MDL-61768 repository_googledocs: Support shared drives

Enables the Google Drive repository to support browsing and searching
for content from the existing shared drives.

repository/googledocs/classes/googledocs_content.php

@@ -0,0 +1,120 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs;
+
+/**
+ * Base class for presenting the googledocs repository contents.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+abstract class googledocs_content {
+
+    /** @var rest The rest API object. */
+    protected $service;
+
+    /** @var string The current path. */
+    protected $path;
+
+    /** @var bool Whether sorting should be applied to the fetched content. */
+    protected $sortcontent;
+
+    /**
+     * Constructor.
+     *
+     * @param rest $service The rest API object
+     * @param string $path The current path
+     * @param bool $sortcontent Whether sorting should be applied to the content
+     */
+    public function __construct(rest $service, string $path, bool $sortcontent = true) {
+        $this->service = $service;
+        $this->path = $path;
+        $this->sortcontent = $sortcontent;
+    }
+
+    /**
+     * Generate and return an array containing all repository node (files and folders) arrays for the existing content
+     * based on the path or search query.
+     *
+     * @param string $query The search query
+     * @param callable $isaccepted The callback function which determines whether a given file should be displayed
+     *                             or filtered based on the existing file restrictions
+     * @return array The array containing the repository content node arrays
+     */
+    public function get_content_nodes(string $query, callable $isaccepted): array {
+        $files = [];
+        $folders = [];
+
+        foreach ($this->get_contents($query) as $gdcontent) {
+            $node = helper::get_node($gdcontent, $this->path);
+            // Create the repository node array.
+            $nodearray = $node->create_node_array();
+            // If the repository node array was successfully generated and the type of the content is accepted,
+            // add it to the repository content nodes array.
+            if ($nodearray && $isaccepted($nodearray)) {
+                // Group the content nodes by type (files and folders). Generate unique array keys for each content node
+                // which will be later used by the sorting function. Note: Using the item id along with the name as key
+                // of the array because Google Drive allows files and folders with identical names.
+                if (isset($nodearray['source'])) { // If the content node has a source attribute, it is a file node.
+                    $files["{$nodearray['title']}{$nodearray['id']}"] = $nodearray;
+                } else {
+                    $folders["{$nodearray['title']}{$nodearray['id']}"] = $nodearray;
+                }
+            }
+        }
+        // If sorting is required, order the results alphabetically by their array keys.
+        if ($this->sortcontent) {
+            \core_collator::ksort($files, \core_collator::SORT_STRING);
+            \core_collator::ksort($folders, \core_collator::SORT_STRING);
+        }
+
+        return array_merge(array_values($folders), array_values($files));
+    }
+
+    /**
+     * Build the navigation (breadcrumb) from a given path.
+     *
+     * @return array Array containing name and path of each navigation node
+     */
+    public function get_navigation(): array {
+        $nav = [];
+        $navtrail = '';
+        $pathnodes = explode('/', $this->path);
+
+        foreach ($pathnodes as $node) {
+            list($id, $name) = helper::explode_node_path($node);
+            $name = empty($name) ? $id : $name;
+            $nav[] = [
+                'name' => $name,
+                'path' => helper::build_node_path($id, $name, $navtrail),
+            ];
+            $tmp = end($nav);
+            $navtrail = $tmp['path'];
+        }
+
+        return $nav;
+    }
+
+    /**
+     * Returns all relevant contents (files and folders) based on the given path or search query.
+     *
+     * @param string $query The search query
+     * @return array The array containing the contents
+     */
+    abstract protected function get_contents(string $query): array;
+}

repository/googledocs/classes/googledocs_content_search.php

@@ -0,0 +1,67 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs;
+
+/**
+ * Utility class for displaying google drive content that matched a given search criteria.
+ *
+ * This class is responsible for generating the content that is returned based on a given search query.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class googledocs_content_search extends googledocs_content {
+
+    /**
+     * Returns all relevant contents based on the given path and/or search query.
+     *
+     * The method fetches all content (files) through an API call that matches a given search criteria.
+     *
+     * @param string $query The search query
+     * @return array The array containing the contents
+     */
+    protected function get_contents(string $query): array {
+        $searchterm = str_replace("'", "\'", $query);
+
+        // Define the parameters required by the API call.
+        // Query all contents which name contains $searchterm and have not been trashed.
+        $q = "fullText contains '{$searchterm}' AND trashed = false";
+        // The file fields that should be returned in the response.
+        $fields = "files(id,name,mimeType,webContentLink,webViewLink,fileExtension,modifiedTime,size,iconLink)";
+
+        $params = [
+            'q' => $q,
+            'fields' => $fields,
+            'spaces' => 'drive',
+        ];
+
+        // If shared drives exist, include the additional required parameters in order to extend the content search
+        // into the shared drives area as well.
+        $response = helper::request($this->service, 'shared_drives_list', []);
+        if (!empty($response->drives)) {
+            $params['supportsAllDrives'] = 'true';
+            $params['includeItemsFromAllDrives'] = 'true';
+            $params['corpora'] = 'allDrives';
+        }
+
+        // Request the content through the API call.
+        $response = helper::request($this->service, 'list', $params);
+
+        return $response->files ?? [];
+    }
+}

repository/googledocs/classes/helper.php

@@ -0,0 +1,143 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs;
+
+use repository_googledocs\local\browser\googledocs_root_content;
+use repository_googledocs\local\browser\googledocs_shared_drives_content;
+use repository_googledocs\local\browser\googledocs_drive_content;
+use repository_googledocs\local\node\node;
+use repository_googledocs\local\node\file_node;
+use repository_googledocs\local\node\folder_node;
+
+/**
+ * Helper class for the googledocs repository.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class helper {
+
+    /**
+     * Generates a safe path to a node.
+     *
+     * Typically, a node will be id|name of the node.
+     *
+     * @param string $id The ID of the node
+     * @param string $name The name of the node, will be URL encoded
+     * @param string $root The path to append the node on (must be a result of this function)
+     * @return string The path to the node
+     */
+    public static function build_node_path(string $id, string $name = '', string $root = ''): string {
+        $path = $id;
+        if (!empty($name)) {
+            $path .= '|' . urlencode($name);
+        }
+        if (!empty($root)) {
+            $path = trim($root, '/') . '/' . $path;
+        }
+        return $path;
+    }
+
+    /**
+     * Returns information about a node in a path.
+     *
+     * @param string $node The node string to extract information from
+     * @return array The array containing the information about the node
+     * @see self::build_node_path()
+     */
+    public static function explode_node_path(string $node): array {
+        if (strpos($node, '|') !== false) {
+            list($id, $name) = explode('|', $node, 2);
+            $name = urldecode($name);
+        } else {
+            $id = $node;
+            $name = '';
+        }
+        $id = urldecode($id);
+
+        return [
+            0 => $id,
+            1 => $name,
+            'id' => $id,
+            'name' => $name,
+        ];
+    }
+
+    /**
+     * Returns the relevant googledocs content browser class based on the given path.
+     *
+     * @param rest $service The rest API object
+     * @param string $path The current path
+     * @return googledocs_content The googledocs repository content browser
+     */
+    public static function get_browser(rest $service, string $path): googledocs_content {
+        $pathnodes = explode('/', $path);
+        $currentnode = self::explode_node_path(array_pop($pathnodes));
+
+        // Return the relevant content browser class based on the ID of the current path node.
+        switch ($currentnode['id']) {
+            case \repository_googledocs::REPOSITORY_ROOT_ID:
+                return new googledocs_root_content($service, $path, false);
+            case \repository_googledocs::SHARED_DRIVES_ROOT_ID:
+                return new googledocs_shared_drives_content($service, $path);
+            default:
+                return new googledocs_drive_content($service, $path);
+        }
+    }
+
+    /**
+     * Returns the relevant repository content node class based on the Google Drive file's mimetype.
+     *
+     * @param \stdClass $gdcontent The Google Drive content (file/folder) object
+     * @param string $path The current path
+     * @return node The content node object
+     */
+    public static function get_node(\stdClass $gdcontent, string $path): node {
+        // Return the relevant content browser class based on the ID of the current path node.
+        switch ($gdcontent->mimeType) {
+            case 'application/vnd.google-apps.folder':
+                return new folder_node($gdcontent, $path);
+            default:
+                return new file_node($gdcontent);
+        }
+    }
+
+    /**
+     * Wrapper function to perform an API call and also catch and handle potential exceptions.
+     *
+     * @param rest $service The rest API object
+     * @param string $api The name of the API call
+     * @param array $params The parameters required by the API call
+     * @return \stdClass The response object
+     * @throws \repository_exception
+     */
+    public static function request(rest $service, string $api, array $params): ?\stdClass {
+        try {
+            // Retrieving files and folders.
+            $response = $service->call($api, $params);
+        } catch (\Exception $e) {
+            if ($e->getCode() == 403 && strpos($e->getMessage(), 'Access Not Configured') !== false) {
+                // This is raised when the service Drive API has not been enabled on Google APIs control panel.
+                throw new \repository_exception('servicenotenabled', 'repository_googledocs');
+            }
+            throw $e;
+        }
+
+        return $response;
+    }
+}

repository/googledocs/classes/local/browser/googledocs_drive_content.php

@@ -0,0 +1,74 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs\local\browser;
+
+use repository_googledocs\googledocs_content;
+use repository_googledocs\helper;
+
+/**
+ * Utility class for browsing content from or within a specified google drive.
+ *
+ * This class is responsible for generating the content that would be displayed for a specified drive such as
+ * 'my drive' or any existing shared drive. It also supports generating data for paths which are located
+ * within a given drive.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class googledocs_drive_content extends googledocs_content {
+
+    /**
+     * Returns all relevant contents based on the given path or search query.
+     *
+     * The method fetches all existing content (files and folders) located in a specific folder under a given drive
+     * through an API call.
+     *
+     * @param string $query The search query
+     * @return array The array containing the contents
+     */
+    protected function get_contents(string $query): array {
+
+        $id = str_replace("'", "\'", $query);
+        // Define the parameters required by the API call.
+        // Query all files and folders which have not been trashed and located directly in the folder whose ID is $id.
+        $q = "'{$id}' in parents AND trashed = false";
+        // The file fields that should be returned in the response.
+        $fields = 'files(id,name,mimeType,webContentLink,webViewLink,fileExtension,modifiedTime,size,iconLink)';
+
+        $params = [
+            'q' => $q,
+            'fields' => $fields,
+            'spaces' => 'drive',
+        ];
+
+        // Check whether there are any shared drives.
+        $response = helper::request($this->service, 'shared_drives_list', []);
+        if (!empty($response->drives)) {
+            // To be able to include content from shared drives, we need to enable 'supportsAllDrives' and
+            // 'includeItemsFromAllDrives'. The Google Drive API requires explicit request for inclusion of content from
+            // shared drives and also a confirmation that the application is designed to handle files on shared drives.
+            $params['supportsAllDrives'] = 'true';
+            $params['includeItemsFromAllDrives'] = 'true';
+        }
+
+        // Request the content through the API call.
+        $response = helper::request($this->service, 'list', $params);
+
+        return $response->files ?? [];
+    }
+}

repository/googledocs/classes/local/browser/googledocs_root_content.php

@@ -0,0 +1,67 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs\local\browser;
+
+use repository_googledocs\googledocs_content;
+use repository_googledocs\helper;
+
+/**
+ * Utility class for browsing the content within the googledocs repository root.
+ *
+ * This class is responsible for generating the content that would be displayed in the googledocs repository root.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class googledocs_root_content extends googledocs_content {
+
+    /**
+     * Returns all relevant contents based on the given path or search query.
+     *
+     * The method predefines the content which will be displayed in the repository root level. Currently,
+     * only the folders representing 'My drives' and 'Shared drives' will be displayed in the root level.
+     *
+     * @param string $query The search query
+     * @return array The array containing the contents
+     */
+    protected function get_contents(string $query): array {
+        // Add 'My drive' folder into the displayed contents.
+        $contents = [
+            (object)[
+                'id' => \repository_googledocs::MY_DRIVE_ROOT_ID,
+                'name' => get_string('mydrive', 'repository_googledocs'),
+                'mimeType' => 'application/vnd.google-apps.folder',
+                'modifiedTime' => '',
+            ],
+        ];
+
+        // If shared drives exists, include 'Shared drives' folder to the displayed contents.
+        $response = helper::request($this->service, 'shared_drives_list', []);
+
+        if (!empty($response->drives)) {
+            $contents[] = (object)[
+                'id' => \repository_googledocs::SHARED_DRIVES_ROOT_ID,
+                'name' => get_string('shareddrives', 'repository_googledocs'),
+                'mimeType' => 'application/vnd.google-apps.folder',
+                'modifiedTime' => '',
+            ];
+        }
+
+        return $contents;
+    }
+}

repository/googledocs/classes/local/browser/googledocs_shared_drives_content.php

@@ -0,0 +1,60 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs\local\browser;
+
+use repository_googledocs\googledocs_content;
+use repository_googledocs\helper;
+
+/**
+ * Utility class for browsing the content within the googledocs repository shared drives root.
+ *
+ * This class is responsible for generating the content that would be displayed in the googledocs repository
+ * shared drives root.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class googledocs_shared_drives_content extends googledocs_content {
+
+    /**
+     * Returns all relevant contents based on the given path or search query.
+     *
+     * The method generates the content which will be displayed in the repository shared drives root level.
+     * All existing shared drives will be fetched through an API call and presented as folders.
+     *
+     * @param string $query The search query
+     * @return array The array containing the contents
+     */
+    protected function get_contents(string $query): array {
+        // Make an API request to get all existing shared drives.
+        $response = helper::request($this->service, 'shared_drives_list', []);
+        // If shared drives exist, create folder for each shared drive.
+        if ($shareddrives = $response->drives) {
+            return array_map(function($shareddrive) {
+                return (object)[
+                    'id' => $shareddrive->id,
+                    'name' => $shareddrive->name,
+                    'mimeType' => 'application/vnd.google-apps.folder',
+                    'modifiedTime' => '',
+                ];
+            }, $shareddrives);
+        }
+
+        return [];
+    }
+}

repository/googledocs/classes/local/node/file_node.php

@@ -0,0 +1,200 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs\local\node;
+
+/**
+ * Class used to represent a file node in the googledocs repository.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class file_node implements node {
+
+    /** @var string The ID of the file node. */
+    private $id;
+
+    /** @var string|null The title of the file node. */
+    private $title;
+
+    /** @var string|null The file's export format. */
+    private $exportformat;
+
+    /** @var string The external link to the file. */
+    private $link;
+
+    /** @var string The timestamp representing the last modified date. */
+    private $modified;
+
+    /** @var string|null The size of the file. */
+    private $size;
+
+    /** @var string The thumbnail of the file. */
+    private $thumbnail;
+
+    /**
+     * Constructor.
+     *
+     * @param \stdClass $gdfile The Google Drive file object
+     */
+    public function __construct(\stdClass $gdfile) {
+        $this->id = $gdfile->id;
+        $this->title = $this->generate_file_title($gdfile);
+        $this->exportformat = $this->generate_file_export_format($gdfile);
+        $this->link = $this->generate_file_link($gdfile);
+        $this->modified = ($gdfile->modifiedTime) ? strtotime($gdfile->modifiedTime) : '';
+        $this->size = !empty($gdfile->size) ? $gdfile->size : null;
+        // Use iconLink as a file thumbnail if set, otherwise use the default icon depending on the file type.
+        // Note: The Google Drive API can return a link to a preview thumbnail of the file (via thumbnailLink).
+        // However, in many cases the Google Drive files are not public and an authorized request is required
+        // to get the thumbnail which we currently do not support. Therefore, to avoid displaying broken
+        // thumbnail images in the repository, the icon of the Google Drive file is being used as a thumbnail
+        // instead as it does not require an authorized request.
+        // Currently, the returned file icon link points to the 16px version of the icon by default which would result
+        // in displaying 16px file thumbnails in the repository. To avoid this, the link can be slightly modified in
+        // order to get a larger version of the icon as there isn't an option to request this through the API call.
+        $this->thumbnail = !empty($gdfile->iconLink) ? str_replace('/16/', '/64/', $gdfile->iconLink) : '';
+    }
+
+    /**
+     * Create a repository file array.
+     *
+     * This method returns an array which structure is compatible to represent a file node in the repository.
+     *
+     * @return array|null The node array or null if the node could not be created
+     */
+    public function create_node_array(): ?array {
+        // Cannot create the file node if the file title was not generated or the export format.
+        // This means that the current file type is invalid or unknown.
+        if (!$this->title || !$this->exportformat) {
+            return null;
+        }
+
+        return [
+            'id' => $this->id,
+            'title' => $this->title,
+            'source' => json_encode(
+                [
+                    'id' => $this->id,
+                    'name' => $this->title,
+                    'link' => $this->link,
+                    'exportformat' => $this->exportformat,
+                ]
+            ),
+            'date' => $this->modified,
+            'size' => $this->size,
+            'thumbnail' => $this->thumbnail,
+            'thumbnail_height' => 64,
+            'thumbnail_width' => 64,
+        ];
+    }
+
+    /**
+     * Generates and returns the title for the file node depending on the type of the Google drive file.
+     *
+     * @param \stdClass $gdfile The Google Drive file object
+     * @return string The file title
+     */
+    private function generate_file_title(\stdClass $gdfile): ?string {
+        // Determine the file type through the file extension.
+        if (isset($gdfile->fileExtension)) { // The file is a regular file.
+            return $gdfile->name;
+        } else { // The file is probably a Google Doc file.
+            // We need to generate the name by appending the proper google doc extension.
+            $type = str_replace('application/vnd.google-apps.', '', $gdfile->mimeType);
+
+            if ($type === 'document') {
+                return "{$gdfile->name}.gdoc";
+            }
+            if ($type === 'presentation') {
+                return "{$gdfile->name}.gslides";
+            }
+            if ($type === 'spreadsheet') {
+                return "{$gdfile->name}.gsheet";
+            }
+            if ($type === 'drawing') {
+                $config = get_config('googledocs');
+                $ext = $config->drawingformat;
+                return "{$gdfile->name}.{$ext}";
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Generates and returns the file export format depending on the type of the Google drive file.
+     *
+     * @param \stdClass $gdfile The Google Drive file object
+     * @return string The file export format
+     */
+    private function generate_file_export_format(\stdClass $gdfile): ?string {
+        // Determine the file type through the file extension.
+        if (isset($gdfile->fileExtension)) { // The file is a regular file.
+            // The file has an extension, therefore we can download it.
+            return 'download';
+        } else {
+            // The file is probably a Google Doc file, we get the corresponding export link.
+            $type = str_replace('application/vnd.google-apps.', '', $gdfile->mimeType);
+            $types = get_mimetypes_array();
+            $config = get_config('googledocs');
+
+            if ($type === 'document' && !empty($config->documentformat)) {
+                $ext = $config->documentformat;
+                if ($ext === 'rtf') {
+                    // Moodle user 'text/rtf' as the MIME type for RTF files.
+                    // Google uses 'application/rtf' for the same type of file.
+                    // See https://developers.google.com/drive/v3/web/manage-downloads.
+                    return 'application/rtf';
+                } else {
+                    return $types[$ext]['type'];
+                }
+            }
+            if ($type === 'presentation' && !empty($config->presentationformat)) {
+                $ext = $config->presentationformat;
+                return $types[$ext]['type'];
+            }
+            if ($type === 'spreadsheet' && !empty($config->spreadsheetformat)) {
+                $ext = $config->spreadsheetformat;
+                return $types[$ext]['type'];
+            }
+            if ($type === 'drawing' && !empty($config->drawingformat)) {
+                $ext = $config->drawingformat;
+                return $types[$ext]['type'];
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Generates and returns the external link to the file.
+     *
+     * @param \stdClass $gdfile The Google Drive file object
+     * @return string The link to the file
+     */
+    private function generate_file_link(\stdClass $gdfile): string {
+        // If the google drive file has webViewLink set, use it as an external link.
+        $link = !empty($gdfile->webViewLink) ? $gdfile->webViewLink : '';
+        // Otherwise, use webContentLink if set or leave the external link empty.
+        if (empty($link) && !empty($gdfile->webContentLink)) {
+            $link = $gdfile->webContentLink;
+        }
+
+        return $link;
+    }
+}

repository/googledocs/classes/local/node/folder_node.php

@@ -0,0 +1,76 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs\local\node;
+
+use repository_googledocs\helper;
+
+/**
+ * Class used to represent a folder node in the googledocs repository.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class folder_node implements node {
+
+    /** @var string The ID of the folder node. */
+    private $id;
+
+    /** @var string The title of the folder node. */
+    private $title;
+
+    /** @var bool The timestamp representing the last modified date. */
+    private $modified;
+
+    /** @var string The path of the folder node. */
+    private $path;
+
+    /**
+     * Constructor.
+     *
+     * @param \stdClass $gdfolder The Google Drive folder object
+     * @param string $path The path of the folder node
+     */
+    public function __construct(\stdClass $gdfolder, string $path) {
+        $this->id = $gdfolder->id;
+        $this->title = $gdfolder->name;
+        $this->modified = $gdfolder->modifiedTime ? strtotime($gdfolder->modifiedTime) : '';
+        $this->path = $path;
+    }
+
+    /**
+     * Create a repository folder array.
+     *
+     * This method returns an array which structure is compatible to represent a folder node in the repository.
+     *
+     * @return array|null The node array or null if the node could not be created
+     */
+    public function create_node_array(): ?array {
+        global $OUTPUT;
+
+        return [
+            'id' => $this->id,
+            'title' => $this->title,
+            'path' => helper::build_node_path($this->id, $this->title, $this->path),
+            'date' => $this->modified,
+            'thumbnail' => $OUTPUT->image_url(file_folder_icon(64))->out(false),
+            'thumbnail_height' => 64,
+            'thumbnail_width' => 64,
+            'children' => [],
+        ];
+    }
+}

repository/googledocs/classes/local/node/node.php

@@ -0,0 +1,37 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace repository_googledocs\local\node;
+
+/**
+ * The googledocs repository content node interface.
+ *
+ * @package    repository_googledocs
+ * @copyright  2021 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+interface node {
+
+    /**
+     * Create a repository node array.
+     *
+     * This method returns an array which structure is compatible to represent a content node (file/folder)
+     * in the repository.
+     *
+     * @return array|null The node array or null if the node could not be created
+     */
+    public function create_node_array(): ?array;
+}