ui.forms.inc

<?php


/**
 * @file
 * Rules User Interface forms.
 */

/**
 * Ajax callback for reloading the whole form.
 */
function rules_ui_form_ajax_reload_form($form, $form_state) {
    return $form;
}

/**
 * Defines #ajax properties.
 */
function rules_ui_form_default_ajax($effect = 'slide') {
    return array(
        'callback' => 'rules_ui_form_ajax_reload_form',
        'wrapper' => 'rules-form-wrapper',
        'effect' => $effect,
        'speed' => 'fast',
    );
}

/**
 * Submit handler for switching the parameter input mode.
 */
function rules_ui_parameter_replace_submit($form, &$form_state) {
    if (isset($form_state['triggering_element'])) {
        $name = $form_state['triggering_element']['#parameter'];
        $form_state['parameter_mode'][$name] = $form_state['parameter_mode'][$name] == 'selector' ? 'input' : 'selector';
    }
    $form_state['rebuild'] = TRUE;
}

/**
 * General form submit handler, that rebuilds the form.
 */
function rules_form_submit_rebuild($form, &$form_state) {
    $form_state['rebuild'] = TRUE;
}

/**
 * Edit a rules configuration.
 */
function rules_ui_form_edit_rules_config($form, &$form_state, $rules_config, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    $form_state += array(
        'rules_element' => $rules_config,
    );
    // Add the rule configuration's form.
    $rules_config->form($form, $form_state, array(
        'show settings' => TRUE,
        'button' => TRUE,
    ));
    $form['#validate'] = array(
        'rules_ui_form_rules_config_validate',
    );
    return $form;
}

/**
 * General rules configuration form validation callback.
 *
 * Also populates the rules configuration with the form values.
 */
function rules_ui_form_rules_config_validate($form, &$form_state) {
    $form_state['rules_element']->form_validate($form, $form_state);
}

/**
 * Edit a rules configuration form submit callback.
 */
function rules_ui_form_edit_rules_config_submit($form, &$form_state) {
    $form_state['rules_element']->form_submit($form, $form_state);
    drupal_set_message(t('Your changes have been saved.'));
    if (empty($form_state['redirect'])) {
        $form_state['redirect'] = RulesPluginUI::defaultRedirect($form_state['rules_element']);
    }
}

/**
 * Clone a rules configuration form.
 */
function rules_ui_form_clone_rules_config($form, &$form_state, $rules_config, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    $rules_config = clone $rules_config;
    $rules_config->id = NULL;
    $rules_config->name = '';
    $rules_config->label .= ' (' . t('cloned') . ')';
    $rules_config->status = ENTITY_CUSTOM;
    $form['#validate'][] = 'rules_ui_form_rules_config_validate';
    $form['#submit'][] = 'rules_ui_form_edit_rules_config_submit';
    $form_state += array(
        'rules_element' => $rules_config,
        'op' => 'clone',
    );
    // Add the rule configuration's form.
    $rules_config->form($form, $form_state, array(
        'show settings' => TRUE,
        'button' => TRUE,
        'init' => TRUE,
    ));
    // Open the settings fieldset so altering the name is easier.
    $form['settings']['#collapsed'] = FALSE;
    return $form;
}

/**
 * A simple form just showing a textarea with the export.
 */
function rules_ui_form_export_rules_config($form, &$form_state, $rules_config, $base_path) {
    $form['export'] = array(
        '#type' => 'textarea',
        '#title' => t('Export'),
        '#description' => t('For importing copy the content of the text area and paste it into the import page.'),
        '#rows' => 25,
        '#default_value' => $rules_config->export(),
    );
    return $form;
}

/**
 * Configuration form to directly execute a rules configuration.
 */
function rules_ui_form_execute_rules_config($form, &$form_state, $rules_config, $base_path) {
    // Only components can be executed.
    if (!$rules_config instanceof RulesTriggerableInterface) {
        RulesPluginUI::$basePath = $base_path;
        // Create either the appropriate action or condition element.
        $element = rules_plugin_factory($rules_config instanceof RulesActionInterface ? 'action' : 'condition', 'component_' . $rules_config->name);
        $form['exec_help'] = array(
            '#prefix' => '<p>',
            '#markup' => t('This form allows you to manually trigger the execution of the @plugin "%label". If this component requires any parameters, input the suiting execution arguments below.', array(
                '@plugin' => $rules_config->plugin(),
                '%label' => $rules_config->label(),
            )),
            '#suffix' => '</p>',
        );
        $element->form($form, $form_state);
        // For conditions hide the option to negate them.
        if (isset($form['negate'])) {
            $form['negate']['#access'] = FALSE;
        }
        $form['submit'] = array(
            '#type' => 'submit',
            '#value' => t('Execute'),
            '#weight' => 20,
        );
        // Re-use the validation callback, which will also populate the action with
        // the configuration settings in the form.
        $form['#validate'] = array(
            'rules_ui_form_rules_config_validate',
        );
        return $form;
    }
    drupal_not_found();
    exit;
}

/**
 * Submit callback for directly executing a component.
 */
function rules_ui_form_execute_rules_config_submit($form, &$form_state) {
    $element = $form_state['rules_element'];
    $result = $element->execute();
    if ($element instanceof RulesActionInterface) {
        drupal_set_message(t('Component %label has been executed.', array(
            '%label' => $element->label(),
        )));
    }
    else {
        drupal_set_message(t('Component %label evaluated to %result.', array(
            '%label' => $element->label(),
            '%result' => $result ? 'true' : 'false',
        )));
    }
}

/**
 * Gets the confirmation question for valid operations, or else FALSE.
 */
function rules_ui_confirm_operations($op, $rules_config) {
    $vars = array(
        '%plugin' => $rules_config->plugin(),
        '%label' => $rules_config->label(),
    );
    switch ($op) {
        case 'enable':
            return array(
                t('Are you sure you want to enable the %plugin %label?', $vars),
                '',
            );
        case 'disable':
            return array(
                t('Are you sure you want to disable the %plugin %label?', $vars),
                '',
            );
        case 'revert':
            return array(
                t('Are you sure you want to revert the %plugin %label?', $vars),
                t('This action cannot be undone.'),
            );
        case 'delete':
            return array(
                t('Are you sure you want to delete the %plugin %label?', $vars),
                t('This action cannot be undone.'),
            );
        default:
            return FALSE;
    }
}

/**
 * Confirmation form for applying the operation to the config.
 */
function rules_ui_form_rules_config_confirm_op($form, &$form_state, $rules_config, $op, $base_path) {
    if (list($confirm_question, $description) = rules_ui_confirm_operations($op, $rules_config)) {
        RulesPluginUI::$basePath = $base_path;
        $form_state += array(
            'rules_config' => $rules_config,
            'op' => $op,
        );
        return confirm_form($form, $confirm_question, $base_path, $description, t('Confirm'), t('Cancel'));
    }
    else {
        drupal_not_found();
        exit;
    }
}

/**
 * Applies the operation and returns the message to show to the user.
 *
 * The operation is also logged to the watchdog. Note that the string is
 * defined two times so that the translation extractor can find it.
 */
function rules_ui_confirm_operation_apply($op, $rules_config) {
    $vars = array(
        '%plugin' => $rules_config->plugin(),
        '%label' => $rules_config->label(),
    );
    $edit_link = l(t('edit'), RulesPluginUI::path($rules_config->name));
    switch ($op) {
        case 'enable':
            $rules_config->active = TRUE;
            $rules_config->save();
            watchdog('rules', 'Enabled %plugin %label.', $vars, WATCHDOG_NOTICE, $edit_link);
            return t('Enabled %plugin %label.', $vars);
        case 'disable':
            $rules_config->active = FALSE;
            $rules_config->save();
            watchdog('rules', 'Disabled %plugin %label.', $vars, WATCHDOG_NOTICE, $edit_link);
            return t('Disabled %plugin %label.', $vars);
        case 'revert':
            $rules_config->delete();
            watchdog('rules', 'Reverted %plugin %label to the defaults.', $vars, WATCHDOG_NOTICE, $edit_link);
            return t('Reverted %plugin %label to the defaults.', $vars);
        case 'delete':
            $rules_config->delete();
            watchdog('rules', 'Deleted %plugin %label.', $vars);
            return t('Deleted %plugin %label.', $vars);
    }
}

/**
 * Rule config deletion form submit callback.
 */
function rules_ui_form_rules_config_confirm_op_submit($form, &$form_state) {
    if ($form_state['values']['confirm']) {
        $msg = rules_ui_confirm_operation_apply($form_state['op'], $form_state['rules_config']);
        drupal_set_message($msg);
    }
}

/**
 * Add a new element a rules configuration.
 */
function rules_ui_add_element($form, &$form_state, $rules_config, $plugin_name, RulesContainerPlugin $parent, $base_path) {
    $cache = rules_get_cache();
    if (!isset($cache['plugin_info'][$plugin_name]['class'])) {
        drupal_not_found();
        exit;
    }
    RulesPluginUI::$basePath = $base_path;
    $plugin_is_abstract = in_array('RulesAbstractPlugin', class_parents($cache['plugin_info'][$plugin_name]['class']));
    // In the first step create the element and in the second step show its edit
    // form.
    if ($plugin_is_abstract && !isset($form_state['rules_element'])) {
        RulesPluginUI::formDefaults($form, $form_state);
        $form_state += array(
            'parent_element' => $parent,
            'plugin' => $plugin_name,
        );
        $form['element_name'] = array(
            '#type' => 'select',
            '#title' => t('Select the %element to add', array(
                '%element' => $plugin_name,
            )),
            '#options' => RulesPluginUI::getOptions($plugin_name),
            '#ajax' => rules_ui_form_default_ajax() + array(
                'trigger_as' => array(
                    'name' => 'continue',
                ),
            ),
        );
        $form['continue'] = array(
            '#type' => 'submit',
            '#name' => 'continue',
            '#value' => t('Continue'),
            '#ajax' => rules_ui_form_default_ajax(),
        );
    }
    elseif (!$plugin_is_abstract) {
        // Create the initial, empty element.
        $element = rules_plugin_factory($plugin_name);
        // Always add the new element at the bottom, thus set an appropriate weight.
        $iterator = $parent->getIterator();
        $iterator_array = iterator_to_array($iterator, TRUE);
        if ($sibling = end($iterator_array)) {
            $element->weight = $sibling->weight + 1;
        }
        $element->setParent($parent);
        $form_state['rules_element'] = $element;
    }
    if (isset($form_state['rules_element'])) {
        $form_state['rules_element']->form($form, $form_state, array(
            'button' => TRUE,
            'init' => TRUE,
        ));
        $form['#validate'][] = 'rules_ui_edit_element_validate';
        $form['#submit'][] = 'rules_ui_edit_element_submit';
    }
    return $form;
}

/**
 * Add element submit callback.
 *
 * Used for "abstract plugins" to create the initial element object with the
 * given implementation name and rebuild the form.
 */
function rules_ui_add_element_submit($form, &$form_state) {
    $element = rules_plugin_factory($form_state['plugin'], $form_state['values']['element_name']);
    // Always add the new element at the bottom, thus set an appropriate weight.
    $iterator = $form_state['parent_element']->getIterator();
    $iterator_array = iterator_to_array($iterator, TRUE);
    if ($sibling = end($iterator_array)) {
        $element->weight = $sibling->weight + 1;
    }
    // Clear the element settings so they won't be processed on serialization as
    // there is nothing to be processed yet.
    $element->settings = array();
    $element->setParent($form_state['parent_element']);
    $form_state['rules_element'] = $element;
    $form_state['rebuild'] = TRUE;
}

/**
 * Delete elements.
 */
function rules_ui_delete_element($form, &$form_state, $rules_config, $rules_element, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    if (empty($form_state['rules_config'])) {
        // Before modifying the rules config we have to clone it, so any
        // modifications won't appear in the static cache of the loading controller.
        $rules_config = clone $rules_config;
        // Also get the element from the cloned config.
        $rules_element = $rules_config->elementMap()
            ->lookup($rules_element->elementId());
        $form_state['rules_config'] = $rules_config;
        $form_state['rules_element'] = $rules_element;
        $form_state['element_parent'] = $rules_element->parentElement();
    }
    // Try deleting the element and warn the user if something breaks, but
    // save the parent for determining the right redirect target on submit.
    $removed_plugin = $form_state['rules_element']->plugin();
    $rules_element->delete();
    if (empty($rules_config->dirty) && empty($form_state['input'])) {
        try {
            $rules_config->integrityCheck();
        } catch (RulesIntegrityException $e) {
            $args = array(
                '@plugin' => $e->element
                    ->plugin(),
                '%label' => $e->element
                    ->label(),
                '@removed-plugin' => $removed_plugin,
                '!url' => url(RulesPluginUI::path($form_state['rules_config']->name, 'edit', $e->element)),
            );
            drupal_set_message(t('Deleting this @removed-plugin would break your configuration as some of its provided variables are utilized by the @plugin <a href="!url">%label</a>.', $args), 'warning');
        }
    }
    $confirm_question = t('Are you sure you want to delete the %element_plugin %element_name?', array(
        '%element_plugin' => $rules_element->plugin(),
        '%element_name' => $rules_element->label(),
    ));
    return confirm_form($form, $confirm_question, RulesPluginUI::path($rules_config->name), t('This action cannot be undone.'), t('Delete'), t('Cancel'));
}

/**
 * Rule config deletion form submit callback.
 */
function rules_ui_delete_element_submit($form, &$form_state) {
    $rules_config = $form_state['rules_config'];
    $rules_config->save();
    if (empty($form_state['redirect'])) {
        $form_state['redirect'] = RulesPluginUI::defaultRedirect($form_state['element_parent']);
    }
}

/**
 * Configure a rule element.
 */
function rules_ui_edit_element($form, &$form_state, $rules_config, $element, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    $form_state += array(
        'rules_element' => $element,
    );
    $form_state['rules_element']->form($form, $form_state, array(
        'button' => TRUE,
    ));
    return $form;
}

/**
 * Validate the element configuration.
 */
function rules_ui_edit_element_validate($form, &$form_state) {
    $form_state['rules_element']->form_validate($form, $form_state);
}

/**
 * Submit the element configuration.
 */
function rules_ui_edit_element_submit($form, &$form_state) {
    $form_state['rules_element']->form_submit($form, $form_state);
    drupal_set_message(t('Your changes have been saved.'));
    if (empty($form_state['redirect'])) {
        $form_state['redirect'] = RulesPluginUI::defaultRedirect($form_state['rules_element']);
    }
}

/**
 * Form builder for the "add event" page.
 */
function rules_ui_add_event_page($form, &$form_state, RulesTriggerableInterface $rules_config, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    RulesPluginUI::formDefaults($form, $form_state);
    $form = rules_ui_add_event($form, $form_state, $rules_config, $base_path);
    $form['#validate'][] = 'rules_ui_add_event_validate';
    return $form;
}

/**
 * Submit the event configuration.
 */
function rules_ui_add_event_page_submit($form, &$form_state) {
    rules_ui_add_event_apply($form, $form_state);
    $rules_config = $form_state['rules_config'];
    // Tell the user if this breaks something, but let him proceed.
    if (empty($rules_config->dirty)) {
        try {
            $rules_config->integrityCheck();
        } catch (RulesIntegrityException $e) {
            $warning = TRUE;
            drupal_set_message(t('Added the event, but it does not provide all variables utilized.'), 'warning');
        }
    }
    $rules_config->save();
    if (!isset($warning)) {
        $events = rules_fetch_data('event_info');
        $label = $events[$form_state['values']['event']]['label'];
        drupal_set_message(t('Added event %event.', array(
            '%event' => $label,
        )));
    }
}

/**
 * Add a new event.
 */
function rules_ui_add_event($form, &$form_state, RulesReactionRule $rules_config, $base_path) {
    $form_state += array(
        'rules_config' => $rules_config,
    );
    $events = array_diff_key(rules_fetch_data('event_info'), array_flip($rules_config->events()));
    $form['help'] = array(
        '#markup' => t('Select the event to add. However note that all added events need to provide all variables that should be available to your rule.'),
    );
    $form['event'] = array(
        '#type' => 'select',
        '#title' => t('React on event'),
        '#options' => RulesPluginUI::getOptions('event', $events),
        '#description' => t('Whenever the event occurs, rule evaluation is triggered.'),
        '#ajax' => rules_ui_form_default_ajax(),
        '#required' => TRUE,
    );
    if (!empty($form_state['values']['event'])) {
        $handler = rules_get_event_handler($form_state['values']['event']);
        $form['event_settings'] = $handler->buildForm($form_state);
    }
    else {
        $form['event_settings'] = array();
    }
    $form['submit'] = array(
        '#type' => 'submit',
        '#value' => t('Add'),
    );
    $form_state['redirect'] = RulesPluginUI::path($rules_config->name);
    return $form;
}

/**
 * Validation callback for adding an event.
 */
function rules_ui_add_event_validate($form, $form_state) {
    $handler = rules_get_event_handler($form_state['values']['event']);
    $handler->extractFormValues($form['event_settings'], $form_state);
    try {
        $handler->validate();
    } catch (RulesIntegrityException $e) {
        form_set_error(implode('][', $e->keys), $e->getMessage());
    }
}

/**
 * Submit callback that just adds the selected event.
 *
 * @see rules_admin_add_reaction_rule()
 */
function rules_ui_add_event_apply($form, &$form_state) {
    $handler = rules_get_event_handler($form_state['values']['event']);
    $handler->extractFormValues($form['event_settings'], $form_state);
    $form_state['rules_config']->event($form_state['values']['event'], $handler->getSettings());
}

/**
 * Form to remove an event from a rule.
 */
function rules_ui_remove_event($form, &$form_state, $rules_config, $event, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    $form_state += array(
        'rules_config' => $rules_config,
        'rules_event' => $event,
    );
    $event_info = rules_get_event_info($event);
    $form_state['event_label'] = $event_info['label'];
    $confirm_question = t('Are you sure you want to remove the event?');
    return confirm_form($form, $confirm_question, RulesPluginUI::path($rules_config->name), t('You are about to remove the event %event.', array(
        '%event' => $form_state['event_label'],
    )), t('Remove'), t('Cancel'));
}

/**
 * Submit the event configuration.
 */
function rules_ui_remove_event_submit($form, &$form_state) {
    $rules_config = $form_state['rules_config'];
    $rules_config->removeEvent($form_state['rules_event']);
    // Tell the user if this breaks something, but let him proceed.
    if (empty($rules_config->dirty)) {
        try {
            $rules_config->integrityCheck();
        } catch (RulesIntegrityException $e) {
            $warning = TRUE;
            drupal_set_message(t('Removed the event, but it had provided some variables which are now missing.'), 'warning');
        }
    }
    $rules_config->save();
    if (!isset($warning)) {
        drupal_set_message(t('Event %event has been removed.', array(
            '%event' => $form_state['event_label'],
        )));
    }
    $form_state['redirect'] = RulesPluginUI::path($rules_config->name);
}

/**
 * Import form for rule configurations.
 */
function rules_ui_import_form($form, &$form_state, $base_path) {
    RulesPluginUI::$basePath = $base_path;
    RulesPluginUI::formDefaults($form, $form_state);
    $form['import'] = array(
        '#type' => 'textarea',
        '#title' => t('Import'),
        '#description' => t('Paste an exported Rules configuration here.'),
        '#rows' => 20,
    );
    $form['overwrite'] = array(
        '#title' => t('Overwrite'),
        '#type' => 'checkbox',
        '#description' => t('If checked, any existing configuration with the same identifier will be replaced by the import.'),
        '#default_value' => FALSE,
    );
    $form['submit'] = array(
        '#type' => 'submit',
        '#value' => t('Import'),
    );
    return $form;
}

/**
 * Validation callback for the import form.
 */
function rules_ui_import_form_validate($form, &$form_state) {
    if ($rules_config = rules_import($form_state['values']['import'], $error_msg)) {
        // Store the successfully imported entity in $form_state.
        $form_state['rules_config'] = $rules_config;
        // Check for existing entities with the same identifier.
        if ($existing_config = rules_config_load($rules_config->name)) {
            // Don't import and overwrite the existing configuration unless the user
            // has checked the 'overwrite' box.
            if (!$form_state['values']['overwrite']) {
                $vars = array(
                    '@entity' => t('Rules configuration'),
                    '%label' => $rules_config->label(),
                );
                form_set_error('import', t('Import of @entity %label failed, a @entity with the same machine name already exists. Check the overwrite option to replace it.', $vars));
            }
            // Don't import if the existing configuration has the status ENTITY_FIXED
            // because that means the configuration can't be modified.
            if ($existing_config->status == ENTITY_FIXED) {
                $vars = array(
                    '@entity' => t('Rules configuration'),
                    '%label' => $rules_config->label(),
                );
                form_set_error('import', t("Import of @entity %label failed, a @entity with the same machine name already exists and is marked as ENTITY_FIXED meaning it can't be mofified.", $vars));
            }
        }
        try {
            $rules_config->integrityCheck();
        } catch (RulesIntegrityException $e) {
            form_set_error('import', t('Integrity check for the imported configuration failed. Error message: %message.', array(
                '%message' => $e->getMessage(),
            )));
        }
        if (!user_access('bypass rules access') && !$rules_config->access()) {
            form_set_error('import', t('You have insufficient access permissions for importing this Rules configuration.'));
        }
    }
    else {
        form_set_error('import', t('Import failed.'));
        if ($error_msg) {
            drupal_set_message($error_msg, 'error');
        }
    }
}

/**
 * Submit callback for the import form.
 */
function rules_ui_import_form_submit($form, &$form_state) {
    $rules_config = $form_state['rules_config'];
    if ($existing_config = rules_config_load($rules_config->name)) {
        // Copy DB id and remove the new indicator to overwrite the existing record.
        $rules_config->id = $existing_config->id;
        // Set the ENTITY_CUSTOM bit in the status bitmask, because the
        // configuration has now been customized by the import.
        $rules_config->status = $existing_config->status | ENTITY_CUSTOM;
        unset($rules_config->is_new);
    }
    $rules_config->save();
    $vars = array(
        '@entity' => t('Rules configuration'),
        '%label' => $rules_config->label(),
    );
    watchdog('rules_config', 'Imported @entity %label.', $vars);
    drupal_set_message(t('Imported @entity %label.', $vars));
    $form_state['redirect'] = RulesPluginUI::$basePath;
}

/**
 * FAPI process callback for the data selection widget.
 *
 * This finalises the auto completion callback path by appending the form build
 * id.
 */
function rules_data_selection_process($element, &$form_state, $form) {
    $element['#autocomplete_path'] .= '/' . $form['#build_id'];
    $form_state['cache'] = TRUE;
    return $element;
}

/**
 * Autocomplete data selection results.
 */
function rules_ui_form_data_selection_auto_completion($parameter, $form_build_id, $string = '') {
    // Get the form and its state from the cache to get the currently edited
    // or created element.
    $form_state = form_state_defaults();
    $form = form_get_cache($form_build_id, $form_state);
    if (!isset($form_state['rules_element'])) {
        return;
    }
    $element = $form_state['rules_element'];
    $params = $element->pluginParameterInfo();
    $matches = array();
    if (isset($params[$parameter])) {
        $parts = explode(':', $string);
        // Remove the last part as it might be unfinished.
        $last_part = array_pop($parts);
        $selector = implode(':', $parts);
        // Start with the partly given selector or from scratch.
        $result = array();
        if ($selector && ($wrapper = $element->applyDataSelector($selector))) {
            $result = RulesData::matchingDataSelector($wrapper, $params[$parameter], $selector . ':', 0);
        }
        elseif (!$selector) {
            $result = RulesData::matchingDataSelector($element->availableVariables(), $params[$parameter], '', 0);
        }
        foreach ($result as $selector => $info) {
            // If we have an incomplete last part, take it into account now.
            $attributes = array();
            if (!$last_part || strpos($selector, $string) === 0) {
                $attributes['class'][] = 'rules-dsac-item';
                $attributes['title'] = isset($info['description']) ? strip_tags($info['description']) : '';
                if ($selector[strlen($selector) - 1] == ':') {
                    $attributes['class'][] = 'rules-dsac-group';
                    $text = check_plain($selector) . '... (' . check_plain($info['label']) . ')';
                }
                else {
                    $text = check_plain($selector) . ' (' . check_plain($info['label']) . ')';
                }
                $matches[$selector] = "<div" . drupal_attributes($attributes) . ">{$text}</div>";
            }
        }
    }
    drupal_json_output($matches);
}

/**
 * FAPI validation of an integer element.
 *
 * Copy of the core Drupal private function _element_validate_integer().
 */
function rules_ui_element_integer_validate($element, &$form_state) {
    $value = $element['#value'];
    if (isset($value) && $value !== '' && (!is_numeric($value) || intval($value) != $value)) {
        form_error($element, t('%name must be an integer value.', array(
            '%name' => isset($element['#title']) ? $element['#title'] : t('Element'),
        )));
    }
}

/**
 * FAPI validation of a decimal element.
 *
 * Improved version of the private function _element_validate_number().
 */
function rules_ui_element_decimal_validate($element, &$form_state) {
    // Substitute the decimal separator ",".
    $value = strtr($element['#value'], ',', '.');
    if ($value != '' && !is_numeric($value)) {
        form_error($element, t('%name must be a number.', array(
            '%name' => $element['#title'],
        )));
    }
    elseif ($value != $element['#value']) {
        form_set_value($element, $value, $form_state);
    }
}

/**
 * FAPI callback to validate an IP address.
 */
function rules_ui_element_ip_address_validate($element, &$form_state) {
    $value = $element['#value'];
    if ($value != '' && !filter_var($value, FILTER_VALIDATE_IP)) {
        form_error($element, t('%name is not a valid IP address.', array(
            '%name' => $element['#title'],
        )));
    }
}

/**
 * FAPI validation of a date element.
 *
 * Makes sure the specified date format is correct and converts date values
 * specify a fixed (= non relative) date to a timestamp. Relative dates are
 * handled by the date input evaluator.
 */
function rules_ui_element_date_validate($element, &$form_state) {
    $value = $element['#value'];
    if ($value == '' || is_numeric($value) && intval($value) == $value) {
        // The value is a timestamp.
        return;
    }
    elseif (is_string($value) && RulesDateInputEvaluator::gmstrtotime($value) === FALSE) {
        form_error($element, t('Wrong date format. Specify the date in the format %format.', array(
            '%format' => gmdate('Y-m-d H:i:s', time() + 86400),
        )));
    }
    elseif (is_string($value) && RulesDateInputEvaluator::isFixedDateString($value)) {
        // As the date string specifies a fixed format, we can convert it now.
        $value = RulesDateInputEvaluator::gmstrtotime($value);
        form_set_value($element, $value, $form_state);
    }
}

/**
 * FAPI process callback for the duration element type.
 */
function rules_ui_element_duration_process($element, &$form_state) {
    $element['value'] = array(
        '#type' => 'textfield',
        '#size' => 8,
        '#element_validate' => array(
            'rules_ui_element_integer_validate',
        ),
        '#default_value' => $element['#default_value'],
        '#required' => !empty($element['#required']),
    );
    $element['multiplier'] = array(
        '#type' => 'select',
        '#options' => rules_ui_element_duration_multipliers(),
        '#default_value' => 1,
    );
    // Put the child elements in a container-inline div.
    $element['value']['#prefix'] = '<div class="rules-duration container-inline">';
    $element['multiplier']['#suffix'] = '</div>';
    // Set an appropriate multiplier.
    if (!empty($element['value']['#default_value'])) {
        foreach (array_keys(rules_ui_element_duration_multipliers()) as $m) {
            if ($element['value']['#default_value'] % $m == 0) {
                $element['multiplier']['#default_value'] = $m;
            }
        }
        // Divide value by the multiplier, so the display is correct.
        $element['value']['#default_value'] /= $element['multiplier']['#default_value'];
    }
    return $element;
}

/**
 * Defines possible duration multiplier.
 */
function rules_ui_element_duration_multipliers() {
    return array(
        1 => t('seconds'),
        60 => t('minutes'),
        3600 => t('hours'),
        // Just use approximate numbers for days (might last 23h on DST change),
        // months and years.
86400 => t('days'),
        86400 * 30 => t('months'),
        86400 * 30 * 12 => t('years'),
    );
}

/**
 * Helper function a rules duration form element.
 *
 * Determines the value for a rules duration form element.
 */
function rules_ui_element_duration_value($element, $input = FALSE) {
    // This runs before child elements are processed, so we cannot calculate the
    // value here. But we have to make sure the value is an array, so the form
    // API is able to process the children to set their values in the array. Thus
    // once the form API has finished processing the element, the value is an
    // array containing the child element values. Then finally the after build
    // callback converts it back to the numeric value and sets that.
    return array();
}

/**
 * FAPI after build callback for the duration parameter type form.
 *
 * Fixes up the form value by applying the multiplier.
 */
function rules_ui_element_duration_after_build($element, &$form_state) {
    if ($element['value']['#value'] !== '') {
        $element['#value'] = $element['value']['#value'] * $element['multiplier']['#value'];
        form_set_value($element, $element['#value'], $form_state);
    }
    else {
        $element['#value'] = NULL;
        form_set_value($element, NULL, $form_state);
    }
    return $element;
}

/**
 * FAPI after build callback to ensure empty form elements result in no value.
 */
function rules_ui_element_fix_empty_after_build($element, &$form_state) {
    if (isset($element['#value']) && $element['#value'] === '') {
        $element['#value'] = NULL;
        form_set_value($element, NULL, $form_state);
    }
    elseif ($element['#type'] == 'text_format' && !isset($element['value']['#value'])) {
        form_set_value($element, NULL, $form_state);
    }
    return $element;
}

/**
 * FAPI after build callback for specifying a list of values.
 *
 * Turns the textual value in an array by splitting the text in chunks using the
 * delimiter set at $element['#delimiter'].
 */
function rules_ui_list_textarea_after_build($element, &$form_state) {
    $element['#value'] = $element['#value'] ? explode($element['#delimiter'], $element['#value']) : array();
    $element['#value'] = array_map('trim', $element['#value']);
    form_set_value($element, $element['#value'], $form_state);
    return $element;
}

/**
 * FAPI pre render callback. Turns the value back to a string for rendering.
 *
 * @see rules_ui_list_textarea_after_build()
 */
function rules_ui_list_textarea_pre_render($element) {
    $element['#value'] = implode($element['#delimiter'], $element['#value']);
    return $element;
}

/**
 * FAPI callback to validate a list of integers.
 */
function rules_ui_element_integer_list_validate($element, &$form_state) {
    foreach ($element['#value'] as $value) {
        if ($value !== '' && (!is_numeric($value) || intval($value) != $value)) {
            form_error($element, t('Each value must be an integer.'));
        }
    }
}

/**
 * FAPI callback to validate a token.
 */
function rules_ui_element_token_validate($element) {
    $value = $element['#value'];
    if (isset($value) && $value !== '' && !entity_property_verify_data_type($value, 'token')) {
        form_error($element, t('%name may only contain lowercase letters, numbers, and underscores and has to start with a letter.', array(
            '%name' => isset($element['#title']) ? $element['#title'] : t('Element'),
        )));
    }
}

/**
 * FAPI callback to validate a list of tokens.
 */
function rules_ui_element_token_list_validate($element, &$form_state) {
    foreach ($element['#value'] as $value) {
        if ($value !== '' && !entity_property_verify_data_type($value, 'token')) {
            form_error($element, t('Each value may only contain lowercase letters, numbers, and underscores and has to start with a letter.'));
        }
    }
}

/**
 * FAPI callback to validate a machine readable name.
 */
function rules_ui_element_machine_name_validate($element, &$form_state) {
    if ($element['#value'] && !preg_match('!^[a-z0-9_]+$!', $element['#value'])) {
        form_error($element, t('Machine-readable names must contain only lowercase letters, numbers, and underscores.'));
    }
}

/**
 * FAPI callback to validate the form for editing variable info.
 *
 * @see RulesPluginUI::getVariableForm()
 */
function rules_ui_element_variable_form_validate($elements, &$form_state) {
    $names = array();
    foreach (element_children($elements['items']) as $item_key) {
        $element =& $elements['items'][$item_key];
        if ($element['name']['#value'] || $element['type']['#value'] || $element['label']['#value']) {
            foreach (array(
                'name' => t('Machine name'),
                'label' => t('Label'),
                'type' => t('Data type'),
            ) as $key => $title) {
                if (!$element[$key]['#value']) {
                    form_error($element[$key], t('!name field is required.', array(
                        '!name' => $title,
                    )));
                }
            }
            if (isset($names[$element['name']['#value']])) {
                form_error($element['name'], t('The machine-readable name %name is already taken.', array(
                    '%name' => $element['name']['#value'],
                )));
            }
            $names[$element['name']['#value']] = TRUE;
        }
    }
}

/**
 * Helper to sort elements by their 'weight' key.
 */
function rules_element_sort_helper($a, $b) {
    $a += array(
        'weight' => 0,
    );
    $b += array(
        'weight' => 0,
    );
    if ($a['weight'] == $b['weight']) {
        return 0;
    }
    return $a['weight'] < $b['weight'] ? -1 : 1;
}

/**
 * Form after build handler to set the static base path.
 *
 * @see RulesPluginUI::formDefaults()
 */
function rules_form_after_build_restore_base_path($form, &$form_state) {
    if (isset($form_state['_rules_base_path'])) {
        RulesPluginUI::$basePath = $form_state['_rules_base_path'];
    }
    return $form;
}

/**
 * AJAX page callback to load tag suggestions.
 *
 * Largely copied from taxonomy_autocomplete().
 */
function rules_autocomplete_tags($tags_typed = '') {
    // The user enters a comma-separated list of tags. We only autocomplete the
    // last tag.
    $tags_typed = drupal_explode_tags($tags_typed);
    $tag_last = drupal_strtolower(array_pop($tags_typed));
    $tag_matches = array();
    if ($tag_last != '') {
        $query = db_select('rules_tags', 'rt');
        // Do not select already entered terms.
        if (!empty($tags_typed)) {
            $query->condition('rt.tag', $tags_typed, 'NOT IN');
        }
        // Select rows that match by tag name.
        $tags_return = $query->distinct()
            ->fields('rt', array(
            'tag',
        ))
            ->condition('rt.tag', '%' . db_like($tag_last) . '%', 'LIKE')
            ->groupBy('rt.tag')
            ->range(0, 10)
            ->execute()
            ->fetchCol();
        $prefix = count($tags_typed) ? drupal_implode_tags($tags_typed) . ', ' : '';
        foreach ($tags_return as $name) {
            $n = $name;
            // Tag names containing commas or quotes must be wrapped in quotes.
            if (strpos($name, ',') !== FALSE || strpos($name, '"') !== FALSE) {
                $n = '"' . str_replace('"', '""', $name) . '"';
            }
            $tag_matches[$prefix . $n] = check_plain($name);
        }
    }
    drupal_json_output($tag_matches);
}