developer-roadmap/src/components/AuthenticationFlow/GitHubButton.tsx

import { useEffect, useState } from 'react';
import { GitHubIcon } from '../ReactIcons/GitHubIcon.tsx';
import {
  FIRST_LOGIN_PARAM,
  COURSE_PURCHASE_PARAM,
  setAuthToken,
} from '../../lib/jwt';
import { cn } from '../../lib/classname.ts';
import { httpGet } from '../../lib/http';
import { Spinner } from '../ReactIcons/Spinner.tsx';
import { CHECKOUT_AFTER_LOGIN_KEY } from './CourseLoginPopup.tsx';
import { triggerUtmRegistration } from '../../lib/browser.ts';

type GitHubButtonProps = {
  isDisabled?: boolean;
  setIsDisabled?: (isDisabled: boolean) => void;
  className?: string;
};

const GITHUB_REDIRECT_AT = 'githubRedirectAt';
const GITHUB_LAST_PAGE = 'githubLastPage';

export function GitHubButton(props: GitHubButtonProps) {
  const { isDisabled, setIsDisabled, className } = props;

  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState('');

  useEffect(() => {
    const urlParams = new URLSearchParams(window.location.search);
    const code = urlParams.get('code');
    const state = urlParams.get('state');
    const provider = urlParams.get('provider');

    if (!code || !state || provider !== 'github') {
      return;
    }

    setIsLoading(true);
    setIsDisabled?.(true);
    httpGet<{ token: string; isNewUser: boolean }>(
      `${import.meta.env.PUBLIC_API_URL}/v1-github-callback${
        window.location.search
      }`,
    )
      .then(({ response, error }) => {
        if (!response?.token) {
          const errMessage = error?.message || 'Something went wrong.';
          setError(errMessage);
          setIsLoading(false);
          setIsDisabled?.(false);

          return;
        }

        triggerUtmRegistration();

        let redirectUrl = new URL('/', window.location.origin);
        const gitHubRedirectAt = localStorage.getItem(GITHUB_REDIRECT_AT);
        const lastPageBeforeGithub = localStorage.getItem(GITHUB_LAST_PAGE);

        // If the social redirect is there and less than 30 seconds old
        // redirect to the page that user was on before they clicked the github login button
        if (gitHubRedirectAt && lastPageBeforeGithub) {
          const socialRedirectAtTime = parseInt(gitHubRedirectAt, 10);
          const now = Date.now();
          const timeSinceRedirect = now - socialRedirectAtTime;

          if (timeSinceRedirect < 30 * 1000) {
            redirectUrl = new URL(lastPageBeforeGithub, window.location.origin);
          }
        }

        const authRedirectUrl = localStorage.getItem('authRedirect');
        if (authRedirectUrl) {
          localStorage.removeItem('authRedirect');
          redirectUrl = new URL(authRedirectUrl, window.location.origin);
        }

        localStorage.removeItem(GITHUB_REDIRECT_AT);
        localStorage.removeItem(GITHUB_LAST_PAGE);
        setAuthToken(response.token);

        redirectUrl.searchParams.set(
          FIRST_LOGIN_PARAM,
          response?.isNewUser ? '1' : '0',
        );

        const shouldTriggerPurchase =
          localStorage.getItem(CHECKOUT_AFTER_LOGIN_KEY) !== '0';

        if (
          redirectUrl.pathname.includes('/courses/sql') &&
          shouldTriggerPurchase
        ) {
          redirectUrl.searchParams.set(COURSE_PURCHASE_PARAM, '1');
          localStorage.removeItem(CHECKOUT_AFTER_LOGIN_KEY);
        }

        window.location.href = redirectUrl.toString();
      })
      .catch((err) => {
        setError('Something went wrong. Please try again later.');
        setIsLoading(false);
        setIsDisabled?.(false);
      });
  }, []);

  const handleClick = async () => {
    setIsLoading(true);
    setIsDisabled?.(true);

    const { response, error } = await httpGet<{ loginUrl: string }>(
      `${import.meta.env.PUBLIC_API_URL}/v1-github-login`,
    );

    if (error || !response?.loginUrl) {
      setError(
        error?.message || 'Something went wrong. Please try again later.',
      );

      setIsLoading(false);
      setIsDisabled?.(false);
      return;
    }

    // For non authentication pages, we want to redirect back to the page
    // the user was on before they clicked the social login button
    if (!['/login', '/signup'].includes(window.location.pathname)) {
      const pagePath = ['/respond-invite', '/befriend', '/r', '/ai-roadmaps'].includes(
        window.location.pathname,
      )
        ? window.location.pathname + window.location.search
        : window.location.pathname;

      localStorage.setItem(GITHUB_REDIRECT_AT, Date.now().toString());
      localStorage.setItem(GITHUB_LAST_PAGE, pagePath);
    }

    window.location.href = response.loginUrl;
  };

  return (
    <>
      <button
        className={cn(
          'inline-flex h-10 w-full items-center justify-center gap-2 rounded border border-slate-300 bg-white p-2 text-sm font-medium text-black outline-none hover:border-gray-400 hover:bg-gray-50 focus:ring-2 focus:ring-[#333] focus:ring-offset-1 disabled:cursor-not-allowed disabled:opacity-60',
          className,
        )}
        disabled={isLoading || isDisabled}
        onClick={handleClick}
      >
        {isLoading ? (
          <Spinner className={'h-[18px] w-[18px]'} isDualRing={false} />
        ) : (
          <GitHubIcon className={'h-[18px] w-[18px]'} />
        )}
        Continue with GitHub
      </button>
      {error && (
        <p className="mb-2 mt-1 text-sm font-medium text-red-600">{error}</p>
      )}
    </>
  );
}