create-automaticgpt-template/src/utils/fetch-polyfill.ts

AutomaticGPT - A production-ready Expo template with AI chat, authentication, conversation management, analytics, and sharing features

// This MUST be first to ensure that `fetch` is defined in the React Native environment.
import 'react-native/Libraries/Core/InitializeCore';
// Ensure fetch is installed before adding our fetch polyfill to ensure Headers and Request are available globally.
import 'whatwg-fetch';
// This MUST be imported to ensure URL is installed.
import 'expo';
// This file configures the runtime environment to increase compatibility with WinterCG.
// https://wintercg.org/
import Constants from 'expo-constants';

import { fetch } from 'expo/fetch';

import structuredClone from '@ungap/structured-clone';

import { polyfillGlobal } from 'react-native/Libraries/Utilities/PolyfillFunctions';

import { TextEncoderStream, TextDecoderStream } from '@stardazed/streams-text-encoding';

// Type declarations for window
declare const window:
  | {
      location?: {
        origin?: string;
      };
    }
  | undefined;

interface ExpoExtraRouterConfig {
  router?: {
    origin?: string | URL | boolean;
    generatedOrigin?: string | URL | boolean;
  };
}

if (!('structuredClone' in global)) {
  // Pending upstream support in Expo:
  // https://github.com/expo/expo/pull/37503
  polyfillGlobal('structuredClone', () => structuredClone);
}

// Pending upstream support in Expo:
// https://github.com/expo/expo/pull/37507
polyfillGlobal('TextEncoderStream', () => TextEncoderStream);
polyfillGlobal('TextDecoderStream', () => TextDecoderStream);

const manifest = Constants.expoConfig;

const polyfillSymbol = Symbol.for('expo.polyfillFetchWithWindowLocation');

export function wrapFetchWithWindowLocation(fetch: any) {
  if (fetch[polyfillSymbol]) {
    return fetch;
  }

  const _fetch = (...props: any[]) => {
    if (props[0] && typeof props[0] === 'string' && props[0].startsWith('/')) {
      props[0] = new URL(props[0], getOrigin()).toString();
    } else if (props[0] && typeof props[0] === 'object') {
      if (props[0].url && typeof props[0].url === 'string' && props[0].url.startsWith('/')) {
        props[0].url = new URL(props[0].url, getOrigin()).toString();
      }
    }

    return fetch(...props);
  };

  _fetch[polyfillSymbol] = true;

  return _fetch;
}

const extra = manifest?.extra as ExpoExtraRouterConfig | null;

function getOrigin() {
  assertOrigin();
  return window?.location?.origin;
}

function assertOrigin() {
  // We use the dev server in development but should attempt to warn early if the origin will be disabled in production.
  if (extra?.router?.origin === false) {
    throw new Error(
      'The server origin cannot be false in the app.json. Setup server deployments to ensure production fetch requests work https://docs.expo.dev/router/reference/api-routes/#native-deployment'
    );
  }
  if (typeof window !== 'undefined' && !window.location) {
    throw new Error(
      'window.location is not defined. Setup server deployments to ensure relative fetch requests work in production https://docs.expo.dev/router/reference/api-routes/#native-deployment'
    );
  }
}

// Defer the assertion in release builds so the app doesn't crash instantly.
if (__DEV__) assertOrigin();

// Polyfill window.location in native runtimes.
if (typeof window !== 'undefined') {
  // Polyfill native fetch to support relative URLs
  Object.defineProperty(global, 'fetch', {
    value: wrapFetchWithWindowLocation(fetch),
  });
}