// Copilot understands your codebase patterns
// Type a comment describing what you need:

// Create a TypeScript class for managing user sessions
// with Redis backend, JWT tokens, and automatic refresh
class SessionManager {
  // Copilot generates the entire implementation
  private redis: Redis;
  private jwtSecret: string;
  
  constructor(redisUrl: string, jwtSecret: string) {
    this.redis = new Redis(redisUrl);
    this.jwtSecret = jwtSecret;
  }

  async createSession(userId: string, metadata: SessionMetadata): Promise<SessionToken> {
    const sessionId = crypto.randomUUID();
    const accessToken = jwt.sign(
      { userId, sessionId, type: 'access' },
      this.jwtSecret,
      { expiresIn: '15m' }
    );
    const refreshToken = jwt.sign(
      { userId, sessionId, type: 'refresh' },
      this.jwtSecret,
      { expiresIn: '7d' }
    );

    await this.redis.setex(
      `session:${sessionId}`,
      7 * 24 * 60 * 60,
      JSON.stringify({ userId, metadata, createdAt: Date.now() })
    );

    return { accessToken, refreshToken, sessionId };
  }

  async refreshSession(refreshToken: string): Promise<SessionToken> {
    const payload = jwt.verify(refreshToken, this.jwtSecret) as JwtPayload;
    
    if (payload.type !== 'refresh') {
      throw new Error('Invalid token type');
    }

    const session = await this.redis.get(`session:${payload.sessionId}`);
    if (!session) {
      throw new Error('Session expired');
    }

    return this.createSession(payload.userId, JSON.parse(session).metadata);
  }
}

// Ask Claude to solve architectural challenges

/*
Context: We have a distributed system with the following issues:
1. Race conditions when multiple services update the same order
2. Eventual consistency delays causing UI glitches
3. Failed events not being replayed properly

Design a solution using event sourcing and CQRS.
*/

// Claude generates a complete solution:
interface OrderEvent {
  eventId: string;
  orderId: string;
  eventType: OrderEventType;
  payload: unknown;
  timestamp: Date;
  version: number;
}

class OrderAggregate {
  private uncommittedEvents: OrderEvent[] = [];
  private version = 0;

  apply(event: OrderEvent): void {
    switch (event.eventType) {
      case 'ORDER_CREATED':
        this.handleOrderCreated(event.payload as OrderCreatedPayload);
        break;
      case 'ITEM_ADDED':
        this.handleItemAdded(event.payload as ItemAddedPayload);
        break;
      case 'ORDER_CONFIRMED':
        this.handleOrderConfirmed(event.payload as OrderConfirmedPayload);
        break;
    }
    this.version = event.version;
  }

  // Optimistic concurrency control
  async save(eventStore: EventStore): Promise<void> {
    const expectedVersion = this.version;
    
    for (const event of this.uncommittedEvents) {
      const saved = await eventStore.appendToStream(
        `order-${this.orderId}`,
        event,
        expectedVersion
      );
      
      if (!saved) {
        throw new ConcurrencyError(
          `Order ${this.orderId} was modified. Expected version ${expectedVersion}`
        );
      }
    }
    
    this.uncommittedEvents = [];
  }
}

// CQRS Read Model
class OrderReadModel {
  constructor(
    private readonly eventStore: EventStore,
    private readonly cache: Redis
  ) {}

  async rebuild(orderId: string): Promise<OrderView> {
    const events = await this.eventStore.getStream(`order-${orderId}`);
    const view = events.reduce(this.applyEvent, new OrderView());
    
    await this.cache.setex(`order:${orderId}`, 300, JSON.stringify(view));
    return view;
  }

  // Subscribe to real-time updates
  async subscribeToUpdates(): Promise<void> {
    this.eventStore.subscribeToAll(async (event) => {
      if (event.streamId.startsWith('order-')) {
        await this.updateProjection(event);
      }
    });
  }
}

// ❌ Poor prompt
// Generate a function to process data

// ✅ Good prompt
/*
 * Context: E-commerce order processing system
 * Input: Array of OrderItem objects with productId, quantity, price
 * Output: OrderSummary with total, tax (8.25%), shipping (free over $50)
 * Constraints: Must handle out-of-stock items gracefully
 * Dependencies: Uses our existing Product and Inventory services
 */
function calculateOrderSummary(items: OrderItem[]): Promise<OrderSummary> {
  // AI generates implementation with full context
}

// Metrics to track AI assistant effectiveness
interface AIProductivityMetrics {
  // Acceptance rate of AI suggestions
  suggestionAcceptanceRate: number;  // Target: > 30%
  
  // Time saved on boilerplate
  boilerplateTimeSaved: Duration;  // Track with time logging
  
  // Bug reduction
  aiAssistedBugFixRate: number;  // Bugs found/fixed with AI help
  
  // Documentation coverage
  docCoverageImprovement: number;  // Before/after comparison
  
  // Test coverage
  testGenerationAccuracy: number;  // Useful tests / generated tests
}