add-page-by-form.php

<?php

namespace Grav\Plugin;

use Composer\Autoload\ClassLoader;
use Grav\Common\Filesystem\Folder;
use Grav\Common\Grav;
use Grav\Common\Page\Page;
use Grav\Common\Plugin;
use RocketTheme\Toolbox\Event\Event;
use RocketTheme\Toolbox\File\YamlFile;
use Symfony\Component\Yaml\Yaml;

/**
 * Class AddPageByFormPlugin
 * @package Grav\Plugin
 */
class AddPageByFormPlugin extends Plugin
{

    private $new_page_route = '';
    private $say_my_name = ['addpage', 'add_page'];
    private $page_frontmatter = array();

    protected $post = array();

    /**
     * Composer autoload.
     *
     * @return \Composer\Autoload\ClassLoader
     */
    public function autoload(): \Composer\Autoload\ClassLoader
    {
        return require __DIR__ . '/vendor/autoload.php';
    }
    
    /**
     * Extends a path
     *
     * @param string path
     * @param mixed page
     * @param string slug
     *
     * @return string
     */
    public function buildPath($path, $page, $slug)
    {
        if (!is_null($page)) {
            return $path . DS . $page->folder();
        } else {
            return $path . DS . $slug;
        }
    }

    /**
     * Extends a route
     *
     * @param string $route
     * @param mixed $page
     * @param string $slug
     *
     * @return string $route
     */
    public function buildRoute($route, $page, $slug)
    {
        if (!is_null($page)) {
            return $route . DS . $page->slug();
        } else {
            return $route . DS . $slug;
        }
    }

    /**
     * Copy uploaded files and return list of properties
     *
     * @param mixed $form
     * @param mixed $new_page
     *
     * @return array $file_fields
     */
    public function copyFiles($form, $new_page)
    {
        // Copy uploaded files to the new page folder
        // and prepare uploaded file properties

        $new_page_path = $new_page->relativePagePath();

        $file_fields = array();
        $deleted_files = array();

        $flash = $form->getFlash();
        $fields = $flash->getFilesByFields();

        foreach ($fields as $file_field => $uploads) {
            $file_fields[$file_field] = array();
            foreach ($uploads as $file_name => $upload) {

                // When upload field has been emptied $upload == null
                if ($upload) {
                    $file_name = $upload->getClientFilename();
                    $destination = $upload->getDestination();

                    // Do the actual file copy unless destination is in tmp/forms
                    if (strpos($destination, 'tmp/forms') === false) {
                        $full_name = $new_page_path . DS . $file_name;
                        $upload->moveTo($full_name);
                    } else {
                        $full_name = $destination;
                        // Leave the copy to the Form plugin
                    }

                    $file_fields[$file_field][$file_name] = [
                        'name' => $file_name,
                        'type' => $upload->getClientMediaType(),
                        'size' => $upload->getSize(),
                        'path' => $full_name
                    ];
                } else {
                    // Uploaded file was removed by the user
                    $to_be_deleted = $new_page_path . DS . $file_name;
                    array_push($deleted_files, array('file_field' => $file_field, 'file_path' => $to_be_deleted));
                }
            }
        }

        return array('uploaded' => $file_fields, 'deleted' => $deleted_files);
    }

    /**
     *
     * @param string $route
     * @param boolean $create
     *
     * @return array|null [route, path]
     *
     * Crawl a route, using modular page folder names as a fallback and
     * optionally creating non existing folders along the way
     */
    public function crawlRoute($route, $create = false)
    {
        $path = USER_DIR . 'pages';
        if (!is_null($route) && isset($route)) {
            if ($route != DS) {
                $slugs = explode(DS, $route);
                $route = '';
                for ($i = 1; $i < count($slugs); $i++) {
                    $page = $this->pageExists($route, $slugs[$i]);
                    if (is_null($page)) {
                        if ($create) {
                            // Create folder if it doesn't exist
                            $slugs[$i] = $this->createFolder($path . DS . $slugs[$i]);
                        } else {
                            return null;
                        }
                    }
                    $route = $this->buildRoute($route, $page, $slugs[$i]);
                    $path = $this->buildPath($path, $page, $slugs[$i]);
                }
            }
        }
        return ['route' => $route, 'path' => $path];
    }

    /**
     * Create a folder if it does not exist
     *
     * @param string $path
     *
     * @return string $folder_name
     */
    public function createFolder($path)
    {
        $folder_names = explode(DS, $path);
        $folder_name = $folder_names[count($folder_names) - 1];
        if (!file_exists($path)) {
            // split and sanitize leaf as a slug (disallowing periods)
            $folder_name = $this->sanitize($folder_name, 'slug');
            unset($folder_names[count($folder_names) - 1]);
            $path = implode(DS, $folder_names);
            Folder::create($path . DS . $folder_name);
        }
        return $folder_name;
    }


    /**
     * Custom filter_var
     *
     * Based upon: https://gist.github.com/chtombleson/10002134
     * Get a value from $_POST and sanitize it
     *
     * @param string $var    Variable to check
     * @param string $type   What type is the value (string, email, int, float, encoded, url, email)
     * @param array  $option Options for filter_var
     * @return mixed will return false on failure
     */
    public function filter_post_var($var, $type = 'string', $options = array())
    {
        if (!isset($this->post[$var])) {
            return false;
        }

        return filter_var($this->post[$var], $this->get_filter($type), $options);
    }

    /**
     * Source: https://gist.github.com/chtombleson/10002134
     *
     */
    private function get_filter($type)
    {
        switch (strtolower($type)) {
            case 'string':
                $filter = FILTER_SANITIZE_STRING;
                break;

            case 'int':
                $filter = FILTER_SANITIZE_NUMBER_INT;
                break;

            case 'float' || 'decimal':
                $filter = FILTER_SANITIZE_NUMBER_FLOAT;
                break;

            case 'encoded':
                $filter = FILTER_SANITIZE_ENCODED;
                break;

            case 'url':
                $filter = FILTER_SANITIZE_URL;
                break;

            case 'email':
                $filter = FILTER_SANITIZE_EMAIL;
                break;

            default:
                $filter = FILTER_SANITIZE_STRING;
        }

        return $filter;
    }

    /**
     * Get parent page
     *
     * @param string $parent
     * @param object $page
     *
     * @return object $parent_page
     */
    public function getParentPage($parent, $page)
    {
        if ($parent != '') {
            // Check for a relative parent
            if ($parent[0] != DS) {
                // Make an absolute route starting from this form page
                $parent = $page->route() . DS . $parent;
            }

            // Check whether the parent page exists, allowing for modular pages
            // but disallowing empty folders in the route
            if (!is_null($this->crawlRoute($parent, false))) {
                $parent_page = $this->grav['page']->find($parent);
            } else {
                // Gracefully continue and falback to adding the
                // new page as a child page of the form page
                $parent_page = $page;
            }
        } else {
            $parent_page = $page;
        }

        return $parent_page; // can be a page or null if there is no page.
    }

    /**
     * @return array
     *
     * The getSubscribedEvents() gives the core a list of events
     *     that the plugin wants to listen to. The key of each
     *     array section is the event that the plugin listens to
     *     and the value (in the form of an array) contains the
     *     callable (or function) as well as the priority. The
     *     higher the number the higher the priority.
     */
    public static function getSubscribedEvents()
    {

        return [
            'onPluginsInitialized' => ['onPluginsInitialized', 0],
            'onFormProcessed' => ['onFormProcessed', 0]
        ];
    }

    /**
     * @return string
     * 
     * Return the state of a tristate configuration variable
     * 
     */
    public function getTriStateConfig($value, $state)
    {

        if (!isset($value)) {
            return '';
        }

        if ($value === $state) {
            return $state;
        }

        if (gettype($value) === "boolean") {
            if ($value) {
                return "true";
            } else {
                return "false";
            }
        }

        if (gettype($value) === "string") {
            $value = trim(strtolower($value));
        };

        if (in_array($value, [1, '1', 'on', 'true'], true)) {
            return 'true';
        } else {
            return 'false';
        }
    }

    /**
     * Handle form action
     *
     * @param $event
     *
     */
    public function onFormProcessed(Event $event)
    {
        $form = $event['form'];
        $action = $event['action'];
        $params = $event['params'];

        switch (true) {
            case (in_array($action, $this->say_my_name)):

                if (isset($_POST)) {

                    $pages = $this->grav['pages'];
                    $page = $this->grav['page'];
                    $header = $page->header();

                    // Get default settings form plugin config
                    $include_username = $this->config->get('plugins.add-page-by-form.include_username');

                    $overwrite_mode = $this->getTriStateConfig($this->config->get('plugins.add-page-by-form.overwrite_mode'), 'edit');

                    $date_format = $this->config->get('plugins.add-page-by-form.date_display_format');
                    $auto_taxonomy_types = $this->config->get('plugins.add-page-by-form.auto_taxonomy_types');
                    $physical_template_name = $this->config->get('plugins.add-page-by-form.physical_template_name');

                    $slug_field = '';

                    // For next plugin version
                    $include_timestamp = false;

                    // Initialize default subroute
                    $sub_route = '';

                    // Get settings from pageconfig block and override values via form fields
                    if (isset($header->pageconfig) && is_array($header->pageconfig)) {

                        $positives = ['1', 'on', 'true'];
                        $pageconfig = $header->pageconfig;

                        if (isset($pageconfig['parent'])) {
                            $parent = strtolower(trim($pageconfig['parent']));
                        }
                        if (isset($pageconfig['subroute'])) {
                            $sub_route = strtolower(trim($pageconfig['subroute']));
                        }
                        if (isset($pageconfig['include_username'])) {
                            $include_username = in_array(strtolower(trim($pageconfig['include_username'])), $positives);
                        }
                        if (isset($pageconfig['overwrite_mode'])) {
                            $overwrite_mode = $this->getTriStateConfig($pageconfig['overwrite_mode'], 'edit');
                        }
                        if (isset($pageconfig['slug_field'])) {
                            $slug_field = strtolower(trim($pageconfig['slug_field']));
                        }
                        if (isset($pageconfig['physical_template_name'])) {
                            $physical_template_name = in_array(strtolower(trim($pageconfig['physical_template_name'])), $positives);
                        }
                    }

                    // Assemble the new page frontmatter from the page_frontmatter block
                    // as set in the form page
                    if (isset($header->pagefrontmatter) && is_array($header->pagefrontmatter)) {
                        $page_frontmatter = $header->pagefrontmatter;
                    } else {
                        $page_frontmatter = array();
                    }

                    // Add username (or not)
                    if ($include_username) {
                        $username = null;
                        if (!is_null($this->grav['session']->user)) {
                            $username = $this->grav['session']->user->username;
                        }
                        if (is_null($username)) {
                            $username = '';
                        }
                        $page_frontmatter['username'] = $username;
                    }

                    // Get all form field values
                    $form_data = $form->value()->toArray();

                    if (isset($form_data)) {

                        // Append taxonomy
                        if (isset($form_data['taxonomy']) && is_array($form_data['taxonomy'])) {
                            // Convert comma separated list into array assuming double quoted items
                            foreach ($form_data['taxonomy'] as $key => $value) {
                                $values = str_getcsv($value, ',', '"');
                                foreach ($values as $k => $v) {
                                    $values[$k] = trim($v);
                                }
                                $form_data['taxonomy'][$key] = $values;
                            }
                            if (isset($page_frontmatter['taxonomy'])) {
                                // Append type/values
                                $page_frontmatter['taxonomy'] = array_merge_recursive($page_frontmatter['taxonomy'], $form_data['taxonomy']);
                                // Remove duplicate values
                                foreach ($page_frontmatter['taxonomy'] as $key => $value) {
                                    if (is_array($page_frontmatter['taxonomy'][$key])) {
                                        $page_frontmatter['taxonomy'][$key] = array_keys(array_flip($page_frontmatter['taxonomy'][$key]));
                                    }
                                }
                            } else {
                                // Add taxonomy, types and values
                                $page_frontmatter['taxonomy'] = $form_data['taxonomy'];
                            }
                            // Remove taxonomy from form data (to prevent merging raw data)
                            unset($form_data['taxonomy']);
                        }

                        if (isset($form_data['content'])) {
                            $form_data['form_content'] = $form_data['content'];
                            unset($form_data['content']);
                        }

                        // Merge variables from pagefrontmatter block and form fields;
                        // Values that have been through a Twig Processor are in the
                        // page_frontmatter and take precedence over the form values
                        $page_frontmatter = array_merge($page_frontmatter, $form_data);
                    }

                    // Here you can insert anything else into the new page frontmatter

                    /*
                    $result = 'Hello World';
                    $page_frontmatter['result'] = $result;
                    */

                    // If content is not included as a form value then fallback to config default
                    if (isset($page_frontmatter['form_content'])) {
                        $content = $page_frontmatter['form_content'];
                    } else {
                        $content = $this->config->get('plugins.add-page-by-form.default_content');
                    }

                    if ($physical_template_name && isset($page_frontmatter['template'])) {
                        $page_template = $page_frontmatter['template'];
                        // Remove the frontmatter variable template as which template
                        // must be used will be determined by the new page filename
                        unset($page_frontmatter['template']);
                    } else {
                        $page_template = 'default';
                    }

                    // Remove unwanted items from new page frontmatter
                    if (isset($page_frontmatter['_json'])) {
                        unset($page_frontmatter['_json']);
                    };
                    
                    if (isset($page_frontmatter['form_content'])) {
                        unset($page_frontmatter['form_content']);
                    };
                    
                    if (isset($page_frontmatter['parent'])) {
                        unset($page_frontmatter['parent']);
                    };

                    if (isset($page_frontmatter['subroute'])) {
                        unset($page_frontmatter['subroute']);
                    };

                    if (isset($page_frontmatter['honeypot'])) {
                        unset($page_frontmatter['honeypot']);
                    };

                    // Initialize default page parent
                    if (isset($header->parent)) {
                        // For backwards compatibility
                        $parent = $header->parent;
                    } else {
                        $parent = '';
                    }

                    // Override parent if set in pageconfig block
                    if (isset($pageconfig['parent'])) {
                        $parent = strtolower(trim($pageconfig['parent']));
                    }
                    // Override parent if set in the form
                    if (isset($form_data['parent'])) {
                        $parent = strtolower(trim($form_data['parent']));
                    }

                    // Removes multiple concatenated slashes plus a trailing slash if present
                    if (strlen($parent) > 1) {
                        $parent = preg_replace('/[\/]+/', DS, $parent);
                        $parent = rtrim($parent, DS);
                    }

                    // Get the "parent to be"
                    $parent_page = $this->getParentPage($parent, $page);

                    $parent_page_path = $parent_page->path();
                    $parent_page_route = $parent_page->route();

                    if ($overwrite_mode === 'edit') {
                        // Get slug of exisiting page
                        // Normal method
                        if (isset($form_data['edit_path'])) {
                            $slug = basename(dirname($form_data['edit_path']));
                        } else {
                            // Alternative method
                            if (isset($form_data['file_path'])) {
                                $slug = basename(dirname($form_data['file_path']));
                            } else {
                                $slug = '';
                            }
                        }
                    } else {
                        // Create the slug for the new page
                        // Override subroute
                        if (isset($form_data['subroute'])) {
                            $sub_route = mb_strtolower(trim($form_data['subroute']));
                        }
                        if ($sub_route != '') {
                            // Remove any multiple concatenated slashes
                            $sub_route = preg_replace('/[\/]+/', DS, $sub_route);
                            // Remove preceding and trailing slashes if present
                            $sub_route = trim($sub_route, DS);
                            // Prepare for crawling
                            $parent_page_route = $parent_page->route() . DS . $sub_route;
                            // Create subroute path if it doesn't exist
                            $parent_destination = $this->crawlRoute($parent_page_route, true);
                            $parent_page_route = $parent_destination['route'];
                            $parent_page_path = $parent_destination['path'];
                        }
                        // Create a slug to be used as the page name (used publicly in URLs etc.)
                        if ($slug_field != '') {
                            if (isset($page_frontmatter[$slug_field])) {
                                $slug = self::slug($page_frontmatter[$slug_field]);
                            }
                        }
                        if (!isset($slug)) {
                            if (isset($page_frontmatter['title'])) {
                                $slug = self::slug($page_frontmatter['title']);
                            } else {
                                $slug = $this->config->get('plugins.add-page-by-form.default_title');
                                $slug = self::slug($slug);
                            }
                        }
                    }

                    if (empty($slug)) {
                        $this->grav->fireEvent('onFormValidationError', new Event([
                            'form' => $form,
                            'message' => '<strong>ERROR</strong> in Add Page by Form Plugin: Variable \'slug\' is empty'
                        ]));
                        $event->stopPropagation();
                        return;
                    }

                    $new_page_folder = $parent_page_path . DS . $slug;

                    // Check overwrite mode
                    //  When overwrite mode == 'true' replace page including media
                    //  When overwrite mode == 'false' create a sequential named page
                    //  When overwrite mode == 'edit' edit page and page media
                    if ($overwrite_mode !== 'false') {
                        if (file_exists($new_page_folder)) {
                            if ($overwrite_mode === 'edit') {
                                $original_frontmatter = (array)$pages->get($new_page_folder)->header();
                            } else {
                                Folder::delete($new_page_folder);
                            }
                        }
                    } else {
                        // Scan for the next available sequential suffix
                        $version = 0;
                        // Keep incrementing the page slug suffix to keep earlier versions / duplicates
                        while (file_exists($new_page_folder)) {
                            $version += 1;
                            $new_page_folder = $parent_page_path . DS . $slug . '-' . $version;
                        }
                        if ($version > 0) {
                            $slug = $slug . '-' . $version;
                        }
                    }

                    // Create and add the page to Grav
                    try {

                        // Create new page
                        $new_page = new Page;

                        // Get active or default language for page filename
                        // (e.g. 'nl' -> 'default.nl.md')
                        $language = Grav::instance()['language']->getLanguage() ?: null;

                        $extension = '.md';

                        if ($language != '') {
                            $new_page_name = $page_template . '.' . $language . $extension;
                        } else {
                            $new_page_name = $page_template . $extension;
                        }

                        // Set the new page route taking the settings about the home page into account
                        if ($parent_page_route == DS) {
                            if ($this->config->get('system.home.hide_in_urls')) {
                                $route = DS . $slug;
                            } else {
                                $route = $this->grav['pages']->getHomeRoute() . DS . $slug;
                            }
                        } else {
                            $route = $parent_page_route . DS . $slug;
                        }

                        // Set page location vars
                        $new_page->name($new_page_name);
                        $new_page->folder($slug);
                        $new_page->path($parent_page_path . DS . $slug);
                        $new_page->extension($extension);
                        $new_page->parent($parent_page);
                        $new_page->filePath($parent_page_path . DS . $slug . DS . $new_page_name);
                        $new_page->routable(true);

                        // Add frontmatter vars
                        $new_page->header((object) $page_frontmatter);
                        $new_page->frontmatter(Yaml::dump((array)$new_page->header(), 20));

                        // Set page markdown content vars
                        $new_page->rawMarkdown((string) $content);
                        $new_page->file()->markdown($new_page->rawMarkdown());

                        // Add routing information
                        $pages->addPage($new_page, $this->new_page_route);


                        // Fire BeforePageSave event
                        $this->grav->fireEvent('onAddPageByFormPluginBeforePageSave', new Event(['page' => &$new_page]));

                        // Set time vars
                        $new_page->modified(time());

                        // First page save (required to have an existing new page folder
                        // to store any files with destination '@self' in)
                        $new_page->save();

                        // Copy uploaded files to the new page folder
                        $copy_files = $this->copyFiles($form, $new_page);
                        // Get uploaded files plus properties
                        $file_fields = $copy_files['uploaded'];

                        // If original frontmatter exists update it to keep
                        // already present page media
                        if (isset($original_frontmatter)) {

                            $file_fields_updated = array();
                            foreach ($file_fields as $file_field => $uploads) {
                                $file_fields_updated[$file_field] = array_merge($original_frontmatter[$file_field], $uploads);

                                // Get any (uploaded and then) deleted files
                                foreach ($copy_files['deleted'] as $file_to_delete) {
                                    if (file_exists($file_to_delete['file_path'])) {
                                        unlink($file_to_delete['file_path']);
                                        if (in_array($file_to_delete['file_path'], $file_fields_updated[$file_field][basename($file_to_delete['file_path'])])) {
                                            unset($file_fields_updated[$file_field][basename($file_to_delete['file_path'])]);
                                        }
                                    }
                                }
                            }
                            $file_fields = $file_fields_updated;
                        }

                        // Add uploaded file properties to frontmatter
                        if (isset($file_fields) && isset($page_frontmatter)) {
                            $page_frontmatter = array_merge($page_frontmatter, $file_fields);
                        }

                        // Add modified frontmatter to the page header
                        $new_page->header((object) $page_frontmatter);
                        $new_page->frontmatter(Yaml::dump((array)$new_page->header(), 20));

                        // Set time vars
                        $new_page->modified(time());

                        // Update the new page
                        $new_page->save();

                        // Store the route so it can be used to redirect to if needed and to be saved as a Twig var
                        $this->new_page_route = $route;
                        $this->page_frontmatter = $page_frontmatter;

                        // Process any new taxonomy types
                        if ($auto_taxonomy_types && isset($page_frontmatter['taxonomy'])) {

                            // Read site configuration
                            $grav = Grav::instance();
                            $locator = $grav['locator'];
                            $filename = 'config://site.yaml';
                            $file = YamlFile::instance($locator->findResource($filename, true, true));
                            $site_config = Yaml::parse($file->load());

                            // Merge taxonomy types
                            $taxonomies = (array) $this->config->get('site.taxonomies');
                            foreach (array_keys($page_frontmatter['taxonomy']) as $type) {
                                $taxonomies = array_merge($taxonomies, (array) $type);
                            }

                            // Don't bother if there are no new taxonomy types
                            if (count(array_unique($taxonomies)) > count($site_config['taxonomies'])) {
                                $this->config->set('site.taxonomies', $taxonomies);
                                $taxonomies_merged = array();
                                $taxonomies_merged['taxonomies'] = array_values(array_unique($taxonomies));
                                $site_config = array_merge($site_config, $taxonomies_merged);

                                // Update taxonomy types in site.yaml
                                $file->save($site_config);
                                $file->free();
                            }
                        }

                        // Fire AfterPageSave event
                        $this->grav->fireEvent('onAddPageByFormPluginAfterPageSave', new Event(['page' => $new_page]));
                    } catch (\Exception $e) {
                        $this->grav['debugger']->addMessage($e->getMessage());
                        $this->grav->fireEvent('onFormValidationError', new Event([
                            'form' => $form,
                            'message' => '<strong>ERROR:</strong> ' . $e->getMessage()
                        ]));
                        $event->stopPropagation();
                        return;
                    }
                }
                break;
            case ($action == 'redirect'):

                // The Form plugin does not know how to handle '@self' as a redirect
                // or display parameter, so prepare the redirect to the new page
                switch (strtolower((string) $params)) {
                    case '@self':
                        $route = $this->new_page_route;
                        break;
                    case '@self-admin':
                        $admin_route = $this->config->get('plugins.admin.route');
                        if ($admin_route && $this->config->get('plugins.admin.enabled')) {
                            $base = DS . trim($admin_route, DS);
                            $route = $base . DS . 'pages' . $this->new_page_route;
                        } else {
                            // Admin not installed or inactive
                            // Fall back to @self
                            $route = $this->new_page_route;
                        }
                        break;
                    default:
                        // No valid redirect to self parameter
                        $route = '';
                }

                // Do the redirect
                // BTW if there is no route the redirect is handed over to the Form plugin
                if ($route) {

                    /** @var Twig $twig */
                    $twig = $this->grav['twig'];
                    $twig->twig_vars['form'] = $form;
                    $twig->twig_vars['pagefrontmatter'] = $this->page_frontmatter;

                    /** @var Pages $pages */
                    $pages = $this->grav['pages'];
                    $page = $pages->dispatch($route, false);

                    // Redirect to the new page
                    unset($this->grav['page']);
                    $this->grav['page'] = $page;
                    $this->grav->redirect($route);
                }
                break;
        }
    }

    /**
     * Add assets
     *
     */
    public function onPageInitialized()
    {
        // Some forms (like forgot_password) do not have frontmatter
        if (null !== ($this->grav['page']->frontmatter())) {
            $data = Yaml::parse($this->grav['page']->frontmatter());
            // Only act upon forms which are intended to be processed by this plugin
            if (
                isset($data['form']) && isset($data['form']['name']) &&
                in_array(strtolower(substr($data['form']['name'], 0, 7)), $this->say_my_name)
            ) {

                if ($this->config->get('plugins.add-page-by-form.use_editor_class', true)) {
                    $assets = $this->grav['assets'];
                    // Add jQuery library (no harm done when already present)
                    $assets->add('jquery', 101);
                    // Add SimpleMDE Markdown Editor
                    $assets->addCss('//cdn.jsdelivr.net/simplemde/latest/simplemde.min.css', 100);
                    $assets->addJs('//cdn.jsdelivr.net/simplemde/latest/simplemde.min.js', 100);
                    // Add custom styles
                    $assets->addCss('plugin://add-page-by-form/assets/css/customstyles.css', 110);
                    // Load inline Javascript code from configuration file
                    $assets->addInlineJs(file_get_contents('plugin://add-page-by-form/assets/js/simplemde_config.js'), 110);
                }
            }
        }
    }

    /**
     * Initialize the plugin
     */
    public function onPluginsInitialized()
    {
        // Don't proceed if we are in the admin plugin
        if ($this->isAdmin()) {
            return;
        }
        // Enable the events we are interested in
        $this->enable([
            'onPageInitialized' => ['onPageInitialized', 0],
        ]);
    }

    /**
     * Check whether a page exists at the specified route irrespective of page type
     *
     * @param string $route
     * @param string $slug
     *
     * @return object $page
     */
    public function pageExists($route, $slug)
    {
        $page = $this->grav['page']->find($route . DS . $slug);
        if (is_null($page) && !empty($slug) && $slug[0] != '_') {
            $page = $this->grav['page']->find($route . DS . '_' . $slug);
        }
        return $page;
    }

    /**
     * Generates a slug of the given string
     * Source: Laravel str_slug()
     *
     * @param string $str
     * @param string $separator (optional)
     * @return string
     */
    public static function slug(string $str, string $separator = '-')
    {
        // Sanitize non-latin characters
        $str = self::sanitize($str, 'slug');

        // Convert all dashes/underscores into separator
        $flip = $separator === '-' ? '_' : '-';
        $str = preg_replace('![' . preg_quote($flip) . ']+!u', $separator, $str);

        // Replace @ with the word 'at'
        $str = str_replace('@', $separator . 'at' . $separator, $str);

        // Remove all characters that are not the separator, letters, numbers, or whitespace.
        $str = preg_replace('![^' . preg_quote($separator) . '\pL\pN\s]+!u', '', strtolower($str));

        // Replace all separator characters and whitespace by a single separator
        $str = preg_replace('![' . preg_quote($separator) . '\s]+!u', $separator, $str);

        return trim($str, $separator);
    }

    /**
     * Sanitize a string into a safe filename or slug
     * Using $type:
     *   'file': Create a valid filename string, allowing hyphens ("-") and dots (".")
     *   any other value: Create a string without dots e.g. to create a safe URL page name (slug)
     * 
     * A combination of various methods to sanitize a string while retaining
     * the "essence" of the original string as much as possible.
     * Note: unsuitable for file paths as '/' and '\' are filtered out.
     * Sources:
     * http://www.house6.com/blog/?p=83
     * and
     * http://stackoverflow.com/a/24984010
     *
     * @param string $f
     * @param string $type
     *
     * @return string
     */
    public static function sanitize($f, $type = 'file')
    {
        $replace_chars = array(
            '&amp;' => '-and-', '@' => '-at-', '©' => 'c', '®' => 'r', 'À' => 'a',
            'Á' => 'a', 'Â' => 'a', 'Ä' => 'a', 'Å' => 'a', 'Æ' => 'ae', 'Ç' => 'c',
            'È' => 'e', 'É' => 'e', 'Ë' => 'e', 'Ì' => 'i', 'Í' => 'i', 'Î' => 'i',
            'Ï' => 'i', 'Ò' => 'o', 'Ó' => 'o', 'Ô' => 'o', 'Õ' => 'o', 'Ö' => 'o',
            'Ø' => 'o', 'Ù' => 'u', 'Ú' => 'u', 'Û' => 'u', 'Ü' => 'u', 'Ý' => 'y',
            'ß' => 'ss', 'à' => 'a', 'á' => 'a', 'â' => 'a', 'ä' => 'a', 'å' => 'a',
            'æ' => 'ae', 'ç' => 'c', 'è' => 'e', 'é' => 'e', 'ê' => 'e', 'ë' => 'e',
            'ì' => 'i', 'í' => 'i', 'î' => 'i', 'ï' => 'i', 'ò' => 'o', 'ó' => 'o',
            'ô' => 'o', 'õ' => 'o', 'ö' => 'o', 'ø' => 'o', 'ù' => 'u', 'ú' => 'u',
            'û' => 'u', 'ü' => 'u', 'ý' => 'y', 'þ' => 'p', 'ÿ' => 'y', 'Ā' => 'a',
            'ā' => 'a', 'Ă' => 'a', 'ă' => 'a', 'Ą' => 'a', 'ą' => 'a', 'Ć' => 'c',
            'ć' => 'c', 'Ĉ' => 'c', 'ĉ' => 'c', 'Ċ' => 'c', 'ċ' => 'c', 'Č' => 'c',
            'č' => 'c', 'Ď' => 'd', 'ď' => 'd', 'Đ' => 'd', 'đ' => 'd', 'Ē' => 'e',
            'ē' => 'e', 'Ĕ' => 'e', 'ĕ' => 'e', 'Ė' => 'e', 'ė' => 'e', 'Ę' => 'e',
            'ę' => 'e', 'Ě' => 'e', 'ě' => 'e', 'Ĝ' => 'g', 'ĝ' => 'g', 'Ğ' => 'g',
            'ğ' => 'g', 'Ġ' => 'g', 'ġ' => 'g', 'Ģ' => 'g', 'ģ' => 'g', 'Ĥ' => 'h',
            'ĥ' => 'h', 'Ħ' => 'h', 'ħ' => 'h', 'Ĩ' => 'i', 'ĩ' => 'i', 'Ī' => 'i',
            'ī' => 'i', 'Ĭ' => 'i', 'ĭ' => 'i', 'Į' => 'i', 'į' => 'i', 'İ' => 'i',
            'ı' => 'i', 'IJ' => 'ij', 'ij' => 'ij', 'Ĵ' => 'j', 'ĵ' => 'j', 'Ķ' => 'k',
            'ķ' => 'k', 'ĸ' => 'k', 'Ĺ' => 'l', 'ĺ' => 'l', 'Ļ' => 'l', 'ļ' => 'l',
            'Ľ' => 'l', 'ľ' => 'l', 'Ŀ' => 'l', 'ŀ' => 'l', 'Ł' => 'l', 'ł' => 'l',
            'Ń' => 'n', 'ń' => 'n', 'Ņ' => 'n', 'ņ' => 'n', 'Ň' => 'n', 'ň' => 'n',
            'ʼn' => 'n', 'Ŋ' => 'n', 'ŋ' => 'n', 'Ō' => 'o', 'ō' => 'o', 'Ŏ' => 'o',
            'ŏ' => 'o', 'Ő' => 'o', 'ő' => 'o', 'Œ' => 'oe', 'œ' => 'oe', 'Ŕ' => 'r',
            'ŕ' => 'r', 'Ŗ' => 'r', 'ŗ' => 'r', 'Ř' => 'r', 'ř' => 'r', 'Ś' => 's',
            'ś' => 's', 'Ŝ' => 's', 'ŝ' => 's', 'Ş' => 's', 'ş' => 's', 'Š' => 's',
            'š' => 's', 'Ţ' => 't', 'ţ' => 't', 'Ť' => 't', 'ť' => 't', 'Ŧ' => 't',
            'ŧ' => 't', 'Ũ' => 'u', 'ũ' => 'u', 'Ū' => 'u', 'ū' => 'u', 'Ŭ' => 'u',
            'ŭ' => 'u', 'Ů' => 'u', 'ů' => 'u', 'Ű' => 'u', 'ű' => 'u', 'Ų' => 'u',
            'ų' => 'u', 'Ŵ' => 'w', 'ŵ' => 'w', 'Ŷ' => 'y', 'ŷ' => 'y', 'Ÿ' => 'y',
            'Ź' => 'z', 'ź' => 'z', 'Ż' => 'z', 'ż' => 'z', 'Ž' => 'z', 'ž' => 'z',
            'ſ' => 'z', 'Ə' => 'e', 'ƒ' => 'f', 'Ơ' => 'o', 'ơ' => 'o', 'Ư' => 'u',
            'ư' => 'u', 'Ǎ' => 'a', 'ǎ' => 'a', 'Ǐ' => 'i', 'ǐ' => 'i', 'Ǒ' => 'o',
            'ǒ' => 'o', 'Ǔ' => 'u', 'ǔ' => 'u', 'Ǖ' => 'u', 'ǖ' => 'u', 'Ǘ' => 'u',
            'ǘ' => 'u', 'Ǚ' => 'u', 'ǚ' => 'u', 'Ǜ' => 'u', 'ǜ' => 'u', 'Ǻ' => 'a',
            'ǻ' => 'a', 'Ǽ' => 'ae', 'ǽ' => 'ae', 'Ǿ' => 'o', 'ǿ' => 'o', 'ə' => 'e',
            'Ё' => 'jo', 'Є' => 'e', 'І' => 'i', 'Ї' => 'i', 'А' => 'a', 'Б' => 'b',
            'В' => 'v', 'Г' => 'g', 'Д' => 'd', 'Е' => 'e', 'Ж' => 'zh', 'З' => 'z',
            'И' => 'i', 'Й' => 'j', 'К' => 'k', 'Л' => 'l', 'М' => 'm', 'Н' => 'n',
            'О' => 'o', 'П' => 'p', 'Р' => 'r', 'С' => 's', 'Т' => 't', 'У' => 'u',
            'Ф' => 'f', 'Х' => 'h', 'Ц' => 'c', 'Ч' => 'ch', 'Ш' => 'sh', 'Щ' => 'sch',
            'Ъ' => '-', 'Ы' => 'y', 'Ь' => '-', 'Э' => 'je', 'Ю' => 'ju', 'Я' => 'ja',
            'а' => 'a', 'б' => 'b', 'в' => 'v', 'г' => 'g', 'д' => 'd', 'е' => 'e',
            'ж' => 'zh', 'з' => 'z', 'и' => 'i', 'й' => 'j', 'к' => 'k', 'л' => 'l',
            'м' => 'm', 'н' => 'n', 'о' => 'o', 'п' => 'p', 'р' => 'r', 'с' => 's',
            'т' => 't', 'у' => 'u', 'ф' => 'f', 'х' => 'h', 'ц' => 'c', 'ч' => 'ch',
            'ш' => 'sh', 'щ' => 'sch', 'ъ' => '-', 'ы' => 'y', 'ь' => '-', 'э' => 'je',
            'ю' => 'ju', 'я' => 'ja', 'ё' => 'jo', 'є' => 'e', 'і' => 'i', 'ї' => 'i',
            'Ґ' => 'g', 'ґ' => 'g', 'א' => 'a', 'ב' => 'b', 'ג' => 'g', 'ד' => 'd',
            'ה' => 'h', 'ו' => 'v', 'ז' => 'z', 'ח' => 'h', 'ט' => 't', 'י' => 'i',
            'ך' => 'k', 'כ' => 'k', 'ל' => 'l', 'ם' => 'm', 'מ' => 'm', 'ן' => 'n',
            'נ' => 'n', 'ס' => 's', 'ע' => 'e', 'ף' => 'p', 'פ' => 'p', 'ץ' => 'C',
            'צ' => 'c', 'ק' => 'q', 'ר' => 'r', 'ש' => 'w', 'ת' => 't', '™' => 'tm',
            'Ã' => 'A', 'Ð' => 'Dj', 'Ê' => 'E', 'Ñ' => 'N', 'Þ' => 'B', 'ã' => 'a',
            'ð' => 'o', 'ñ' => 'n', '#' => '-nr-'
        );
        // "Translate" multi byte characters to 'corresponding' ASCII characters
        $f = strtr($f, $replace_chars);
        // Convert special characters to a hyphen
        $f = str_replace(array(
            ' ', '!', '\\', '/', '\'', '`', '"', '~', '%', '|',
            '*', '$', '^', '(', ')', '[', ']', '{', '}',
            '+', ',', ':', ';', '<', '=', '>', '?', '|'
        ), '-', $f);
        // Remove any non ASCII characters
        $f = preg_replace('/[^(\x20-\x7F)]*/', '', $f);
        if ($type == 'file') {
            // Remove non-word chars (leaving hyphens and periods)
            $f = preg_replace('/[^\w\-\.]+/', '', $f);
            // Convert multiple adjacent dots into a single one
            $f = preg_replace('/[\.]+/', '.', $f);
        } else { // Do not allow periods, for instance for a Grav slug
            // Convert period to hyphen
            $f = str_replace('.', '-', $f);
            // Remove non-word chars (leaving hyphens)
            $f = preg_replace('/[^\w\-]+/', '', $f);
        }
        // Convert multiple adjacent hyphens into a single one
        $f = preg_replace('/[\-]+/', '-', $f);
        // Change into a lowercase string; BTW no need to use mb_strtolower() here ;)
        $f = strtolower($f);
        return $f;
    }
}