import { Arr, Optional } from '@ephox/katamari';

import type { Gene } from '../api/Gene';

import * as Detach from './Detach';
import * as Locator from './Locator';
import * as Up from './Up';

const before = (anchor: Gene, item: Gene): void => {
  anchor.parent.each((parent) => {
    const index = Locator.indexIn(parent, anchor);

    const detached = Detach.detach(Up.top(anchor), item).getOr(item);
    detached.parent = Optional.some(parent);
    index.each((ind) => {
      parent.children = parent.children.slice(0, ind).concat([ detached ]).concat(parent.children.slice(ind));
    });
  });
};

const after = (anchor: Gene, item: Gene): void => {
  anchor.parent.each((parent) => {
    const index = Locator.indexIn(parent, anchor);

    const detached = Detach.detach(Up.top(anchor), item).getOr(item);
    detached.parent = Optional.some(parent);
    index.each((ind) => {
      parent.children = parent.children.slice(0, ind + 1).concat([ detached ]).concat(parent.children.slice(ind + 1));
    });
  });
};

const append = (parent: Gene, item: Gene): void => {
  const detached = Detach.detach(Up.top(parent), item).getOr(item);
  parent.children = parent.children || [];
  parent.children = parent.children.concat([ detached ]);
  detached.parent = Optional.some(parent);
};

const appendAll = (parent: Gene, items: Gene[]): void => {
  Arr.map(items, (item) => {
    append(parent, item);
  });
};

const afterAll = (anchor: Gene, items: Gene[]): void => {
  anchor.parent.each((parent) => {
    const index = Locator.indexIn(parent, anchor);

    const detached = Arr.map(items, (item) => {
      const ditem = Detach.detach(Up.top(anchor), item).getOr(item);
      ditem.parent = Optional.some(parent);
      return ditem;
    });
    index.each((ind) => {
      parent.children = parent.children.slice(0, ind + 1).concat(detached).concat(parent.children.slice(ind + 1));
    });
  });
};

const prepend = (parent: Gene, item: Gene): void => {
  const detached = Detach.detach(Up.top(parent), item).getOr(item);
  parent.children = parent.children || [];
  parent.children = [ detached ].concat(parent.children);
  detached.parent = Optional.some(parent);
};

const wrap = (anchor: Gene, wrapper: Gene): void => {
  // INVESTIGATE: At this stage, mutation is necessary to act like the DOM
  anchor.parent.each((parent) => {
    wrapper.parent = Optional.some(parent);
    parent.children = Arr.map(parent.children || [], (c) => {
      return c === anchor ? wrapper : c;
    });
    wrapper.children = [ anchor ];
    anchor.parent = Optional.some(wrapper);
  });
};

export {
  before,
  after,
  afterAll,
  append,
  appendAll,
  prepend,
  wrap
};