import { useEffect, useState } from 'react';
import { Keyboard, Platform } from 'react-native';

/** Live keyboard height in px, 0 when hidden. */
export function useKeyboardHeight(): number {
  const [height, setHeight] = useState(0);

  useEffect(() => {
    // "will" fires before the animation on iOS, so the cap resizes in step with the
    // keyboard instead of jumping after; Android only reliably fires "did".
    const showEvent = Platform.OS === 'ios' ? 'keyboardWillShow' : 'keyboardDidShow';
    const hideEvent = Platform.OS === 'ios' ? 'keyboardWillHide' : 'keyboardDidHide';
    const showSub = Keyboard.addListener(showEvent, (event) => setHeight(event.endCoordinates.height));
    const hideSub = Keyboard.addListener(hideEvent, () => setHeight(0));
    return () => {
      showSub.remove();
      hideSub.remove();
    };
  }, []);

  return height;
}