import { logger } from '../../utils/logger.js'

export interface HeartbeatCallback {
  (): Promise<void>
}

export interface HeartbeatState {
  lastHeartbeat: Date
  isRunning: boolean
}

const DEFAULT_HEARTBEAT_INTERVAL = 60000

export class HeartbeatService {
  private interval: NodeJS.Timeout | null = null
  private lastHeartbeat: Date = new Date()
  private readonly intervalMs: number
  private callback: HeartbeatCallback | null = null

  constructor(intervalMs: number = DEFAULT_HEARTBEAT_INTERVAL) {
    this.intervalMs = intervalMs
  }

  setCallback(callback: HeartbeatCallback): void {
    this.callback = callback
  }

  start(): void {
    if (this.interval) {
      this.stop()
    }

    this.interval = setInterval(async () => {
      if (this.callback) {
        try {
          this.lastHeartbeat = new Date()
          await this.callback()
        } catch (err) {
          logger.error('Heartbeat callback failed:', err)
        }
      }
    }, this.intervalMs)

    this.lastHeartbeat = new Date()
  }

  stop(): void {
    if (this.interval) {
      clearInterval(this.interval)
      this.interval = null
    }
  }

  isRunning(): boolean {
    return this.interval !== null
  }

  getLastHeartbeat(): Date {
    return this.lastHeartbeat
  }

  updateHeartbeat(): void {
    this.lastHeartbeat = new Date()
  }

  getState(): HeartbeatState {
    return {
      lastHeartbeat: this.lastHeartbeat,
      isRunning: this.isRunning()
    }
  }

  restoreState(state: { lastHeartbeat: string }): void {
    this.lastHeartbeat = new Date(state.lastHeartbeat)
  }
}

export const createHeartbeatService = (intervalMs?: number): HeartbeatService => {
  return new HeartbeatService(intervalMs)
}