API Keys and Authentication

// Example API keys (these are fake!)
const weatherKey = "k7j3h5g9d2m8n4b6v1c9x0z2";
const googleKey = "AIzaSyB-1234567890abcdefghijk";
const stripeKey = "sk_test_4eC39HqLyjWDarjtT1zdp7dc";

// BAD: Key visible in code
const apiKey = "abc123xyz789"; // Anyone can see this!

fetch(`https://api.example.com/data?key=${apiKey}`);

// Store in separate file (don't commit to GitHub!)
// config.js
const API_KEY = "your-key-here";

// main.js
fetch(`https://api.example.com/data?key=${API_KEY}`);

// Use environment variables
const apiKey = process.env.API_KEY;

// Or prompt user to enter their key
const apiKey = prompt("Enter your API key:");

// Key in the URL
async function getWeather(city) {
  const apiKey = "your-key-here";
  const url = `https://api.openweathermap.org/data/2.5/weather?q=${city}&appid=${apiKey}`;

  const response = await fetch(url);
  const data = await response.json();
  return data;
}

// Key in request headers
async function getData() {
  const response = await fetch('https://api.example.com/data', {
    headers: {
      'X-API-Key': 'your-key-here',
      'Content-Type': 'application/json'
    }
  });

  const data = await response.json();
  return data;
}

// Bearer token format
async function getProtectedData() {
  const response = await fetch('https://api.example.com/protected', {
    headers: {
      'Authorization': 'Bearer your-token-here'
    }
  });

  const data = await response.json();
  return data;
}

// Headers tell you about limits
const response = await fetch(apiUrl);

// Check rate limit headers
console.log(response.headers.get('X-RateLimit-Limit'));     // Max requests
console.log(response.headers.get('X-RateLimit-Remaining')); // Requests left
console.log(response.headers.get('X-RateLimit-Reset'));     // Reset time

// 429 = Too Many Requests
if (response.status === 429) {
  console.log("Slow down! Too many requests!");
  // Wait before trying again
  setTimeout(() => retry(), 60000); // Wait 1 minute
}

// Complete weather app with authentication
class WeatherApp {
  constructor(apiKey) {
    this.apiKey = apiKey;
    this.baseURL = 'https://api.openweathermap.org/data/2.5';
  }

  async getWeather(city) {
    try {
      const url = `${this.baseURL}/weather?q=${city}&appid=${this.apiKey}&units=metric`;
      const response = await fetch(url);

      // Check for errors
      if (response.status === 401) {
        throw new Error('Invalid API key');
      }
      if (response.status === 404) {
        throw new Error('City not found');
      }
      if (response.status === 429) {
        throw new Error('Rate limit exceeded');
      }

      const data = await response.json();
      return {
        city: data.name,
        temp: Math.round(data.main.temp),
        description: data.weather[0].description
      };

    } catch (error) {
      console.error('Weather API Error:', error);
      return null;
    }
  }
}

// Use it
const weather = new WeatherApp('your-api-key');
const data = await weather.getWeather('Paris');

async function testAPIKey(key) {
  const testURL = `https://api.example.com/test?key=${key}`;

  try {
    const response = await fetch(testURL);

    if (response.ok) {
      console.log('✅ API key is valid!');
      return true;
    } else if (response.status === 401) {
      console.log('❌ Invalid API key');
      return false;
    }
  } catch (error) {
    console.log('❌ Network error');
    return false;
  }
}

// Organize your keys
const apiKeys = {
  weather: 'weather-key-here',
  news: 'news-key-here',
  maps: 'maps-key-here'
};

// Helper function
function getAPIKey(service) {
  return apiKeys[service] || null;
}

// Usage
const weatherKey = getAPIKey('weather');