init.php

<?php

if ( !defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly
}

if ( learn_press_bbpress_is_active() ) {


    /**
     * Add custom bbPress forum metabox in course editing
     *
     * @param $meta_boxes
     *
     * @return mixed
     */
    function learn_press_add_bbpress_forum_metabox( $meta_boxes ) {
        $meta_boxes['fields'][] = array(
            'name'    => __( 'Course Forum', 'learn_press' ),
            'id'      => "_lpr_course_forum",
            'type'    => 'radio',
            'desc'    => __( 'A bbPress forum will be created and connected to this course automatically. If option no discussion be chosen, all data of forum will be deleted permanently!', 'learn_press' ),
            'options' => array(
                'yes' => __( 'Connect to forum', 'learn_press' ),
                'no'  => __( 'No discussion', 'learn_press' ),
            )
        );
        return $meta_boxes;
    }

    add_filter( 'learn_press_course_settings_meta_box_args', 'learn_press_add_bbpress_forum_metabox' );

    /**
     * Process forum from course settings
     *
     * @param $course_id
     */
    function learn_press_process_course_forum( $course_id ) {
        if ( learn_press_is_connect_forum( $course_id ) ) {
            if ( !learn_press_is_exist_forum( $course_id ) ) {
                $new_forum = array(
                    'post_title'   => get_post( $course_id )->post_title,
                    'post_content' => __( 'Forum of course "' . get_post( $course_id )->post_title . '"', 'learn_press' ),
                    'post_author'  => get_post( $course_id )->post_author,
                );
                $forum_id  = bbp_insert_forum( $new_forum, array() );
                update_post_meta( $forum_id, '_lpr_forum_course_id', $course_id );
                update_post_meta( $course_id, '_lpr_course_forum_id', $forum_id );
            }
        } else {
            $forum_id = learn_press_get_forum_id( $course_id );
            if ( !$forum_id ) {
                return;
            }
            wp_delete_post( $forum_id );
            update_post_meta( $course_id, '_lpr_course_forum_id', '' );
        }

    }

    add_action( 'save_post', 'learn_press_process_course_forum', 100, 1 );

    /**
     * Remove forum after delete course permanently
     *
     * @param $course_id
     */
    function learn_press_remove_forum( $course_id ) {
        $forum_id = learn_press_get_forum_id( $course_id );
        if ( !$forum_id ) {
            return;
        }
        wp_delete_post( $forum_id );
    }

    add_action( 'before_delete_post', 'learn_press_remove_forum' );

    /**
     * Add link to forum in course display
     */
    function learn_press_forum_link() {
        do_action( 'learn_press_before_course_forum' );
        if ( learn_press_is_connect_forum( get_the_ID() ) ) {
            printf(
                '<div class="forum-link">
					<span><a href="%s">%s</a></span>
				</div>',
                learn_press_get_forum_link( get_the_ID() ),
                apply_filters( 'learn_press_forum_link_text', __( 'Forum', 'learn_press' ) )
            );
        }
        do_action( 'learn_press_after_course_forum' );
    }

    add_action( 'learn_press_course_landing_content', 'learn_press_forum_link', 80 );
    add_action( 'learn_press_course_learning_content', 'learn_press_forum_link', 30 );

    /**
     * Get forum link from respective course
     *
     * @param $course_id
     *
     * @return string
     */
    function learn_press_get_forum_link( $course_id ) {
        $forum_id = learn_press_get_forum_id( $course_id );
        return esc_url( bbp_get_forum_permalink( $forum_id ) );
    }

    /**
     * Process limit access forum
     */
    function learn_press_limit_access_course_forum() {
        global $post;
        if ( !learn_press_is_access_forum( $post->ID, $post->post_type ) ) {
            ob_start();
        }
    }

    add_action( 'bbp_template_before_single_topic', 'learn_press_limit_access_course_forum' );
    add_action( 'bbp_template_before_single_forum', 'learn_press_limit_access_course_forum' );

    /**
     * Restrict forum content
     */
    function learn_press_restrict_forum_content() {
        global $post;
        if ( !learn_press_is_access_forum( $post->ID, $post->post_type ) ) {
            ob_end_clean();
            wp_enqueue_style( 'lp-dashicons', get_site_url() . '/wp-includes/css/dashicons.css' );
            echo '<p>' . __( 'You have to enroll the respective course!', 'learn_press' ) . '<p>';
        }
    }

    add_action( 'bbp_template_after_single_topic', 'learn_press_restrict_forum_content' );
    add_action( 'bbp_template_after_single_forum', 'learn_press_restrict_forum_content' );

    /**
     * Process ability to access forum
     *
     * @param $id
     * @param $type
     *
     * @return bool
     */
    function learn_press_is_access_forum( $id, $type ) {
        $user_id = get_current_user_id();
        // Case: invalid user or post
        if ( !$user_id || !$id ) {
            return false;
        }
        $course_id = 0;
        if ( $type == 'forum' ) {
            $course_id = learn_press_get_forum_course_id( $id );
        } elseif ( $type == 'topic' ) {
            $forum_id = get_post_meta( $id, '_bbp_forum_id', true );
            if ( !empty( $forum_id ) ) {
                $course_id = learn_press_get_forum_course_id( $forum_id );
            }
        }
        // Case: a normal forum which has no connecting with any courses
        if ( !$course_id ) {
            return true;
        }
        // Case: user is the course author
        $object = get_post( $course_id );
        if ( $user_id == $object->post_author ) {
            return true;
        }
        $object = get_user_meta( $user_id, '_lpr_user_course', true );
        // Case: users haven't enrolled any one
        if ( !$object ) {
            return false;
        }
        // Case: users enrolled this course
        if ( in_array( $course_id, $object ) ) {
            return true;
        }
        $object = get_userdata( $user_id );
        // Case: user is bbPress Keymaster or Moderator
        if ( in_array( 'bbp_keymaster', $object->roles ) || in_array( 'bbp_moderator', $object->roles ) ) {
            return true;
        }

        return false;
    }

    /**
     * Process ability a course can connect with a forum
     *
     * @param $course_id
     *
     * @return bool
     */
    function learn_press_is_connect_forum( $course_id ) {
        $check = get_post_meta( $course_id, '_lpr_course_forum', true );
        if ( !empty ( $check ) && $check == 'yes' ) {
            return true;
        }
        return false;
    }

    /**
     * Process ability a course connected to a forum
     *
     * @param $course_id
     *
     * @return bool
     */
    function learn_press_is_exist_forum( $course_id ) {
        $check = get_post_meta( $course_id, '_lpr_course_forum_id', true );
        if ( !empty ( $check ) ) {
            return true;
        }
        return false;
    }

    /**
     * Ger forum id from respective course
     *
     * @param $course_id
     *
     * @return int|mixed
     */
    function learn_press_get_forum_id( $course_id ) {
        if ( learn_press_is_exist_forum( $course_id ) ) {
            return get_post_meta( $course_id, '_lpr_course_forum_id', true );
        }
        return 0;
    }

    /**
     * Get course id from respective forum
     *
     * @param $forum_id
     *
     * @return int|mixed
     */
    function learn_press_get_forum_course_id( $forum_id ) {
        $course_id = get_post_meta( $forum_id, '_lpr_forum_course_id', true );
        if ( !empty ( $course_id ) ) {
            return $course_id;
        }
        return 0;
    }
}