import { scope, CircuitBreaker } from 'go-go-scope'

// Service client with circuit breaker
class UserServiceClient {
  private breaker = new CircuitBreaker({
    failureThreshold: 5,
    resetTimeout: 60000,     // 1 minute
    halfOpenRequests: 3
  })

  async getUser(id: string) {
    await using s = scope({ timeout: 5000 })

    const [err, user] = await s.task(
      async ({ signal }) => {
        const response = await fetch(
          `http://user-service/users/${id}`,
          { signal }
        )
        if (!response.ok) {
          throw new Error(`HTTP ${response.status}: ${response.statusText}`)
        }
        return response.json()
      },
      {
        circuitBreaker: this.breaker,
        retry: 'exponential',  // Exponential backoff
        timeout: 3000
      }
    )

    if (err) {
      console.error(`Failed to fetch user ${id}:`, err.message)
      return null
    }

    return user
  }

  async getUserOrders(userId: string) {
    await using s = scope()

    // Parallel service calls
    const [err, results] = await s.parallel([
      () => this.getUser(userId),
      () => this.getOrderHistory(userId),
      () => this.getPaymentMethods(userId)
    ])

    if (err) throw err

    const [user, orders, payments] = results.map(r => r[1])

    return { user, orders, payments }
  }

  private async getOrderHistory(userId: string) {
    // Similar implementation with circuit breaker
    await using s = scope({ timeout: 5000 })
    const [err, orders] = await s.task(
      async ({ signal }) => {
        const response = await fetch(
          `http://order-service/orders?userId=${userId}`,
          { signal }
        )
        return response.json()
      },
      { circuitBreaker: this.breaker, retry: 'exponential' }
    )
    return orders || []
  }

  private async getPaymentMethods(userId: string) {
    await using s = scope({ timeout: 5000 })
    const [err, payments] = await s.task(
      async ({ signal }) => {
        const response = await fetch(
          `http://payment-service/methods?userId=${userId}`,
          { signal }
        )
        return response.json()
      },
      { circuitBreaker: this.breaker, retry: 'exponential' }
    )
    return payments || []
  }
}

import { scope } from 'go-go-scope'

// Event processor service
class EventProcessor {
  async start() {
    await using s = scope({ name: 'event-processor' })

    // Create broadcast channel for events
    const events = s.broadcast<{
      type: string
      data: unknown
      timestamp: number
    }>()

    // Subscribe multiple handlers
    s.task(async () => {
      for await (const event of events.subscribe()) {
        if (event.type === 'order.created') {
          await this.handleOrderCreated(event.data)
        }
      }
    })

    s.task(async () => {
      for await (const event of events.subscribe()) {
        if (event.type === 'user.registered') {
          await this.handleUserRegistered(event.data)
        }
      }
    })

    // Analytics processor
    s.task(async () => {
      for await (const event of events.subscribe()) {
        await this.recordAnalytics(event)
      }
    })

    // Listen to message queue
    s.task(async ({ signal }) => {
      while (!signal.aborted) {
        const message = await this.messageQueue.receive({ signal })
        
        if (message) {
          await events.send({
            type: message.type,
            data: message.payload,
            timestamp: Date.now()
          })
        }
      }
    })

    // Keep service running
    await new Promise((resolve) => {
      process.on('SIGTERM', resolve)
    })
  }

  private async handleOrderCreated(data: unknown) {
    console.log('Processing order:', data)
    // Send confirmation email, update inventory, etc.
  }

  private async handleUserRegistered(data: unknown) {
    console.log('New user registered:', data)
    // Send welcome email, create profile, etc.
  }

  private async recordAnalytics(event: unknown) {
    // Send to analytics service
  }
}

import { scope, parallel } from 'go-go-scope'
import type { FastifyInstance } from 'fastify'

class HealthChecker {
  constructor(
    private db: Database,
    private redis: Redis,
    private messageQueue: MessageQueue
  ) {}

  async check() {
    await using s = scope({ timeout: 5000 })

    const [err, results] = await s.parallel([
      () => this.checkDatabase(),
      () => this.checkRedis(),
      () => this.checkMessageQueue(),
      () => this.checkDiskSpace(),
      () => this.checkMemory()
    ])

    const checks = {
      database: results?.[0]?.[1] ?? false,
      redis: results?.[1]?.[1] ?? false,
      messageQueue: results?.[2]?.[1] ?? false,
      diskSpace: results?.[3]?.[1] ?? false,
      memory: results?.[4]?.[1] ?? false
    }

    const healthy = !err && Object.values(checks).every(v => v)

    return {
      status: healthy ? 'healthy' : 'unhealthy',
      checks,
      timestamp: new Date().toISOString()
    }
  }

  private async checkDatabase(): Promise<boolean> {
    try {
      await this.db.query('SELECT 1')
      return true
    } catch {
      return false
    }
  }

  private async checkRedis(): Promise<boolean> {
    try {
      await this.redis.ping()
      return true
    } catch {
      return false
    }
  }

  private async checkMessageQueue(): Promise<boolean> {
    try {
      return await this.messageQueue.isConnected()
    } catch {
      return false
    }
  }

  private async checkDiskSpace(): Promise<boolean> {
    // Check available disk space
    return true
  }

  private async checkMemory(): Promise<boolean> {
    const usage = process.memoryUsage()
    // Return false if memory usage is critical
    return usage.heapUsed < usage.heapTotal * 0.9
  }
}

// Register health check endpoints
app.get('/health', async (request, reply) => {
  const health = await healthChecker.check()
  return reply.code(health.status === 'healthy' ? 200 : 503).send(health)
})

app.get('/ready', async (request, reply) => {
  // Readiness probe for Kubernetes
  const health = await healthChecker.check()
  return reply.code(health.status === 'healthy' ? 200 : 503).send({
    ready: health.status === 'healthy'
  })
})