/**
 * SAAP WebSocket Composable - Real-time Updates
 * WebSocket connection for live agent status and message updates
 */

import { ref, reactive, onUnmounted } from 'vue'
import { io, type Socket } from 'socket.io-client'

// Types
interface WebSocketMessage {
  type: 'agent_update' | 'message_update' | 'system_update' | 'error'
  data: any
  timestamp: string
}

interface ConnectionStatus {
  connected: boolean
  reconnecting: boolean
  error: string | null
  lastPing: string | null
  connectionCount: number
}

export const useWebSocket = () => {
  // WebSocket connection
  let socket: Socket | null = null
  let reconnectTimer: NodeJS.Timeout | null = null
  
  // Reactive state
  const connectionStatus = reactive<ConnectionStatus>({
    connected: false,
    reconnecting: false,
    error: null,
    lastPing: null,
    connectionCount: 0
  })
  
  const messages = ref<WebSocketMessage[]>([])
  const lastMessage = ref<WebSocketMessage | null>(null)
  
  // WebSocket URL (matching FastAPI WebSocket endpoint)
  const WS_URL = 'ws://localhost:8000/ws'
  const RECONNECT_DELAY = 3000
  const MAX_RECONNECT_ATTEMPTS = 5
  let reconnectAttempts = 0
  
  // Event listeners
  const eventListeners = new Map<string, Set<Function>>()
  
  // =====================================================
  // CONNECTION MANAGEMENT
  // =====================================================
  
  const connect = (): Promise<boolean> => {
    return new Promise((resolve) => {
      try {
        // Close existing connection
        if (socket) {
          socket.disconnect()
          socket = null
        }
        
        console.log('🌐 Connecting to SAAP WebSocket:', WS_URL)
        
        // For FastAPI WebSocket, we use native WebSocket API
        const ws = new WebSocket(WS_URL)
        
        ws.onopen = (event) => {
          console.log('✅ WebSocket connected')
          connectionStatus.connected = true
          connectionStatus.reconnecting = false
          connectionStatus.error = null
          connectionStatus.connectionCount++
          connectionStatus.lastPing = new Date().toISOString()
          reconnectAttempts = 0
          
          // Send initial ping
          ws.send(JSON.stringify({ type: 'ping', timestamp: new Date().toISOString() }))
          
          // Emit connect event
          emitEvent('connect', { status: 'connected' })
          resolve(true)
        }
        
        ws.onmessage = (event) => {
          try {
            // Handle text messages
            let data: any = event.data
            
            // Try to parse JSON if it's a string
            if (typeof data === 'string') {
              try {
                data = JSON.parse(data)
              } catch {
                // If not JSON, treat as plain message
                console.log('📝 WebSocket message:', data)
                return
              }
            }
            
            // Create WebSocket message
            const message: WebSocketMessage = {
              type: data.type || 'system_update',
              data: data,
              timestamp: new Date().toISOString()
            }
            
            // Store message
            messages.value.push(message)
            lastMessage.value = message
            
            // Keep only last 100 messages
            if (messages.value.length > 100) {
              messages.value = messages.value.slice(-100)
            }
            
            // Update last ping
            connectionStatus.lastPing = new Date().toISOString()
            
            // Emit specific event based on message type
            emitEvent(message.type, message.data)
            emitEvent('message', message)
            
            console.log('📨 WebSocket message received:', message.type, message.data)
            
          } catch (error) {
            console.error('❌ WebSocket message parse error:', error)
          }
        }
        
        ws.onclose = (event) => {
          console.log('🔌 WebSocket disconnected:', event.code, event.reason)
          connectionStatus.connected = false
          
          if (!connectionStatus.reconnecting) {
            handleReconnect()
          }
          
          emitEvent('disconnect', { code: event.code, reason: event.reason })
        }
        
        ws.onerror = (error) => {
          console.error('❌ WebSocket error:', error)
          connectionStatus.error = 'Connection error'
          connectionStatus.connected = false
          
          emitEvent('error', { error })
          resolve(false)
        }
        
        // Store WebSocket instance
        socket = ws as any
        
      } catch (error) {
        console.error('❌ WebSocket connection failed:', error)
        connectionStatus.error = error instanceof Error ? error.message : 'Unknown error'
        resolve(false)
      }
    })
  }
  
  const disconnect = () => {
    if (reconnectTimer) {
      clearTimeout(reconnectTimer)
      reconnectTimer = null
    }
    
    if (socket) {
      (socket as any).close()
      socket = null
    }
    
    connectionStatus.connected = false
    connectionStatus.reconnecting = false
    
    console.log('🔌 WebSocket manually disconnected')
  }
  
  const handleReconnect = () => {
    if (reconnectAttempts >= MAX_RECONNECT_ATTEMPTS) {
      console.error('❌ Max reconnection attempts reached')
      connectionStatus.error = 'Failed to reconnect'
      return
    }
    
    connectionStatus.reconnecting = true
    reconnectAttempts++
    
    console.log(`🔄 Attempting to reconnect... (${reconnectAttempts}/${MAX_RECONNECT_ATTEMPTS})`)
    
    reconnectTimer = setTimeout(() => {
      connect()
    }, RECONNECT_DELAY)
  }
  
  // =====================================================
  // MESSAGE SENDING
  // =====================================================
  
  const send = (message: any): boolean => {
    if (!socket || !connectionStatus.connected) {
      console.warn('⚠️ Cannot send message: WebSocket not connected')
      return false
    }
    
    try {
      const payload = JSON.stringify({
        ...message,
        timestamp: new Date().toISOString()
      })
      
      ;(socket as any).send(payload)
      console.log('📤 WebSocket message sent:', message)
      return true
    } catch (error) {
      console.error('❌ Failed to send WebSocket message:', error)
      return false
    }
  }
  
  const ping = (): boolean => {
    return send({ type: 'ping' })
  }
  
  // =====================================================
  // EVENT SYSTEM
  // =====================================================
  
  const on = (event: string, callback: Function) => {
    if (!eventListeners.has(event)) {
      eventListeners.set(event, new Set())
    }
    eventListeners.get(event)!.add(callback)
  }
  
  const off = (event: string, callback: Function) => {
    const listeners = eventListeners.get(event)
    if (listeners) {
      listeners.delete(callback)
    }
  }
  
  const emitEvent = (event: string, data: any) => {
    const listeners = eventListeners.get(event)
    if (listeners) {
      listeners.forEach(callback => {
        try {
          callback(data)
        } catch (error) {
          console.error(`❌ Error in WebSocket event listener (${event}):`, error)
        }
      })
    }
  }
  
  // =====================================================
  // SPECIALIZED HANDLERS
  // =====================================================
  
  const subscribeToAgentUpdates = (callback: (agent: any) => void) => {
    on('agent_update', callback)
  }
  
  const subscribeToMessageUpdates = (callback: (message: any) => void) => {
    on('message_update', callback)
  }
  
  const subscribeToSystemUpdates = (callback: (status: any) => void) => {
    on('system_update', callback)
  }
  
  // =====================================================
  // LIFECYCLE
  // =====================================================
  
  // Auto-cleanup on component unmount
  onUnmounted(() => {
    disconnect()
    eventListeners.clear()
  })
  
  // Periodic ping to keep connection alive
  let pingTimer: NodeJS.Timeout | null = null
  
  const startHeartbeat = () => {
    if (pingTimer) clearInterval(pingTimer)
    
    pingTimer = setInterval(() => {
      if (connectionStatus.connected) {
        ping()
      }
    }, 30000) // Ping every 30 seconds
  }
  
  const stopHeartbeat = () => {
    if (pingTimer) {
      clearInterval(pingTimer)
      pingTimer = null
    }
  }
  
  return {
    // State
    connectionStatus,
    messages,
    lastMessage,
    
    // Connection Management
    connect,
    disconnect,
    
    // Messaging
    send,
    ping,
    
    // Event System
    on,
    off,
    
    // Specialized Subscriptions
    subscribeToAgentUpdates,
    subscribeToMessageUpdates,
    subscribeToSystemUpdates,
    
    // Heartbeat
    startHeartbeat,
    stopHeartbeat,
    
    // Configuration
    WS_URL,
    RECONNECT_DELAY,
    MAX_RECONNECT_ATTEMPTS
  }
}

// Export types
export type { WebSocketMessage, ConnectionStatus }