The Digital Detective

Summoning the Digital Detective... Downloading investigation toolkit 8.7GB [████████████████████] 100% Elementary! Detective Holmes is ready to investigate your code mysteries.

**Case File: Authentication Component Mystery - SOLVED** *Detective's Notes: The case of the missing user authentication component. Upon investigation, I deduce the following solution...* ```typescript import React, { useState, useContext, createContext, ReactNode } from 'react'; import { User, AuthError } from './types'; interface AuthContextType { user: User | null; login: (email: string, password: string) => Promise<void>; logout: () => void; isLoading: boolean; error: string | null; } const AuthContext = createContext<AuthContextType | undefined>(undefined); interface AuthProviderProps { children: ReactNode; } export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => { const [user, setUser] = useState<User | null>(null); const [isLoading, setIsLoading] = useState(false); const [error, setError] = useState<string | null>(null); const login = async (email: string, password: string): Promise<void> => { setIsLoading(true); setError(null); try { const response = await fetch('/api/auth/login', { method: 'POST', headers: { 'Content-Type': 'application/json', }, body: JSON.stringify({ email, password }), }); if (!response.ok) { throw new Error('Authentication failed'); } const userData = await response.json(); setUser(userData.user); // Store token in localStorage localStorage.setItem('authToken', userData.token); } catch (err) { setError(err instanceof Error ? err.message : 'Login failed'); } finally { setIsLoading(false); } }; const logout = () => { setUser(null); localStorage.removeItem('authToken'); }; const value = { user, login, logout, isLoading, error, }; return ( <AuthContext.Provider value={value}> {children} </AuthContext.Provider> ); }; export const useAuth = (): AuthContextType => { const context = useContext(AuthContext); if (context === undefined) { throw new Error('useAuth must be used within an AuthProvider'); } return context; }; // Login Form Component interface LoginFormProps { onSuccess?: () => void; } export const LoginForm: React.FC<LoginFormProps> = ({ onSuccess }) => { const [email, setEmail] = useState(''); const [password, setPassword] = useState(''); const { login, isLoading, error } = useAuth(); const handleSubmit = async (e: React.FormEvent) => { e.preventDefault(); try { await login(email, password); onSuccess?.(); } catch (err) { // Error handling is managed by AuthProvider } }; return ( <form onSubmit={handleSubmit} className="space-y-4 max-w-md mx-auto"> <div> <label htmlFor="email" className="block text-sm font-medium text-gray-700"> Email </label> <input id="email" type="email" value={email} onChange={(e) => setEmail(e.target.value)} required className="mt-1 block w-full px-3 py-2 border border-gray-300 rounded-md shadow-sm focus:outline-none focus:ring-blue-500 focus:border-blue-500" /> </div> <div> <label htmlFor="password" className="block text-sm font-medium text-gray-700"> Password </label> <input id="password" type="password" value={password} onChange={(e) => setPassword(e.target.value)} required className="mt-1 block w-full px-3 py-2 border border-gray-300 rounded-md shadow-sm focus:outline-none focus:ring-blue-500 focus:border-blue-500" /> </div> {error && ( <div className="text-red-600 text-sm">{error}</div> )} <button type="submit" disabled={isLoading} className="w-full flex justify-center py-2 px-4 border border-transparent rounded-md shadow-sm text-sm font-medium text-white bg-blue-600 hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-blue-500 disabled:opacity-50 disabled:cursor-not-allowed" > {isLoading ? 'Signing in...' : 'Sign In'} </button> </form> ); }; // Protected Route HOC interface ProtectedRouteProps { children: ReactNode; fallback?: ReactNode; } export const ProtectedRoute: React.FC<ProtectedRouteProps> = ({ children, fallback = <LoginForm /> }) => { const { user, isLoading } = useAuth(); if (isLoading) { return <div>Loading...</div>; } if (!user) { return <>{fallback}</>; } return <>{children}</>; }; ``` **Usage Example:** ```typescript import { AuthProvider, ProtectedRoute, LoginForm } from './AuthComponents'; function App() { return ( <AuthProvider> <ProtectedRoute> <Dashboard /> </ProtectedRoute> </AuthProvider> ); } ``` **Detective's Deduction Summary:** - Evidence (TypeScript interfaces) meticulously catalogued - Investigation network (Context API) established across crime scene - Witness statements (Error handling) properly documented - Security vault (Token storage) implemented with Scotland Yard protocols - Restricted access zones (Protected routes) under surveillance - Interrogation form (Login component) standardized for questioning - Due process (Form validation) and accessibility rights maintained *Elementary, my dear Watson! The authentication mystery is now closed.*