import { useState, useEffect } from 'react';

function useWindowSize() {
  // Initialize state with undefined width/height so server and client match
  // Learn more here: https://joshwcomeau.com/react/the-complete-guide-to-useeffect/#on-the-server
  const [windowSize, setWindowSize] = useState({
    width: undefined,
    height: undefined,
  });

  useEffect(() => {
    // Handler to call on window resize
    function handleResize() {
      // Set window width/height to state
      setWindowSize({
        width: window.innerWidth,
        height: window.innerHeight,
      });
    }

    // Add event listener
    window.addEventListener('resize', handleResize);

    // Call handler right away so state gets updated with initial window size
    handleResize();

    // Remove event listener on cleanup
    return () => window.removeEventListener('resize', handleResize);
  }, []); // Empty array ensures that effect is only run on mount and unmount

  return windowSize;
}

// Usage example:
// function MyComponent() {
//   const { width, height } = useWindowSize();

//   return (
//     <div>
//       <p>Window width: {width || 'N/A'}</p>
//       <p>Window height: {height || 'N/A'}</p>
//       {width && width < 768 && <p>This is a small screen!</p>}
//     </div>
//   );
// }