I need a PHP if/else statement that if the sign-in.php or register.php page is access over HTTP I would like to redirect to HTTPS else if any other page is accessed over HTTPS redirect to HTTP plus have any query string appended for example if a user tries to access a restricted page (http://domain.com/my-account.php) the site redirects the user to http://domain.com/sign-in.php?redirect=my-account however, I would like the page to redirect to https://domain.com/sign-in.php?redirect=my-account.
I know I could simply change the header redirects to include https instead of http but users may type http://domain.com/sign-in.php?redirect=my-account so just need to ensure if this happens sign in (or others) happen over https.
Any help is appreciated