import { string } from 'alga-js'
import type { H3Event } from 'h3'
import { sendNewOrderNotification } from '../../../utils/pushNotifier'

// ============================================================================
// CONNECTION REGISTRY
// ============================================================================

interface ClientConnection {
  res: any // Response stream
  roleId: number // User's role ID from JWT
  filters: {
    orgId?: string
    documentNo?: string
    externalOrderId?: string
    openOnly?: boolean
  }
}

// Global registry of all active SSE connections
const activeConnections = new Map<string, ClientConnection>()

// ============================================================================
// GLOBAL POLLING STATE
// ============================================================================

let globalPollingInterval: NodeJS.Timeout | null = null
let globalLastOrderId = 0
const POLLING_INTERVAL = 30000 // 30 seconds
const HEARTBEAT_INTERVAL = 15000 // 15 seconds

// ============================================================================
// SSE HELPER FUNCTIONS
// ============================================================================

/**
 * Send SSE message to a specific client
 */
function sendSSEToClient(res: any, data: any) {
  try {
    res.write(`data: ${JSON.stringify(data)}\n\n`)
  } catch (err) {
    console.error('[SSE] Error writing to stream:', err)
  }
}

/**
 * Broadcast SSE message to all connected clients
 */
function broadcastSSE(data: any) {
  activeConnections.forEach((connection, clientId) => {
    sendSSEToClient(connection.res, data)
  })
}

// ============================================================================
// FILTERING LOGIC
// ============================================================================

/**
 * Filter orders for a specific client based on:
 * 1. Role-based organization access (using AD_Role_OrgAccess)
 * 2. Client-specific filters (documentNo, externalOrderId, openOnly)
 */
async function filterOrdersForClient(
  orders: any[],
  connection: ClientConnection,
  orgRoleAccessMap: Map<number, Set<number>>
): Promise<any[]> {
  return orders.filter(order => {
    const orderOrgId = order.AD_Org_ID?.id

    if (orderOrgId === undefined) {
      return false // Skip orders without org ID
    }

    // 1. Check role-based organization access
    if (!hasRoleAccessToOrg(orgRoleAccessMap, connection.roleId, orderOrgId)) {
      return false // User's role doesn't have access to this org
    }

    // 2. Apply client-specific filters
    const filters = connection.filters

    // Organization filter (if client requested specific org)
    if (filters.orgId && orderOrgId != parseInt(filters.orgId)) {
      return false
    }

    // Document number filter
    if (filters.documentNo) {
      const docNo = order.DocumentNo || order.documentNo || ''
      if (!docNo.includes(filters.documentNo)) {
        return false
      }
    }

    // External order ID filter
    if (filters.externalOrderId) {
      const extId = order.ExternalOrderId || order.externalOrderId || ''
      if (!extId.includes(filters.externalOrderId)) {
        return false
      }
    }

    // Note: openOnly filter is handled at query level, not here

    return true
  })
}

// ============================================================================
// GLOBAL POLLING LOOP
// ============================================================================

/**
 * Single global polling function that queries ALL new orders
 * and broadcasts them to connected clients with appropriate filtering
 */
async function pollForNewOrders() {
  if (activeConnections.size === 0) {
    return // No clients connected, skip polling
  }

  try {
    // Get any connection's event to use for token/fetch
    const firstConnection = activeConnections.values().next().value
    if (!firstConnection) return

    // Get a dummy event from the first connection to fetch token
    // Note: We need a proper token, ideally a system-level token or the first user's token
    const token = await getTokenHelper(firstConnection.event)

    // Fetch org-role access mapping (cached)
    const orgRoleAccessMap = await getOrgRoleAccessMap(firstConnection.event)

    // Build filter for querying ALL new orders (no org-specific filters)
    let filterParts = [`c_order_id gt ${globalLastOrderId}`]
    const filter = filterParts.join(' AND ')

    // Check if any client has openOnly filter enabled
    const hasOpenOnlyClients = Array.from(activeConnections.values()).some(
      conn => conn.filters.openOnly === true
    )
    const hasRegularClients = Array.from(activeConnections.values()).some(
      conn => conn.filters.openOnly !== true
    )

    // If we have mixed clients (some with openOnly, some without), we need to fetch both
    // For simplicity, we'll fetch regular orders and filter fulfilled ones client-side
    const model = 'models/c_order'

    const filterString = string.urlEncode('isSOTrx eq true AND (isActive eq true OR isActive eq false) AND ') + string.urlEncode(filter)

    const res: any = await firstConnection.event.context.fetch(
      `${model}?$filter=${filterString}&$expand=c_ordersource_id,c_bpartner_location_id,bill_location_id,c_orderline,m_inout($expand=M_Shipper_ID),M_Shipper_ID&$orderby=${string.urlEncode('c_order_id desc')}&$top=100`,
      'GET',
      token,
      null
    )

    if (res?.records && res.records.length > 0) {
      const allNewOrders = res.records

      // Update global last order ID
      const maxId = Math.max(...allNewOrders.map((order: any) => order.id || 0))
      if (maxId > globalLastOrderId) {
        globalLastOrderId = maxId

        console.log(`[SSE Poll] Found ${allNewOrders.length} new orders, broadcasting to ${activeConnections.size} clients`)

        // Collect all unique role IDs that should receive push notifications
        const notifiedRoles = new Set<number>()

        // Broadcast filtered orders to each connected client
        for (const [clientId, connection] of activeConnections.entries()) {
          const filteredOrders = await filterOrdersForClient(
            allNewOrders,
            connection,
            orgRoleAccessMap
          )

          if (filteredOrders.length > 0) {
            sendSSEToClient(connection.res, {
              type: 'newOrders',
              orders: filteredOrders,
              lastOrderId: maxId,
              count: filteredOrders.length
            })
            console.log(`[SSE] Sent ${filteredOrders.length} orders to client ${clientId} (role ${connection.roleId})`)

            // Track roles for push notifications
            notifiedRoles.add(connection.roleId)
          }
        }

        // Send push notifications to all roles that have access to these orders
        if (notifiedRoles.size > 0) {
          const roleIds = Array.from(notifiedRoles)
          console.log(`[SSE] Sending push notifications to roles:`, roleIds)

          // Send push notification in background (don't wait)
          sendNewOrderNotification(roleIds, allNewOrders.length, {
            maxOrderId: maxId
          }).catch((error) => {
            console.error('[SSE] Error sending push notifications:', error)
          })
        }
      }
    }
  } catch (error: any) {
    console.error('[SSE Poll] Error polling for orders:', error.message)
    // Notify all clients of the error
    broadcastSSE({
      type: 'error',
      message: 'Error fetching orders',
      error: error.message
    })
  }
}

/**
 * Start the global polling loop (only if not already running)
 */
function startGlobalPolling() {
  if (globalPollingInterval) {
    return // Already running
  }

  console.log('[SSE] Starting global polling loop')

  // Initial poll
  pollForNewOrders()

  // Set up recurring poll
  globalPollingInterval = setInterval(pollForNewOrders, POLLING_INTERVAL)
}

/**
 * Stop the global polling loop (when no clients are connected)
 */
function stopGlobalPolling() {
  if (globalPollingInterval) {
    console.log('[SSE] Stopping global polling loop')
    clearInterval(globalPollingInterval)
    globalPollingInterval = null
  }
}

// ============================================================================
// HEARTBEAT
// ============================================================================

let globalHeartbeatInterval: NodeJS.Timeout | null = null

function startGlobalHeartbeat() {
  if (globalHeartbeatInterval) {
    return // Already running
  }

  globalHeartbeatInterval = setInterval(() => {
    broadcastSSE({
      type: 'heartbeat',
      timestamp: Date.now(),
      connectedClients: activeConnections.size
    })
  }, HEARTBEAT_INTERVAL)
}

function stopGlobalHeartbeat() {
  if (globalHeartbeatInterval) {
    clearInterval(globalHeartbeatInterval)
    globalHeartbeatInterval = null
  }
}

// ============================================================================
// EVENT HANDLER
// ============================================================================

export default defineEventHandler(async (event) => {
  const query = getQuery(event)
  const clientId = query.clientId as string || `client_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`

  // Set SSE headers
  setResponseHeaders(event, {
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache',
    'Connection': 'keep-alive',
    'X-Accel-Buffering': 'no'
  })

  // Extract user's role ID from JWT token
  const token = await getTokenHelper(event)
  let roleId: number

  try {
    // Decode JWT to get role ID
    const tokenPayload = JSON.parse(Buffer.from(token.split('.')[1], 'base64').toString())
    roleId = tokenPayload.AD_Role_ID

    if (!roleId) {
      throw new Error('Role ID not found in token')
    }
  } catch (error: any) {
    console.error('[SSE] Error extracting role from token:', error.message)
    sendSSEToClient(event.node.res, {
      type: 'error',
      message: 'Authentication error: Invalid token'
    })
    return
  }

  // Register this connection
  activeConnections.set(clientId, {
    res: event.node.res,
    roleId,
    filters: {
      orgId: query.orgId as string,
      documentNo: query.documentNo as string,
      externalOrderId: query.externalOrderId as string,
      openOnly: query.openOnly === 'true'
    },
    event // Store event for later use in polling
  } as any)

  // Initialize globalLastOrderId from client's lastOrderId if this is the first connection
  if (activeConnections.size === 1 && query.lastOrderId) {
    const clientLastOrderId = parseInt(query.lastOrderId as string) || 0
    if (clientLastOrderId > globalLastOrderId) {
      globalLastOrderId = clientLastOrderId
      console.log(`[SSE] Initialized global lastOrderId from client: ${globalLastOrderId}`)
    }
  }

  console.log(`[SSE] Client ${clientId} connected (role: ${roleId}, lastOrderId: ${query.lastOrderId}, global: ${globalLastOrderId}, total clients: ${activeConnections.size})`)

  // Send initial connection message
  sendSSEToClient(event.node.res, {
    type: 'connected',
    clientId,
    roleId,
    lastOrderId: globalLastOrderId,
    message: 'Connected to order stream'
  })

  // Start global polling if this is the first client
  if (activeConnections.size === 1) {
    startGlobalPolling()
    startGlobalHeartbeat()
  }

  // Clean up on disconnect
  event.node.req.on('close', () => {
    activeConnections.delete(clientId)
    console.log(`[SSE] Client ${clientId} disconnected (remaining clients: ${activeConnections.size})`)

    // Stop polling if no clients remain
    if (activeConnections.size === 0) {
      stopGlobalPolling()
      stopGlobalHeartbeat()
    }
  })

  // Keep connection alive
  return new Promise(() => {})
})