'argument');

      $context->original_argument = $arg;

      if (!empty($context->empty)) {

        $context->placeholder = array(

          'type' => 'argument',

          'conf' => $argument,

        );

      }

    }

    return $context;

  }

}

/**

 * Retrieve a list of empty contexts for all arguments.

 */

function ctools_context_get_placeholders_from_argument($arguments) {

  $contexts = array();

  foreach ($arguments as $argument) {

    $context = ctools_context_get_context_from_argument($argument, NULL, TRUE);

    if ($context) {

      $contexts[ctools_context_id($argument, 'argument')] = $context;

    }

  }

  return $contexts;

}

/**

 * Load the contexts for a given list of arguments.

 *

 * @param $arguments

 *   The array of argument definitions.

 * @param &$contexts

 *   The array of existing contexts. New contexts will be added to this array.

 * @param $args

 *   The arguments to load.

 *

 * @return

 *   FALSE if an argument wants to 404.

 */

function ctools_context_get_context_from_arguments($arguments, &$contexts, $args) {

  foreach ($arguments as $argument) {

    // pull the argument off the list.

    $arg = array_shift($args);

    $id = ctools_context_id($argument, 'argument');

    // For % arguments embedded in the URL, our context is already loaded.

    // There is no need to go and load it again.

    if (empty($contexts[$id])) {

      if ($context = ctools_context_get_context_from_argument($argument, $arg)) {

        $contexts[$id] = $context;

      }

    }

    else {

      $context = $contexts[$id];

    }

    if ((empty($context) || empty($context->data)) && !empty($argument['default']) && $argument['default'] == '404') {

      return FALSE;

    }

  }

  return TRUE;

}

// ---------------------------------------------------------------------------

// Functions related to contexts from relationships.

/**

 * Fetch metadata on a specific relationship plugin.

 *

 * @param $content type

 *   Name of a panel content type.

 *

 * @return

 *   An array with information about the requested relationship.

 */

function ctools_get_relationship($relationship) {

  ctools_include('plugins');

  return ctools_get_plugins('ctools', 'relationships', $relationship);

}

/**

 * Fetch metadata for all relationship plugins.

 *

 * @return

 *   An array of arrays with information about all available relationships.

 */

function ctools_get_relationships() {

  ctools_include('plugins');

  return ctools_get_plugins('ctools', 'relationships');

}

/**

 *

 * @param $relationship

 *   The configuration of a relationship. It must contain the following data:

 *   - name: The name of the relationship plugin being used.

 *   - relationship_settings: The configuration based upon the plugin forms.

 *   - identifier: The human readable identifier for this relationship, usually

 *     defined by the UI.

 *   - keyword: The keyword used for this relationship for substitutions.

 *

 * @param $source_context

 *   The context this relationship is based upon.

 *

 * @param $placeholders

 *   If TRUE, placeholders are acceptable.

 *

 * @return

 *   A context object if one can be loaded.

 */

function ctools_context_get_context_from_relationship($relationship, $source_context, $placeholders = FALSE) {

  ctools_include('plugins');

  if ($function = ctools_plugin_load_function('ctools', 'relationships', $relationship['name'], 'context')) {

    // Backward compatibility: Merge old style settings into new style:

    if (!empty($relationship['relationship_settings'])) {

      $relationship += $relationship['relationship_settings'];

      unset($relationship['relationship_settings']);

    }

    $context = $function($source_context, $relationship, $placeholders);

    if ($context) {

      $context->identifier = $relationship['identifier'];

      $context->page_title = isset($relationship['title']) ? $relationship['title'] : '';

      $context->keyword    = $relationship['keyword'];

      if (!empty($context->empty)) {

        $context->placeholder = array(

          'type' => 'relationship',

          'conf' => $relationship,

        );

      }

      return $context;

    }

  }

}

/**

 * Fetch all relevant relationships.

 *

 * Relevant relationships are any relationship that can be created based upon

 * the list of existing contexts. For example, the 'node author' relationship

 * is relevant if there is a 'node' context, but makes no sense if there is

 * not one.

 *

 * @param $contexts

 *   An array of contexts used to figure out which relationships are relevant.

 *

 * @return

 *   An array of relationship keys that are relevant for the given set of

 *   contexts.

 */

function ctools_context_get_relevant_relationships($contexts) {

  $relevant = array();

  $relationships = ctools_get_relationships();

  // Go through each relationship

  foreach ($relationships as $rid => $relationship) {

    // For each relationship, see if there is a context that satisfies it.

    if (empty($relationship['no ui']) && ctools_context_filter($contexts, $relationship['required context'])) {

      $relevant[$rid] = $relationship['title'];

    }

  }

  return $relevant;

}

/**

 * Fetch all active relationships

 *

 * @param $relationships

 *   An keyed array of relationship data including:

 *   - name: name of relationship

 *   - context: context id relationship belongs to. This will be used to

 *     identify which context in the $contexts array to use to create the

 *     relationship context.

 *

 * @param $contexts

 *   A keyed array of contexts used to figure out which relationships

 *   are relevant. New contexts will be added to this.

 *

 * @param $placeholders

 *   If TRUE, placeholders are acceptable.

 */

function ctools_context_get_context_from_relationships($relationships, &$contexts, $placeholders = FALSE) {

  $return = array();

  foreach ($relationships as $rdata) {

    if (!isset($rdata['context'])) {

      continue;

    }

    if (is_array($rdata['context'])) {

      $rcontexts = array();

      foreach ($rdata['context'] as $cid) {

        if (empty($contexts[$cid])) {

          continue 2;

        }

        $rcontexts[] = $contexts[$cid];

      }

    }

    else {

      if (empty($contexts[$rdata['context']])) {

        continue;

      }

      $rcontexts = $contexts[$rdata['context']];

    }

    $cid = ctools_context_id($rdata, 'relationship');

    if ($context = ctools_context_get_context_from_relationship($rdata, $rcontexts)) {

      $contexts[$cid] = $context;

    }

  }

}

// ---------------------------------------------------------------------------

// Functions related to loading contexts from simple context definitions.

/**

 * Fetch metadata on a specific context plugin.

 *

 * @param $context

 *   Name of a context.

 *

 * @return

 *   An array with information about the requested panel context.

 */

function ctools_get_context($context) {

  static $gate = array();

  ctools_include('plugins');

  $plugin = ctools_get_plugins('ctools', 'contexts', $context);

  if (empty($gate['context']) && !empty($plugin['superceded by'])) {

    // This gate prevents infinite loops.

    $gate[$context] = TRUE;

    $new_plugin = ctools_get_plugins('ctools', 'contexts', $plugin['superceded by']);

    $gate[$context] = FALSE;

    // If a new plugin was returned, return it. Otherwise fall through and

    // return the original we fetched.

    if ($new_plugin) {

      return $new_plugin;

    }

  }

  return $plugin;

}

/**

 * Fetch metadata for all context plugins.

 *

 * @return

 *   An array of arrays with information about all available panel contexts.

 */

function ctools_get_contexts() {

  ctools_include('plugins');

  return ctools_get_plugins('ctools', 'contexts');

}

/**

 *

 * @param $context

 *   The configuration of a context. It must contain the following data:

 *   - name: The name of the context plugin being used.

 *   - context_settings: The configuration based upon the plugin forms.

 *   - identifier: The human readable identifier for this context, usually

 *     defined by the UI.

 *   - keyword: The keyword used for this context for substitutions.

 * @param $type

 *   This is either 'context' which indicates the context will be loaded

 *   from data in the settings, or 'required_context' which means the

 *   context must be acquired from an external source. This is the method

 *   used to pass pure contexts from one system to another.

 *

 * @return

 *   A context object if one can be loaded.

 */

function ctools_context_get_context_from_context($context, $type = 'context', $argument = NULL) {

  ctools_include('plugins');

  $plugin = ctools_get_context($context['name']);

  if ($function = ctools_plugin_get_function($plugin, 'context')) {

    // Backward compatibility: Merge old style settings into new style:

    if (!empty($context['context_settings'])) {

      $context += $context['context_settings'];

      unset($context['context_settings']);

    }

    if (isset($argument) && isset($plugin['placeholder name'])) {

      $context[$plugin['placeholder name']] = $argument;

    }

    $return = $function($type == 'requiredcontext', $context, TRUE, $plugin);

    if ($return) {

      $return->identifier = $context['identifier'];

      $return->page_title = isset($context['title']) ? $context['title'] : '';

      $return->keyword    = $context['keyword'];

      if (!empty($context->empty)) {

        $context->placeholder = array(

          'type' => 'context',

          'conf' => $context,

        );

      }

      return $return;

    }

  }

}

/**

 * Retrieve a list of base contexts based upon a simple 'contexts' definition.

 *

 * For required contexts this will always retrieve placeholders.

 *

 * @param $contexts

 *   The list of contexts defined in the UI.

 * @param $type

 *   Either 'context' or 'requiredcontext', which indicates whether the contexts

 *   are loaded from internal data or copied from an external source.

 * @param $placeholders

 *   If true, placeholders are acceptable.

 */

function ctools_context_get_context_from_contexts($contexts, $type = 'context', $placeholders = FALSE) {

  $return = array();