const theme = require('../theme');
const Spacer = require('./Spacer');

/**
 * @typedef {Object} RuntimeErrorFooterProps
 * @property {string} [initialFocus]
 * @property {boolean} multiple
 * @property {function(MouseEvent): void} onClickCloseButton
 * @property {function(MouseEvent): void} onClickNextButton
 * @property {function(MouseEvent): void} onClickPrevButton
 */

/**
 * A fixed footer that handles pagination of runtime errors.
 * @param {Document} document
 * @param {HTMLElement} root
 * @param {RuntimeErrorFooterProps} props
 * @returns {void}
 */
function RuntimeErrorFooter(document, root, props) {
  const footer = document.createElement('div');
  footer.style.backgroundColor = '#' + theme.dimgrey;
  footer.style.bottom = '0';
  footer.style.boxShadow = '0 -1px 4px rgba(0, 0, 0, 0.3)';
  footer.style.height = '2.5rem';
  footer.style.left = '0';
  footer.style.lineHeight = '2.5rem';
  footer.style.position = 'fixed';
  footer.style.textAlign = 'center';
  footer.style.width = '100vw';
  footer.style.zIndex = '2';

  const BUTTON_CONFIGS = {
    prev: {
      id: 'prev',
      label: '◀ Prev',
      onClick: props.onClickPrevButton,
    },
    close: {
      id: 'close',
      label: '× Close',
      onClick: props.onClickCloseButton,
    },
    next: {
      id: 'next',
      label: 'Next ▶',
      onClick: props.onClickNextButton,
    },
  };

  let buttons = [BUTTON_CONFIGS.close];
  if (props.multiple) {
    buttons = [BUTTON_CONFIGS.prev, BUTTON_CONFIGS.close, BUTTON_CONFIGS.next];
  }

  /** @type {HTMLButtonElement | undefined} */
  let initialFocusButton;
  for (let i = 0; i < buttons.length; i += 1) {
    const buttonConfig = buttons[i];

    const button = document.createElement('button');
    button.id = buttonConfig.id;
    button.innerHTML = buttonConfig.label;
    button.tabIndex = 1;
    button.style.backgroundColor = '#' + theme.dimgrey;
    button.style.border = 'none';
    button.style.color = '#' + theme.white;
    button.style.cursor = 'pointer';
    button.style.fontSize = 'inherit';
    button.style.height = '100%';
    button.style.padding = '0.5rem 0.75rem';
    button.style.width = (100 / buttons.length).toString(10) + '%';
    button.addEventListener('click', buttonConfig.onClick);

    if (buttonConfig.id === props.initialFocus) {
      initialFocusButton = button;
    }

    footer.appendChild(button);
  }

  root.appendChild(footer);

  Spacer(document, root, { space: '2.5rem' });

  if (initialFocusButton) {
    initialFocusButton.focus();
  }
}

module.exports = RuntimeErrorFooter;