import { authService } from './auth/auth.service';

// Mock OAuth configuration
const GOOGLE_CLIENT_ID = 'mock_google_client_id';
const GITHUB_CLIENT_ID = 'mock_github_client_id';

// Mock OAuth endpoints
const GOOGLE_AUTH_URL = 'https://accounts.google.com/o/oauth2/v2/auth';
const GITHUB_AUTH_URL = 'https://github.com/login/oauth/authorize';

// Mock token exchange endpoints

// Mock OAuth scopes
const GOOGLE_SCOPES = 'openid email profile';
const GITHUB_SCOPES = 'user:email';

// Mock redirect URI
const REDIRECT_URI = 'http://localhost:3000/auth/callback';

// Mock OAuth state generation
const generateState = () => crypto.randomUUID();

export const googleAuth = () => {
  const state = generateState();
  const url = new URL(GOOGLE_AUTH_URL);
  url.searchParams.append('client_id', GOOGLE_CLIENT_ID);
  url.searchParams.append('response_type', 'code');
  url.searchParams.append('scope', GOOGLE_SCOPES);
  url.searchParams.append('redirect_uri', REDIRECT_URI);
  url.searchParams.append('state', state);

  // In a real implementation, we would store the state in the session or localStorage
  localStorage.setItem('oauth_state', state);

  // Redirect to Google's auth endpoint
  window.location.href = url.toString();
};

export const githubAuth = () => {
  const state = generateState();
  const url = new URL(GITHUB_AUTH_URL);
  url.searchParams.append('client_id', GITHUB_CLIENT_ID);
  url.searchParams.append('response_type', 'code');
  url.searchParams.append('scope', GITHUB_SCOPES);
  url.searchParams.append('redirect_uri', REDIRECT_URI);
  url.searchParams.append('state', state);

  // In a real implementation, we would store the state in the session or localStorage
  localStorage.setItem('oauth_state', state);

  // Redirect to GitHub's auth endpoint
  window.location.href = url.toString();
};

// Mock token exchange
const mockExchangeCodeForToken = async (
  provider: 'google' | 'github',
  _code: string
): Promise<string> => {
  // In a real implementation, we would make a POST request to the token endpoint
  // with the code, client_id, client_secret, and redirect_uri

  // For this mock, we'll just return a mock access token
  return `mock_${provider}_access_token_${crypto.randomUUID()}`;
};

// Mock user info retrieval
const mockGetUserInfo = async (
  provider: 'google' | 'github',
  _accessToken: string
): Promise<{ email: string; name: string }> => {
  // In a real implementation, we would make a GET request to the user info endpoint
  // with the access token

  // For this mock, we'll return mock user info
  return {
    email: `mock_${provider}_user_${crypto.randomUUID()}@example.com`,
    name: `Mock ${provider.charAt(0).toUpperCase() + provider.slice(1)} User`,
  };
};

export const handleGoogleCallback = async () => {
  const params = new URLSearchParams(window.location.search);
  const code = params.get('code');
  const state = params.get('state');
  const storedState = localStorage.getItem('oauth_state');

  // Verify state to prevent CSRF attacks
  if (state !== storedState) {
    throw new Error('Invalid OAuth state');
  }

  // Clear stored state
  localStorage.removeItem('oauth_state');

  // Exchange code for token
  const accessToken = await mockExchangeCodeForToken('google', code);

  // Get user info
  const userInfo = await mockGetUserInfo('google', accessToken);

  // Register or login the user
  return authService.loginWithOAuth('google', {
    email: userInfo.email,
    username: userInfo.name,
  });
};

export const handleGithubCallback = async () => {
  const params = new URLSearchParams(window.location.search);
  const code = params.get('code');
  const state = params.get('state');
  const storedState = localStorage.getItem('oauth_state');

  // Verify state to prevent CSRF attacks
  if (state !== storedState) {
    throw new Error('Invalid OAuth state');
  }

  // Clear stored state
  localStorage.removeItem('oauth_state');

  // Exchange code for token
  const accessToken = await mockExchangeCodeForToken('github', code);

  // Get user info
  const userInfo = await mockGetUserInfo('github', accessToken);

  // Register or login the user
  return authService.loginWithOAuth('github', {
    email: userInfo.email,
    username: userInfo.name,
  });
};