import React from 'react';
import styled from 'styled-components';

function App() {
  const [isOpen, setIsOpen] = React.useState(false);

  return (
    <>
      <button
        onClick={() => setIsOpen(!isOpen)}
      >
        Toggle Modal
      </button>
      <Modal
        title="Example Modal"
        isOpen={isOpen}
        handleDismiss={() => setIsOpen(false)}
      >
        Hello World
      </Modal>
    </>
  )
}

/*
  NOTE: This is NOT a very robust modal implementation.
  Please use something like Reach UI! This is a quick and
  dirty implementation to teach the animation concept.
*/
const Modal = ({ title, isOpen, handleDismiss }) => {
  // Close modal on "Escape"
  React.useEffect(() => {
    function handleKeydown(ev) {
      if (ev.key === 'Escape') {
        handleDismiss();
      }
    }

    window.addEventListener('keydown', handleKeydown);

    return () => {
      window.removeEventListener('keydown', handleKeydown);
    };
  });

  const {
    backdropStyles,
    modalStyles,
    closeButtonStyles
  } = getTransitionStyles(isOpen);

  return (
    <ModalWrapper
      style={{
        pointerEvents: isOpen ? 'auto' : 'none',
      }}
    >
      <ModalBackdrop
        onClick={handleDismiss}
        style={{
          opacity: isOpen ? 0.75 : 0,
          ...backdropStyles,
        }}
      />
      <ModalContent
        style={{
          transform: isOpen
            ? 'translateY(0vh)'
            : 'translateY(100vh)',
          ...modalStyles,
        }}
      >
        <ButtonWrapper>
          <CloseButton
            onClick={handleDismiss}
            style={{
              opacity: isOpen ? 1 : 0,
              transform: isOpen
                ? 'translateY(0)'
                : 'translateY(25%)',
              ...closeButtonStyles,
            }}
          >
            Close
          </CloseButton>
        </ButtonWrapper>
        <Title>{title}</Title>
        <p>This is a modal!</p>
      </ModalContent>
    </ModalWrapper>
  );
}

function getTransitionStyles(isOpen) {
  return {
    backdropStyles: {
      transition: 'opacity',
      transitionDuration: isOpen ? '1000ms' : '500ms',
      transitionDelay: isOpen ? '0ms' : '100ms',
    },
    modalStyles: {
      transition: 'transform',
      transitionDuration: isOpen
        ? '400ms'
        : '250ms',
      transitionDelay: isOpen
        ? '250ms'
        : '0ms',
      transitionTimingFunction: isOpen
        ? 'ease-out'
        : 'ease-in',
    },
    closeButtonStyles: {
      transition: 'opacity, transform',
      transitionDuration: '250ms',
      transitionDelay: isOpen ? '600ms' : '0ms',
    }
  };
}

const Wrapper = styled.div`
  min-height: 100vh;
  display: grid;
  place-content: center;
`;

const ModalWrapper = styled.div`
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  /*
    Don't allow the slid-down modal to
    introduce a scrollbar.
  */
  overflow: hidden;
`

const ModalBackdrop = styled.div`
  pointer-events: none;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: black;
`;

const ModalContent = styled.div`
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 80%;
  height: 60%;
  margin: auto;
  background: white;
  padding: 32px;
  border-radius: 8px;
  pointer-events: auto;
`;

const Title = styled.h1`
  font-size: 2rem;
  margin-bottom: 32px;
`

const ButtonWrapper = styled.div`
  position: absolute;
  top: 0;
  right: 0;
  transform: translateY(-100%);
`

const CloseButton = styled.button`
  display: grid;
  place-content: center;
  width: 64px;
  height: 64px;
  background: transparent;
  border: none;
  color: white;
`;

export default App;