impress-2020/src/app/util.js

import React from "react";
import { Box, Heading } from "@chakra-ui/core";

/**
 * Delay hides its content and first, then shows it after the given delay.
 *
 * This is useful for loading states: it can be disruptive to see a spinner or
 * skeleton element for only a brief flash, we'd rather just show them if
 * loading is genuinely taking a while!
 *
 * 300ms is a pretty good default: that's about when perception shifts from "it
 * wasn't instant" to "the process took time".
 * https://developers.google.com/web/fundamentals/performance/rail
 */
export function Delay({ children, ms = 300 }) {
  const [isVisible, setIsVisible] = React.useState(false);

  React.useEffect(() => {
    const id = setTimeout(() => setIsVisible(true), ms);
    return () => clearTimeout(id);
  }, [ms, setIsVisible]);

  return (
    <Box opacity={isVisible ? 1 : 0} transition="opacity 0.5s">
      {children}
    </Box>
  );
}

/**
 * Heading1 is a large, page-title-ish heading, with our DTI-brand-y Delicious
 * font and some special typographical styles!
 */
export function Heading1({ children, ...props }) {
  return (
    <Heading
      fontFamily="Delicious, sans-serif"
      fontWeight="800"
      size="2xl"
      {...props}
    >
      {children}
    </Heading>
  );
}

/**
 * Heading2 is a major subheading, with our DTI-brand-y Delicious font and some
 * special typographical styles!!
 */
export function Heading2({ children, ...props }) {
  return (
    <Heading
      size="xl"
      color="green.800"
      fontFamily="Delicious, sans-serif"
      fontWeight="700"
      {...props}
    >
      {children}
    </Heading>
  );
}

/**
 * safeImageUrl returns an HTTPS-safe image URL for Neopets assets!
 */
export function safeImageUrl(url) {
  return `/api/assetProxy?url=${encodeURIComponent(url)}`;
}

/**
 * useDebounce helps make a rapidly-changing value change less! It waits for a
 * pause in the incoming data before outputting the latest value.
 *
 * We use it in search: when the user types rapidly, we don't want to update
 * our query and send a new request every keystroke. We want to wait for it to
 * seem like they might be done, while still feeling responsive!
 *
 * Adapted from https://usehooks.com/useDebounce/
 */
export function useDebounce(value, delay, { waitForFirstPause = false } = {}) {
  // State and setters for debounced value
  const initialValue = waitForFirstPause ? null : value;
  const [debouncedValue, setDebouncedValue] = React.useState(initialValue);

  React.useEffect(
    () => {
      // Update debounced value after delay
      const handler = setTimeout(() => {
        setDebouncedValue(value);
      }, delay);

      // Cancel the timeout if value changes (also on delay change or unmount)
      // This is how we prevent debounced value from updating if value is changed ...
      // .. within the delay period. Timeout gets cleared and restarted.
      return () => {
        clearTimeout(handler);
      };
    },
    [value, delay] // Only re-call effect if value or delay changes
  );

  return debouncedValue;
}

/**
 * usePageTitle sets the page title!
 */
export function usePageTitle(title) {
  React.useEffect(() => {
    document.title = title;
  }, [title]);
}

/**
 * useFetch uses `fetch` to fetch the given URL, and returns the request state.
 *
 * Our limited API is designed to match the `use-http` library!
 */
export function useFetch(url, { responseType }) {
  // Just trying to be clear about what you'll get back ^_^` If we want to
  // fetch non-binary data later, extend this and get something else from res!
  if (responseType !== "arrayBuffer") {
    throw new Error(`unsupported responseType ${responseType}`);
  }

  const [loading, setLoading] = React.useState(true);
  const [error, setError] = React.useState(null);
  const [data, setData] = React.useState(null);

  React.useEffect(() => {
    let canceled = false;

    fetch(url)
      .then(async (res) => {
        if (canceled) {
          return;
        }

        const arrayBuffer = await res.arrayBuffer();
        setLoading(false);
        setError(null);
        setData(arrayBuffer);
      })
      .catch((error) => {
        if (canceled) {
          return;
        }

        setLoading(false);
        setError(error);
        setData(null);
      });

    return () => {
      canceled = true;
    };
  }, [url]);

  return { loading, error, data };
}