<?php
/**
 * Google Classroom Integration
 *
 * @package TutorPro\Addons
 * @subpackage GoogleClassroom
 * @author Themeum <support@themeum.com>
 * @link https://themeum.com
 * @since 2.0.0
 */

namespace TUTOR_GC;

use \Google_Service_Classroom;
use \Google_Client;

use \Google_Service_Script;
use \Google_Service_Script_CreateProjectRequest;
use \Google_Service_Script_ScriptFile;
use \Google_Service_Script_Content;
use \Google_Service_Script_ExecutionRequest;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

require_once tutor_pro()->path . '/vendor/autoload.php';

/**
 * Class Classroom
 */
class Classroom {

	private $upload_dir;
	private $credential_path;
	private $token_path;
	private $google_callback_url;
	private $client;

	private $service_classroom;
	private $current_credential;
	private $credential_owner;

	private $gc_user_identifier        = 'tutor_gc_user_from_class';
	private $gc_post_time              = 'tutor_gc_post_time';
	private $remote_class              = 'tutor_gc_remote_class_cache';
	private $remote_class_owner        = 'tutor_gc_remote_class_owner';
	private $course_credential         = 'tutor_gc_engaged_credential_serial';
	private $credential_serial         = 'tutor_gc_user_current_credential_serial';
	private $classroom_key             = 'tutor_gc_classroom_id';
	private $temporary_password        = 'tutor_gc_temp_raw_password';
	public static $password_reset_base = 'tutor-student-password-reset';

	private $required_scopes = array(
		Google_Service_Classroom::CLASSROOM_COURSES_READONLY,
		Google_Service_Classroom::CLASSROOM_ROSTERS_READONLY,
		Google_Service_Classroom::CLASSROOM_PROFILE_PHOTOS,
		Google_Service_Classroom::CLASSROOM_PROFILE_EMAILS,
		Google_Service_Classroom::CLASSROOM_TOPICS_READONLY,
		Google_Service_Classroom::CLASSROOM_ANNOUNCEMENTS_READONLY,
		Google_Service_Classroom::CLASSROOM_COURSEWORK_ME_READONLY,
		Google_Service_Classroom::CLASSROOM_COURSEWORK_STUDENTS_READONLY,
	);

	// Initialize necessary rsource.
	public function __construct( $owner_id = null, $post_id = null, $ret = false ) {

		if ( $ret ) {
			return;
		}

		// Set credential owner.
		$this->credential_owner = $owner_id ? $owner_id : ( $post_id ? get_post_field( 'post_author', $post_id ) : get_current_user_id() );

		// Set credential serial.
		$credential_serial            = get_user_meta( $this->credential_owner, $this->credential_serial, true );
		$post_id ? $credential_serial = get_post_meta( $post_id, $this->course_credential, true ) : 0;

		$this->current_credential = ( $credential_serial && is_numeric( $credential_serial ) ) ? $credential_serial : 0;

		$this->upload_dir          = wp_upload_dir()['basedir'] . DIRECTORY_SEPARATOR . 'tutor-gc' . DIRECTORY_SEPARATOR . $this->credential_owner;
		$this->credential_path     = $this->get_credential_path();
		$this->token_path          = $this->get_token_path();
		$this->google_callback_url = get_home_url() . '/' . init::$google_callback_string . '/';

		// Init client if credential loaded.
		$this->is_credential_loaded() ? $this->init_client() : 0;

		// Init services.
		( $this->is_credential_loaded() && $this->is_app_permitted() ) ? $this->init_service() : 0;
	}

	private function get_credential_path( $serial = null ) {
		return $this->upload_dir . DIRECTORY_SEPARATOR . 'credential-' . ( $serial ? $serial : $this->current_credential ) . '.json';
	}

	private function get_token_path( $serial = null ) {
		return $this->upload_dir . DIRECTORY_SEPARATOR . 'token-' . ( $serial ? $serial : $this->current_credential ) . '.json';
	}

	// Set up google client.
	private function init_client() {

		$this->client = new Google_Client();
		$this->client->setApplicationName( get_bloginfo( 'name' ) );
		$this->client->setAuthConfig( $this->credential_path );
		$this->client->setRedirectUri( $this->google_callback_url );
		$this->client->addScope( $this->required_scopes );
		$this->client->setAccessType( 'offline' );
		$this->client->setApprovalPrompt( 'force' );

		$this->assign_token();
	}

	private function init_service() {
		$this->service_classroom = new Google_Service_Classroom( $this->client );
	}

	public function get_who_logged_in() {
		return $this->service_classroom->userProfiles->get( 'me' );
	}

	public function upgrade_credential_serial() {
		$serial = $this->current_credential + 1;
		update_user_meta( $this->credential_owner, $this->credential_serial, $serial );
	}

	// Check if credential file uploaded.
	public function is_credential_loaded() {
		return file_exists( $this->credential_path );
	}

	// Check if the app is permitted by user via consent screen.
	public function is_app_permitted() {
		return $this->assign_token() === false ? false : true;
	}

	// Upload credential file.
	public function save_credential( $file ) {

		// Create dir if already not.
		wp_mkdir_p( $this->upload_dir );

		// Store the file.
		$serial = $this->current_credential + 1;
		$path   = $this->get_credential_path( $serial );
		move_uploaded_file( $file['tmp_name'], $path );

		// Assign the current credential serial.
		update_user_meta( $this->credential_owner, $this->credential_serial, $serial );
	}

	// Return consent screen url.
	public function get_consent_screen_url() {
		return $this->client->createAuthUrl();
	}

	/**
	 * Assign the existing token, or try to refresh if expired.
	 *
	 * @return mixed
	 */
	public function assign_token() {

		if ( file_exists( $this->token_path ) ) {
			$token = json_decode( file_get_contents( $this->token_path ), true );
			try {
				$this->client->setAccessToken( $token );
			} catch ( \Throwable $th ) {
				tutor_log( $token, $th->getMessage() );
			}
		}

		// Check if token expired.
		if ( $this->client->isAccessTokenExpired() ) {

			$refresh_token = $this->client->getRefreshToken();

			if ( ! $refresh_token ) {
				return false;
			}

			$new_token = null;

			try {
				$new_token = $this->client->fetchAccessTokenWithRefreshToken( $refresh_token );
			} catch ( \Exception $e ) {
				if ( $e ) {
					return false;
				}
			}

			$this->save_token( null, $new_token );
		}
	}

	/**
	 * Save token provided by google.
	 *
	 * @param mixed $code code.
	 * @param mixed $token token.
	 *
	 * @return void
	 */
	public function save_token( $code = null, $token = null ) {

		if ( ! $token ) {
			$token = $this->client->fetchAccessTokenWithAuthCode( $code );
			$this->client->setAccessToken( $token );
			$token = $this->client->getAccessToken();
		}

		file_put_contents( $this->get_token_path(), json_encode( $token ) );
	}

	// Fetch class list from google.
	public function get_class_list() {
		// Get classroom list from google.
		$course_list = $this->service_classroom->courses->listCourses( array( 'courseStates' => 'ACTIVE' ) );
		$courses     = $course_list->getCourses();

		// Determine if locally imported class exists for the remote classroom ID.
		$posts = get_posts(
			array(
				'meta_key'       => $this->classroom_key,
				'post_type'      => tutor()->course_post_type,
				'post_status'    => array( 'publish', 'draft', 'trash' ),
				'posts_per_page' => -1,
			)
		);

		if ( is_array( $posts ) ) {

			// Loop through all the local post.
			foreach ( $posts as $post ) {
				$connected_class_id = get_post_meta( $post->ID, $this->classroom_key, true );

				// Loop through all the classroom.
				foreach ( $courses as $index => $course ) {
					if ( $course->id == $connected_class_id ) {
						$courses[ $index ]->local_class_post = $post;
					}
				}
			}
		}

		return $courses;
	}

	public function get_imported_class_list( $page = 1 ) {

		$per_page = 16;
		$page     = $page - 1;
		$offset   = $page * $per_page;

		$post_args = array(
			'meta_key'       => $this->classroom_key,
			'post_type'      => tutor()->course_post_type,
			'post_status'    => array( 'publish' ),
			'posts_per_page' => $per_page,
			'offset'         => $offset,
		);

		$posts                        = get_posts( $post_args );
		! is_array( $posts ) ? $posts = array() : 0;

		$src = tutor()->url . 'assets/images/placeholder.svg';

		foreach ( $posts as $index => $post ) {
			$posts[ $index ]->remote_class       = $this->get_remote_class( $post->ID );
			$posts[ $index ]->remote_class_owner = get_post_meta( $post->ID, $this->remote_class_owner, true );

			$post_thumbnail_id                   = (int) get_post_thumbnail_id( $post->ID );
			$posts[ $index ]->post_thumbnail_url = $post_thumbnail_id ? wp_get_attachment_image_url( $post_thumbnail_id, 300, false ) : $src;
		}

		return $posts;
	}

	public function is_google_class( $course_id, $return_classroom_url = false ) {
		$remote_id   = get_post_meta( $course_id, $this->classroom_key, true );
		$remote_post = $this->get_remote_class( $course_id );

		return ( is_numeric( $remote_id ) && $remote_id > 0 ) ? ( $return_classroom_url ? $remote_post->alternateLink : true ) : false;
	}

	private function get_course_students( $course ) {

		$course_id = is_object( $course ) ? $course->id : $course;
		$students  = array();

		if ( $this->service_classroom ) {
			$students = $this->service_classroom->courses_students->listCoursesStudents( $course_id );
			$students = $students->getStudents();
		}

		return is_array( $students ) ? $students : array();
	}

	private function filter_privileged_content( $remote_id, $contents ) {

		$current_user  = get_userdata( get_current_user_id() );
		$current_email = $current_user->user_email;

		$remote_students = $this->get_course_students( $remote_id );
		$new_contents    = array();

		foreach ( $contents as $content ) {
			if ( ! isset( $content->individualStudentsOptions ) ) {
				$new_contents[] = $content;
				continue;
			}

			$specific_students                        = $content->individualStudentsOptions->studentIds;
			! $specific_students ? $specific_students = array() : 0;

			foreach ( $remote_students as $student ) {
				$id    = $student->profile->id;
				$email = $student->profile->emailAddress;

				if ( in_array( $id, $specific_students ) && $email == $current_email ) {
					$new_contents[] = $content;
					break;
				}
			}
		}

		return $new_contents;
	}

	public function get_stream( $local_id, $token = null, $only_stream = false ) {

		$remote_id = get_post_meta( $local_id, $this->classroom_key, true );

		$page_arg                       = array( 'pageSize' => 10 );
		$token ? $page_arg['pageToken'] = $token : 0;

		$announcements = array();
		$next_token    = '';

		try {
			if ( $this->service_classroom ) {
				$announcements_list = $this->service_classroom->courses_announcements->listCoursesAnnouncements( $remote_id, $page_arg );
				$announcements      = $announcements_list->getAnnouncements();
				$next_token         = $announcements_list->getNextPageToken();
			}
		} catch ( \Exception $e ) {

		}

		! is_array( $announcements ) ? $announcements = array() : 0;

		if ( $only_stream ) {
			return $announcements;
		}

		$announcements = $this->filter_privileged_content( $remote_id, $announcements );
		$user_cache    = array();

		// Assign bulk user object.
		foreach ( $announcements as $index => $announcement ) {

			$creator_id = $announcement->creatorUserId;

			if ( ! array_key_exists( $creator_id, $user_cache ) ) {
				// Load user data if not loaded already.
				$user_cache[ $creator_id ] = $this->service_classroom->userProfiles->get( $creator_id );
			}

			$announcements[ $index ]->creator_user_object = $user_cache[ $creator_id ];
		}

		return array(
			'announcements' => $announcements,
			'next_token'    => $next_token,
		);
	}

	public function get_remote_class( $local_id ) {
		$remote = get_post_meta( $local_id, $this->remote_class, true );
		return is_object( $remote ) ? $remote : null;
	}

	public function get_all_remote_attachments( $local_id ) {
		$remote_class = $this->get_remote_class( $local_id );
		$remote_id    = ( is_object( $remote_class ) && property_exists( $remote_class, 'id' ) ) ? $remote_class->id : null;
		$materials    = array();

		if ( ! $remote_id ) {
			// It might be null somewhere.
			return $materials;
		}

		// Get Assignment/Coursework Materials.
		$course_works = array();
		try {
			if ( $this->service_classroom ) {
				$course_works = $this->service_classroom->courses_courseWork->listCoursesCourseWork( $remote_id );
				$course_works = $course_works->getCourseWork();
			}
		} catch ( \Exception $e ) {

		}

		$course_works = is_array( $course_works ) ? $this->filter_privileged_content( $remote_id, $course_works ) : array();
		foreach ( $course_works as $work ) {
			$materials = array_merge( $materials, ( $work->materials ? $work->materials : array() ) );
		}

		// Get stream materials.
		$streams = $this->get_stream( $local_id, null, true );
		foreach ( $streams as $stream ) {
			$materials = array_merge( $materials, ( $stream->materials ? $stream->materials : array() ) );
		}

		return $materials;
	}

	/* ------------------Import class from Google to WP------------------ */
	public function import_class( $class_id, bool $enroll_student ) {

		// Set execution time to 60 seconds.
		// Now there are heavy tasks like interaction with google and mail sending to auto registered students.
		set_time_limit( 60 );

		$course = $this->service_classroom->courses->get( $class_id );

		// Create course at first.
		$post_id = $this->import_course_post( $course );

		// Register students.
		if ( $enroll_student ) {
			$student_ids = $this->register_students( $course );

			// Enroll students.
			foreach ( $student_ids as $user_id ) {
				tutor_utils()->do_enroll( $post_id, 0, $user_id );
			}
		}

		return $post_id;
	}

	private function get_local_id( $remote_id ) {

		// Check if already imported.
		$existing_arg = array(
			'meta_key'       => $this->classroom_key,
			'meta_value'     => $remote_id,
			'post_type'      => tutor()->course_post_type,
			'post_status'    => array( 'publish', 'draft', 'trash' ),
			'posts_per_page' => 1,
		);

		$posts = get_posts( $existing_arg );

		return ( is_array( $posts ) && isset( $posts[0] ) ) ? $posts[0]->ID : null;
	}

	// Import Root course post.
	private function import_course_post( $course ) {

		$post =
		array(
			'post_author'    => get_current_user_id(),
			'post_title'     => $course->descriptionHeading,
			'post_content'   => $course->description ? $course->description : '',
			'post_status'    => 'draft',
			'comment_status' => 'closed',
			'ping_status'    => 'closed',
			'post_type'      => tutor()->course_post_type,
			'post_parent'    => 0,
		);

		// Avoid accidental duplication.
		$existing_id = $this->get_local_id( $course->id );
		if ( $existing_id ) {
			$post['ID'] = $existing_id;
		} else {
			$post_name         = sanitize_title( $course->descriptionHeading ? $course->descriptionHeading : '' );
			$post_name         = $this->get_unique_value( 'posts', 'post_name', $post_name );
			$post['post_name'] = $post_name;
		}

		// Insert now.
		$post_id            = wp_insert_post( $post );
		$remote_class_owner = $this->service_classroom->userProfiles->get( $course->ownerId );

		// Set single line room, section.
		$room_section                      = array();
		$course->room ? $room_section[]    = $course->room : 0;
		$course->section ? $room_section[] = $course->section : 0;
		$course->room_and_section          = implode( ', ', $room_section );

		// Set remote ID as identifier.
		update_post_meta( $post_id, $this->classroom_key, $course->id );
		update_post_meta( $post_id, $this->course_credential, $this->current_credential );
		update_post_meta( $post_id, $this->remote_class, $course );
		update_post_meta( $post_id, $this->remote_class_owner, $remote_class_owner );
		update_post_meta( $post_id, $this->gc_post_time, gmdate( 'Y-m-d h:i a', tutor_time() ) );

		return $post_id;
	}

	public function is_reset_token_valid( $token, $return_id = false ) {
		$segments = explode( '_', $token );

		$user_id = isset( $segments[0] ) ? $segments[0] : '';
		$hash    = implode( '_', array_slice( $segments, 1 ) );

		if ( is_numeric( $user_id ) && strlen( $hash ) ) {
			$user_data = get_userdata( $user_id );

			if ( is_object( $user_data ) ) {
				$user_id = $user_data->ID;

				$temp_pass                = get_user_meta( $user_id, $this->temporary_password, true );
				! $temp_pass ? $temp_pass = '' : 0;

				$valid = wp_check_password( $temp_pass, $hash );

				return $valid ? ( $return_id ? $user_id : true ) : false;
			}
		}

		return false;
	}

	private function get_unique_value( string $table, string $column, $value, $index = 1 ) {

		global $wpdb;
		$table_name = $wpdb->prefix . $table;

		$value                   = trim( $value );
		empty( $value ) ? $value = 'untitled' : 0;
		$compare_value           = $value . ( $index > 1 ? '-' . $index : '' );

		$duplicate = $wpdb->get_results( 'SELECT ' . $column . ' FROM ' . $table_name . ' WHERE ' . $column . '="' . esc_sql( $compare_value ) . '"' );

		return count( $duplicate ) > 0 ? $this->get_unique_value( $table, $column, $value, $index + 1 ) : $compare_value;
	}

	public function set_student_password( $token, $password ) {
		$user_id = $this->is_reset_token_valid( $token, true );

		if ( $user_id && is_numeric( $user_id ) ) {
			wp_set_password( $password, $user_id );
			delete_user_meta( $user_id, $this->temporary_password );
		}
	}

	private function generate_password_link( $user_id, $user_pass ) {
		$token = $user_id . '_' . wp_hash_password( $user_pass );
		return get_home_url() . '/' . self::$password_reset_base . '/?token=' . $token;
	}

	private function send_auto_registration_email( $user_data, $user_id, $class_name ) {

		$password_reset_link = $this->generate_password_link( $user_id, $user_data['user_pass'] );

		ob_start();
		include dirname( __DIR__ ) . '/views/email/auto-registration-verification.php';
		$html_mail = ob_get_clean();

		// Send the mail content to the user email address.
		wp_mail( $user_data['user_email'], __( 'Password Setup', 'tutor-pro' ), $html_mail, array( 'Content-Type: text/html; charset=UTF-8' ) );
	}

	private function register_students( $course ) {

		$students = $this->get_course_students( $course );

		$user_ids = array();
		foreach ( $students as $student ) {
			$email_address = $student->profile->emailAddress;
			$full_name     = $student->profile->name->fullName;
			$password      = substr( str_shuffle( str_repeat( $x = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', ceil( 8 / strlen( $x ) ) ) ), 1, 8 );

			$existing = get_user_by( 'user_email', $email_address );

			if ( $existing ) {
				continue;
			}

			$user_login = str_replace( ' ', '-', sanitize_user( strtolower( $full_name ) ) );
			$user_login = $this->get_unique_value( 'users', 'user_login', $user_login );

			$new_user = array(
				'user_email'   => $email_address,
				'user_pass'    => $password,
				'user_login'   => $user_login,
				'display_name' => $full_name,
			);

			$user_id = wp_insert_user( $new_user );

			if ( is_numeric( $user_id ) ) {

				$user_ids[] = $user_id;
				update_user_meta( $user_id, $this->gc_user_identifier, $course->id );
				update_user_meta( $user_id, $this->temporary_password, $password );

				$this->send_auto_registration_email( $new_user, $user_id, $course->descriptionHeading );
			}
		}

		return $user_ids;
	}
}
