I was looking for a way to verify the url to be from a specified url. Support for more urls will be added later.

Here is a snippet of the code used to validate the TradingView URL.

$tradingview = 'https://www.tradingview.com/x/zWY79CPs/';
      // Replace these to make the string smaller.
      $ar = str_replace(['https://', 'www.'], '', $tradingview); 
      // Explode the string into an array of strings.
      $ar = explode('/', $ar);
      // Is it an allowed url. 
      if  ($ar[0] !== 'tradingview.com') { 
        echo 'The Link must be from TradingView';
      }
      // Is it a valid screenshot
      if (strlen($ar[2]) !== 8) { 
        echo 'The code at the end of the link is usually only 8 characters.';               
      }
      else {
      echo 'All checks passed, next we add MIME types.';
      }