LifterLMS redirect users to login and back from email links of restricted content

llms-email-unit-redirection.php

<?php

/*
 * Any links to restricted pages added to emails should contain a redirection parameter.
 * When user lands on a restricted screen with a redirection parameter,
 * they are redirected to the login screen (with the usual notice).
 * On loggin in, the user is redirected back to the restricted page.
 */

add_action( 'lifterlms_content_restricted', 'llms_maybe_email_unit_redirect', 10, 1);

function llms_maybe_email_unit_redirect( $restriction ){

	// do nothing in case the ?redir_login parameter isn't set
	if( empty( llms_filter_input( INPUT_GET, 'login' ) ) ){
		return;
	}
	
	// otherwise, filter the restriction
	add_filter( 'llms_restricted_by_' . $restriction['reason'] . '_redirect', 'llms_email_unit_login_redirect', 10, 2 );
	add_filter( 'llms_restricted_by_' . $restriction['reason'] . '_message', 'llms_email_unit_login_message', 10, 2 );
}

function llms_email_unit_login_message( $message, $restriction ){
	return 'Please login to view <em>'. get_the_title( $restriction['content_id'] ) . '</em>.';
}

function llms_email_unit_login_redirect( $url, $restriction ){

	$redirect_back_to = get_permalink( $restriction['content_id'] );
  
	// intercept redirection by sending the dashboard url instead with a redirect paramater
	$url = add_query_arg( array( 'redirect' => esc_url($redirect_back_to) ), llms_person_my_courses_url() );
	
	return $url;
}

// hook into login form's redirection
add_filter( 'llms_student_dashboard_login_redirect', 'llms_maybe_redirect_to_unit' );

function llms_maybe_redirect_to_unit( $url ){

	// since the login form's action is going to be current url, we can expect it in the querystring if redirection was set.
	$unit_redirect = llms_filter_input( INPUT_GET, 'redirect' );

	// do nothing in case the ?redir_login
  	return empty( $unit_redirect ) ? $url : $unit_redirect;

}