// These patterns trigger immediate alerts:
import axios from 'axios';              // Heavy dependency (13KB)
import moment from 'moment';             // Heavy dependency (68KB)
import _ from 'lodash';                 // Heavy dependency (71KB)

// Sequential operations that could be parallel
const user = await env.USERS.get(id);
const settings = await env.SETTINGS.get(id);
const prefs = await env.PREFS.get(id);

// These patterns are validated as correct:
// Native Web APIs instead of heavy libraries
const response = await fetch(url);      // Built-in fetch (0KB)
const now = new Date();                // Native Date (0KB)

// Parallel operations
const [user, settings, prefs] = await Promise.all([
  env.USERS.get(id),
  env.SETTINGS.get(id),
  env.PREFS.get(id),
]);

// ❌ Critical: Heavy dependencies (150KB+ bundle)
import axios from 'axios';              // 13KB
import moment from 'moment';             // 68KB  
import _ from 'lodash';                 // 71KB
// Total: 152KB just for utilities!

// ✅ Correct: Native Web APIs (minimal bundle)
// Use fetch instead of axios
const response = await fetch(url);
const data = await response.json();

// Use native Date instead of moment
const now = new Date();
const tomorrow = new Date(Date.now() + 86400000);

// Use native methods instead of lodash
const unique = [...new Set(array)];
const grouped = array.reduce((acc, item) => {
  const key = item.category;
  if (!acc[key]) acc[key] = [];
  acc[key].push(item);
  return acc;
}, {});
// Total: < 5KB for utilities

// ❌ High: Sequential KV operations (3x network round-trips)
export default {
  async fetch(request: Request, env: Env) {
    const user = await env.USERS.get(userId);      // 10-30ms
    const settings = await env.SETTINGS.get(id);    // 10-30ms  
    const prefs = await env.PREFS.get(id);         // 10-30ms
    // Total: 30-90ms just for storage!
  }
}

// ✅ Correct: Parallel operations (single round-trip)
export default {
  async fetch(request: Request, env: Env) {
    const [user, settings, prefs] = await Promise.all([
      env.USERS.get(userId),
      env.SETTINGS.get(id),
      env.PREFS.get(id),
    ]);
    // Total: 10-30ms (single round-trip)
  }
}

// ❌ Critical: No edge caching (slow globally)
export default {
  async fetch(request: Request, env: Env) {
    const config = await fetch('https://api.example.com/config');
    // Every request goes to origin!
    // Sydney user → US origin = 200ms+ just for config
  }
}

// ✅ Correct: Edge caching pattern
export default {
  async fetch(request: Request, env: Env) {
    const cache = caches.default;
    const cacheKey = new Request('https://example.com/config', {
      method: 'GET'
    });

    // Try cache first
    let response = await cache.match(cacheKey);

    if (!response) {
      // Cache miss - fetch from origin
      response = await fetch('https://api.example.com/config');
      
      // Cache at edge with 1-hour TTL
      response = new Response(response.body, {
        ...response,
        headers: {
          ...response.headers,
          'Cache-Control': 'public, max-age=3600',
        }
      });
      
      await cache.put(cacheKey, response.clone());
    }

    // Sydney user → Sydney edge cache = < 10ms
    return response;
  }
}

// ❌ High: Large synchronous processing (CPU time bomb)
export default {
  async fetch(request: Request, env: Env) {
    const users = await env.DB.prepare('SELECT * FROM users').all();
    // If 10,000 users, this loops for 100ms+ CPU time
    const enriched = users.results.map(user => {
      return {
        ...user,
        fullName: `${user.firstName} ${user.lastName}`,
        // ... expensive computations
      };
    });
  }
}

// ✅ Correct: Bounded operations
export default {
  async fetch(request: Request, env: Env) {
    // Option 1: Limit at database level
    const users = await env.DB.prepare(
      'SELECT * FROM users LIMIT ? OFFSET ?'
    ).bind(10, offset).all();  // Only 10 users, bounded CPU

    // Option 2: Stream processing for large datasets
    const { readable, writable } = new TransformStream();
    // Process in chunks without loading everything into memory

    // Option 3: Offload to Durable Object
    const id = env.PROCESSOR.newUniqueId();
    const stub = env.PROCESSOR.get(id);
    return stub.fetch(request);  // DO can run longer
  }
}

// Developer types: npm install moment
// SKILL immediately activates: "❌ CRITICAL: moment is 68KB and will slow cold starts. Use native Date instead for 0KB impact."

// Developer types: sequential KV gets
// SKILL immediately activates: "⚠️ HIGH: Sequential KV operations detected. Use Promise.all() to parallelize and reduce latency by 3x."

// Developer types: fetch without caching
// SKILL immediately activates: "⚠️ HIGH: No edge caching for API call. Add Cache API to serve from edge locations globally."