Conditional Custom Login Redirects in WordPress

functions.php

function wip_login_redirect( $url, $request, $user ){
	// Define referrer
	$slug = $_SERVER["REQUEST_URI"];
	
	// Define slugs of any referrers you want here
	// For example, if they page you want to target
	// is www.testsite.com/hello-world
	// you'll want this:
	// $islogin = strpos($slug, 'hello-world');
	$islogin = strpos($slug, 'log-in');
	
	// Need to tap into the WP_User Object
	// And make sure they are a user
	if( $user && is_object( $user ) && is_a( $user, 'WP_User' ) ) {
		
		// If user is an Admin and they're 
		// logging in at our custom login page
		// redirect them to wp-admin
		if(($user->has_cap('edit_users')) && ($islogin==true)) {
			$url = admin_url('index.php');
		
		// But, if they are logging in at
		// our custom login page and ARE NOT
		// an Admin, redirect them to the homepage
		} elseif ((!$user->has_cap('edit_users')) && ($islogin==true)) { 
			$url = home_url();
			
		// If neither of those is true,
		// They the user is logging in via a front-end form
		// So it's best to just redirect them to that page
		} else {
			$url = $slug;
		}
	}
    
	return $url;
}
 
add_filter('login_redirect', 'wip_login_redirect', 10, 3 );