import React from 'react';
import { render, act } from '@testing-library/react';
import 'jest-styled-components';

import { Grommet, Image, Box, InfiniteScrollProps } from '../..';
import { InfiniteScroll } from '..';

type InfiniteScrollItemType = InfiniteScrollProps['items'] extends (infer U)[]
  ? U
  : never;

const simpleItems = (value: number) =>
  Array(value)
    .fill(``)
    .map((_, i) => `item ${i + 1}`);

const createPageItems = (allChildren: HTMLElement[]) => {
  const unfiltered = Array.from(allChildren);
  // Removing any children which are serving as refs
  return unfiltered.filter((childItem) => childItem.outerHTML.includes('item'));
};

describe('InfiniteScroll', () => {
  const items: InfiniteScrollProps['items'] = [];
  while (items.length < 4) items.push(items.length);

  test('basic', () => {
    const { container } = render(
      <Grommet>
        <InfiniteScroll />
        <InfiniteScroll items={items}>
          {(
            item: InfiniteScrollItemType,
            index: number,
            ref: React.MutableRefObject<HTMLInputElement>,
          ) => (
            <div ref={ref} key={index}>
              {item}
            </div>
          )}
        </InfiniteScroll>
        <InfiniteScroll items={items}>
          {(item: InfiniteScrollItemType, index: number) => (
            <div key={index}>{item}</div>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    expect(container.firstChild).toMatchSnapshot();
  });

  test('step', () => {
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={items} step={2}>
          {(item: InfiniteScrollItemType, index: number) => (
            <div key={index}>{item}</div>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    expect(container.firstChild).toMatchSnapshot();
  });

  test('show', () => {
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={items} step={2} show={3}>
          {(item: InfiniteScrollItemType, index: number) => (
            <div key={index}>{item}</div>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    expect(container.firstChild).toMatchSnapshot();
  });

  test('renderMarker', () => {
    const { container } = render(
      <Grommet>
        <InfiniteScroll
          items={items}
          step={2}
          renderMarker={(m) => <div>{m}</div>}
        >
          {(item: InfiniteScrollItemType, index: number) => (
            <div key={index}>{item}</div>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    expect(container.firstChild).toMatchSnapshot();
  });

  test('replace', () => {
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={items} step={2} replace>
          {(item: InfiniteScrollItemType, index: number) => (
            <div key={index}>{item}</div>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    expect(container.firstChild).toMatchSnapshot();
  });

  test(`should render expected items when supplied
  assortment of mixed items`, () => {
    const lorem = `Lorem ipsum dolor sit amet, consectetur adipisicing elit,
    sed do eiusmod temporincididunt ut labore et dolore magna
    aliqua. Ut enim ad minim veniam, quis nostrud exercitation
    ullamco laboris nisi ut aliquip ex ea commodo consequat.
    Duis aute irure dolor in reprehenderit in voluptate velit
    esse cillum dolore eu fugiat nulla pariatur. Excepteur sint
    occaecat cupidatat non proident, sunt in culpa qui officia
    deserunt mollit anim id est laborum.`;
    const mixedItems: InfiniteScrollProps['items'] = [];
    // Generate large array of mixed items to test different elements on a page
    for (let i = 0; i < 200; i += 1) {
      switch (i % 5) {
        case 0:
          mixedItems.push(<Box>Hello World</Box>);
          break;
        case 1:
          mixedItems.push(`This is a string at index ${i}`);
          break;
        case 2:
          mixedItems.push(
            <Image
              a11yTitle="Gremlin"
              src="https://v2.grommet.io/img/stak-hurrah.svg"
            />,
          );
          break;
        case 3:
          switch (i % 4) {
            case 0:
              mixedItems.push(lorem);
              break;
            case 1:
              mixedItems.push(lorem.slice(140));
              break;
            case 2:
              mixedItems.push(lorem + lorem);
              break;
            case 3:
              mixedItems.push(lorem.slice(i, Math.min(i * 3, lorem.length)));
              break;
            default:
              break;
          }
          break;
        case 4:
          mixedItems.push(i * 186282);
          break;
        default:
          break;
      }
    }
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={mixedItems}>
          {(item: InfiniteScrollItemType, index: number) => (
            <div key={index}>{item}</div>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    expect(container.firstChild).toMatchSnapshot();
  });
});

describe('Number of Items Rendered', () => {
  test(`Should render items equal to the length of 
  step when step < items.length`, () => {
    const step = 50;
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={simpleItems(1000)} step={step}>
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    const expectedItems = step;
    expect(pageItems.length).toEqual(expectedItems);
  });

  test(`Should render items equal to the length of
  step when step = array.length`, () => {
    const step = 200;
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={simpleItems(200)} step={step}>
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    const expectedItems = step;
    expect(pageItems.length).toEqual(expectedItems);
  });

  test(`Should render items equal to the length of
  item array when step > array`, () => {
    const numItems = 1000;
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={simpleItems(numItems)} step={1050}>
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    const expectedItems = numItems;
    expect(pageItems.length).toEqual(expectedItems);
  });

  test(`Should only contain unique items (i.e no duplicates)`, () => {
    const step = 25;
    const numItems = 200;
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={simpleItems(numItems)} step={step}>
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    const distinctItems = new Set(pageItems);
    /* Expected number of items should be at the show value rounded
    up to the next step increment/ */
    const expectedItems = step;
    /* If the number of distinct items is equivalent to the length 
    of results, then we have unique items. */
    expect(distinctItems.size).toEqual(expectedItems);
    expect(container.firstChild).toMatchSnapshot();
  });
});

describe('show scenarios', () => {
  test(`When show, show item should be visible in window`, () => {
    jest.useFakeTimers();
    // Mock scrollIntoView since JSDOM doesn't do layout.
    // https://github.com/jsdom/jsdom/issues/1695#issuecomment-449931788
    window.HTMLElement.prototype.scrollIntoView = jest.fn();
    const { container } = render(
      <Grommet>
        <InfiniteScroll items={simpleItems(300)} show={105}>
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );
    // advance timers so InfiniteScroll can scroll to show index
    act(() => {
      jest.advanceTimersByTime(200);
    });
    // item(104) = 'item 105' because indexing starts at 0.
    // Need to modify this next selection to only be concerned with the
    // visible window.
    // @ts-ignore
    const renderedItems = container.firstChild.children.item(104).outerHTML;
    expect(renderedItems).toContain('item 105');
  });

  test(`When show, should only contain unique 
          items (i.e no duplicates)`, () => {
    const step = 25;
    const numItems = 200;
    const showIndex = 67;
    const { container } = render(
      <Grommet>
        <InfiniteScroll
          items={simpleItems(numItems)}
          show={showIndex}
          step={step}
        >
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    const distinctItems = new Set(pageItems);
    /* Expected number of items should be at the show value rounded
    up to the next step increment/ */
    const expectedItems = Math.ceil(showIndex / step) * step;
    /* If the number of distinct items is equivalent to the length
    of results, then we have unique items. */
    expect(distinctItems.size).toEqual(expectedItems);
    expect(container.firstChild).toMatchSnapshot();
  });

  test(`should display specified item when show is greater than step`, () => {
    const step = 8;
    const numItems = 200;
    const showIndex = 41;
    const { container, getByText } = render(
      <Grommet>
        <InfiniteScroll
          items={simpleItems(numItems)}
          show={showIndex}
          step={step}
        >
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // Check to see that expected item exists
    const expectedItem = getByText('item 42').innerHTML;
    expect(expectedItem).toMatch(simpleItems(numItems)[showIndex]);

    // Check to see that we have the total number of items we expect
    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    /* Expected number of items should be at the show value rounded
    up to the next step increment/ */
    const expectedItems = Math.ceil(showIndex / step) * step;
    expect(pageItems.length).toEqual(expectedItems);
  });

  test(`should display specified item when show is less than step`, () => {
    const step = 30;
    const numItems = 200;
    const showIndex = 26;
    const { container, getByText } = render(
      <Grommet>
        <InfiniteScroll
          items={simpleItems(numItems)}
          show={showIndex}
          step={step}
        >
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // Check to see that expected item exists
    const expectedItem = getByText('item 27').innerHTML;
    expect(expectedItem).toMatch(simpleItems(numItems)[showIndex]);

    // Check to see that we have the total number of items we expect
    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);

    /* Expected number of items should be at the show value rounded
    up to the next step increment/ */
    const expectedItems = Math.ceil(showIndex / step) * step;
    expect(pageItems.length).toEqual(expectedItems);
  });

  test(`should display specified item when show is 
        greater than step and replace is true`, () => {
    const step = 18;
    const numItems = 200;
    const showIndex = 88;
    const { container, getByText } = render(
      <Grommet>
        <InfiniteScroll
          items={simpleItems(numItems)}
          replace
          show={showIndex}
          step={step}
        >
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // Check to see that expected item exists
    const expectedItem = getByText('item 89').innerHTML;
    expect(expectedItem).toMatch(simpleItems(numItems)[showIndex]);

    // Check to see that our replace items have been removed from the DOM.
    expect(container.firstChild).not.toContain('item 7');

    /* Check to see that we have the total number of items we expect.
     * When replace is true, the expected number of items should be less
     * than or equal to the step * 2.
     */

    /*
     * The following needs to be uncommented to for this test to pass.
     */
    // const pageItems = createPageItems(container.firstChild.children);
    // const expectedItems = step * 2;
    // expect(pageItems.length).toBeLessThanOrEqual(expectedItems);
  });

  test(`should display specified item when show is 
        less than step and replace is true`, () => {
    const step = 30;
    const numItems = 200;
    const showIndex = 26;
    const { container, getByText } = render(
      <Grommet>
        <InfiniteScroll
          items={simpleItems(numItems)}
          replace
          show={showIndex}
          step={step}
        >
          {(item: InfiniteScrollItemType, index: number) => (
            <Box key={index}>{item}</Box>
          )}
        </InfiniteScroll>
      </Grommet>,
    );

    // Check to see that expected item exists
    const expectedItem = getByText('item 27').innerHTML;
    expect(expectedItem).toMatch(simpleItems(numItems)[showIndex]);

    /* Check to see that we have the total number of items we expect.
     * When replace is true, the expected number of items should be less
     * than or equal to the step * 2.
     */
    // @ts-ignore
    const pageItems = createPageItems(container.firstChild.children);
    const expectedItems = step * 2;
    expect(pageItems.length).toBeLessThanOrEqual(expectedItems);
  });
});