import React, { useEffect } from "react";
import { mount } from "@quilted/react-testing";

import {
  BlankAreaTrackerConfig,
  BlankAreaTrackerResult,
  useBlankAreaTracker,
} from "../benchmark/useBlankAreaTracker";
import FlashList from "../FlashList";

import { MockFlashListProps, renderFlashList } from "./helpers/mountFlashList";

type BlankTrackingFlashListProps = MockFlashListProps & {
  onCumulativeBlankAreaResult?: (result: BlankAreaTrackerResult) => void;
  onCumulativeBlankAreaChange?: (updatedResult: BlankAreaTrackerResult) => void;
  blankAreaTrackerConfig?: BlankAreaTrackerConfig;
  instance?: React.RefObject<FlashList<any>>;
};

const BlankTrackingFlashList = (props?: BlankTrackingFlashListProps) => {
  const ref = props?.instance!;
  const [blankAreaTrackerResult, onBlankArea] = useBlankAreaTracker(
    ref,
    props?.onCumulativeBlankAreaChange,
    {
      startDelayInMs: props?.blankAreaTrackerConfig?.startDelayInMs ?? 500,
      sumNegativeValues:
        props?.blankAreaTrackerConfig?.sumNegativeValues ?? false,
    }
  );
  useEffect(() => {
    return () => {
      props?.onCumulativeBlankAreaResult?.(blankAreaTrackerResult);
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);
  return renderFlashList(
    { ...props, onBlankArea, estimatedItemSize: 400 },
    ref
  );
};

const mountBlankTrackingFlashList = (props?: BlankTrackingFlashListProps) => {
  const flashListRef: React.RefObject<FlashList<any>> = {
    current: null,
  };
  const blankTrackingFlashList = mount(
    <BlankTrackingFlashList {...props} instance={flashListRef} />
  );
  return {
    root: blankTrackingFlashList,
    instance: flashListRef.current!,
  };
};

describe("useBlankAreaTracker Hook", () => {
  beforeEach(() => {
    jest.clearAllMocks();
    jest.useFakeTimers();
  });

  it("ignores blank events for 500ms on mount and if content is not enough to fill the list", () => {
    const onCumulativeBlankAreaChange = jest.fn();
    const flashList = mountBlankTrackingFlashList({
      onCumulativeBlankAreaChange,
    });
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    jest.advanceTimersByTime(400);
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    expect(onCumulativeBlankAreaChange).toHaveBeenCalledTimes(0);
    jest.advanceTimersByTime(100);
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    expect(onCumulativeBlankAreaChange).toHaveBeenCalledTimes(1);
    onCumulativeBlankAreaChange.mockClear();

    flashList.root.setProps({ data: ["1"] });
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    expect(onCumulativeBlankAreaChange).toHaveBeenCalledTimes(0);
    flashList.root.unmount();
  });
  it("keeps result object updated with correct values on unmount", () => {
    let resultObjectCopy: BlankAreaTrackerResult | undefined;
    const onCumulativeBlankAreaChange = jest.fn(
      (result: BlankAreaTrackerResult) => {
        if (!resultObjectCopy) {
          resultObjectCopy = result;
        }
      }
    );
    const onCumulativeBlankAreaResult = jest.fn();
    const flashList = mountBlankTrackingFlashList({
      onCumulativeBlankAreaResult,
      onCumulativeBlankAreaChange,
      blankAreaTrackerConfig: { startDelayInMs: 300 },
    });
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    jest.advanceTimersByTime(300);
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    expect(resultObjectCopy!.cumulativeBlankArea).toBe(100);
    expect(resultObjectCopy!.maxBlankArea).toBe(100);

    flashList.instance.props.onBlankArea!({
      blankArea: 200,
      offsetEnd: 200,
      offsetStart: 0,
    });
    flashList.instance.props.onBlankArea!({
      blankArea: -200,
      offsetEnd: -200,
      offsetStart: 0,
    });
    expect(resultObjectCopy!.cumulativeBlankArea).toBe(300);
    expect(resultObjectCopy!.maxBlankArea).toBe(200);

    flashList.root.unmount();
    expect(onCumulativeBlankAreaResult).toHaveBeenCalledWith(resultObjectCopy!);
  });
  it("can track negative values on demand", () => {
    const onCumulativeBlankAreaResult = jest.fn();
    const flashList = mountBlankTrackingFlashList({
      onCumulativeBlankAreaResult,
      blankAreaTrackerConfig: { sumNegativeValues: true },
    });
    flashList.instance.props.onBlankArea!({
      blankArea: -200,
      offsetEnd: -200,
      offsetStart: 0,
    });
    jest.advanceTimersByTime(500);
    flashList.instance.props.onBlankArea!({
      blankArea: -200,
      offsetEnd: -200,
      offsetStart: 0,
    });
    flashList.instance.props.onBlankArea!({
      blankArea: -200,
      offsetEnd: -200,
      offsetStart: 0,
    });
    flashList.root.unmount();
    expect(onCumulativeBlankAreaResult).toHaveBeenCalledWith({
      cumulativeBlankArea: -400,
      maxBlankArea: 0,
    });
  });
  it("only calls onCumulativeBlankAreaChange when values have a change", () => {
    const onCumulativeBlankAreaChange = jest.fn();
    const flashList = mountBlankTrackingFlashList({
      onCumulativeBlankAreaChange,
    });
    flashList.instance.props.onBlankArea!({
      blankArea: -200,
      offsetEnd: -200,
      offsetStart: 0,
    });
    jest.advanceTimersByTime(500);
    flashList.instance.props.onBlankArea!({
      blankArea: -200,
      offsetEnd: -200,
      offsetStart: 0,
    });
    expect(onCumulativeBlankAreaChange).toHaveBeenCalledTimes(0);
    flashList.instance.props.onBlankArea!({
      blankArea: -100,
      offsetEnd: -100,
      offsetStart: 0,
    });
    expect(onCumulativeBlankAreaChange).toHaveBeenCalledTimes(0);
    flashList.instance.props.onBlankArea!({
      blankArea: 100,
      offsetEnd: 100,
      offsetStart: 0,
    });
    expect(onCumulativeBlankAreaChange).toHaveBeenCalledTimes(1);
    flashList.root.unmount();
  });
});